Dr. John is a fellowship-trained cardiologist with more than 25 years of experience. He is a clinical professor in the Department of Medicine at Stanford University School of Medicine.

He originally earned board certification in clinical cardiac electrophysiology in 1996 and has continued to recertify. He also has earned board certification in cardiovascular disease and internal medicine.

Dr. John diagnoses and manages all forms of cardiac arrhythmias including atrial fibrillation and ventricular arrhythmias. His special interests include catheter ablation for SVT, atrial arrhythmias, pacemaker and defibrillator implants, and lead extraction.

He has conducted extensive research. He has participated in large multi-center clinical trials, including over 30 studies as a primary investigator of drugs, devices, and ablation techniques. He helped pioneer a new way to manage scar-related ventricular tachycardia. He also helped develop innovations in cardiac pacemaker technology.

Dr. John has authored over 200 publications that include 126 original research papers. They have appeared in reputed journals such as the New England Journal of Medicine, Circulation, Lancet, Journal of the American College of Cardiology, European Heart Journal, Heart Rhythm, Journal of Cardiovascular Electrophysiology, and many more. Topics have included innovative, new techniques and technologies for the treatment of supraventricular arrhythmias, atrial fibrillation, ventricular tachycardia, catheter ablation, lead extraction, cardiac pacing, and defibrillation.

He was a member of the editorial board for Circulation and is currently on the editorial board of the publications Heart Rhythm Journal, Arrhythmia and Electrophysiology, Journal of Cardiac Electrophysiology, and Journal of Innovations in Cardiac Rhythm Management.

Dr. John also has written several chapters for medical textbooks such as Harrison’s Principles of Internal Medicine, Zipes Textbook on Cardiac Electrophysiology - Cell to Bedside, Conn’s Current Therapy, Electrical Disorders of the Heart, Cardiac Mapping, and many more.

He has made invited presentations to his peers at scientific sessions of the Heart Rhythm Society, American Heart Association, American College of Cardiology, and Heart Failure Society. He has delivered more than 60 national and international lectures. Subjects include cardiac pacing, defibrillation, heart failure, and arrhythmia management including catheter ablation for arrhythmias.

Dr. John is a fellow of the American College of Cardiology, Heart Rhythm Society, and Royal College of Physicians of London.

He has volunteered his time and expertise to provide free cardiac care to underserved patients in Bolivia, India, and Kenya.

Clinical Focus

  • Arrhythmias, Cardiac
  • Atrial Fibrillation
  • Ventricular Tachycardia
  • supraventricular tachycardia
  • WPW Syndrome
  • Catheter ablation
  • Artificial Biventricular Pacemaker
  • Defibrillators, Implantable
  • Pacemaker and Defibrillator Lead Extraction
  • Left atrial appendage occlusion
  • Clinical Cardiac Electrophysiology

Academic Appointments

Professional Education

  • Fellowship: West Roxbury VA Hospital Medical Ctr GME Programs (1993) MA
  • Board Certification: American Board of Internal Medicine, Clinical Cardiac Electrophysiology (2017)
  • Board Certification: American Board of Internal Medicine, Cardiovascular Disease (1995)
  • Board Certification: American Board of Internal Medicine, Internal Medicine (1994)
  • Residency: University College Hospital (1991) UK
  • Residency: Groby Road Medical Centre (1986)
  • Residency: Pinderfields Hospital (1986) United Kingdom
  • Medical Education: Medical College Thiruvananthapuram University of Kerala (1979) India

All Publications

  • Advanced Electroanatomic Mapping: Current and Emerging Approaches CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE Narayan, S. M., John, R. M. 2024
  • Intramyocardial Hematoma During Catheter Ablation for Scar-Related Ventricular Tachycardia. JACC. Clinical electrophysiology John, R. M., Tedrow, U., Tadros, T., Richardson, T. D., Kanagasundram, A., Hoffman, R. D., Kapp, M. E., Shah, A., Michaud, G., Stevenson, W. 2023


    Intramural hematoma during ablation for scar-related ventricular tachycardia (VT) is a rare but life-threatening complication.The goal of this study was to describe the features and outcomes of intramural hematoma during ablation for scar-related VT.From 2010 to 2022, >3,514 ablations for ventricular arrhythmias were performed at 2 institutions. Four cases of intramural hematoma complicating VT ablation for scar-related VT were identified. Intraprocedural details, imaging data, and surgical notes were reviewed to create a recognizable pattern of events highlighting this complication.In 3 of 4 cases, intramural hematoma occurred during catheter ablation with an open irrigated 3.5 mm tipped catheter using normal saline for irrigation. In one case, hematoma was noted after ablation using an investigational needle electrode catheter. The occurrence of a steam pop preceded detection of an expanding intramural hematoma in 3 cases. ST-segment elevation on electrocardiography was evident in 3 cases; intracardiac echocardiographic imaging detected the hematoma in all cases. Epicardial rupture and pericardial effusion requiring drainage occurred in 3 cases, whereas 1 hematoma was self-contained and did not require intervention. Surgical intervention was performed in 2 cases, with successful outcomes. One patient who was deemed not a surgical candidate died of progressive cardiogenic shock.Intramural hematoma during ablation for scar-related VT is a rare but potentially catastrophic complication that requires prompt recognition. Steam pops during ablation frequently precede the hematoma formation. Surgical intervention may be life-saving, although contained hematomas can occasionally be managed conservatively.

