Vikas Thondapu
Clinical Scholar, Radiology
Fellow in Rad/Cardiovascular Imaging
Academic Appointments
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Clinical Scholar, Radiology
All Publications
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Epidemiology of Coronary Atherosclerosis Among People Living With HIV in Uganda: A Cross-Sectional Study
ANNALS OF INTERNAL MEDICINE
2025; 178 (4): 468-478
Abstract
Data on the prevalence of coronary atherosclerotic disease (CAD) in the African region among people with and without HIV are lacking.To estimate the prevalence of CAD in Uganda and determine whether well-controlled HIV infection is associated with increased presence or severity of CAD.Cross-sectional study.Southwestern Uganda.Ambulatory people living with HIV (PWH), aged older than 40 years, taking antiretroviral therapy for 3 or more years, and population-based, age- and sex-similar people without HIV (PWoH).Participants had cardiovascular (CV) disease (CVD) risk profiling and computed tomography scanning for detection of CAD, defined as the presence of calcified or noncalcified plaque.Of 630 screened, 586 (93%) met criteria and had evaluable images. Of these, 287 (49.0%) were PWH and nearly all (272 of 287 [95%]) were virologically suppressed. Mean age (57.9 vs. 57.4 years), proportion female (49%), and median CVD risk score (4.1 vs. 3.4) did not differ by HIV serostatus. The prevalence of CAD was low overall (45 of 586 [7.7%]) and among both PWH (26 of 287 [9.1%]) and PWoH (19 of 299 [6.4%]; absolute prevalence difference, 2.7% [95% CI, -1.6% to 7.0%]). Results were similar after adjustment for CVD risk factors.Our findings may not generalize to symptomatic populations or those with greater predicted CVD risk. The study was not powered to detect small differences in CAD prevalence between HIV subgroups. Both PWH and PWoH had similar CV risk factor profiles, but residual confounding between HIV and CAD cannot be excluded.The prevalence of CAD in Uganda was low compared with population-based cohorts from the Global North with similar CVD risk profiles and was similar between HIV serostatus subgroups. Our results suggest that CAD may not be a major cause of morbidity in Uganda.National Institutes of Health.
View details for DOI 10.7326/ANNALS-24-02233
View details for Web of Science ID 001470098400004
View details for PubMedID 40073231
View details for PubMedCentralID PMC12022967
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Selective Use of CT Fractional Flow at a Large Academic Medical Center: Insights from Clinical Implementation after 1 Year of Practice
RADIOLOGY-CARDIOTHORACIC IMAGING
2024; 6 (2): e230073
Abstract
Purpose This special report outlines a retrospective observational study of CT fractional flow reserve (CT-FFR) analysis using dual-source coronary CT angiography (CTA) scans performed without heart rate control and its impact on clinical outcomes. Materials and Methods All patients who underwent clinically indicated coronary CTA between August 2020 and August 2021 were included in this retrospective observational study. Scans were performed in the late systolic to early diastolic period without heart rate control and analyzed at the interpreting physician's discretion. Demographics, coronary CTA features, and rates of invasive coronary angiography (ICA), percutaneous coronary intervention (PCI), myocardial infarction, and all-cause death at 3 months were assessed by chart review. Results During the study period, 3098 patients underwent coronary CTA, of whom 113 with coronary bypass grafting were excluded. Of the remaining 2985 patients, 292 (9.7%) were referred for CT-FFR analysis. Two studies (0.7%) were rejected from CT-FFR analysis, and six (2.1%) analyses did not evaluate the lesion of concern. A total of 160 patients (56.3%) had CT-FFR greater than 0.80. Among patients with significant stenosis at coronary CTA, patients who underwent CT-FFR analysis presented with lower rates of ICA (74.5% vs 25.5%, P = .04) and PCI (78.9% vs 21.1%, P = .05). Conclusion CT-FFR was implemented in patients not requiring heart rate control by using dual-source coronary CTA acquisition and showed the potential to decrease rates of ICA and PCI without compromising safety in patients with significant stenosis and an average heart rate of 65 beats per minute. Keywords: Angiography, CT, CT-Angiography, Fractional Flow Reserve, Cardiac, Heart, Arteriosclerosis Supplemental material is available for this article. © RSNA, 2024.
View details for DOI 10.1148/ryct.230073
View details for Web of Science ID 001223126200007
View details for PubMedID 38573127
View details for PubMedCentralID PMC11056747
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Optical coherence tomography in coronary atherosclerosis assessment and intervention (vol 19, pg 684, 2022)
NATURE REVIEWS CARDIOLOGY
2024; 21 (5): 348
View details for DOI 10.1038/s41569-023-00982-z
View details for Web of Science ID 001127252600001
View details for PubMedID 38110566
View details for PubMedCentralID PMC11987009
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Bone marrow adipocytes fuel emergency hematopoiesis after myocardial infarction
NATURE CARDIOVASCULAR RESEARCH
2023; 2 (12): 1277-+
Abstract
After myocardial infarction (MI), emergency hematopoiesis produces inflammatory myeloid cells that accelerate atherosclerosis and promote heart failure. Since the balance between glycolysis and mitochondrial metabolism regulates hematopoietic stem cell homeostasis, metabolic cues may influence emergency myelopoiesis. Here, we show in humans and female mice that hematopoietic progenitor cells increase fatty acid metabolism after MI. Blockade of fatty acid oxidation by deleting carnitine palmitoyltransferase (Cpt1A) in hematopoietic cells of Vav1Cre/+Cpt1Afl/fl mice limited hematopoietic progenitor proliferation and myeloid cell expansion after MI. We also observed reduced bone marrow adiposity in humans, pigs and mice following MI. Inhibiting lipolysis in adipocytes using AdipoqCreERT2Atglfl/fl mice or local depletion of bone marrow adipocytes in AdipoqCreERT2iDTR mice also curbed emergency hematopoiesis. Furthermore, systemic and regional sympathectomy prevented bone marrow adipocyte shrinkage after MI. These data establish a critical role for fatty acid metabolism in post-MI emergency hematopoiesis.
View details for DOI 10.1038/s44161-023-00388-7
View details for Web of Science ID 001124837200016
View details for PubMedID 38344689
View details for PubMedCentralID PMC10857823
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Clinical characteristics, treatment and outcomes of patients with spontaneous renal artery dissections
JOURNAL OF NEPHROLOGY
2023; 36 (2): 377-384
Abstract
The natural history and optimal management of spontaneous renal artery dissections (SRADs) are poorly understood. We compared baseline characteristics, presentation, management, and outcomes between patients with symptomatic versus asymptomatic SRADs.We performed a retrospective review of medical charts for patients diagnosed with SRAD at a single, tertiary care center. Patients were identified using billing codes. Patient demographics, medical history, clinical presentation, treatment, and follow up were recorded. We compared patients based on presence or absence of symptoms at the time of SRAD diagnosis.A total of 125 patients were included; 73 (58.4%) patients had symptoms at the time of SRAD diagnosis. Symptomatic patients were younger at the time of diagnosis (47.4 vs. 54.3 years, p = 0.008) and more likely male (74.0% vs. 44.2%, p = 0.005). Most patients received medical therapy (93.2% vs. 82.6%, p = 0.32). Endovascular therapy utilization was low in both groups (8.2% vs. 7.7%, p = 0.9). Outcomes between the two groups were comparable; renal function remained stable, and mortality was rare.Most patients who presented with SRAD were treated with medical therapy alone and usually experienced a benign course. Further studies are needed to understand the pathophysiology and natural history of renal artery dissections.
