About

Saman Nazarian, MD, PhD, is a Professor of Medicine in the Department of Cardiovascular Medicine at the Hospital of the University of Pennsylvania and a faculty member at the Perelman School of Medicine. He earned his BS in Chemistry and Biology from the University of California, Davis, graduating Summa Cum Laude in 1995. He completed his MD at Stanford University School of Medicine in 1999 and obtained a PhD in Clinical Epidemiology from Johns Hopkins Bloomberg School of Public Health in 2012. Dr. Nazarian completed his internship and residency in Internal Medicine at Harvard's Brigham and Women’s Hospital, followed by fellowships in Cardiovascular Medicine and Clinical Cardiac Electrophysiology at Johns Hopkins University School of Medicine. He initially joined the Johns Hopkins faculty, where he developed a busy clinical practice and an active research portfolio funded by the NIH, and was promoted to Associate Professor and Director of the Ventricular Arrhythmia Ablation service by 2014. In 2016, he joined the University of Pennsylvania, continuing his focus on clinical interests such as atrial and ventricular arrhythmia substrate identification and ablation, prevention of sudden cardiac death, and management of arrhythmias in various cardiac conditions. Dr. Nazarian is a clinical and translational investigator specializing in cardiac electrophysiology, with particular interest in advanced imaging modalities for optimizing ablation procedures for complex ventricular arrhythmias in structural heart disease. He oversees a research team dedicated to atrial and ventricular arrhythmia research and clinical care, and has served as principal investigator on several NIH grants. He is also an active mentor to medical students, residents, and post-doctoral fellows, and is a member of the Heart Rhythm Journal Editorial Board. His professional affiliations include fellowships in the American Heart Association, American College of Cardiology, and the Heart Rhythm Society.

Research topics

• Genetics
• Biology
• Cardiology
• Virology
• Internal medicine
• Medicine
• Mathematics
• Evolutionary biology
• Computational biology

Selected publications

• Role of Cardiovascular Magnetic Resonance in Diagnosis and Management of Muscular Dystrophies

  Journal of Cardiovascular Magnetic Resonance · 2026-01-01 · 2 citations

  articleOpen access

  Muscular dystrophies encompass a heterogeneous spectrum of inherited myopathies characterized by progressive skeletal muscle degeneration frequently accompanied by life-threatening cardiac involvement. Cardiovascular magnetic resonance (CMR) has become the reference non-invasive imaging modality for the detection, characterization, and longitudinal monitoring of cardiomyopathy involvement across this group of disorders. This state-of-the-art review synthesizes contemporary evidence on the diagnostic and prognostic value of CMR in the most prevalent muscular dystrophies, including Myotonic dystrophy, Duchenne and Becker muscular dystrophies, Emery-Dreifuss muscular dystrophy, laminopathies, facioscapulohumeral muscular dystrophy, and mitochondrial myopathies. CMR uniquely enables high-resolution assessment of ventricular volumes and function, tissue characterization through late gadolinium enhancement (LGE) and parametric mapping (native T1, T2, extracellular volume fraction), and quantitative strain imaging. These techniques uncover subclinical myocardial involvement years before overt dysfunction occurs, providing a robust substrate for early therapeutic intervention. Disease-specific CMR signatures, such as inferolateral subepicardial fibrosis in dystrophinopathies or mid-wall septal enhancement in laminopathies, allow for refined etiological diagnosis and targeted risk stratification. LGE burden and distribution are independently associated with ventricular arrhythmias and adverse cardiac events, transcending the limitations of traditional criteria based on left ventricular ejection fraction for implantable cardioverter-defibrillator selection. Emerging evidence further supports the integration of CMR biomarkers into genotype-guided management strategies and prospective therapeutic trials.

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• PO-04-064 ANATOMICAL APPROACH FOR SLOW PATHWAY ABLATION USING INTRACARDIAC ECHOCARDIOGRAPHY

  Heart Rhythm · 2026-04-01

  article
  PublisherDOI

• PO-03-133 EARLY SUPRAVENTRICULAR ARRHYTHMIA RISK AFTER ACUTE PULMONARY EMBOLISM

  Heart Rhythm · 2026-04-01

  articleSenior author
  PublisherDOI

• Abstract 4366692: Left Atrial Lipomatous Metaplasia in Patients with Atrial Fibrillation