    View details for DOI 10.1016/j.jacep.2023.07.004

    View details for PubMedID 37632506

  • World Wide Experience With an Irrigated Needle Catheter for Ablation of Refractory Ventricular Arrhythmias: Final Report. JACC. Clinical electrophysiology Tedrow, U. B., Kurata, M., Kawamura, I., Batnyam, U., Dukkipati, S., Nakamura, T., Tanigawa, S., Fuji, A., Richardson, T. D., Kanagasundram, A. N., Koruth, J. S., John, R. M., Hasegawa, K., Abdelwahab, A., Sapp, J., Reddy, V. Y., Stevenson, W. G. 2023


    We previously reported feasibility of irrigated needle ablation (INA) with a retractable 27-G end-hole needle catheter to treat nonendocardial ventricular arrhythmia substrate, an important cause of ablation failure.The purpose of this study was to report outcomes and complications in our entire INA-treated population.Patients with recurrent sustained monomorphic ventricular tachycardia (VT) or high-density premature ventricular contractions (PVCs) despite radiofrequency ablation were prospectively enrolled at 4 centers. Endpoints included a 70% decrease in VT frequency or PVC burden decrease to <5,000/24 h at 6 months.INA was performed in 111 patients (median: 2 failed prior ablations, 71% nonischemic heart disease, and left ventricular ejection fraction 36 ± 14%). INA acutely abolished targeted PVCs in 33 of 37 patients (89%), and PVCs were reduced to <5,000/day in 29 patients (78%). During 6-month follow-up, freedom from hospitalization was observed in 50 of 72 patients with VT (69%), and improvement or abolition of VT occurred in 47%. All patients received multiple INA applications, with more in the VT group than in the PVC group (median: 12 (IQR: 7-19) vs 7 (5-15); P < 0.01). After INA, additional endocardial standard radiofrequency ablation was required in 23% of patients. Adverse events included 4 pericardial effusions (3.5%), 3 cases of (anticipated) atrioventricular block (2.6%), and 3 heart failure exacerbations (2.6%). During 6-month follow-up, 5 deaths occurred; none were procedure-related.INA achieves improved arrhythmia control in 78% of patients with PVCs and avoids hospitalization in 69% of patients with VT refractory to standard ablation at 6-month follow-up. Procedural risks are acceptable. (Intramural Needle Ablation for Ablation of Recurrent Ventricular Tachycardia; NCT01791543) (Intramural Needle Ablation for the Treatment of Refractory Ventricular Arrhythmias; NCT03204981).

    View details for DOI 10.1016/j.jacep.2023.05.014

    View details for PubMedID 37278684

  • Leadless Pacemakers: The Leap from Single to Dual Chamber Pacing. Heart rhythm John, R. M., De Larochelliere, H. 2023

    View details for DOI 10.1016/j.hrthm.2023.04.053

    View details for PubMedID 37149205

  • Ablation of ectopic atrial foci for successful management of symptomatic bradycardia: A case series (Bradycardia and Ectopic Atrial Beats). Pacing and clinical electrophysiology : PACE Cunn, G., Willner, J., John, R. M. 2023


    Atrial premature contractions (PACs) that block at the atrial ventricular (AV) nodal level and occurring in a bigeminal frequency are recognized as a cause of symptomatic bradycardia. Appropriate suppression of the PACs often results in restoration of a regular rhythm with resolution of bradycardia-related symptoms. We report a series of three patients with non-conducted bigeminal PACs arising from the mitral annulus that resulted in symptomatic bradycardia and who were referred for consideration of cardiac pacing. Focal ablation suppressed PACs restoring a normal heart rate and resolution of symptoms without resorting to cardiac pacing. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/pace.14639

    View details for PubMedID 36660967

  • Same-day discharge after transvenous lead extraction: feasibility and outcomes. Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology Atteya, G., Alston, M., Sweat, A., Saleh, M., Beldner, S., Mitra, R., Willner, J., John, R. M., Epstein, L. M. 2022