View details for DOI 10.1007/s40620-022-01444-4
View details for Web of Science ID 000862242700001
View details for PubMedID 36178591
View details for PubMedCentralID 7320080
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High endothelial shear stress and stress gradient at plaque erosion persist up to 12 months
INTERNATIONAL JOURNAL OF CARDIOLOGY
2022; 357: 1-7
Abstract
Local hemodynamics are known to play an important role in the development of plaque erosion. Recent studies showed that erosion patients might be treated conservatively without stent implantation. We investigated evolution of hemodynamic parameters on the plaque erosion site in conservatively treated patients.Computational fluid dynamics (CFD) simulations were performed using the coronary angiogram and optical coherence tomography (OCT) images of non-stent treated erosion patients who had serial OCT studies. Calculated CFD parameters included endothelial shear stress (ESS), ESS gradient (ESSG), and oscillatory shear index (OSI).The CFD parameters at the erosion and non-erosion sites were compared among baseline (n = 23), and 1-month (n = 20) and 12-month (n = 16) follow-ups. The erosion site had higher ESS and ESSG values than the non-erosion sites at baseline (mean ESS: 3.00 vs 1.36 Pa, p < 0.01; mean ESSG: 1.71 vs. 0.65 Pa/mm, p = 0.01), 1-month (mean ESS: 2.89 vs 1.19 Pa, p < 0.01; mean ESSG: 1.71 vs. 0.60 Pa/mm, p < 0.01), and 12-month (mean ESS: 3.26 vs 1.59 Pa, p < 0.01; mean ESSG: 1.87 vs. 0.78 Pa/mm, p < 0.01). OSI was not different between erosion and and non-erosion sites.ESS and ESSG values were higher at the plaque erosion sites compared to non-erosion sites. Elevated ESS and ESSG at the erosion site persisted up to 12 months. These data indicate that a local thrombogenic milieu related to hemodynamic perturbation persists up to 12 months at the plaque erosion sites following conservative treatment.https://clinicaltrials.gov: NCT02041650.
View details for DOI 10.1016/j.ijcard.2022.03.035
View details for Web of Science ID 000806170400001
View details for PubMedID 35306029
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Optical coherence tomography in coronary atherosclerosis assessment and intervention
NATURE REVIEWS CARDIOLOGY
2022; 19 (10): 684-703
Abstract
Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.
View details for DOI 10.1038/s41569-022-00687-9
View details for Web of Science ID 000784619500002
View details for PubMedID 35449407
View details for PubMedCentralID PMC9982688
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Non-Newtonian Endothelial Shear Stress Simulation: Does It Matter?
FRONTIERS IN CARDIOVASCULAR MEDICINE
2022; 9: 835270
Abstract
Patient-specific coronary endothelial shear stress (ESS) calculations using Newtonian and non-Newtonian rheological models were performed to assess whether the common assumption of Newtonian blood behavior offers similar results to a more realistic but computationally expensive non-Newtonian model. 16 coronary arteries (from 16 patients) were reconstructed from optical coherence tomographic (OCT) imaging. Pulsatile CFD simulations using Newtonian and the Quemada non-Newtonian model were performed. Endothelial shear stress (ESS) and other indices were compared. Exploratory indices including local blood viscosity (LBV) were calculated from non-Newtonian simulation data. Compared to the Newtonian results, the non-Newtonian model estimates significantly higher time-averaged ESS (1.69 (IQR 1.36)Pa versus 1.28 (1.16)Pa, p < 0.001) and ESS gradient (0.90 (1.20)Pa/mm versus 0.74 (1.03)Pa/mm, p < 0.001) throughout the cardiac cycle, under-estimating the low ESS (<1Pa) area (37.20 ± 13.57% versus 50.43 ± 14.16%, 95% CI 11.28-15.18, p < 0.001). Similar results were also found in the idealized artery simulations with non-Newtonian median ESS being higher than the Newtonian median ESS (healthy segments: 0.8238Pa versus 0.6618Pa, p < 0.001 proximal; 0.8179Pa versus 0.6610Pa, p < 0.001 distal; stenotic segments: 0.8196Pa versus 0.6611Pa, p < 0.001 proximal; 0.2546Pa versus 0.2245Pa, p < 0.001 distal) On average, the non-Newtonian model has a LBV of 1.45 times above the Newtonian model with an average peak LBV of 40-fold. Non-Newtonian blood model estimates higher quantitative ESS values than the Newtonian model. Incorporation of non-Newtonian blood behavior may improve the accuracy of ESS measurements. The non-Newtonian model also allows calculation of exploratory viscosity-based hemodynamic indices, such as local blood viscosity, which may offer additional information to detect underlying atherosclerosis.
View details for DOI 10.3389/fcvm.2022.835270
View details for Web of Science ID 000796195300001
View details for PubMedID 35497989
View details for PubMedCentralID PMC9046559
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Optical Coherence Tomography of Coronary Plaque Progression and Destabilization
JACC-JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY
2021; 78 (12): 1275-1287
Abstract
The development of optical coherence tomography (OCT) has revolutionized our understanding of coronary artery disease. In vivo OCT research has paralleled with advances in computational fluid dynamics, providing additional insights in the various hemodynamic factors influencing plaque growth and stability. Recent OCT studies introduced a new concept of plaque healing in relation to clinical presentation. In addition to known mechanisms of acute coronary syndromes such as plaque rupture and plaque erosion, a new classification of calcified plaque was recently reported. This review will focus on important new insights that OCT has provided in recent years into coronary plaque development, progression, and destabilization, with a focus on the role of local hemodynamics and endothelial shear stress, the layered plaque (signature of previous subclinical plaque destabilization and healing), and the calcified culprit plaque.
View details for DOI 10.1016/j.jacc.2021.07.032
View details for Web of Science ID 000698684800011
View details for PubMedID 34531029
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High spatial endothelial shear stress gradient independently predicts site of acute coronary plaque rupture and erosion
CARDIOVASCULAR RESEARCH
2021; 117 (8): 1974-1985
Abstract
To investigate local haemodynamics in the setting of acute coronary plaque rupture and erosion.Intracoronary optical coherence tomography performed in 37 patients with acute coronary syndromes caused by plaque rupture (n = 19) or plaque erosion (n = 18) was used for three-dimensional reconstruction and computational fluid dynamics simulation. Endothelial shear stress (ESS), spatial ESS gradient (ESSG), and oscillatory shear index (OSI) were compared between plaque rupture and erosion through mixed-effects logistic regression. Lipid, calcium, macrophages, layered plaque, and cholesterol crystals were also analysed. By multivariable analysis, only high ESSG [odds ratio (OR) 5.29, 95% confidence interval (CI) 2.57-10.89, P < 0.001], lipid (OR 12.98, 95% CI 6.57-25.67, P < 0.001), and layered plaque (OR 3.17, 95% CI 1.82-5.50, P < 0.001) were independently associated with plaque rupture. High ESSG (OR 13.28, 95% CI 6.88-25.64, P < 0.001), ESS (OR 2.70, 95% CI 1.34-5.42, P = 0.005), and OSI (OR 2.18, 95% CI 1.33-3.54, P = 0.002) independently associated with plaque erosion. ESSG was higher at rupture sites than erosion sites [median (interquartile range): 5.78 (2.47-21.15) vs. 2.62 (1.44-6.18) Pa/mm, P = 0.009], OSI was higher at erosion sites than rupture sites [1.04 × 10-2 (2.3 × 10-3-4.74 × 10-2) vs. 1.29 × 10-3 (9.39 × 10-5-3.0 × 10-2), P < 0.001], but ESS was similar (P = 0.29).High ESSG is independently associated with plaque rupture while high ESSG, ESS, and OSI associate with plaque erosion. While ESSG is higher at rupture sites than erosion sites, OSI is higher at erosion sites and ESS was similar. These results suggest that ESSG and OSI may play critical roles in acute plaque rupture and erosion, respectively.
