To assess in MVP-patients, MAD prevalence, phenotypic characteristics and long-term outcome.

A cohort of 595 (278 female, age 61±16 years) patients with isolated MVP, clinical, rhythmic, Doppler-echocardiographic and MAD assessment was examined. MAD prevalence, phenotype and outcome (survival, clinical arrhythmic events) starting at diagnostic echocardiogram were analyzed. To balance important baseline differences, we also propensity-score matched patients with and without MAD (no-MAD).

MAD presence was common (186–31%) in MVP, generally in younger patients and independently associated with severe-myxomatous-MVP and larger-LV (P≤0.005). Age-matched-cohort survival after MVP diagnosis was not worse with MAD (10-year 93±2% for no-MAD and 97±1% for MAD, P=0.4), even adjusted-comprehensively for MVP-characteristics (P=0.8) and accounting for time-dependent (TD) mitral-surgery (P=0.6). During follow-up, 170 patients had clinical-arrhythmic-events [ventricular tachycardia (n=159), arrhythmia-ablation (n=14), Cardioverter-defibrillator-implantation (n=14) and sudden-cardiac-death (n=3)]. MAD was independently associated with higher risk of arrhythmic-events [adjusted-HR 2.60(1.87–3.62), P<0.0001]. MAD link to arrhythmic-events persisted with TD mitral-surgery [adjusted-HR 2.54(1.84–3.50), P<0.0001], was strong under medical-management [adjusted-HR 3.21 (2.03–5.06), P<0.0001] but was weaker post-mitral-surgery (Fig. 1).

This large cohort with MVP comprehensively characterized, shows that MAD is frequent at MVP diagnosis and strongly linked to advanced-myxomatous-degeneration. MAD presence is independently associated with long-term excess-incidence arrhythmic-events. However, within the first 10 years post-diagnosis MAD is not linked to excess-mortality and while reassurance should be provided from the survival point of view careful monitoring for arrhythmias is in order with MAD.