    AIMS: Same-day discharge (SDD) is safe for patients undergoing electrophysiology procedures. There is no existing data regarding SDD for patients undergoing transvenous lead extraction (TLE). We report our experience with SDD for patients undergoing TLE.METHODS AND RESULTS: The study group included patients undergoing TLE between February 2020 and July 2021 without an infectious indication. A modified SDD protocol for device implants/ablations was applied to TLE patients. Patient characteristics, extraction details, outcomes, and complications were reviewed. Of 239 patients undergoing TLE, 210 were excluded (94 infections and 116 did not meet SDD criteria). Of the remaining 29 patients, seven stayed due to patient preference and 22 were discharged home the same day. The SDD group had an average age of 65.9 ± 12 (47-84), 41% female, and LVEF of 52.2 ± 18% (10-80). The indication for TLE was malfunction (20), upgrade (4), advisory lead (2), and magnetic resonance imaging compatibility (1). Extractions included four implantable cardioverter-defibrillators (ICDs), 17 pacemakers (PPM), and one cardiac resynchronization therapy (CRT)-P system. The leads were 9.6 years (1.5-21.7) old, and 1.8 leads were removed per patient (1-3); the lead extraction difficulty (LED) score was 11.6 ± 7. Twenty underwent cardiovascular implantable electronic device (CIED) re-implantation (2 ICD, 3 CRT-D, 13 PPM, and 2 CRT-P). For CIED re-implants, patients sent a remote transmission the next day, and all patients received a next-day call. There were no procedure or device-related issues, morbidities, or mortalities in the 30 days after discharge.CONCLUSION: Same-day discharge after TLE for non-infectious aetiologies is safe and feasible in a select group of patients with early procedure completion who meet strict SDD criteria.

    View details for DOI 10.1093/europace/euac185

    View details for PubMedID 36575941

  • Leadless Pacing after Transvenous Lead Extraction: Are we out of the Woods? Heart rhythm Baykaner, T., John, R. M. 2022

    View details for DOI 10.1016/j.hrthm.2022.12.029

    View details for PubMedID 36572151

  • Tyrosine kinase inhibitor-associated ventricular arrhythmias: a case series and review of literature. Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing Fazal, M., Wei, C., Chuy, K. L., Hussain, K., Gomez, S. E., Ba, S. S., Pietrasik, G., Yadav, N., Ghazizadeh, Z., Kapoor, R., Witteles, R. M., Blackmon, A., Wang, P. J., John, R. M., Narayan, S. M., Cheng, P., Rhee, J., Baykaner, T. 2022


    BACKGROUND: Tyrosine kinase inhibitors (TKIs) have been increasingly used as first-line therapy in hematologic and solid-organ malignancies. Multiple TKIs have been linked with the development of cardiovascular complications, especially atrial arrhythmias, but data on ventricular arrhythmias (VAs) is scarce.METHODS: Herein we describe five detailed cases of VAs related to TKI use in patients with varied baseline cardiovascular risk factors between 2019 and 2022 at three centers. Individual chart review was conducted retrospectively.RESULTS: Patient ages ranged from 43 to 83years. Three patients were on Bruton's TKI (2 ibrutinib and 1 zanubrutinib) at the time of VAs; other TKIs involved were afatinib and dasatinib. Three patients had a high burden of non-sustained ventricular tachycardia (NSVT) requiring interventions, whereas two patients had sustained VAs. While all patients in our case series had significant improvement in VA burden after TKI cessation, two patients required new long-term antiarrhythmic drug therapy, and one had an implantable defibrillator cardioverter (ICD) placed due to persistent VAs after cessation of TKI therapy. One patient reinitiated TKI therapy after control of arrhythmia was achieved with antiarrhythmic drug therapy.CONCLUSIONS: Given the expanding long-term use of TKIs among a growing population of cancer patients, it is critical to acknowledge the association of TKIs with cardiovascular complications such as VAs, to characterize those at risk, and deploy preventive and therapeutic measures to avoid such complications and interference with oncologic therapy. Further efforts are warranted to develop monitoring protocols and optimal treatment strategies for TKI-induced VAs.

    View details for DOI 10.1007/s10840-022-01400-z

    View details for PubMedID 36411365

  • Proarrhythmic effect of radiofrequency catheter ablation on the right ventricular moderator band. Journal of arrhythmia John, R. M., Willner, J. 2022; 38 (5): 813-816


    Following ablation on the RV moderator band for suppression of monomorphic PVCs, recurrent VT and VF were triggered by the same PVC at shorter coupling intervals. This is likely a pro arrhythmic effect of ablation on the moderator band.