View details for DOI 10.1093/cvr/cvaa251
View details for Web of Science ID 000698482600022
View details for PubMedID 32832991
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Venous thrombosis, thromboembolism, biomarkers of inflammation, and coagulation in coronavirus disease 2019
JOURNAL OF VASCULAR SURGERY-VENOUS AND LYMPHATIC DISORDERS
2021; 9 (4): 835-+
Abstract
Coronavirus disease 2019 (COVID-19) is associated with abnormal inflammatory and coagulation markers, potentially mediating thrombotic events. Our objective was to investigate the incidence, time course, laboratory features, and in-hospital outcomes of COVID-19 patients with suspected venous thromboembolism (VTE).A retrospective observational cohort study was conducted of patients hospitalized with COVID-19 who had undergone ultrasound imaging for suspected VTE from March 13 to May 18, 2020. The medical records of the included patients were reviewed for D-dimer, fibrinogen, prothrombin time, partial thromboplastin time, platelet count, C-reactive protein (CRP), and high-sensitivity troponin T at admission and at up to seven time points before and after ultrasound examination. The clinical outcomes included superficial venous thrombosis, deep vein thrombosis, pulmonary embolism, intubation, and death. Mixed effects logistic, linear, and Cox proportional hazards methods were used to evaluate the relationships between the laboratory markers and VTE and other in-hospital outcomes.Of 138 patients who had undergone imaging studies, 44 (31.9%) had evidence of VTE. On univariable analysis, an elevated admission CRP (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.01-1.09; P = .02; per 10-U increase in CRP), platelet count (OR, 1.48; 95% CI, 1.04-2.12; P = .03; per 1000-U increase in platelet count), and male sex (OR, 2.64; 95% CI, 1.19-5.84; P = .02), were associated with VTE. However only male sex remained significant on multivariable analysis (OR, 2.37; 95% CI, 1.01-5.56; P = .048). The independent predictors of death included older age (hazard ratio [HR], 1.04; 95% CI, 1.00-1.07; P = .04), active malignancy (HR, 4.39; 95% CI, 1.39-13.91; P = .01), elevated admission D-dimer (HR, 1.016; 95% CI, 1.003-1.029; P = .02), and evidence of disseminated intravascular coagulation (HR, 4.81; 95% CI, 1.76-13.10; P = .002).Male sex, elevated CRP, and elevated platelet count at admission were associated with VTE on univariable analysis. However, only male sex remained significant on multivariable analysis. Older age, active malignancy, disseminated intravascular coagulation, and elevated D-dimer at admission were independently associated with death for patients hospitalized with COVID-19.
View details for DOI 10.1016/j.jvsv.2020.11.006
View details for Web of Science ID 000667721800002
View details for PubMedID 33188961
View details for PubMedCentralID PMC7657877
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Coronary Artery Disease Reporting and Data System (CAD-RADS) Adoption: Analysis of Local Trends in a Large Academic Medical Center
RADIOLOGY-CARDIOTHORACIC IMAGING
2021; 3 (3): e210016
Abstract
To perform a retrospective review of Coronary Artery Disease Reporting and Data System (CAD-RADS) adoption at a high-volume cardiac CT service.In this retrospective study, the adoption of CAD-RADS in 6562 coronary CT angiography (CTA) reports from January 1, 2017, to February 13, 2020, was evaluated. Reports without CAD-RADS were classified as opt-outs or exceptions to CAD-RADS. CAD-RADS classifications were retrospectively assigned to the opt-outs and the clinical indications for coronary CTA.CAD-RADS scores were reported in 95% (6264 of 6562) of cases. Among the 5% (n = 298) of reports not reported according to CAD-RADS, 58% (n = 172) were considered opt-outs and 42% (n = 126) were exceptions. Cases with higher degree of stenosis, stents, and coronary artery bypass grafts (CABGs) occurred more often in opt-outs versus reports with CAD-RADS (odds ratio [OR], 8.3 [95% CI: 1.6, 42.1]; P < .001). The quarterly opt-out rate decreased over consecutive quarters in the 1st year (OR, 0.77 [95% CI: 0.61, 0.96]; P = .01), then stabilized. Quarterly opt-out rate for patients with stents decreased over time (OR, 0.82 [95% CI: 0.73, 0.92]; P = .008), as did the opt-out rates in patients with CABG (OR, 0.83 [95% CI: 0.76, 0.91]; P < .001). Exceptions (n = 126) included coronary dissections (44%), anomalous coronary arteries (41%), coronary artery aneurysms or pseudoaneurysms (10%), vasculitis (2%), stent complications (2%), and extrinsic compression of grafts (2%).CAD-RADS was adopted rapidly and widely. Readers opted out of its use most often in complex cases of CAD, and the most common exceptions were coronary dissections and anomalous coronary artery.Keywords: Coronary Arteries, CT Angiography© RSNA, 2021.
View details for DOI 10.1148/ryct.2021210016
View details for Web of Science ID 000906554300009
View details for PubMedID 34235445
View details for PubMedCentralID PMC8250406
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Deep vein thrombosis protocol optimization to minimize healthcare worker exposure in coronavirus disease-2019
JOURNAL OF VASCULAR SURGERY-VENOUS AND LYMPHATIC DISORDERS
2021; 9 (2): 299-306
Abstract
There are no societal ultrasound (US) guidelines detailing appropriate patient selection for deep vein thrombosis (DVT) imaging in patients with COVID-19, nor are there protocol recommendations aimed at decreasing exposure time for US technologists. We aimed to provide COVID-19-specific protocol optimization recommendations limiting US technologist exposure while optimizing patient selection.A novel two-pronged algorithm was implemented to limit the DVT US studies on patients with COVID-19 prospectively, which included direct physician communication with the care team and a COVID-19-specific imaging protocol was instated to reduce US technologist exposure. To assess the pretest risk of DVT, the sensitivity and specificity of serum d-dimer in 500-unit increments from 500 to 8000 ng/mL and a receiver operating characteristic curve to assess performance of serum d-dimer in predicting DVT was generated. Rates of DVT, pulmonary embolism, and scan times were compared using t-test and Fisher's exact test (before and after implementation of the protocol).Direct physician communication resulted in cancellation or deferral of 72% of requested examinations in COVID-19-positive patients. A serum d-dimer of >4000 ng/mL yielded a sensitivity of 80% and a specificity of 70% (95% confidence interval, 0.54-0.86) for venous thromboembolism. Using the COVID-19-specific protocol, there was a significant (50%) decrease in the scan time (P < .0001) in comparison with the conventional protocol.A direct physician communication policy between imaging physician and referring physician resulted in deferral or cancellation of a majority of requested DVT US examinations. An abbreviated COVID-19-specific imaging protocol significantly decreased exposure time to the US technologist.
View details for DOI 10.1016/j.jvsv.2020.08.005
View details for Web of Science ID 000640644500003
View details for PubMedID 32795617
View details for PubMedCentralID PMC7418643
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Characteristics of non-culprit plaques in acute coronary syndrome patients with layered culprit plaque
EUROPEAN HEART JOURNAL-CARDIOVASCULAR IMAGING
2020; 21 (12): 1421-1430
Abstract
Layered plaques represent signs of previous plaque destabilization. A recent study showed that acute coronary syndrome (ACS) patients with layered culprit plaque have more vulnerability at the culprit lesion and systemic inflammation. We aimed to compare the characteristics of non-culprit plaques between patients with or without layered plaque at the culprit lesion. We also evaluated the characteristics of layered non-culprit plaques, irrespective of culprit plaque phenotype.We studied ACS patients who had undergone pre-intervention optical coherence tomography (OCT) imaging. The number of non-culprit lesions was evaluated on coronary angiogram and morphological characteristics of plaques were studied by OCT. In 349 patients, 99 (28.4%) had layered culprit plaque. The number of non-culprit plaques in patients with or without layered culprit plaque was similar (3.2 ± 0.8 and 2.8 ± 0.8, P = 0.23). Among 465 non-culprit plaques, 145 from patients with layered culprit plaque showed a higher prevalence of macrophage infiltration (71.0% vs. 60.9%, P = 0.050). When analysed irrespective of culprit plaque phenotype, layered non-culprit plaques showed higher prevalence of lipid (93.3% vs. 86.0%, P = 0.028), thin cap fibroatheroma (29.7% vs. 13.7%, P < 0.001), and macrophage infiltration (82.4% vs. 54.0%, P < 0.001) than non-layered plaques. Plaques with layered phenotype at both culprit and non-culprit lesions had the highest vulnerability.In ACS patients, those with layered phenotype at the culprit lesion demonstrated greater macrophage infiltration at the non-culprit sites. Layered plaque at the non-culprit lesions was associated with more features of plaque vulnerability, particularly when the culprit lesion also had a layered pattern.
View details for DOI 10.1093/ehjci/jez308
View details for Web of Science ID 000606542900018
View details for PubMedID 31848590
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Validation of Wall Shear Stress Assessment in Non-invasive Coronary CTA versus Invasive Imaging: A Patient-Specific Computational Study.
