AbstractAimsArrhythmic mitral valve syndrome is linked to life-threatening ventricular arrhythmias. The incidence, morphology and methods for risk stratification are not well known. This prospective study aimed to describe the incidence and the morphology of ventricular arrhythmia and propose risk stratification in patients with arrhythmic mitral valve syndrome.MethodsArrhythmic mitral valve syndrome patients were monitored for ventricular tachyarrhythmias by implantable loop recorders (ILR) and secondary preventive implantable cardioverter-defibrillators (ICD). Severe ventricular arrhythmias included ventricular fibrillation, appropriate or aborted ICD therapy, sustained ventricular tachycardia and non-sustained ventricular tachycardia with symptoms of hemodynamic instability.ResultsDuring 3.1 years of follow-up, severe ventricular arrhythmia was recorded in seven (12%) of 60 patients implanted with ILR [first event incidence rate 4% per person-year, 95% confidence interval (CI) 2–9] and in four (20%) of 20 patients with ICD (re-event incidence rate 8% per person-year, 95% CI 3–21). In the ILR group, severe ventricular arrhythmia was associated with frequent premature ventricular complexes, more non-sustained ventricular tachycardias, greater left ventricular diameter and greater posterolateral mitral annular disjunction distance (all P < 0.02).ConclusionsThe yearly incidence of ventricular arrhythmia was high in arrhythmic mitral valve syndrome patients without previous severe arrhythmias using continuous heart rhythm monitoring. The incidence was even higher in patients with secondary preventive ICD. Frequent premature ventricular complexes, non-sustained ventricular tachycardias, greater left ventricular diameter and greater posterolateral mitral annular disjunction distance were predictors of first severe arrhythmic event.