    View details for DOI 10.1002/joa3.12752

    View details for PubMedID 36237867

    View details for PubMedCentralID PMC9535760

  • Proarrhythmic effect of radiofrequency catheter ablation on the right ventricular moderator band JOURNAL OF ARRHYTHMIA John, R. M., Willner, J. 2022

    View details for DOI 10.1002/joa3.12752

    View details for Web of Science ID 000822264900001

  • Durable pulmonary vein isolation with diffuse posterior left atrial ablation using low-flow, median power, short-duration strategy. Journal of cardiovascular electrophysiology Li, D. L., El-Harasis, M., Montgomery, J. A., Richardson, T. D., Kanagasundram, A., Estrada, J. C., Lean, M., Benjamin Shoemaker, M., Saavedra, P. J., Touchton, S., Patel, B., Herrmann, T., John, R. M., Michaud, G. F. 2022


    INTRODUCTION: To target posterior wall isolation (PWI) in atrial fibrillation (AF) ablation, diffuse ablation theoretically confers a lower risk of conduction recovery compared to box set. We sought to assess the safety and efficacy of diffuse PWI with low-flow, medium-power, and short-duration (LF-MPSD) ablation, and evaluate the PVI and PWI durability among patients undergoing repeat ablations.METHODS: We retrospectively studied patients undergoing LF-MPSD ablation for AF (PVI + diffuse PWI) between 8/2017 and 12/2019. Clinical characteristics were collected. Kaplan-Meier survival analysis was performed to study AF/atrial flutter (AFL) recurrence. Ablation data were analyzed in patients who underwent a repeat AF/AFL ablation.RESULTS: Of the 463 patients undergoing LF-MPSD AF ablation (PVI alone, or PVI + diffuse PWI), 137 patients had PVI + diffuse PWI. Acute PWI with complete electrocardiogram elimination was achieved in 134 (97.8%) patients. Among the 126 patients with consistent follow up, 38 (30.2%) patients had AF/AFL recurrence during a median duration of 14 months. Eighteen patients underwent a repeat AF/AFL ablation after PVI + diffuse PWI, and 16 (88.9%) patients had durable PVI, in contrast to 10 of 45 (23.9%) patients who had redo ablation after LF-MPSD PVI alone. Seven patients (38.9%) had durable PWI, while 11 patients had partial electrical recovery at the posterior wall. The median percentage of area without electrical activity at the posterior wall was 70.7%. Conduction block across the posterior wall was maintained in 16 (88.9%) patients.CONCLUSION: There was a high rate of PVI durability in patients undergoing diffuse PWI and PVI. Partial posterior wall electrical recovery was common but conduction block across the posterior wall was maintained in most patients. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/jce.15550

    View details for PubMedID 35598280

  • Case Volume and Procedural Outcomes in Ablation for Atrial Fibrillation: Practice Makes Perfect? Journal of cardiovascular electrophysiology Muthalaly, R. G., John, R. M. 2022


    Ablation for atrial fibrillation (AF) is an established therapy that continues to grow in scope and indication This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/jce.15500

    View details for PubMedID 35437861

  • Interventricular septal substrates for scar-related monomorphic ventricular tachycardia. Indian pacing and electrophysiology journal John, R. M., Stevenson, W. 2022; 22 (1): 10-11

    View details for DOI 10.1016/j.ipej.2021.12.004

    View details for PubMedID 35101203

  • Idiopathic Ventricular Outflow Tract Arrhythmias: Avoid the Use of a Sledgehammer to Crack a Nut. Journal of cardiovascular electrophysiology John, R. M., Perino, A. C. 2021


    Ventricular outflow is a common site for idiopathic PVCs and repetitive ventricular arrhythmias. Sites of origin of these arrhythmias may vary from the sites of earliest activation mapped. Better definition of the site of origin can help avoid unnecessary large volume ablation to suppress these arrhythmia. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/jce.15298

    View details for PubMedID 34796995

  • Percutaneous management of superior vena cava syndrome in patients with cardiovascular implantable electronic devices. Heart rhythm Gabriels, J., Chang, D., Maytin, M., Tadros, T., John, R. M., Sobieszczyk, P., Eisenhauer, A., Epstein, L. M. 2021; 18 (3): 392-398


    There is no consensus regarding the optimal management of cardiovascular implantable electronic device (CIED)-related superior vena cava (SVC) syndrome.We report our experience with transvenous lead extractions (TLEs) in the setting of symptomatic CIED-related SVC syndrome.We reviewed all TLEs performed at a high-volume center over a 14-year period and identified patients in which TLE was performed for symptomatic SVC syndrome. Patient characteristics, extraction details, percutaneous management of SVC occlusions, and clinical follow up data were analyzed.Over a 14-year period, more than 1600 TLEs were performed. Of these, 16 patients underwent TLE for symptomatic SVC syndrome. The mean age was 53.1 ± 12.8 years, and 9 (56.3%) were men. Thirty-seven leads, with a mean dwell time of 5.8 years (range 2-12 years), were extracted. After extraction, 6 patients (37.5%) received an SVC stent. Balloon angioplasty was performed before stenting in 5 cases (31.3%). There was 1 major complication (6.3%) due to an SVC tear that was managed surgically with a favorable outcome. Eleven patients underwent reimplantation of a CIED. Over a median follow-up of 5.5 years (interquartile range 2.0-8.5 years), 12 patients (75%) remained free of symptoms.Combining TLE with the percutaneous treatment of symptomatic SVC syndrome is a safe and viable treatment strategy.

