Long-term effects of cardiac resynchronization therapy on electrical remodeling in heart failure-A prospective study.

INTRODUCTION: Effects of cardiac resynchronization therapy (CRT) on arrhythmogenicity and sudden death have not been fully ascertained. CRT has been shown to increase transmural dispersion of repolarization (TDR) immediately on implantation, which may favorably remodel on long-term follow-up. However, such a hypothesis has not been prospectively evaluated.

METHODS AND RESULTS: We included 35 consecutive patients who underwent CRT implantation between September 2013 and August 2014 (mean age 56.8 ± 11.09 years; 71.43% males). QT and Tpeak-Tend (Tp-e) intervals were measured during endocardial (RVendoP), epicardial (LVepiP), and biventricular pacing (BiVP) at CRT implantation and 1-year follow-up. Compared to RVendoP (130.41 ± 16.75 ms), Tp-e was significantly prolonged during BiVP (142.06 ± 21.98 ms; P < 0.001) and LVepiP (183.45 ± 27.87 ms; P < 0.001) at baseline. There was a significant decrease in Tp-e during BiVP on follow-up (117.93 ± 15.03 ms; P < 0.001). High responders had significantly lower Tp-e at 1 year compared to low responders (113.16 ± 14.3 ms vs 129.59 ± 9.75 ms, P  =  0.004). Tp-e at 1 year had strong negative correlation with reduction in LV end-systolic volumes (r  =  - 0.51; P  =  0.003). Seven patients with sustained ventricular arrhythmias during follow-up had significantly longer baseline Tp-e compared to those without arrhythmias (158.19 ± 17.59 ms vs 139.72 ± 20.94 ms, P  =  0.043). A baseline Tp-e value of ≥ 148 ms had a specificity of 75% and sensitivity of 71% to predict ventricular arrhythmias.

CONCLUSIONS: Baseline TDR is greater during BiVP and LV epiP compared with RVendoP in patients with heart failure. However, BiVP causes a significant reduction in TDR reflective of reverse electrical remodeling on long-term follow-up.