Abstract 15331: Ventricular Conduction and Repolarization Prolongation Noted During Right Ventricular Pacing as Predictors of Ventricular Arrhythmias and Cardiac Mortality in Subjects With Cardiomyopathy

Abstract

Introduction: Clinical predictive value of transient prolonged ventricular conduction and repolarization during right ventricular (RV) pacing have not been studied. Hypothesis: Ventricular conduction and repolarization prolongation during RV pacing predict risk of arrhythmic and mortality events. Methods: Electrophysiology studies in 501 patients with cardiomyopathy (CM) were reviewed. Duration changes of QRS and QT interval during pacing from the RV apex were measured. Subjects were followed up for a mean of 3.2 years for arrhythmic events and total mortality. Results: Participants had a mean age 65 yrs, 80% male, 74% funcional class II or III, and a mean EF of 33.1%. A paced QRS duration > 190 ms was associated with more severe CM and in multi-variable analysis it was associated with a 3.5 times higher risk of ventricular arrhythmias or appropriate defibrillator therapy (HR 3.5, 95% CI 2.3-5.4, p<0.01) and 2.6 times higher risk of total mortality or arrhythmic events (HR 2.6, 95% CI 2.3-3.4, p<0.01) compared to a paced QRS duration <190 ms, independent of baseline EF or baseline QRS duration, and after adjustment for electrophysiology study results, baseline functional class, type of cardiomyopathy and other relevant clinical factors. Similarly a QTc interval during RV pacing > 620 ms was associated with a 2.7 times higher risk of arrhythmic events compared to a QTc interval during RV pacing < 620 ms. Conclusions: Prolongation of ventricular conduction (QRS > 190 ms) and repolarization (QTc > 620 ms) observed during RV pacing in subjects with CM are associated with higher risk of arrhythmic events, defibrillator therapies and all-cause mortality.