Cardiac arrest secondary to mitral annular disjunction: a case report

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.

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.

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.