Mitral-valve-prolapse (MVP) is often considered benign but recent suggestion of an arrhythmic MVP form (AMVP) remains incompletely defined and uncertain.

To determine ventricular-arrhythmia prevalence, severity, phenotypical context and independent impact on outcome in patients with MVP.

A cohort of 595 (65±16 years, 278 female) consecutive patients with MVP and comprehensive clinical, arrhythmia (24-hour-Holter) and Doppler-echocardiographic characterization, was identified and long-term outcome analyzed.

Ventricular-arrhythmia was frequent (43% with at least ventricular ectopy≥5%), most often moderate. Presence of ventricular arrhythmia was associated with male sex, bileaflet-prolapse, marked leaflet-redundancy, mitral-annulus-disjunction (MAD), and T-wave-inversion/ST-depression (all P≤0.001). Overall mortality after arrhythmia diagnosis (8-year 13±2%) was strongly associated with arrhythmia-severity (8-year 10±2% for no/trivial, 15±3% for mild/moderate and 24±7% for severe arrhythmia; P=0.02). Excess-mortality was substantial for severe-arrhythmia (univariate-hazard-ratio 2.70[1.27–5.77], P=0.01 vs. no/trivial arrhythmia), even adjusted comprehensively including for MVP-characteristics (adjusted-hazard-ratio 2.94[1.36–6.36], P=0.006). Severe-arrhythmia was also associated with higher rates of mortality, defibrillator-implantation, VT-ablation (adjusted-hazard-ratio 4.68[2.45–8.92], P<0.0001), but the association was weaker post-mitral surgery (adjusted-hazard-ratio 3.69[0.93–14.74], P=0.06) (Figure 1).

AMVP is independently associated with phenotype dominated by MAD, marked leaflet redundancy and repolarization abnormalities. Long-term, severe-arrhythmia is independently associated with notable excess-mortality and reduced event-free survival. Therefore, arrhythmic MVP is a clinical entity strongly associated with outcome warranting careful risk-assessment and well-designed clinical trials.