Annals of biomedical engineering
2020
Abstract
Endothelial shear stress (ESS) identifies coronary plaques at high risk for progression and/or rupture leading to a future acute coronary syndrome. In this study an optimized methodology was developed to derive ESS, pressure drop and oscillatory shear index using computational fluid dynamics (CFD) in 3D models of coronary arteries derived from non-invasive coronary computed tomography angiography (CTA). These CTA-based ESS calculations were compared to the ESS calculations using the gold standard with fusion of invasive imaging and CTA. In 14 patients paired patient-specific CFD models based on invasive and non-invasive imaging of the left anterior descending (LAD) coronary arteries were created. Ten patients were used to optimize the methodology, and four patients to test this methodology. Time-averaged ESS (TAESS) was calculated for both coronary models applying patient-specific physiological data available at the time of imaging. For data analysis, each 3D reconstructed coronary artery was divided into 2mm segments and each segment was subdivided into 8 arcs (45°).TAESS and other hemodynamic parameters were averaged per segment as well as per arc. Furthermore, the paired segment- and arc-averaged TAESS were categorized into patient-specific tertiles (low, medium and high). In the ten LADs, used for optimization of the methodology, we found high correlations between invasively-derived and non-invasively-derived TAESS averaged over segments (n=263, r=0.86) as well as arcs (n=2104, r=0.85, p<0.001). The correlation was also strong in the four testing-patients with r=0.95 (n=117 segments, p=0.001) and r=0.93 (n=936 arcs, p=0.001).There was an overall high concordance of 78% of the three TAESS categories comparing both methodologies using the segment- and 76% for the arc-averages in the first ten patients. This concordance was lower in the four testing patients (64 and 64% in segment- and arc-averaged TAESS). Although the correlation and concordance were high for both patient groups, the absolute TAESS values averaged per segment and arc were overestimated using non-invasive vs. invasive imaging [testing patients: TAESS segment: 30.1(17.1-83.8) vs. 15.8(8.8-63.4) and TAESS arc: 29.4(16.2-74.7) vs 15.0(8.9-57.4) p<0.001]. We showed that our methodology can accurately assess the TAESS distribution non-invasively from CTA and demonstrated a good correlation with TAESS calculated using IVUS/OCT 3D reconstructed models.
View details for DOI 10.1007/s10439-020-02631-9
View details for PubMedID 33067688
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Spatial Distribution of Vulnerable Plaques Comprehensive In Vivo Coronary Plaque Mapping
JACC-CARDIOVASCULAR IMAGING
2020; 13 (9): 1989-1999
Abstract
The authors performed a comprehensive analysis on the distribution of coronary plaques with different phenotypes from our 3-vessel optical coherence tomography (OCT) database.Previous pathology studies demonstrated that thin-cap fibroatheroma (TCFA) is localized in specific segments of the epicardial coronary arteries. A detailed description of in vivo coronary plaques of various phenotypes has not been reported.OCT images of all 3 coronary arteries in 131 patients were analyzed every 1 mm to assess plaque phenotype and features of vulnerability. In addition, plaques were divided into tertiles according to percent area stenosis (%AS).Among 534 plaques identified in 393 coronary arteries, 27.0% were fibrous plaques, 13.3% were fibrocalcific plaques, 40.8% were thick-cap fibroatheromas, and 18.9% were TCFAs. TCFAs showed clustering in the proximal segment, particularly in the left anterior descending artery. On the other hand, fibrous plaques were relatively evenly distributed throughout the entire length of the coronary arteries. In patients with acute coronary syndromes (ACS), TCFAs showed stronger proximal clustering in the left anterior descending, 2 clustering peaks in the right coronary artery, and 1 clustering peak in the circumflex artery. The pattern of TCFA distribution was less obvious in patients without ACS. The prevalence of TCFA was higher in the highest %AS tertile, compared with the lowest %AS tertile (30% vs. 9%; p < 0.001).The present 3-vessel OCT study showed that TCFAs cluster at specific locations in the epicardial coronary arteries, especially in patients with ACS. TCFA was more prevalent in segments with tight stenosis. (The Massachusetts General Hospital Optical Coherence Tomography Registry; NCT01110538).
View details for DOI 10.1016/j.jcmg.2020.01.013
View details for Web of Science ID 000569134000020
View details for PubMedID 32912472
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Response by Russo et al Regarding Article, "Healed Plaques in Patients With Stable Angina Pectoris"
ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY
2020; 40 (9): E258-E259
View details for DOI 10.1161/ATVBAHA.120.314971
View details for Web of Science ID 000567549000003
View details for PubMedID 32845770
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Physiology and coronary artery disease: emerging insights from computed tomography imaging based computational modeling
INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING
2020; 36 (12): 2319-2333
Abstract
Improvements in spatial and temporal resolution now permit robust high quality characterization of presence, morphology and composition of coronary atherosclerosis in computed tomography (CT). These characteristics include high risk features such as large plaque volume, low CT attenuation, napkin-ring sign, spotty calcification and positive remodeling. Because of the high image quality, principles of patient-specific computational fluid dynamics modeling of blood flow through the coronary arteries can now be applied to CT and allow the calculation of local lesion-specific hemodynamics such as endothelial shear stress, fractional flow reserve and axial plaque stress. This review examines recent advances in coronary CT image-based computational modeling and discusses the opportunity to identify lesions at risk for rupture much earlier than today through the combination of anatomic and hemodynamic information.
View details for DOI 10.1007/s10554-020-01954-x
View details for Web of Science ID 000558183700002
View details for PubMedID 32779078
View details for PubMedCentralID PMC8323761
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Seasonal Variations in the Pathogenesis of Acute Coronary Syndromes
JOURNAL OF THE AMERICAN HEART ASSOCIATION
2020; 9 (13): e015579
Abstract
Background Seasonal variations in acute coronary syndromes (ACS) have been reported, with incidence and mortality peaking in the winter. However, the underlying pathophysiology for these variations remain speculative. Methods and Results Patients with ACS who underwent optical coherence tomography were recruited from 6 countries. The prevalence of the 3 most common pathologies (plaque rupture, plaque erosion, and calcified plaque) were compared between the 4 seasons. In 1113 patients with ACS (885 male; mean age, 65.8±11.6 years), the rates of plaque rupture, plaque erosion, and calcified plaque were 50%, 39%, and 11% in spring; 44%, 43%, and 13% in summer; 49%, 39%, and 12% in autumn; and 57%, 30%, and 13% in winter (P=0.039). After adjusting for age, sex, and other coronary risk factors, winter was significantly associated with increased risk of plaque rupture (odds ratio [OR], 1.652; 95% CI, 1.157-2.359; P=0.006) and decreased risk of plaque erosion (OR, 0.623; 95% CI, 0.429-0.905; P=0.013), compared with summer as a reference. Among patients with rupture, the prevalence of hypertension was significantly higher in winter (P=0.010), whereas no significant difference was observed in the other 2 groups. Conclusions Seasonal variations in the incidence of ACS reflect differences in the underlying pathobiology. The proportion of plaque rupture is highest in winter, whereas that of plaque erosion is highest in summer. A different approach may be needed for the prevention and treatment of ACS depending on the season of its occurrence. Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT03479723.
View details for DOI 10.1161/JAHA.119.015579
View details for Web of Science ID 000550988200043
View details for PubMedID 32611221
View details for PubMedCentralID PMC7670515
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Ethnic Differences in the Pathobiology of Acute Coronary Syndromes Between Asians and Whites
AMERICAN JOURNAL OF CARDIOLOGY
2020; 125 (12): 1757-1764
Abstract
Ethnic differences in the pathobiology of acute coronary syndromes (ACS) have not been systematically studied. We compared the underlying mechanisms of ACS between Asians and Whites. ACS patients with the culprit lesion imaged by optical coherence tomography were included. Patients were stratified into ST-elevation myocardial infarction (STEMI) and non-ST-elevation-ACS (NSTE-ACS), and baseline characteristics, underlying mechanisms of ACS, and culprit plaque characteristics were compared between Asians and Whites. Of 1,225 patients, 1,019 were Asian (567 STEMI and 452 NSTE-ACS) and 206 were White (71 STEMI and 135 NSTE-ACS). Asians had more diabetes and hypertension among STEMI patients; among NSTE-ACS patients, Asians had higher prevalence of diabetes and renal insufficiency, and lower prevalence of hyperlipidemia. There were no differences in the incidence of plaque rupture, plaque erosion and calcified plaque between Asians and Whites with STEMI (61.2%, 28.6%, 10.2% vs 46.5%, 38.0%, 15.5%, respectively, p = 0.055). Among NSTE-ACS patients, there was a significant difference between Asians and Whites (40.5%, 47.6%, 11.9% vs 27.4%, 48.9%, 23.7%, respectively, p = 0.001). After adjustment for clinical confounders, the risk of plaque rupture (p = 0.713), plaque erosion (p = 0.636), and calcified plaque (p = 0.986) was similar between the groups with STEMI. In NSTE-ACS patients, the only difference was an increased risk of calcified plaque in Whites (odds ratio: 2.125, 95% confidence interval: 1.213 to 3.723, p = 0.008). In conclusion, after adjustment for clinical confounders, Asian and White patients presenting with STEMI and NSTE-ACS showed similar underlying mechanisms of ACS, except for a higher risk of calcified plaque in Whites with NSTE-ACS.
