Mitral Annular Disjunction: Where Is the Cut-Off Value? Case Series and Literature Review

Mitral annular disjunction (MAD) is a structural abnormality of the mitral valve increasingly detected with advanced cardiac imaging, particularly cardiac magnetic resonance (CMR). However, the clinical impact of different degrees of disjunction and the lack of standardized measurement criteria remain controversial. This study aimed to describe a series of patients with MAD assessed by CMR and to discuss, in the context of current literature, potential cut-off values that may distinguish physiological from pathological MAD. We retrospectively identified all CMR examinations performed at our institution over a 6-month period in which MAD was visible in at least two cine steady-state free precession (SSFP) projections. For each patient, we recorded MAD extent, presence of mitral valve prolapse/regurgitation, late gadolinium enhancement (LGE) pattern, and main clinical presentation. Nine patients (mean age 57 years; 5 men) were included. Larger MAD distances (>4 mm) were frequently associated with non-ischemic LGE in the basal lateral wall and with valvular abnormalities, whereas smaller disjunctions (≤3 mm) were often observed in patients without significant structural disease. Non-ischemic LGE was present in 6/9 patients, all with MAD > 5 mm. These observations, together with published data, support the hypothesis that small degrees of MAD may represent a frequent anatomical variant, while more extensive disjunction, especially when associated with fibrosis, may indicate a pathological substrate for arrhythmias. Standardized CMR-based criteria and validated MAD cut-off values are needed to improve risk stratification and to incorporate MAD assessment into routine clinical practice.