Abstract 12520: Baseline Mechanical Dyssynchrony is Associated with Improvement in Mitral Regurgitation and Left Ventricular Reverse Remodeling after Cardiac Resynchronization Therapy

Abstract

Background: Mitral regurgitation (MR) is a marker of poor outcome in patients with chronic heart failure. Cardiac resynchronization therapy (CRT) has been shown to improve MR and left ventricular (LV) remodeling. However, it is still unclear how echocardiographic mechanical dyssynchrony relates to reduction in MR and LV reverse remodeling after CRT.

Methods: We prospectively studied 224 consecutive patients with NYHA class III/IV heart failure, QRS width ≥120ms, and LV ejection fraction (EF) ≤35%. Quantitative echocardiography was performed before CRT and 6±3 months after CRT. LV volumes were calculated by biplane Simpson's rule. Baseline dyssynchrony was assessed as interventricular mechanical delay (IVMD) > 40ms, tissue Doppler opposing wall delay (OWD) > 65ms, Yu Index > 32ms, and mid-LV speckle tracking radial strain delay >130ms. The severity of MR was quantitatively assessed by vena contracta width and jet area.

Results: Of 224 CRT patients aged 65±12 yrs with EF 24±6%, 106 patients (47%) had significant MR (≥grade 2+) before CRT, and 74 (33%) had after CRT. Patients with baseline mechanical dyssynchrony by IVMD, OWD, Yu Index, and speckle tracking had significant reductions in MR (all p<0.03) after CRT, whereas MR reductions were modest in patients who lacked dyssynchrony. Furthermore, patients with baseline mechanical dyssynchrony had greater reductions in LV end-systolic volume index after CRT than those without mechanical dyssynchrony (all p<0.05).

Conclusion: Echocardiographic mechanical dyssynchrony at baseline is important factor for improvement in MR and LV reverse remodeling in patients undergoing CRT. These observations have clinical implications.