Antemortem and Post-Mortem Characteristics of Lethal Mitral Valve Prolapse Among All Countywide Sudden Deaths.

OBJECTIVES

The goal of this study was to investigate the characteristics of mitral valve prolapse (MVP) in a post-mortem study of consecutive sudden cardiac deaths (SCDs) in subjects up to 90 years of age.

BACKGROUND

Up to 2.3% of subjects with MVPs experience SCD, but by convention SCD is rarely confirmed by autopsy. In a post-mortem study of persons <40 years of age, 7% of SCDs were caused by MVP; bileaflet involvement, mitral annular disjunction (MAD), and replacement fibrosis were common.

METHODS

In the San Francisco POST SCD (Postmortem Systematic Investigation of Sudden Cardiac Death) study, autopsies have been performed on >1,000 consecutive World Health Organization-defined (presumed) cases of SCD in subjects aged 18 to 90 years since 2011; a total of 603 were adjudicated. Autopsy-defined sudden arrhythmic death (SAD) required absence of nonarrhythmic cause; MVP diagnosis required leaflet billowing. One hundred antemortem echocardiograms were revised to identify additional MVPs missed on autopsy.

RESULTS

Among the 603 presumed SCDs, 339 (56%) were autopsy-defined SADs, with MVP identified in 7 (1%). Six additional MVPs were identified by review of echocardiograms, for a prevalence of at least 2% among 603 presumed SCDs and 4% among 339 SADs (vs. 264 non-SADs; p = 0.02). All 6 additional MVPs had monoleaflet rather than bileaflet involvement and mild mitral regurgitation, ruling out hemodynamic cause. Less than one-half had MAD with replacement fibrosis, but all had multisite interstitial fibrosis.

CONCLUSIONS

In a countywide post-mortem study of all adult cases of SCD, MVP prevalence was at least 4% of SADs, but one-half were missed on autopsy. Monoleaflet MVP was often underdiagnosed post-mortem. Compared with young cases of SCD, lethal MVP in older cases of SCD did not consistently have bileaflet anatomy, replacement fibrosis, or MAD.