Arrhythmic Mitral Valve Prolapse and Sudden Cardiac Death

Abstract

Background—Mitral valve prolapse (MVP) may present with ventricular arrhythmias and sudden cardiac death (SCD) even in the absence of hemodynamic impairment. The structural basis of ventricular electrical instability remains elusive.

Methods and Results—A) The Cardiac Registry of 650 young adults (≤40 yrs) with SCD was reviewed and cases with MVP as the only cause of SCD were reexamined. Forty-three MVP cases (26 female, age range 19-40, median 32 yrs) were identified (7% of all SCD, 13% of women). Among 12 with available ECG, 10 (83%) had inverted T waves on inferior leads and all right bundle branch block ventricular arrhythmias. A bileaflet involvement was found in 70%. LV fibrosis was detected at histology at the level of papillary muscles in all and infero-basal wall in 88%. B) MVP patients with complex ventricular arrhythmias (N=30) and without (controls, N=14) underwent a study protocol including contrast-enhanced cardiac magnetic resonance (CE-CMR). Patients with complex ventricular arrhythmias (22 female, age range 28-43, median 41 yrs), either right bundle branch block-type or polymorphic, showed a bileaflet involvement in 70% of cases. LV late-enhancement was identified by CE-CMR in 93% vs. 14% of controls (p<0.001), with a regional distribution overlapping the histopathology findings.

Conclusions—MVP is an under-estimated cause of arrhythmic SCD, mostly in young adult women. Fibrosis of papillary muscles and infero-basal LV wall, suggesting a myocardial stretch by the prolapsing leaflet, is the structural hallmark and correlates with ventricular arrhythmias origin. CE-CMR may help to identify this concealed substrate for risk stratification.

Source: circ.ahajournals.org