Mitral Annular Disjunction and Arrhythmic Risk: Case Series and State of the Art

Background: Mitral annular disjunction (MAD) is an anatomical abnormality associated with an increased risk of major arrhythmic events, regardless of the presence of mitral valve prolapse. Cardiac magnetic resonance (CMR) plays a key role in diagnosing MAD and identifying myocardial fibrosis, a marker of arrhythmic vulnerability. Aim: This study reports the experience of the De Gasperis Cardiology Centre at Niguarda Hospital (Milan, Italy) in managing high-risk MAD patients who underwent implantable cardioverter-defibrillator (ICD) implantation and describes their main clinical characteristics. Methods: Between January 2020 and April 2025, five patients with MAD who received ICDs were identified and monitored remotely. Although the small sample size limits generalizability, the objective was to characterize factors associated with arrhythmic susceptibility. Results: Four patients exhibited documented ventricular arrhythmias: two with non-sustained and two with sustained ventricular tachycardia. Notably, CMR did not reveal myocardial fibrosis in two symptomatic cases, suggesting that arrhythmic vulnerability may precede detectable structural abnormalities. The observed coexistence of MAD with arrhythmogenic cardiomyopathies and channelopathies underscores the relevance of comprehensive genetic evaluation in these patients. Conclusions: MAD should be considered a potential arrhythmogenic substrate rather than a benign anatomical variant. A multimodal diagnostic approach and individualized risk stratification-potentially integrating genetic findings-are essential for optimal patient management.