Ventricular Parasystole in Cardiomyopathy Patients A Link Between His-Purkinje System Damage and Ventricular Fibrillation

BACKGROUND The clinical relevance and prognostic implications of ventricular parasystole are unknown. OBJECTIVES This study sought to assess the prevalence of ventricular parasystole in patients with implantable cardioverter-defibrillators (ICDs) and ventricular parasystole's association with ventricular arrhythmias and conduction system abnormalities. METHODS This study retrospectively evaluated patients who underwent ICD interrogation at a single center between June 1, 2019, and August 31, 2020, and reviewed all available ICD and electrocardiogram data. This study identified patients with ventricular parasystole and compared the prevalence of ventricular fibrillation (VF), ventricular tachycardia (VT), and new conduction system abnormalities in those with >= 5 years of intrinsic QRS-complex electrocardiograms to those without parasystole. RESULTS This study included 374 patients (age 57 +/- 21 years, 72% male, 45% nonischemic, 32% ischemic cardiomyopathy), of which, 104 (28%) had VT only, 39 (10%) VF only, and 10 (3%) both VT/VF. Ventricular parasystole was identified in 33 patients (9%); parasystolic foci were predominantly from the His-Purkinje system. Compared with those without parasystole, patients with parasystole had a significantly higher rate of VF (36% vs 11%; P < 0.01), but not VT (42% vs 29%; P = 0.12). Patients with parasystole, compared with those without parasystole, had a higher prevalence of new conduction abnormalities, particularly progressive intraventricular conduction delay (11 of 18 [61%] vs 12 of 83 [14%]; P < 0.01) and new right bundle branch block (4 of 18 [22%] vs 1 of 83 [1%]; P < 0.01). CONCLUSIONS Ventricular parasystole was strongly associated with new conduction system abnormalities and VF in patients who have cardiomyopathy with ICDs, suggesting a potential link between VF and His-Purkinje damage in this patient population. (c) 2023 by the American College of Cardiology Foundation.

Automated summary

This study examines the association between ventricular parasystole and ventricular arrhythmias and conduction system abnormalities in patients with implantable cardioverter-defibrillators (ICDs). The findings suggest that ventricular parasystole is strongly associated with ventricular fibrillation (VF) and new conduction system abnormalities, indicating a potential link between VF and damage to the His-Purkinje system.