Replacement Myocardial Fibrosis in Patients with Mitral Valve Prolapse: Relation to Mitral Regurgitation, Ventricular Remodeling and Arrhythmia

Circulation. 2021 Mar 12. doi: 10.1161/CIRCULATIONAHA.120.050214. Online ahead of print.

Abstract

Background: Mitral valve prolapse (MVP) is a frequent disease that can be complicated by mitral regurgitation (MR), heart failure, arterial embolism, rhythm disorders and death. Left ventricular (LV) replacement myocardial fibrosis, a marker of maladaptive remodeling, has been described in patients with MVP, but the implications of this finding remain scarcely explored. We aimed at assessing the prevalence, pathophysiological and prognostic significance of LV replacement myocardial fibrosis through late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) in patients with MVP. Methods: Four hundred patients (53±15 years, 55% male) with MVP (trace to severe MR by echocardiography) from 2 centers, who underwent a comprehensive echocardiography and LGE CMR, were included. Correlates of replacement myocardial fibrosis (LGE+), influence of MR degree, and ventricular arrhythmia were assessed. The primary outcome was a composite of cardiovascular events (cardiac death, heart failure, new-onset atrial fibrillation, arterial embolism, and life-threatening ventricular arrhythmia). Results: Replacement myocardial fibrosis (LGE+) was observed in 110 patients (28%; 91 myocardial wall including 71 basal inferolateral wall, 29 papillary muscle). LGE+ prevalence was 13% in trace-mild MR, 28% in moderate and 37% in severe MR, and was associated with specific features of mitral valve apparatus, more dilated LV and more frequent ventricular arrhythmias (45 vs 26%, P<0.0001). In trace-mild MR, despite the absence of significant volume overload, abnormal LV dilatation was observed in 16% of patients and ventricular arrhythmia in 25%. Correlates of LGE+ in multivariable analysis were LV mass (OR 1.01, 95% CI [1.002-1.017], P=0.009) and moderate-severe MR (OR: 2.28, 95% CI [1.21-4.31], P=0.011). LGE+ was associated with worse 4-year cardiovascular event-free survival (49.6±11.7 in LGE+ vs 73.3±6.5% in LGE-, P<0.0001). In a stepwise multivariable Cox model, MR volume and LGE+ (HR: 2.6 [1.4-4.9], P=0.002) were associated with poor outcome. Conclusions: LV replacement myocardial fibrosis is frequent in patients with MVP, is associated with mitral valve apparatus alteration, more dilated LV, MR grade, ventricular arrhythmia, and is independently associated with cardiovascular events. These findings suggest a MVP-related myocardial disease. Finally, CMR provides additional information to echocardiography in MVP.

Keywords: Mitral valve prolapse; mitral regurgitation; replacement myocardial fibrosis.