Background. Mitral annular disjunction (MAD) is the spatial separation of the mitral annulus and the left-ventricular myocardium. Although currently an emergent research topic due to its postulated association to malignant arrhythmias, its prevalence in patients with ST-segment elevation myocardial infarction (STEMI) as well as possible prognostic implications are still unknown.

Purpose. In our study, we investigated the prevalence and extent of MAD as well as its association with malignant arrhythmias in the setting of acute STEMI via cardiovascular magnetic resonance imaging (CMR).

Methods. 621 subsequent STEMI patients, which were revascularized via primary percutaneous coronary intervention (pPCI), underwent CMR 4 days (interquartile range 2-5) after infarction. Long axis cine-images were obtained, including two-, three- and four-chamber-views. In synopsis with short-axis cine-images of the mitral annular plane, the different segments of the mitral valve were screened for the presence of MAD and longitudinal extent was measured. During hospitalization period, ventricular fibrillation, sustained ventricular tachycardia (VT), cardiac arrest and sudden cardiac death (SCD) were defined as severe arrhythmic events.

Results: In our STEMI cohort, a total of 310 patients (50%) presented MAD with an average extent of 3.5±2.5mm and the P3-segment being affected most often (n=263, 63.7% of MAD patients). Within their hospital stay, 15 patients (2.4%) presented severe arrhythmic events (9 with vs. 6 without MAD, p=0.429), with SCD and VT only occurring in MAD patients. At a cut-off of 5.7mm, severe arrhythmic events occurred significantly more often in patients presenting with MAD ≥ 5.7mm (7% vs. 2%, p=0.026, relative risk: 3.34).

Conclusion: MAD is a rather common finding in STEMI patients. Disjunction extent of ≥5.7mm seems to predispose for the development of periinterventional severe arrhythmic events in these patients.