Cardiac arrest secondary to mitral annular disjunction: a case report.

Background: Mitral annular disjunction with bileaflet mitral valve prolapse is increasingly recognized as a substrate for malignant ventricular arrhythmia and sudden cardiac arrest. Prior myocardial fibrosis adjacent to papillary muscles and frequent ventricular ectopy increase arrhythmic risk. Case Summary: We describe the case of a woman in her 40s who suffered an out-of-hospital ventricular fibrillation cardiac arrest with immediate bystander CPR and ambulance arrival within 5 min. Return of spontaneous circulation occurred approximately 30 minutes after multiple shocks. She had a background of bileaflet mitral valve prolapse discovered on routine investigation following a syncopal episode in her youth. She was known to have significant mitral annular disjunction and focal mid-wall/subepicardial late gadolinium enhancement on serial cardiac MRI. An implantable loop recorder previously demonstrated frequent multifocal ventricular ectopy but had reached end-of-life by the time of the case. Subsequent testing excluded coronary disease, pulmonary embolus, and long QT as causes for her arrest. A transvenous implantable cardioverter defibrillator was inserted for secondary prevention and pacing capability should she require it, with mitral valve replacement following this. Discussion: This case exemplifies mitral annular disjunction arrhythmic syndrome presenting as ventricular fibrillation arrest in a patient with bileaflet prolapse, focal myocardial fibrosis, and frequent ventricular ectopy, managed with ICD implantation and eventual surgical valve replacement. Current consensus would have graded her arrhythmic risk as intermediate.