Mitral Valve Prolapse Associated with Mitral Annular Disjunction: Diagnosis, Prognosis, and Arrhythmic Risk

Abstract Mitral valve prolapse (MVP) is the most common valvular heart disease, with a reported prevalence of 2–3% in the general population, and represents the leading structural cause of mitral regurgitation in Western countries. MVP has long been considered predominantly a benign condition; however, it may be associated with adverse clinical events, including severe mitral regurgitation, atrial fibrillation, congestive heart failure, endocarditis, stroke, and ventricular arrhythmias, potentially leading to sudden cardiac death. The so-called “malignant” mitral valve prolapse syndrome has been described in a subset of patients, predominantly young women, characterized by bileaflet MVP, a mid-systolic click, biphasic or inverted T waves in the inferior leads, and complex ventricular arrhythmias with polymorphic or right bundle branch block morphology, in the absence of significant mitral regurgitation. In addition to electrocardiographic and clinical features, myocardial fibrosis involving the basal inferolateral wall and the papillary muscles has been documented. Fibrosis in these two specific myocardial regions plays a crucial role and, in clinical practice, can be identified in vivo by contrast-enhanced cardiac magnetic resonance imaging. Distinct morpho-functional abnormalities of the mitral annulus, including annular disjunction and systolic curling, have been described in patients with arrhythmic MVP and are considered possible primum movens of alterations in mitral valve apparatus mechanics, leading to leaflet remodeling and myocardial injury/fibrosis.