Posterior MAD, Fibrosis, and Bileaflet MVP: A High-Risk Imaging Phenotype for Sudden Cardiac Arrest.

backgroundMitral annular disjunction (MAD) is an under-recognized abnormality frequently associated with mitral valve prolapse (MVP) and linked to malignant arrhythmias and sudden cardiac death. CASE SUMMARY: A 42-year-old woman with bileaflet MVP presented with sudden cardiac arrest from ventricular fibrillation. Prior electrocardiography revealed inferior T-wave inversions, whereas transthoracic echocardiography identified posterior MAD. Cardiac magnetic resonance demonstrated focal late gadolinium enhancement, consistent with myocardial fibrosis. Together, these multimodality findings defined a malignant arrhythmogenic substrate and reinforced the indication for implantable cardioverter-defibrillator placement. DISCUSSION: This case highlights the malignant potential of the MVP-MAD phenotype and the challenge of early detection. Risk stratification should integrate clinical history, arrhythmic burden assessment, and advanced imaging to collectively delineate high-risk features. Longitudinal surveillance remains essential, as the phenotype may evolve and culminate in sudden cardiac arrest. TAKE-HOME MESSAGE: In MVP, recognition of MAD and cardiac magnetic resonance-detected fibrosis is essential, as malignant phenotypes may go undetected until presenting with sudden cardiac arrest.