Mitral Annular Disjunction: A Diagnosis to Save Lives

Abstract

Introduction Mitral annular disjunction (MAD) is caused by a variation in the attachment of posterior mitral valve (MV) leaflet causing a wide separation between the left atrial wall-MV junction and left ventricular (LV) wall. Longitudinal MAD distance from left atrial wall-MV junction to LV wall during end-systole in the echocardiographic parasternal long axis view should be in excess of 2mm to suspect MAD. Recent evidence suggests that MAD magnitude is linked to higher incidence of ventricular arrhythmias. We present a case of an individual presenting with unexplained syncope, MAD and multiple episodes of non sustained ventricular tachycardia (NSVT). Case description 68 year old male with history of hypertension presented to ER with syncope. Initial EKG showed sinus bradycardia without ischemic changes. His troponins were negative and electrolytes were normal. Exercise stress test for chronotropic competence revealed premature ventricular contractions (PVCs) and an episode of 9 beats NSVT. Patient continued to have multiple episodes of NSVT with significant PVC burden. Echo showed normal systolic-diastolic function, myxomatous MV, bileaflet mitral valve prolapse (MVP), mild mitral regurgitation and MAD with magnitude of 12mm. Myocardial perfusion imaging did not reveal any defects. Cardiac MRI (CMR) showed delayed enhancement of basal mid-lateral and mid-septal walls. He received a dual chamber implantable cardioverter defibrillator to decrease the risk of sudden cardiac death related to MAD. Discussion Papillary muscle fibrosis and MAD magnitude are markers for severe arrhythmic events. Both are commonly seen with bileaflet MVP. Typical findings seen on echocardiogram are curling motion of the basal lateral LV wall from hypercontraction of regional area which causes paradoxical increase in the MV annulus diameter during systole. It also causes myxomatous MV and myocardial stretch in the LV inferobasal segment eventually causing fibrosis as identified on CMR. MVP is associated with MAD but MAD can also occur without underlying MVP and should be considered an independent risk factor for arrhythmias. Physicians should consider MAD in patients with no apparent cause for PVCs and refer them for echocardiogram. There is currently no consensus regarding pharmacological or device therapy for MAD. Conclusion Identification and recognition of MAD, with or without MVP, as an independent arrhythmic risk factor should be routinely done by non invasive methods.