    View details for DOI 10.1016/j.hrthm.2020.11.012

    View details for PubMedID 33212249

  • Candidemia in patients with cardiovascular implantable electronic devices. Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing Nakamura, T., Narui, R., Holmes, B., Norton, C., Kim, E. J., Nakajima, I., Stevenson, W. G., Greene, M. H., John, R. M., Ellis, C. R., Crossley, G. H., Montgomery, J. A. 2021; 60 (1): 69-75


    Current guidelines recommend complete extraction of cardiovascular implantable electronic devices (CIEDs) in the case of persistent or recurrent fungemia without other identifiable sources, though supporting evidence is lacking. We sought to evaluate the prognosis of patients with candidemia and CIEDs.Twelve consecutive patients (54 ± 12 years, 8 male) with CIED and concurrent candidemia were reviewed.At the time of diagnosis with candidemia, seven patients were immunocompromised, six were on long-term antibacterial therapy, two were intravenous drug users, four were on chronic hemodialysis, and six had a central venous catheter. Four patients were confirmed as definite CIED infection as vegetation was visible on lead by echocardiogram. The other 8 patients were considered possible CIED infection with candidemia of unknown focus. All patients with visible vegetation underwent CIED removal without complications, and other patients were initially managed non-operatively. After 1 year of follow-up, 7 patients had died and at extended follow-up, all patients without lead removal died while 3 of 4 patients with lead extraction survived. Of note, 50% of deaths in the patients without lead removal were associated with fungal sepsis.Candida fungemia is associated with a high mortality. CIED removal should be an early consideration in these patients even if lead vegetations are not seen.

    View details for DOI 10.1007/s10840-020-00706-0

    View details for PubMedID 32048116

  • Percutaneous approaches for retrieval of an embolized or malpositioned left atrial appendage closure device: A multicenter experience. Heart rhythm Afzal, M. R., Ellis, C. R., Gabriels, J., El-Chami, M., Amin, A., Fanari, Z., Delurgio, D., John, R. M., Patel, A., Haldis, T. A., Goldstein, J. A., Yakubov, S., Daoud, E. G., Hummel, J. D. 2020; 17 (9): 1545-1553


    Experience with retrieval of a Watchman left atrial (LA) appendage (LAA) closure device (WD) is limited. An embolized or grossly malpositioned WD warrants retrieval to minimize the risk of thromboembolic complications and vascular occlusion.The purpose of this study was to report approaches for percutaneous retrieval of a WD from multicenter experience.Data on successful WD retrievals were obtained from high-volume operators. Data included clinical characteristics; structural characteristics of the LA and LAA; and procedural details of the deployment and retrieval procedure, type of retrieval (immediate: during the same procedure; delayed: during a separate procedure after the successful deployment), equipment used, complications, and postretrieval management.Ten successful percutaneous and 1 surgical retrievals comprised this study. Seven patients had immediate retrieval, while 4 had delayed retrieval. The median duration before delayed retrieval was 45 days (range 1-45 days). The median LAA diameter and size of a successfully deployed WD was 16 mm (range 14-24 mm) and 21 mm (range 21-30 mm), respectively. A WD was retrieved from the LA (n = 1), LAA (n = 2), left ventricle (n = 2), and aorta (n = 6). The reason for retrieval from the LAA was inadequate deployment, resulting in a significant peri-device leak. Retrieval from the LA or LAA was successfully performed using snares (n = 2) and a Raptor grasping device (n = 1). Retrieval from the left ventricle was achieved with a snare (n = 1) and surgery (n = 1). Retrieval from the aorta required snares (n = 5) and retrieval forceps (n = 1). Five patients were successfully reimplanted with a larger size WD. The only complication during percutaneous retrieval was a pseudoaneurysm.Retrieval of an embolized or malpositioned WD is feasible, and familiarity with snares and grasping tools can facilitate a successful removal.

