169-07: Long term changes in transmural dispersion of repolarisation in patients with heart failure after cardiac resynchronisation therapy- A prospective study

Abstract

Purpose of the Study: Effects of CRT on sudden cardiac death have not been fully ascertained. Biventricular pacing alters LV depolarisation sequence which may exacerbate transmural dispersion of repolarisation ( TDR). CRT has been proposed to reduce Tpeak-end interval (Tp-e) on long term follow up. However such a hypothesis hasn't been prospectively evaluated. Methods: This is a prospective study of patients with LV dysfunction who underwent CRT implantation between August 2013 & September 2014. Twelve-lead ECGs were recorded at 50mm/s during RV endocardial (EndoP), LV epicardial (EpiP) & biventricular pacing (BiVP) at constant pacing cycle length of 750ms at baseline (within 5 days of CRT implant) and again at 1 year follow up. QRS duration, QT and Tp-e intervals were measured using digital callipers and the highest values in any of the precordial leads were reported. Based on reduction in LV end systolic volumes (LVESV) at 1 year, patients were classified as high CRT responders (>25% reduction) and low responders (<25% reduction). Results: During the study period, 35 consecutive patients (mean age 56.8 ± 11.09 yr; 71.43% males) who underwent CRT implantation were included in the study. Compared to EndoP (130.41 ± 16.75ms), Tp-e was significantly prolonged during BiVP (142.06 ± 21.98ms; p < 0.001) and EpiP (183.45 ± 27.87ms; p < 0.001) at baseline. Follow up data were available for 31 patients of which 22 were high responders while the rest 9 were low responders. There was significant decrease in Tp-e during BiVP on follow up ( 117.93 ± 15.03ms; p < 0.001). High responders had significantly lower Tp-e at 1 year compared to low responders (113.16 ± 14.3ms vs. 129.59 ± 9.75ms, p = 0.004). Tp-e at 1 year had significant negative correlation with reduction in LVESV ( r = -0.51; p = 0.003). Seven patients had sustained ventricular arrhythmias on follow-up and these patients had significantly longer baseline Tp-e (158.19 ± 17.59ms vs. 139.72 ± 20.94ms, p = 0.043). Conclusions: Baseline TDR is greater during BiVP and EpiP compared with EndoP in patients with heart failure. However, BiVP causes significant reduction in TDR on long term follow up. CRT induced reverse LV mechanical remodeling is associated with reverse electrical remodeling.