View details for DOI 10.1016/j.amjcard.2020.03.017
View details for Web of Science ID 000536947200001
View details for PubMedID 32312492
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Healed Plaques in Patients With Stable Angina Pectoris
ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY
2020; 40 (6): 1587-1597
Abstract
Healed plaques, signs of previous plaque destabilization, are frequently found in the coronary arteries. Healed plaques can now be diagnosed in living patients. We investigated the prevalence, angiographic, and optical coherence tomography features of healed plaques in patients with stable angina pectoris. Approach and Results: Patients with stable angina pectoris who had undergone optical coherence tomography imaging were included. Healed plaques were defined as plaques with one or more signal-rich layers of different optical density. Patients were divided into 2 groups based on layered or nonlayered phenotype at the culprit lesion. Among 163 patients, 87 (53.4%) had layered culprit plaque. Patients with layered culprit plaque had more multivessel disease (62.1% versus 44.7%, P=0.027) and more angiographically complex culprit lesions (64.4% versus 35.5%, P<0.001). Layered culprit plaques had higher prevalence of lipid plaque (83.9% versus 64.5%, P=0.004), macrophage infiltration (58.6% versus 35.5%, P=0.003), calcifications (78.2% versus 63.2%, P=0.035), and thrombus (28.7% versus 14.5%, P=0.029). Lipid index (P=0.001) and percent area stenosis (P=0.015) were greater in the layered group. The number of nonculprit plaques, evaluated using coronary angiograms, tended to be greater in patients with layered culprit plaque (4.2±2.5 versus 3.5±2.1, P=0.053). Nonculprit plaques in patients with layered culprit lesion had higher prevalence of layered pattern (P=0.002) and lipid phenotype (P=0.005). Lipid index (P=0.013) and percent area stenosis (P=0.002) were also greater in this group.In patients with stable angina pectoris, healed culprit plaques are common and have more features of vulnerability and advanced atherosclerosis both at culprit and nonculprit lesions.
View details for DOI 10.1161/ATVBAHA.120.314298
View details for Web of Science ID 000537864200021
View details for PubMedID 32295419
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Predictors for layered coronary plaques: an optical coherence tomography study
JOURNAL OF THROMBOSIS AND THROMBOLYSIS
2020; 50 (4): 886-894
Abstract
Healed coronary plaques, morphologically characterized by a layered pattern, are signatures of previous plaque disruption and healing. Recent optical coherence tomography (OCT) studies showed that layered plaque is associated with vascular vulnerability. However, factors associated with layered plaques have not been studied. The aim of this study was to investigate predictors for layered plaque at the culprit plaques and at non-culprit plaques. Patients with coronary artery disease who underwent pre-intervention OCT imaging of the culprit lesion were included. Layered plaques were defined as plaques with one or more layers of different optical density and a clear demarcation from underlying components. Among 313 patients, layered plaque at the culprit lesion was observed in 18.8% of ST-segment elevation myocardial infarction patients, 36.3% of non-ST-segment elevation acute coronary syndrome patients, and 53.4% of stable angina pectoris (SAP) patients (p < 0.001). In the multivariable model, SAP, multivessel disease, type B2/C lesion, and diameter stenosis > 70% were independent predictors for layered plaque at the culprit lesion. In addition, 394 non-culprit plaques in 190 patients were assessed to explore predictors for layered plaques at non-culprit lesions. SAP, and thin-cap fibroatheroma and layered plaque at the culprit lesion were independent predictors for layered plaques at non-culprit lesions. In conclusion, clinical presentation of SAP was a strong predictor for layered plaque at both culprit plaques and non-culprit plaques. Development and biologic significance of layered plaques may be related to a balance between pan-vascular vulnerability and endogenous anti-thrombotic protective mechanism.
View details for DOI 10.1007/s11239-020-02116-5
View details for Web of Science ID 000527900900003
View details for PubMedID 32306291
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Using Contrast Motion to Generate Patient-Specific Blood Flow Simulations During Invasive Coronary Angiography
JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME
2020; 142 (2)
Abstract
Virtual fractional flow reserve (vFFR) is an emerging technology employing patient-specific computational fluid dynamics (CFD) simulations to infer the hemodynamic significance of a coronary stenosis. Patient-specific boundary conditions are an important aspect of this approach and while most efforts make use of lumped parameter models to capture key phenomena, they lack the ability to specify the associated parameters on a patient-specific basis. When applying vFFR in a catheter laboratory setting using X-ray angiograms as the basis for creating the simulations, there is some indirect functional information available through the observation of the radio-opaque contrast agent motion. In this work, we present a novel method for tuning the lumped parameter arterial resistances (commonly incorporated in such simulations), based on simulating the physics of the contrast motion and comparing the observed and simulated arrival times of the contrast front at key points within a coronary tree. We present proof of principle results on a synthetically generated coronary tree comprised of multiple segments, demonstrating that the method can successfully optimize the arterial resistances to reconstruct the underlying velocity and pressure fields, providing a potential new means to improve the patient specificity of simulation-based technologies in this area.
View details for DOI 10.1115/1.4044095
View details for Web of Science ID 000518552200002
View details for PubMedID 31233099
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Relative risk of plaque erosion among different age and sex groups in patients with acute coronary syndrome
JOURNAL OF THROMBOSIS AND THROMBOLYSIS
2020; 49 (3): 352-359
Abstract
Postmortem studies reported plaque erosion is frequent in young women. Recent in vivo studies failed to show age and sex differences in the plaque erosion prevalence. The aim of this study was to investigate the prevalence of plaque erosion by age and sex among acute coronary syndromes (ACS) patients. From 1699 ACS patients, 1083 with plaque erosion or rupture were analyzed. Patients were categorized as 5 age groups (≤ 50, 51-60, 61-70, 71-80, ≥ 81 years). Overall prevalence of plaque erosion was similar between males and females (p = 0.831). Males age ≤ 50 had higher (p = 0.018) and age 71-80 had lower (p = 0.006) prevalence of plaque erosion. Females age 61-70 had higher (p = 0.021) and age 71-80 had lower (p = 0.045) prevalence of plaque erosion. In advanced age groups (≥ 71 years), rupture was the dominant etiology in both sexes. In multivariate analysis of males, age ≤ 50 demonstrated a trend to increase (OR 1.418, 95% CI 0.961-2.093, p = 0.078) the erosion risk. Females age ≤ 70 independently increased (OR 2.138, 95% CI 1.249-3.661, p = 0.006) the risk for erosion. The prevalence of plaque erosion was similar between males and females. Plaque erosion risk was increased in the males age ≤ 50 and in the females age ≤ 70 among ACS patients.