  Circulation · 2025-11-03

  articleSenior author

  Background: Epicardial adipose tissue is associated with prevalent and incident atrial fibrillation (AF). The mechanism for this association has been at least partially attributed to fatty atrial infiltration, or lipomatous metaplasia (LM), of the left atrium (LA). Objective: The purpose of this study was to quantitate the extent of LA LM using contrast enhanced computed tomography (CECT) and to examine its association with intracardiac electrogram characteristics using high density electroanatomic mapping in patients referred for AF ablation. Methods: The retrospective cohort included consecutive patients who underwent CECT and LA high-density mapping (Pentaray, Biosense Webster) prior to AF ablation between January 2021- 2023. Univariable associations were examined using nonparametric tests. The association of bipolar voltage amplitude and mid-LA myocardial CECT image intensity (< 0 Hounsfield units indicative of LM, ADAS 3D software), at each electroanatomic map point, was examined using a mixed effects linear regression model clustered by patient. Results: The cohort consisted of 34 patients with mean age 66.4 ± 9.5 years, BMI of 31.7 ± 9.5 kg/m2, left atrial volume index (LAVI) 38.0 ± 8.1 mL, and EF 51 ±13%. Of all patients, 41% were female, 65% had persistent AF, 74% had hypertension, 41% had coronary disease, 12% had diabetes, 33% had sleep apnea, and 15% had prior stroke or TIA. LM was detected among 53% of patients (95% CI 36-69%), and was unassociated with age, BMI, LAVI, AF type, sex, diabetes, sleep apnea, or hypertension. Bipolar voltage was associated with CECT attenuation (-0.2 mV/ Hounsfield unit, P<0.001), but was unassociated with LM. Conclusions: LA LM was prevalent in a small cohort of patients undergoing AF ablation and was unassociated with traditional risk factors and voltage mapping. Additional studies are warranted to refine the understanding of LM as an atrial myopathy.

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• Stereotactic Body Radiation Therapy for Ventricular Tachycardia is Safe and Effective: Results from a Large Retrospective Cohort

  International Journal of Radiation Oncology*Biology*Physics · 2025-09-01

  articleOpen access
  PublisherOA PDFDOI

• Abstract 4345633: Left Atrial Lipomatous Metaplasia Quantified by Contrast-Enhanced Cardiac Computed Tomography in Patients with Atrial Fibrillation

  Circulation · 2025-11-03

  articleSenior author

  Introduction/Background: Left atrial (LA) pericardial and epicardial fat are associated with atrial fibrillation (AF). However, the association of LA intramyocardial fat, i.e. lipomatous metaplasia (LALM), with AF persistence and ablation outcomes is understudied. Research Question/Hypothesis: Do the total and regional distributions of LALM differ between paroxysmal and persistent AF, and does higher LALM burden predict early AF recurrence after catheter ablation? Methods/Approach: We retrospectively analyzed 100 patients who underwent contrast-enhanced cardiac computed tomography less than one year before AF ablation. The LA was segmented using ADAS software into standardized regions (Panel A) and LALM was quantified using intensity thresholds [−180 to 0 Hounsfield unit (HU)]. Total and regional LALM burdens were expressed as percentages of total LA myocardial and respective regional volumes. For transmural analysis, the myocardium was equally divided into 20%, 40%, 60%, and 80% wall depth-layers from sub-endocardium to sub-epicardium. Patients were stratified by AF persistence and by freedom from or recurrence of AF (≥30 s) beyond a three-month blanking period. Results/Data: Total LALM comprised a median of 16.6% (interquartile range: 11.0–21.1%) of the total LA myocardial volume. Regional burden was highest at the right (28.1%) and left (19.8%) pulmonary vein (PV) carinae, followed by the inferior wall (19.6%), interatrial septum (15.0%), posterior wall (14.1%), lateral wall (12.7%), and superior wall (10.7%). Patients with persistent AF (n = 43) had a significantly higher LALM percentage than those with paroxysmal AF (n = 57; 17.2% vs 16.1%, p = 0.03) (Panel B). No significant difference was found between patients with and without AF recurrence following ablation (16.4% vs 16.8%, p = 0.82) (Panel C). A transmural gradient was observed, with LALM increasing from the sub-endocardium (3.5%) to the sub-epicardium (24.9%, p < 0.001) (Panel D). Conclusions: LALM percentage is significantly greater in persistent than paroxysmal AF. Regionally, the highest percentages are found at the right and left PV carinae, followed by the inferior wall, and interatrial septum. Further investigation into LALM pathogenesis and its association with treatment outcomes is warranted.

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• Sequencing in over 50,000 cases identifies coding and structural variation underlying atrial fibrillation risk

  UNC Libraries · 2025-09-07

  articleOpen access
  PublisherDOI

• Left Bundle Branch Area Pacing in Patients With Cardiac Sarcoidosis

  JACC. Clinical electrophysiology · 2025-11-20 · 2 citations

  article
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• Intracardiac echocardiography for left ventricular diastolic function assessment during atrial fibrillation ablation

