Mitral valve and left ventricular features in malignant mitral valve prolapse

Mitral valve prolapse is a benign condition, however with occasional reports of sudden cardiac death or out-of-hospital cardiac arrest in the absence of severe mitral regurgitation or coronary artery disease, suggesting the existence of a malignant form. The objective of our study was to contribute to the characterisation of malignant mitral valve prolapse.

We performed a retrospective analysis of pathology findings in 68 consecutive cases of sudden cardiac death with mitral valve prolapse as lone abnormal finding, reported as cause of death.

All mitral valve prolapse sudden death cases had mitral valve characteristics of Barlow disease, with extensive bileaflet multisegmental prolapse and dilatation of the annulus. The majority of cases (80.9%) had microscopic left ventricular fibrosis with associated hypertrophy and degenerative features of the myocytes, and some cases (10.9%) had right ventricular fibrosis as well.

Malignant mitral valve prolapse is Barlow disease. Sudden cardiac death in mitral valve prolapse is due to Barlow disease, which besides the typical mitral valve degeneration may comprise a distinct Barlow disease cardiomyopathy, as suggested by myocyte degeneration and bi-ventricular involvement.