    View details for DOI 10.1016/j.hrthm.2020.04.024

    View details for PubMedID 32464184

  • Outcomes in patients with cardiac amyloidosis and implantable cardioverter-defibrillator. Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology Kim, E. J., Holmes, B. B., Huang, S., Lugo, R., Al Aboud, A., Goodman, S., Hung, R. R., Slosky, D., Stevenson, W. G., Michaud, G. F., John, R. M. 2020; 22 (8): 1216-1223


    Cardiac amyloidosis (CA) is associated with increased mortality due to arrhythmias, heart failure, and electromechanical dissociation. However, the role of an implantable cardioverter-defibrillator (ICD) remains unclear. We conducted case-control study to assess survival in CA patients with and without a primary prevention ICD and compared outcomes to an age, sex, and device implant year-matched non-CA group with primary prevention ICD.There were 91 subjects with CA [mean age= 71.2 ± 10.2, female 22.0%, 49 AL with Mayo Stage 2.9 ± 1.0, 41 transthyretin amyloidosis (ATTR), 1 other] followed by Vanderbilt Amyloidosis centre. Patients with ICD (n = 23) were compared with those without (n = 68) and a non-amyloid group with ICD (n = 46). All subjects with ICD had implantation for primary prevention. Mean left ventricular ejection fraction was 36.2% ± 14.4% in CA with ICD, 41.0% ± 10.6% in CA without ICD, and 33.5% ± 14.4% in non-CA patients. Over 3.5 ± 3.1 years, 6 (26.1%) CA, and 12 (26.1%) non-CA subjects received ICD therapies (P = 0.71). Patients with CA had a significantly higher mortality (43.9% vs. 17.4%, P = 0.002) compared with the non-CA group. Mean time from device implantation to death was 21.8 months in AL and 22.8 months in ATTR patients. There was no significant difference in mortality between CA patients who did and did not receive an ICD (39.0% vs. 46.0%, P = 0.59).Despite comparable event rates patients with CA had a significantly higher mortality and ICDs were not associated with longer survival. With the emergence of effective therapy for AL amyloidosis, further study of ICD is needed in this group.

    View details for DOI 10.1093/europace/euaa094

    View details for PubMedID 32514579

  • Frequency Content of Unipolar Electrograms May Predict Deep Intramural Excitable Substrate: Insights From Intramural Needle Catheter Ablation of Ventricular Tachycardia. JACC. Clinical electrophysiology Qian, P. C., Oberfeld, B., Schaeffer, B., Nakamura, T., John, R. M., Sapp, J. L., Stevenson, W. G., Tedrow, U. B. 2020; 6 (7): 760-769


    This study sought to identify midmyocardial arrhythmogenic substrates by examining the frequency content of unipolar endocardial surface electrograms, comparing sites with transmural scar versus sites with intramural excitable substrate (IES) as identified during needle catheter ablation for ventricular tachycardia (VT).Midmyocardial arrhythmogenic substrates are a common reason catheter ablation for VT may fail.A total of 659 intramural needle sites were studied in 26 patients (age 61 ± 9 years, 85% male, 69% nonischemic cardiomyopathy) who underwent intramural needle catheter ablation for VT. Among 136 sites where endocardial pacing did not capture (threshold >10 mA), needle pacing captured at 29 indicating IES, and did not capture at 107 indicating transmural scar. Intramural needle ablation was performed at 21 of 29 IES sites. Analysis of voltage amplitude, duration, and power spectra of endocardial and intramural needle electrograms was performed.IES sites compared with transmural scar had higher endocardial unipolar electrogram voltage, 0.99 (interquartile range [IQR]: 0.69 to 1.62) mV versus 0.78 (IQR: 0.61 to 1.09) mV; p = 0.038; higher unipolar intramural needle electrogram voltage, 1.16 (0.80 to 1.69) mV versus 0.76 (0.6 to 1.12) mV; p = 0.003; higher endocardial unipolar frequency power particularly in the 5- to 20-Hz band, 1.97 (IQR: 0.93 to 3.89) mV2/s versus 1.03 (IQR: 0.63 to 2.22) mV2/s; p = 0.002; and higher unipolar intramural electrogram frequency particularly in the 0 to 10 Hz range, 3.02 (IQR: 0.98 to 6.95) mV2/s versus 1.33 (IQR: 0.70 to 3.13) mV2/s; p = 0.018. Endocardial unipolar frequency in the 5- to 20-Hz band identified sites with IES, area under the curve of 0.676; p = 0.002; power frequency integral of >0.77 mV2/s provided a 90% sensitivity and 41% specificity.The frequency content of unipolar electrograms may complement voltage in the detection of deep intramural substrates to facilitate VT catheter ablation. (Intramural Needle Ablation for Ablation of Recurrent Ventricular Tachycardia; NCT01791543).

