Mitral Annular Disjunction: A Roadmap for the Surgeon

Mitral annular disjunction (MAD) is a structural abnormality of the mitral annulus fibrosus, associated with myxomatous leaflet degeneration, mitral valve prolapse (MVP), and ventricular arrhythmias. The combination of annular dilatation and abnormal annular motion increases mechanical stress on the mitral leaflets, triggering the degenerative process.

This review summarizes the major pathophysiologic, diagnostic and therapeutic measures for the treatment of patients with MAD and an indication for mitral surgery.

The diagnosis is primarily based on non-invasive imaging techniques. Echocardiography is the first choice due to its ability to assess real-time mitral valve function. Cardiac computed tomography and magnetic resonance imaging provide more detailed information on the extent of MAD and the presence of calcifications. Indications for surgical mitral valve treatment are based on current recommendations. In cases with MAD and moderate mitral regurgitation, early intervention may be advocated in the presence of arrhythmogenic MVP. Long-term outcomes after treatment are assessed through multimodal imaging and electrocardiogram monitoring. A ring annuloplasty is an important cornerstone of treatment. Stabilization of the mitral annulus abolishes functional prolapse and increases the antiarrhythmic effect of mitral surgery. However, postoperative arrhythmic burden may persist in some cases, requiring continuous monitoring and sometimes an additional device therapy.

MAD represents a complex anatomical and functional entity associated with diagnostic challenges and rhythm abnormalities. Although the current indications for surgical treatment follow the recommendations for treatment of primary mitral regurgitation, early treatment may be important especially in patients with arrhythmias.