Determinants and prognostic significance of myocardial replacement fibrosis in patients with mitral valve prolapse

Abstract

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) myocardial replacement fibrosis, a marker of maladaptive remodelling in numerous pathological conditions, has been evidenced in mitral valve prolapse (MVP) patients. To evaluate the prevalence, determinants, and prognostic significance of LV myocardial fibrosis assessed through late gadolinium enhancement (LGE+) by cardiac magnetic resonance (CMR) imaging in MVP patients. We included 426 patients from 2 centres (55 ± 16 years, 56% male) with MVP (trace to severe MR) who underwent a comprehensive echocardiography and CMR imaging. Gadolinium was injected in 411 (96%) patients. The primary outcome endpoint was a composite of cardiovascular events. Of 411 patients, myocardial fibrosis (LGE+) was observed in 118 (29%; 100 myocardial wall including 66 basal inferolateral wall, 30 papillary muscle). LGE+ prevalence was 14% in trace-mild MR, 28% in moderate and 39% in severe MR, and was associated with worse heart chambers remodelling, larger mitral annulus, longer MV leaflets and presence of flail leaflet. Determinants of LGE+ in multivariable analysis were mainly LV mass (OR 1.01, P = 0.008) associated to the magnitude of MR and coronary artery disease. Four years cardiovascular events-free survival was decreased in patients with LGE+ (49.7 ± 11.9 vs. 76.2 ± 6.2%, P < 0.0001). In a stepwise multivariable Cox model, MR volume, LA volume index and LGE+ (HR: 2.69 [1.38–5.25], P = 0.004) were associated with impaired outcome ( Fig. 1 ). LV myocardial replacement fibrosis is frequent in MVP patients, related to both mitral valve apparatus alteration and MR grade (trace-mild 14%, moderate 28%, severe 39%), and emerges as a predictor of cardiovascular events. CMR imaging provides additional information to echocardiography in MVP.