View details for DOI 10.1007/s11239-019-01969-9
View details for Web of Science ID 000489285100002
View details for PubMedID 31598930
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Angiographic features of patients with coronary plaque erosion
INTERNATIONAL JOURNAL OF CARDIOLOGY
2019; 288: 12-16
Abstract
Although an in vivo diagnosis of coronary plaque erosion has become possible by optical coherence tomography (OCT), angiographic characteristics of erosion have not been studied. The aim of this study was to investigate the angiographic features of plaque erosion in patients with non-ST elevation acute coronary syndromes (NSTE-ACS).Patients with NSTE-ACS who underwent OCT of the culprit lesion were collected at 11 institutions from 6 countries. Patients were classified as erosion or non-erosion based on OCT images. Angiographic features of both groups were compared.Among 494 cases with NSTE-ACS, 242 had plaque erosion and 252 had non-erosion. Compared to non-erosion group, erosion patients had less multivessel disease (28.5% vs. 49.6%, p < 0.001), lower Jeopardy score (4.2 vs. 5.0, p < 0.001), lower Gensini score (21.3 vs. 25.6, p = 0.014), and lower Syntax score (8.9 vs. 11.5, p < 0.001). With regard to the culprit lesion morphology, plaque erosion group had smaller reference diameter (2.8 mm vs. 3.0 mm, p = 0.032), less frequent type B2/C lesions (51.2% vs. 71.8%, p < 0.001), and lower prevalence of calcification (4.1% vs. 13.9%, p < 0.001) and thrombus (16.5% vs. 28.2%, p = 0.002). In the mid left anterior descending artery (LAD), erosion was significantly more frequent than non-erosion (30.2% vs. 21.8%, p = 0.034).Patients with NSTE-ACS caused by plaque erosion have less complex angiographic features both at the 3-vessel level and at the culprit lesion level. Plaque erosion was frequently found in the mid LAD.
View details for DOI 10.1016/j.ijcard.2019.03.039
View details for Web of Science ID 000467812500003
View details for PubMedID 30928256
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Early strut protrusion and late neointima thickness in the Absorb bioresorbable scaffold: a serial wall shear stress analysis up to five years
EUROINTERVENTION
2019; 15 (4): E370-+
Abstract
The aim of the study was to evaluate the effect of strut protrusion (SP) on wall shear stress (WSS) and neointimal growth (NG) one and five years after implantation of an Absorb bioresorbable vascular scaffold.Eight patients were selected from a first-in-man study. Following three-dimensional (3D) reconstruction of coronaries, WSS was quantified using Newtonian steady-flow simulation in each cross-section at 5° subunits (sectors) of the circumferential luminal surface. At one year, neointimal thickness (NT) was measured by optical coherence tomography (OCT) and correlated to WSS and SP post procedure. Median SP was 112.9 (90.8, 133.1) µm post implantation. Post procedure, a logarithmic inverse relationship between SP and post-implantation WSS (r=-0.425, p<0.001; correlation coefficients in a range from -0.143 to -0.553) was observed, whereas a correlation between baseline logarithm-transformed WSS (log-WSS) and NT (r=-0.451, p<0.001; correlation coefficients ranged from -0.140 to -0.662) was documented at one year. Mixed-effects analysis between baseline log-WSS and NT at follow-up yielded a slope of 30 µm/ln Pascal (Pa) and a y-intercept of 98 µm. As a result of NG, median flow area decreased from 6.91 (6.53, 7.48) mm2 post implantation to 5.65 (5.47, 6.02) mm2 at one-year follow-up (p=0.01) and to 5.75±1.37 mm2 at five-year follow-up (p=0.024). However, the vessel surface exposed to low WSS (<1 Pa) decreased significantly post procedure (42%) to one year (35.9%) and five years (15.2%) (p-overall <0.0001).SP disturbs laminar flow, creates regions of low WSS (<1.0 Pa) that are associated with NG and lumen area reduction. Low WSS post implantation reduced significantly at long-term follow-up. Thin struts with effective embedment would substantially reduce NG and accelerate homogenisation of WSS towards physiological values.
View details for DOI 10.4244/EIJ-D-18-00381
View details for Web of Science ID 000476642700014
View details for PubMedID 29969424
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Computational particle tracking to model platelet behaviour near malapposed coronary stent struts
EUROPEAN HEART JOURNAL
2019; 40 (23): 1890-1891
View details for DOI 10.1093/eurheartj/ehy919
View details for Web of Science ID 000490135400016
View details for PubMedID 30770709
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Comparison of Rosuvastatin Versus Atorvastatin for Coronary Plaque Stabilization
AMERICAN JOURNAL OF CARDIOLOGY
2019; 123 (10): 1565-1571
Abstract
Statins are widely used to lower cholesterol and to reduce cardiovascular events. Whether all statins have similar effects on plaque stabilization is unknown. We aimed to investigate coronary plaque response to treatment with different statins that result in similar lipid reduction using serial multimodality intracoronary imaging. Patients with de novo coronary artery disease requiring intervention were randomized to rosuvastatin 10mg (R10) or atorvastatin 20mg (A20) daily. Optical coherence tomography and intravascular ultrasound were performed at baseline, 6 months, and 12 months. Untreated nonculprit plaques were analyzed by optical coherence tomography for thin-cap fibroatheroma, minimum fibrous cap thickness, lipid arc, and lipid length. Total and percent atheroma volume, respectively were analyzed by intravascular ultrasound. Forty-three patients completed the protocol (R10: 24 patients, 31 plaques; A20: 19 patients, 30 plaques). The decrease in serum lipids was similar. From baseline to 6 months to 12 months, minimum fibrous cap thickness increased in the R10 group (61.4 ± 15.9 µm to 120.9 ± 57.9 µm to 171.5 ± 67.8 µm, p <0.001) and the A20 group (60.8 ± 18.1 µm to 99.2 ± 47.7 µm to 127.0± 66.8 µm, p <0.001). Prevalence of thin-cap fibroatheroma significantly decreased in the R10 and A20 groups (-48% and -53%, respectively, p <0.001 for intragroup comparisons). Only the R10 group had a decrease in macrophage density (-23%, p = 0.04) and microvessels (-12%, p = 0.002). Total atheroma volume decreased in the R10 group (109.2 ± 62.1 mm3 to 101.8 ± 61.1 mm3 to 102.5 ± 62.2 mm3, p = 0.047) but not in the A20 group (83.3 ± 48.5mm3 to 77.6 ± 43.0 mm3 to 77.9 ± 48.6 mm3, p = 0.07). In conclusion, although both statins demonstrated similar reductions in lipid profiles, the rosuvastatin group showed more rapid and robust plaque stabilization, and regression of plaque volume compared to the atorvastatin group.
View details for DOI 10.1016/j.amjcard.2019.02.019
View details for Web of Science ID 000469897900002
View details for PubMedID 30851941
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Comparison of Vascular Response to Statin Therapy in Patients With Versus Without Diabetes Mellitus
AMERICAN JOURNAL OF CARDIOLOGY
2019; 123 (10): 1559-1564
Abstract
Diabetes mellitus (DM) increases cardiovascular morbidity and mortality. A statin is routinely prescribed to patients with DM. However, whether a statin therapy is equally effective in plaque stabilization in DM patients compared with non-DM patients is unknown. A total of 117 lipid-rich plaques were imaged in 90 patients (54 plaques in 41 DM patients and 63 plaques in 49 non-DM patients) with coronary artery disease, those who were treated with a statin and underwent serial optical coherence tomography imaging were included in this study (mean follow-up period, 362 ± 38 days). The changes in minimum fibrous cap thickness (FCT) and lipid index between baseline and 1-year follow-up were compared between the 2 groups. Minimum FCT increased and lipid index decreased with statin therapy in both groups. No significant differences were observed in percent changes of minimum FCT (p = 0.796) and lipid index (p = 0.336) between DM and non-DM patients. Statin therapy induced a significant increase in FCT and a significant decrease in lipid index in both groups. Vascular response to statin therapy was similar between the 2 groups irrespective of DM status.
View details for DOI 10.1016/j.amjcard.2019.02.020
View details for Web of Science ID 000469897900001
View details for PubMedID 30851939
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Numerical Study of Incomplete Stent Apposition Caused by Deploying Undersized Stent in Arteries With Elliptical Cross Sections
JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME
2019; 141 (5)
Abstract
Incomplete stent apposition (ISA) is one of the causes leading to poststent complications, which can be found when an undersized or an underexpanded stent is deployed at lesions. The previous research efforts have focused on ISA in idealized coronary arterial geometry with circular cross section. However, arterial cross section eccentricity plays an important role in both location and severity of ISA. Computational fluid dynamics (CFD) simulations are carried out to systematically study the effects of ISA in arteries with elliptical cross section, as such stents are partially embedded on the minor axis sides of the ellipse and malapposed elsewhere. Overall, ISA leads to high time-averaged wall shear stress (TAWSS) at the proximal end of the stent and low TAWSS at the ISA transition region and the distal end. Shear rate depends on both malapposition distance and blood stream locations, which is found to be significantly higher at the inner stent surface than the outer surface. The proximal high shear rate signifies increasing possibility in platelet activation, when coupled with low TAWSS at the transition and distal regions which may indicate a nidus for in-stent thrombosis.
