Time-Dependent Relationship between Ventricular Repolarization and Arrhythmia in Patients with Cardiac Resynchronization Therapy

Abstract

Background: Cardiac resynchronization therapy (CRT) improves the clinical status of patients with severe heart failure, but there is some evidence that left ventricular (LV) pacing may have proarrhythmic potential. LV pacing results in a change of transmural dispersion of repolarization (TDR), which may be associated with prolongation of Tpeak to Tend interval (Tp-e). Methods: The study group consisted of 55 patients with CRT (66±12 years old, 41 males, 44 ischemic and 11 non-ischemic cardiomyopathy, NHYA class 3.1±0.6, QRS duration 171±33 ms and EF 25.9±9.8%). Twelve-leads ECG were digitally-recorded and Tp-e was measured at baseline and 1 week, 1 month, 3 months, 6 months and 12 months after CRT device implantation. We investigated the time-dependent relationship between Tp-e and the occurrence of ventricular arrhythmia (VA) and compared those parameters in responder group with non-responder group of CRT. Result: 5 of 12 VA episodes (42%) occurred within one month after the implantation. Tp-e reduced significantly at 6 and 12 months after the implantation compared with baseline (P<0.05). Tp-e in responder group was lower compared with that in non-responder group over time (P=0.06). Kaplan-Meier event-free survival analysis demonstrated that the responder group had a significantly lower rate of appropriate ICD therapy (log-rank test, P=0.005). Conclusion: The prolonged TDR and the proarrhythmic effect occurred within one month after CRT device implantation but reduced over time, especially in CRT responder.