Abstract 12532: Atrial Fibrillation and Left Ventricular Dilatation as Risk Factors for Newly Developed Mitral Regurgitation after Cardiac Resynchronization Therapy: Impact on Outcome

Abstract

Background: Cardiac resynchronization therapy (CRT) is associated overall with reduction in mitral regurgitation (MR). However, an important subset of patients have newly developed significant MR after CRT.

Objective: To determine risk factors associated with newly developed MR after CRT and their impact on patient outcome.

Methods: We prospectively studied 224 CRT patients with NYHA III/IV heart failure, QRS ≥120ms, and ejection fraction (EF) ≤35%. Echo was performed before and 6±3 months after CRT. Left ventricular (LV) volume was assessed by biplane Simpson's rule. MR was quantified by vena contracta width and jet area, and severity graded from 0 to 4+. MR ≥2+ was defined as significant MR. Long-term outcome events were pre-specified as death, transplant or LV assist device (LVAD).

Results: Of 224 CRT patients, there were 118 (53%) who started with 0-1+ MR. Of these patients without baseline MR, 22 (18%) had newly developed significant MR after CRT. Multivariate analysis demonstrated atrial fibrillation (AF) and increased LVESVI as significant independent of risk factors for newly developed significant MR after CRT (p: 0.01 and 0.03, respectively). Using a cut-off determined by receiver operated characteristic curve analysis, patients with LVESVI ≥62ml/m² and /or AF had a significantly higher rate of newly developed significant MR (p=0.006). In this group of 118 patients with no baseline MR, there were 28 outcome events included 20 deaths, 6 transplants, and 2 LVADs over 4 years. Importantly, patients with newly developed significant MR after CRT had a higher unfavorable event rate than those who remained without significant MR after CRT (p=0.0003).

Conclusion: Although CRT is typically associated with MR reduction, an important subset of patients has newly developed MR, which is associated with poor outcome. AF and a dilated LV at baseline are risk factors for newly developed significant MR after CRT. These observations have prognostic significance.