View details for DOI 10.1115/1.4042899
View details for Web of Science ID 000462958800013
View details for PubMedID 30778567
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Endothelial Shear Stress and Plaque Erosion A Computational Fluid Dynamics and Optical Coherence Tomography Study
JACC-CARDIOVASCULAR IMAGING
2019; 12 (2): 374-375
View details for DOI 10.1016/j.jcmg.2018.07.024
View details for Web of Science ID 000457781900022
View details for PubMedID 30343069
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Expert recommendations on the assessment of wall shear stress in human coronary arteries: existing methodologies, technical considerations, and clinical applications.
European heart journal
2019
View details for DOI 10.1093/eurheartj/ehz551
View details for PubMedID 31566246
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Endothelial Shear Stress and Local Viscosity Assessment of Coronary Bioresorbable Scaffold: A Five-Year Follow Up
ELSEVIER SCIENCE INC. 2018: B68
View details for DOI 10.1016/j.jacc.2018.08.1269
View details for Web of Science ID 000455137100158
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Post-implantation Strut Protrusion and Neointimal Thickness at follow-up in Absorn Bioresorbable Scaffold: A serial Shear Stress Analysis Up to Five Years
ELSEVIER SCIENCE INC. 2018: B67-B68
View details for DOI 10.1016/j.jacc.2018.08.1268
View details for Web of Science ID 000455137100157
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Endothelial shear stress 5 years after implantation of a coronary bioresorbable scaffold
EUROPEAN HEART JOURNAL
2018; 39 (18): 1602-+
Abstract
As a sine qua non for arterial wall physiology, local hemodynamic forces such as endothelial shear stress (ESS) may influence long-term vessel changes as bioabsorbable scaffolds dissolve. The aim of this study was to perform serial computational fluid dynamic (CFD) simulations to examine immediate and long-term haemodynamic and vascular changes following bioresorbable scaffold placement.Coronary arterial models with long-term serial assessment (baseline and 5 years) were reconstructed through fusion of intravascular optical coherence tomography and angiography. Pulsatile non-Newtonian CFD simulations were performed to calculate the ESS and relative blood viscosity. Time-averaged, systolic, and diastolic results were compared between follow-ups. Seven patients (seven lesions) were included in this analysis. A marked heterogeneity in ESS and localised regions of high blood viscosity were observed post-implantation. Percent vessel area exposed to low averaged ESS (<1 Pa) significantly decreased over 5 years (15.92% vs. 4.99%, P < 0.0001) whereas moderate (1-7 Pa) and high ESS (>7 Pa) did not significantly change (moderate ESS: 76.93% vs. 80.7%, P = 0.546; high ESS: 7.15% vs. 14.31%, P = 0.281), leading to higher ESS at follow-up. A positive correlation was observed between baseline ESS and change in lumen area at 5 years (P < 0.0001). Maximum blood viscosity significantly decreased over 5 years (4.30 ± 1.54 vs. 3.21± 0.57, P = 0.028).Immediately after scaffold implantation, coronary arteries demonstrate an alternans of extremely low and high ESS values and localized areas of high blood viscosity. These initial local haemodynamic disturbances may trigger fibrin deposition and thrombosis. Also, low ESS can promote neointimal hyperplasia, but may also contribute to appropriate scaffold healing with normalisation of ESS and reduction in peak blood viscosity by 5 years.
View details for DOI 10.1093/eurheartj/ehx810
View details for Web of Science ID 000431491400009
View details for PubMedID 29409057
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Elevated Blood Viscosity and Microrecirculation Resulting From Coronary Stent Malapposition
JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME
2018; 140 (5)
Abstract
One particular complexity of coronary artery is the natural tapering of the vessel with proximal segments having larger caliber and distal tapering as the vessel get smaller. The natural tapering of a coronary artery often leads to proximal incomplete stent apposition (ISA). ISA alters coronary hemodynamics and creates pathological path to develop complications such as in-stent restenosis, and more worryingly, stent thrombosis (ST). By employing state-of-the-art computer-aided design software, generic stent hoops were virtually deployed in an idealized tapered coronary artery with decreasing malapposition distance. Pulsatile blood flow simulations were carried out using computational fluid dynamics (CFD) on these computer-aided design models. CFD results reveal unprecedented details in both spatial and temporal development of microrecirculation environments throughout the cardiac cycle (CC). Arterial tapering also introduces secondary microrecirculation. These primary and secondary microrecirculations provoke significant fluctuations in arterial wall shear stress (WSS). There has been a direct correlation with changes in WSS and the development of atherosclerosis. Further, the presence of these microrecirculations influence strongly on the local levels of blood viscosity in the vicinity of the malapposed stent struts. The observation of secondary microrecirculations and changes in blood rheology is believed to complement the wall (-based) shear stress, perhaps providing additional physical explanations for tissue accumulation near ISA detected from high resolution optical coherence tomography (OCT).
View details for DOI 10.1115/1.4039306
View details for Web of Science ID 000428700000006
View details for PubMedID 29450473
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Coronary optical coherence tomography-derived virtual fractional flow reserve (FFR): anatomy and physiology all-in-one
EUROPEAN HEART JOURNAL
2017; 38 (48): 3604-3605
View details for DOI 10.1093/eurheartj/ehx594
View details for Web of Science ID 000418697400018
View details for PubMedID 29045625
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Improvement in local haemodynamics 5 years after implantation of a coronary bioresorbable scaffold: a pulsatile non-Newtonian shear stress analysis
EUROPEAN HEART JOURNAL-CARDIOVASCULAR IMAGING
2017; 18 (11): 1294
View details for DOI 10.1093/ehjci/jex165
View details for Web of Science ID 000413460100017
View details for PubMedID 28977391
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Haemodynamic effects of incomplete stent apposition in curved coronary arteries
JOURNAL OF BIOMECHANICS
2017; 63: 164-173
Abstract
Incomplete stent apposition (ISA, also known as malapposition) is a complication that affects day-to-day coronary stenting procedures. ISA is more prominent in complex arterial geometries, such as curvature, asa result of the limited conformability of coronary stents. These malapposed struts disturb the otherwise near-wall laminar blood flow and form a micro-recirculation environment. The micro-recirculation environment is often associated with low wall shear stress (WSS) and upsets the delicate balance of vascular biology, providing possible nidus for thrombosis and restenosis. In this study, a three-dimensional (3D) stent model was virtually deployed into an idealised curved coronary artery. Computational fluid dynamics (CFD) simulations were carried out to systematically analyse the haemodynamic effects of increasing maximum ISA distances, ranging from 180 (moderate), 400 (intermediate) to 910μm (severe) in an artery with decreasing radius of curvature (ROC). Micro-recirculations around both proximal and distal malapposed struts become more pronounced as compared to fully-apposed struts. The accompanying areas of low temporally-averaged WSS (AL-TAWSS) can increase twofold compared to the fully-apposed condition. Furthermore, substantial regions (∼5.2% and 9.0%) of AL-TAWSS are detached from the distal end of the malapposed struts in both moderate and intermediate cases respectively. Malapposed stents also induce more variation of TAWSS at the inner bend of the artery. At the stent surface, maximum WSS increases threefold from the fully-apposed case to intermediate ISA. High WSS on the strut surface is known to activate platelets which when exposed to the micro-recirculation environment may lead to their deposition and thrombosis.