    View details for DOI 10.1016/j.jacep.2020.03.003

    View details for PubMedID 32703556

  • Atrial conduction velocity and risk of recurrent atrial fibrillation after ablation: Time to blank the blanking period? JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY John, R. M., Mitra, R. 2020; 31 (8): 1950-1952

    View details for DOI 10.1111/jce.14580

    View details for Web of Science ID 000538862700001

    View details for PubMedID 32445411

  • Concomitant leadless pacemaker implantation and lead extraction during an active infection. Journal of cardiovascular electrophysiology Chang, D., Gabriels, J. K., Soo Kim, B., Ismail, H., Willner, J., Beldner, S. J., John, R. M., Epstein, L. M. 2020; 31 (4): 860-867


    The need for transvenous lead extractions due to cardiac implantable electronic device (CIED)-related infections continues to rise. Current guidelines recommend complete device removal in the setting of an active infection, which can be challenging in pacemaker-dependent patients.We retrospectively reviewed all leadless pacemaker implants between January 2018 and November 2019 and identified a subset of patients who had undergone a concomitant CIED extraction in the setting of an active infection. Baseline characteristics, procedural details, and clinical follow-ups were recorded.Seventeen patients received a leadless pacemaker during the same procedure as the CIED extraction. There were no procedural complications. All patients were being treated for an active CIED infection at the time of the procedure. Fourteen patients (82.4%) were completely pacemaker-dependent and four patients (23.5%) had positive blood cultures at the time of the leadless pacemaker implantation. During a median follow-up of 143 days (interquartile range: 57, 181 days), there were no recurrent infections.Simultaneous leadless pacemaker implantation and CIED extraction are safe and feasible in the setting of an active infection. This strategy may be particularly useful in patients that are pacemaker-dependent.

    View details for DOI 10.1111/jce.14390

    View details for PubMedID 32048776

  • Characteristics of myocardial tissue staining and lesion creation with an infusion-needle ablation catheter for the treatment of ventricular tachycardia in humans. Heart rhythm Schaeffer, B., Tanigawa, S., Nakamura, T., Muthalaly, R. G., Sapp, J., John, R., Ghidoli, D., Pellegrini, C., Tedrow, U., Stevenson, W. G. 2020; 17 (3): 398-405


    Intramural substrate causing ventricular tachycardia can be targeted by radiofrequency (RF) infusion-needle catheter ablation.The purpose of the study was to assess fluid distribution within the myocardium after needle-ablation catheter infusion and its evidence to RF lesion creation.In 25 patients (21 (84%) male; 67 ± 9 years; 8 (32%) with ischemic cardiomyopathy) intramural ablation of ventricular tachycardia was performed with a needle catheter. Fluoroscopic images of myocardial staining patterns produced by pre-RF saline/contrast infusion were analyzed. Lesion creation was defined as tissue inexcitability to high-output needle pacing.Data from 155 sites were eligible for analysis. Tissue staining was evident in 111 (72%) and absent in 44 (28%). The stain shapes were variable, with average dimensions of 20 ± 10 × 8 ± 4 mm with an area of 68 ± 58 mm2. Round/oval-shaped stains were most common (62 [56%]), while multisegmented (36 [32%]) and long flat (13 [12%]) configurations were less frequent. Evidence of staining was associated with evidence of lesion creation (92/111 (83%) vs 17/44 (39%); P ≤ .0001). Contrast staining around the needle was present in 50%, usually had blurred margins, and was associated with lesion creation. When staining extended well beyond the needle, the margins were often sharp, suggesting dissection through tissue planes, and lesion creation tended to be less effective.With infusion-needle ablation, preablation injection of contrast can help confirm an intramural position and predict lesion creation. Tissue diffusion patterns vary markedly, and studies to assess its relation to tissue architecture and ablation lesion geometry warrants further investigation. The findings also have implications for the injection of therapeutic agents into the regions of scar.

    View details for DOI 10.1016/j.hrthm.2019.10.007

    View details for PubMedID 31604127

  • Use of Implantable Electronic Devices in Patients With Cardiac Amyloidosis. The Canadian journal of cardiology John, R. M., Stern, D. L. 2020; 36 (3): 408-415


    Arrhythmias are a major cause of morbidity and mortality in the course of cardiac amyloidosis (CA). Less commonly, they may be the initial manifestation that lead to the diagnosis. With improved therapeutic interventions for amyloidosis, it is no longer considered to be a terminal untreatable condition, and there is increasing recognition of the role of implantable electronic devices in CA. The frequency and nature of arrhythmias are largely determined by the type of amyloidosis. Bradyarrhythmias are more common in the transthyretin form of amyloidosis, and risk for ventricular arrhythmias is higher in the light-chain form. Pacemaker implantation is often required and effective for alleviation of symptoms. The role of implantable cardioverter-defibrillators (ICDs) remains controversial, especially for primary prevention of sudden death. Traditional risk stratification tools for sudden death do not appear to be applicable to CA, because decline of left ventricular (LV) systolic dysfunction to the point of the usual indication for an ICD implant in other cardiomyopathies, ie, LV ejection fraction ≤ 35%, usually marks end-stage disease in CA when pump failure becomes the predominant cause of death. The challenge remains the identification of markers for sudden death in early stages of the disease. Included in this review is a general overview of available data on the nature of bradycardia and ventricular arrhythmias, including the role of implantable electronic devices for the treatment of these conditions. Published series of ICD use in CA are summarized and the role of newer pacing techniques, including biventricular pacing, is discussed.