  Journal of Interventional Cardiac Electrophysiology · 2025-08-27

  articleOpen access

  BACKGROUND: Left ventricular (LV) diastolic dysfunction is associated with the development of atrial fibrillation (AF) and risk of recurrence after ablation. The use of an intracardiac echocardiography (ICE) for diastolic function assessment during ablation procedures has not been evaluated. OBJECTIVES: To evaluate the feasibility and utility of ICE obtained measures of LV diastolic function including peak tricuspid regurgitation velocity, trans-mitral flow velocity, mitral annular tissue Doppler velocities, and pulmonary vein flow velocities in patients undergoing AF ablation. METHODS: We conducted a single-center, prospective evaluation of patients undergoing AF ablation between 2022 and 2024. During sinus rhythm, diastolic parameters were measured with the ICE catheter and direct left atrial pressure (LAP) was recorded prior to AF ablation. Elevated LAP was defined as ≥ 12 mmHg. ICE measured diastolic parameters were compared with those measured on transthoracic echocardiography (TTE). RESULTS: -VASc score of 3 ± 2) were analyzed, of which 80 had normal LAP (< 12 mmHg) by direct measurement. Several ICE parameters were found to be significantly associated with mean LAP, including greater peak tricuspid regurgitation velocity (β = 3.5; p = 0.005) and average E/e' (β = 0.7; p < 0.001). In multivariable model, post-procedure intravenous diuretics were more commonly required in patients with abnormal diastolic function by ICE (mitral E/A OR = 8.1; average E/e' OR = 24.2). CONCLUSIONS: ICE can be used to assess diastolic function with traditional parameters correlating with both TTE diastolic function and LAP. ICE measures of restrictive filling are associated with the need for post-procedural intravenous diuretics.

  PublisherOA PDFDOI

• Abstract 4360314: Association of Epicardial Adipose Tissue with Lipomatous Metaplasia and Ventricular Tachycardia Recurrence Following Ablation in Patients with Non-Ischemic Cardiomyopathy

  Circulation · 2025-11-03

  articleSenior author

  Introduction: Patients with non-ischemic cardiomyopathy (NICM), present with complex intramural ventricular tachycardia (VT) circuitry and relatively high post-ablation recurrences. Hypothesis: We hypothesize that left ventricular epicardial adipose tissue (LV-EAT) is associated with myocardial lipomatous metaplasia (LM) and post-ablation VT recurrence in NICM patients. Methods: In this retrospective study, we quantified LV-EAT and LM in a cohort of consecutive NICM patients with cardiac contrast-enhanced CT prior to VT ablation. Cox proportional hazard regression models were used to determine the association of LV-EAT and LM with time to VT recurrence and mortality as the competing risk. Results: Among 113 patients, 50 experienced VT recurrence during 1.7 (IQR 0.7, 4.0) years median follow-up. Patients with VT recurrence demonstrated significantly greater LV-EAT volume (median 32.9 vs. 28.2 ml, p = 0.026), greater LV-EAT thickness (median 1.0 vs. 0.9 mm, p = 0.043), and a more negative LV-EAT attenuation (median -65.1 vs. -58.4 HU, p &lt; 0.001; Figure 1A). Univariable Cox regression demonstrated associations between all LV-EAT parameters and VT recurrence, which persisted after adjustment for heart failure and amiodarone use (adjusted hazard ratio [aHR]: 1.01 [95% CI: 1.00–1.02] per 1 ml increase of LV-EAT volume; 1.79 [1.14–2.80] per 1 mm increase of thickness; 0.94 [0.91–0.97] per 1 HU increase of attenuation value). When incorporating LM, only LV-EAT attenuation remained independently associated (aHR 0.96 per 1 HU increase, p = 0.039), alongside LM volume (aHR 1.09 per 1 ml increase, p = 0.012). Distribution analysis, using the AHA-17 segment model, demonstrated an association between lateral and inferior wall LV-EAT and VT recurrence (Figure 1B). Moderate correlation was noted between LV-EAT attenuation and LM volume (r = 0.37). Mediation analysis revealed that 10% of the effect of LM on VT recurrence was mediated by LV-EAT attenuation, while 55% of the effect of LV-EAT attenuation on VT recurrence was mediated by LM (Figure 1C). Conclusions: LV-EAT demonstrates independent association with post-ablation VT recurrence in NICM patients while exhibiting significant statistical interaction with LM.

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Recent grants

• NIH Grant R01HL116280

  NIH · $1.2M · 2020

• NIH Grant K23HL089333

  NIH · $686k · 2016

• Implications of Intra-Myocardial Fat Deposition upon Propensity for Malignant Arrhythmia

  NIH · $2.5M · 2018–2024

Frequent coauthors

• Hugh Calkins

  Johns Hopkins Hospital

  411 shared

• Ronald D. Berger

  338 shared

• David Spragg

  229 shared

• Joseph E. Marine

  Johns Hopkins University

  228 shared

• Henry R. Halperin

  Johns Hopkins Hospital

  186 shared

• Francis E. Marchlinski

  166 shared

• Hiroshi Ashikaga

  Johns Hopkins Medicine

  156 shared

• Alan Cheng

  McMaster University

  140 shared

Education

• PhD, Clinical Epidemiology

  Johns Hopkins University

• MD

  Stanford University School of Medicine

  1999