View details for DOI 10.1016/j.jbiomech.2017.09.016
View details for Web of Science ID 000414818400022
View details for PubMedID 29032800
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Numerical and experimental investigations of the flow-pressure relation in multiple sequential stenoses coronary artery
INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING
2017; 33 (7): 1083-1088
Abstract
Virtual fractional flow reserve (vFFR) has been evaluated as an adjunct to invasive fractional flow reserve (FFR) in the light of its operational and economic benefits. The accuracy of vFFR and the complexity of hyperemic flow simulation are still not clearly understood. This study investigates the flow-pressure relation in an idealised multiple sequential stenoses coronary artery model via numerical and experimental approaches. Pressure drop is linearly correlated with flow rate irrespective of the number of stenosis. Computational fluid dynamics results are in good agreement with the experimental data, demonstrating reasonable accuracy of vFFR. It was also found that the difference between data obtained with steady and pulsatile flows is negligible, indicating the steady flow may be used instead of pulsatile flow conditions in vFFR computation. This study adds to the current understanding of vFFR and may improve its clinical applicability as an adjunct to invasively determined FFR.
View details for DOI 10.1007/s10554-017-1093-3
View details for Web of Science ID 000404611600012
View details for PubMedID 28220273
View details for PubMedCentralID PMC5489574
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Five-year follow-up of underexpanded and overexpanded bioresorbable scaffolds: self-correction and impact on shear stress
EUROINTERVENTION
2017; 12 (17): 2158-2159
View details for DOI 10.4244/EIJ-D-17-00081
View details for Web of Science ID 000400781000019
View details for PubMedID 28246061
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Biomechanical stress in coronary atherosclerosis: emerging insights from computational modelling
EUROPEAN HEART JOURNAL
2017; 38 (2): 81-92C
Abstract
Coronary plaque rupture is the most common cause of vessel thrombosis and acute coronary syndrome. The accurate early detection of plaques prone to rupture may allow prospective, preventative treatment; however, current diagnostic methods remain inadequate to detect these lesions. Established imaging features indicating vulnerability do not confer adequate specificity for symptomatic rupture. Similarly, even though experimental and computational studies have underscored the importance of endothelial shear stress in progressive atherosclerosis, the ability of shear stress to predict plaque progression remains incremental. This review examines recent advances in image-based computational modelling that have elucidated possible mechanisms of plaque progression and rupture, and potentially novel features of plaques most prone to symptomatic rupture. With further study and clinical validation, these markers and techniques may improve the specificity of future culprit plaque detection.
View details for DOI 10.1093/eurheartj/ehv689
View details for Web of Science ID 000394006900007
View details for PubMedID 28158723
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The effects of the pulsatile period on the size of recirculation bubble in the vicinity of stent struts
edited by Tso, C. P.
IOP PUBLISHING LTD. 2017
View details for DOI 10.1088/1742-6596/822/1/012068
View details for Web of Science ID 000404176200067
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Computational fluid dynamics study of common stent models inside idealised curved coronary arteries
COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING
2017; 20 (6): 671-681
Abstract
The haemodynamic behaviour of blood inside a coronary artery after stenting is greatly affected by individual stent features as well as complex geometrical properties of the artery including tortuosity and curvature. Regions at higher risk of restenosis, as measured by low wall shear stress (WSS < 0.5 Pa), have not yet been studied in detail in curved stented arteries. In this study, three-dimensional computational modelling and computational fluid dynamics methodologies were used to analyse the haemodynamic characteristics in curved stented arteries using several common stent models. Results in this study showed that stent strut thickness was one major factor influencing the distribution of WSS in curved arteries. Regions of low WSS were found behind struts, particularly those oriented at a large angle relative to the streamwise flow direction. These findings were similar to those obtained in studies of straight arteries. An uneven distribution of WSS at the inner and outer bends of curved arteries was observed where the WSS was lower at the inner bend. In this study, it was also shown that stents with a helical configuration generated an extra swirling component of the flow based on the helical direction; however, this extra swirl in the flow field did not cause significant changes on the distribution of WSS under the current setup.
View details for DOI 10.1080/10255842.2017.1289374
View details for Web of Science ID 000399346400012
View details for PubMedID 28349764
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Invasive sealing of vulnerable, high-risk lesions
BIORESORBABLE SCAFFOLDS: FROM BASIC CONCEPT TO CLINICAL APPLICATIONS
edited by Onuma, Y., Serruys, P. W.
2017: 398-409
View details for Web of Science ID 000486259900046
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The Nidus for Possible Thrombus Formation Insight From the Microenvironment of Bioresorbable Vascular Scaffold
JACC-CARDIOVASCULAR INTERVENTIONS
2016; 9 (20): 2167-2168
View details for DOI 10.1016/j.jcin.2016.08.019
View details for Web of Science ID 000385716000019
View details for PubMedID 27692818
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Examining the Potential Effects of Coronary Stent Malapposition: Insights from Optical Coherence Tomography (OCT) and Computational Fluid Dynamics
ELSEVIER SCIENCE INC. 2016: S64-S65
View details for DOI 10.1016/j.jacc.2016.03.177
View details for Web of Science ID 000375193400140
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Reversal of flow between serial bifurcation lesions: insights from computational fluid dynamic analysis in a population-based phantom model.
EuroIntervention : journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology
2015; 11 (5): e1-3
View details for DOI 10.4244/EIJV11I5A111
View details for PubMedID 26390509
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Advances in three-dimensional coronary imaging and computational fluid dynamics: is virtual fractional flow reserve more than just a pretty picture?
CORONARY ARTERY DISEASE
2015; 26: E43-E54
Abstract
Percutaneous coronary intervention (PCI) has shown a high success rate in the treatment of coronary artery disease. The decision to perform PCI often relies on the cardiologist's visual interpretation of coronary lesions during angiography. This has inherent limitations, particularly due to the low resolution and two-dimensional nature of angiography. State-of-the-art modalities such as three-dimensional quantitative coronary angiography, optical coherence tomography and invasive fractional flow reserve (FFR) may improve clinicians' understanding of both the anatomical and physiological importance of coronary lesions. While invasive FFR is the gold standard technique for assessment of the haemodynamic significance of coronary lesions, recent studies have explored a surrogate for FFR derived solely from three-dimensional reconstruction of the invasive angiogram, and therefore eliminating need for a pressure wire. Utilizing advanced computational fluid dynamics research, this virtual fractional flow reserve (vFFR) has demonstrated reasonable correlation with invasive measurements and remains an intense area of ongoing study. However, at present, several limitations and computational fluid dynamic assumptions may preclude vFFR from widespread clinical use. This review demonstrates the tight integration of advanced three-dimensional imaging techniques and vFFR in assessing coronary artery disease, reviews the advantages and disadvantages of such techniques and attempts to provide a glimpse of how such advances may benefit future clinical decision-making during PCI.
View details for DOI 10.1097/MCA.0000000000000219
View details for Web of Science ID 000846865300009
View details for PubMedID 26247271
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Optical coherence tomography to evaluate coronary stent implantation and complications
CORONARY ARTERY DISEASE
2015; 26: E55-E68
Abstract
Coronary optical coherence tomography (OCT) is now an established imaging technique in many catheterization laboratories worldwide. With its near-histological view of the vessel wall and lumen interface, it offers unprecedented imaging quality to improve our understanding of the pathophysiology of atherosclerosis, plaque vulnerability, and vascular biology. Not only is OCT used to accurately detect atherosclerotic plaque and optimize stent position, but it can further characterize plaque composition, quantify stent apposition, and assess stent tissue coverage. Given that its resolution of 15 μm is well above that of angiography and intravascular ultrasound, OCT has become the invasive imaging method of choice to examine the interaction between stents and the vessel wall. This review focuses on the application of OCT to examine coronary stents, the mechanisms of stent complications, and future directions of OCT-guided intervention.
View details for DOI 10.1097/MCA.0000000000000215
View details for Web of Science ID 000846865300010
View details for PubMedID 26247272
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Serial three-dimensional optical coherence tomography to assess contained coronary artery perforation
CORONARY ARTERY DISEASE
2015; 26: E71-E72
View details for DOI 10.1097/MCA.0000000000000245
View details for Web of Science ID 000846865300012
View details for PubMedID 26247274
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Optical coherence tomography guiding intervention in acute coronary syndrome
CORONARY ARTERY DISEASE
2015; 26: E73-E74
View details for DOI 10.1097/MCA.0000000000000214
View details for Web of Science ID 000846865300013
View details for PubMedID 26247275