B-PO04-181 AN EVALUATION OF LEFT VENTRICULAR REVERSE REMODELING IN PATIENTS WITH LEFT BUNDLE BRANCH BLOCK AND QRS DURATION LESS THAN 150MS

Abstract

The benefit of cardiac resynchronization therapy (CRT) for patients with left bundle branch block (LBBB) and QRS duration (QRSd) between 120 and 150 milliseconds (ms) remains contested. Left ventricular (LV) reverse remodeling may help identify the benefit of CRT in these patients. We hypothesized that patients with LBBB QRSd between 120 and 150ms would have significant LV reverse remodeling on echocardiography after initiation of CRT comparable to patients with LBBB QRSd > 150ms. We aimed to study the effects of CRT on LV reverse remodeling in patients with LBBB QRSd < 150ms compared to patients with QRSd > 150ms. From a cohort of 258 patients who initiated CRT between 2016 and 2019, we performed a retrospective case-control study comparing the reduction in LV end-systolic volume (LVESV) of 19 patients with New York Heart Association Class II-III symptoms on goal-directed medical therapy (GDMT) with LBBB and QRSd < 150ms who received CRT and 19 controls with QRSd > 150ms. LVESV was measured on echocardiography within 6 months prior to CRT implantation and at least 1 year after implantation. There was a significant reduction in LVESV (mL) in patients with QRSd < 150ms from 121.25 to 84.91 (p = 0.0399) and in patients with QRSd > 150ms from 162.2 to 140.1 (p = 0.019). There was no significant difference in the absolute or relative magnitude of the reduction in LVESV between the two groups (absolute: 25.74 vs 44.98 mL, p = 0.48, relative: 27.67% and 28.91%, p = 0.91). Spacing of the echocardiograms before and after CRT introduction did not significantly differ between cases and controls (432.4 vs 460.9 days, p = 0.579). LV reverse remodeling occurred significantly and comparably in both patients with LBBB and QRSd < 150ms and patients with LBBB and QRSd > 150ms. As reduction in LVESV is an important predictor of survival with biventricular pacing, CRT may provide benefit to patients with systolic dysfunction on GDMT with LBBB and QRSd < 150ms.