    View details for DOI 10.1016/j.cjca.2019.12.002

    View details for PubMedID 32037105

  • Arrhythmias from the Right Ventricular Moderator Band: Diagnosis and Management. Arrhythmia & electrophysiology review Barber, M., Chinitz, J., John, R. 2020; 8 (4): 294-299


    The moderator band in the right ventricle is being increasingly recognised as a source for arrhythmias in the absence of identifiable structural heart disease. Because it carries part of the conduction system from the right ventricle septum to the free wall, it is a source of Purkinje-mediated ventricular arrhythmias that manifest as premature ventricular contractions (PVC) or repetitive ventricular tachycardia. More importantly, short coupled PVCs triggering polymorphic ventricular tachycardia and VF have been localised to the moderator band and ablation of these Purkinje mediated PVCs can effectively prevent recurrent VF. The exact mechanism of arrhythmogenesis is still debated but stretch, fibrosis and ion channel alterations might be responsible. Arrhythmias originating in this region of the right ventricle may thus be another cause for idiopathic VF that is potentially treatable with catheter-based ablation techniques. Recognition of the typical PVC morphology can point to the moderator band as the source of idiopathic VF and an opportunity for timely intervention. The available data on the anatomy, electrophysiology and management options are reviewed.

    View details for DOI 10.15420/aer.2019.18

    View details for PubMedID 32685160

    View details for PubMedCentralID PMC7358944

  • Sustained quality-of-life improvement post-cryoballoon ablation in patients with paroxysmal atrial fibrillation: Results from the STOP-AF Post-Approval Study. Heart rhythm Jain, S. K., Novak, P. G., Sangrigoli, R., Champagne, J., Dubuc, M., Adler, S. W., Svinarich, J. T., Essebag, V., Martien, M., Anderson, C., John, R. M., Mansour, M., Knight, B. P. 2020; 17 (3): 485-491


    Pulmonary vein isolation by catheter ablation is a class IA indication for the treatment of symptomatic, drug-refractory, paroxysmal atrial fibrillation (PAF). Quality of life (QoL) has been identified as a clinically meaningful endpoint but has not been comprehensively evaluated to date.The purpose of this study was to evaluate the effects of cryoballoon ablation on long-term QoL.As part of the STOP-AF Post-Approval Study, QoL was assessed using the Short Form-12 Health Survey (SF-12) along with evaluation of arrhythmia-related symptoms through 36 months. A multivariate linear mixed effects regression was used to determine the association between atrial fibrillation symptoms and QoL scores, and univariate linear regressions were used to assess predictors of 36-month change in QoL scores.Three hundred thirty-five subjects fully completed SF-12 forms at baseline, with 319, 308, 291, and 278 subjects completing surveys at the subsequent follow-up visits. Both physical and mental composite scores increased significantly from baseline (P <.001), and all arrhythmia symptoms significantly decreased from baseline (P <.001), with 62.0% of subjects reporting no symptoms at 6 months compared to 5.7% at baseline (P <.001). Presence of dyspnea and fatigue at baseline were univariate predictors of physical QoL improvement (P = .045 and 0.0497, respectively), whereas each year of age and each year of PAF duration were predictors of a decrease in mental QoL (P = .014 and .04, respectively).Cryoballoon ablation for treatment of PAF results in a significant, and sustained, QoL improvement. The observed improvement in physical and mental health likely may be mediated by a reduction in symptom and arrhythmia burden.

    View details for DOI 10.1016/j.hrthm.2019.10.014

    View details for PubMedID 31606461

  • Contraindication to Anticoagulation in Nonvalvular Atrial Fibrillation: Are We Still to Fear the Clot and Not the Bleed? JACC. Clinical electrophysiology John, R. M., Sharma, D. 2019; 5 (12): 1393-1395

    View details for DOI 10.1016/j.jacep.2019.07.008

    View details for PubMedID 31857037

  • Sustained Monomorphic Ventricular Tachycardia in Nonischemic Heart Disease: Arrhythmia-Substrate Correlations That Inform the Approach to Ablation. Circulation. Arrhythmia and electrophysiology Kanagasundram, A., John, R. M., Stevenson, W. G. 2019; 12 (11): e007312


    As the population of patients with implanted defibrillators has grown, an increasing number of patients nonischemic cardiomyopathies are requiring therapy to reduce ventricular arrhythmias. Most of these arrhythmias are related to areas of ventricular scar. Although the pathophysiology of scar development is not well understood in these diseases, advances in cardiac imaging and mapping are better characterizing the scar locations that give rise to the arrhythmias. Here, we review the pathophysiologic and electrocardiographic correlations that inform ablation strategies for ventricular tachycardia in these diseases.

    View details for DOI 10.1161/CIRCEP.119.007312

    View details for PubMedID 31661970