Abstract 13300: Does Mechanical Dyssynchrony in Addition to QRS Area Ensure Sustained Response to Cardiac Resynchronization Therapy?

Abstract

Introduction: Judicious patient selection for CRT may further enhance treatment response. Progress has been made by using improved markers of electrical dyssynchrony and mechanical discoordination, using QRS AREA , and systolic rebound stretch of the septum (SRSsept) or systolic stretch index (SSI), respectively. Hypothesis: We hypothesize that the presence of combined electrical and mechanical dysfunction are of added benefit in predicting a sustained CRT-response. Methods: A total of 240 CRT patients were prospectively enrolled from six centers. Patients underwent standard 12-lead electrocardiography, and echocardiography, at baseline, 6 month, and 12 month follow-up. QRS AREA was derived using vectorcardiography, and SRSsept and SSI were measured using strain-analysis. Reverse remodelling was measured as the relative decrease in left ventricular end-systolic volume, indexed to body surface area (ΔLVESVi). Sustained response was defined as ≥ 15% decrease in LVESVi, at both 6 and 12 month follow-up. Presence of left bundle branch block (LBBB) was determined according to strict American Heart Association criteria. Results: QRS AREA and SRSsept were both strong, multivariably adjusted, predictors of reverse remodelling. The presence of SRSsept ≥ 2.5%, in addition to QRS AREA ≥ 120 μVs, significantly increased the extent of reverse remodelling when compared to high QRS AREA alone (ΔLVESVi 38±21 versus 22±21%). As a result, 100% of LBBB-patients and 74% of non-LBBB patients with combined electrical and mechanical dysfunction were sustained volumetric responders, as opposed to 53% and 46% with high QRS AREA alone, respectively. Conclusions: In patients with high QRS AREA , concomitant presence of high SRSsept significantly increases 6-month remodelling after CRT. Combined presence of high SRSsept and QRS AREA , but not high QRS AREA alone, is of importance in order to ensure a sustained response after CRT in LBBB patients.