Impact of Forward Stroke Volume Response on Clinical and Structural Outcomes after Percutaneous Mitral Valve Repair with MitraClip

Abstract

Background - An increase of systolic forward flow was frequently observed after successful MitraClip implantation in patients with significant mitral regurgitation. However, the impact of systolic forward flow improvement on post-MitraClip outcomes remains unknown. Methods and Results - Study population included 160 patients who underwent successful MitraClip implantation. The systolic forward flow was noninvasively calculated as the forward stroke volume (FSV) at baseline before the MitraClip procedure and before discharge with pulse-wave Doppler using transthoracic echocardiography. The optimal threshold of discharge/baseline FSV ratio for 3-year all-cause death was assessed. The best cutoff ratio was 1.09 (9% FSV increase from baseline, P=0.006). The FSV responders were defined as those with >9% increase of FSV from baseline (n=93). From discharge to 12-month follow-up, a significant reduction of LV end-diastolic and end-systolic volumes was observed in the responders, whereas no significant change was observed in the nonresponders. Furthermore, the proportion of New York Heart Association functional class III/IV was significantly lower in the responders at 12 months (2.9% versus 14.6%; P=0.03). Among patients with estimated glomerular filtration rate <60 mL/min per 1.73 m2, estimated glomerular filtration rate was significantly improved at 12 months only in the responders. All-cause mortality at 3 years was significantly lower in the responders than in the nonresponders (17.6% versus 42.3%; P=0.002). Multivariable logistic analysis identified higher baseline FSV, less mitral regurgitation severity, and functional mitral regurgitation as independent predictors of the nonresponders. Conclusions - FSV increase after MitraClip implantation was associated with more favorable clinical and anatomic outcomes. Severity and pathogenesis of mitral regurgitation and pre-MitraClip FSV predicted postprocedural FSV response.