Malignant Bileaflet Mitral Valve Prolapse Syndrome in Patients with Otherwise Idiopathic Out-of-hospital Cardiac Arrest

Objectives: The aim of this study was to investigate the prevalence of mitral valve prolapse (MVP) and its association with ventricular arrhythmias in a cohort with "unexplained" out-of-hospital cardiac arrest.

Background: Ventricular arrhythmias are an important cause of sudden unexpected death in the young. The role of MVP in sudden unexpected death remains controversial.

Methods: Of 1,200 patients evaluated between July 2000 and December 2009 in the Mayo Clinic's Long QT Syndrome/Genetic Heart Rhythm Clinic, all 24 (16 women, median age 33.5 years) with idiopathic out-of-hospital cardiac arrest (i.e., negative for ischemia, cardiomyopathy, and channelopathy) were reviewed.

Results: All 24 patients had implantable cardioverter-defibrillators (ICDs). Out-of-hospital cardiac arrest was the sentinel event in 22 (92%). Bileaflet MVP was found in 10 (42%). Compared with patients with normal mitral valves, patients with bileaflet MVP: 1) were over-represented by women (9 of 10 [90%] vs. 7 of 14 [50%], p = 0.04); 2) had a higher prevalence of biphasic or inverted T waves (7 of 9 [77.8%] vs. 4 of 14 [29%], p = 0.04); and 3) on Holter interrogation had higher prevalence of ventricular bigeminy (9 of 9 [100%] vs. 1 of 10 [10%], p < 0.0001), ventricular tachycardia (7 of 9 [78%] vs. 1 of 10 [10%], p = 0.006), and premature ventricular contractions originating from the outflow tract alternating with the papillary muscle or fascicular region (7 of 9 [78%] vs. 2 of 10 [20%], p = 0.02). Over a median 1.8 years (range: 0.1 to 11.9 years) from ICD placement, 13 of 24 patients (54%) received appropriate ventricular fibrillation-terminating ICD shocks. Only bileaflet MVP was associated with ventricular fibrillation recurrences requiring ICD therapy on follow-up (logistic regression odds ratio: 7.2; 95% confidence interval: 1.1 to 48; p = 0.028).

Conclusions: The authors describe a "malignant" subset of patients with MVP who experienced life-threatening ventricular arrhythmias. This phenotype is characterized by bileaflet MVP, female sex, and frequent complex ventricular ectopic activity, including premature ventricular contractions of the outflow tract alternating with papillary muscle or fascicular origin.