Arrhythmic Mitral Valve Prolapse, Mitral Annular Disjunction Complex and Non-Ischemic Fibrosis: Evolution of Ventricular Electrical Instability and Implantable Cardioverter Defibrillator Indication

Description of Clinical Presentation: A 43 year-old female presented in 2010 with extrasystolic and tachycardic palpitations along with syncopal episodes during pregnancy. Her 24 hours holter monitoring (Holter) showed 21.000 premature ventricular contractions (PVCs) in addition to left ventricular (LV) enlargement on transthoracic echocardiography (TTE). She underwent radiofrequency ablation of PVCs, reducing arrhythmic burden, although complete suppression was not achieved. She remained on bisoprolol 20 mg daily with good control. Ten years later had minor symptoms and TTE showed mitral valve prolapse (MVP), along with normal-sized LV and 1.575 PVCs at Holter. In 2024 she returned with history of a syncopal episode with very frequent palpitations for the last 60 days despite beta-blocker use. A new Holter revealed 15.345 isolated polymorphic PVCs and 6 episodes of non-sustained ventricular tachycardia (NSVT), the longest with 11 beats and heart rate of 221 bpm. Given the arrhythmic progression, recent syncope, and NSVTs, cardiac magnetic resonance (CMR) was performed, and based on its findings, described below, she was referred to an electrophysiologist for implantable cardioverter defibrillator (ICD) planning.

Diagnostic Techniques and Their Most Important Findings: CMR was performed on a 1.5 Tesla scanner. Localizer sequences were followed by cine CMR, which in the long-axis views — particularly the LV outflow tract plane — demonstrated a 14mm mitral annular disjunction (MAD) with systolic curling, MVP and valvar regurgitant jet. The LV showed increased end-diastolic diameter (61mm), indexed dimensions and biventricular systolic function preserved. Double and Triple IR sequences were subsequently acquired, followed by T1 maps for tissue characterization and edema assessment. No myocardial edema was detected, and T1 mapping and extracellular volume were within normal limits. Late gadolinium enhancement (LGE) sequences identified fibrosis in the inferolateral basal segment, adjacent to the disjunction site, as well as tenuous fibrosis of the lateral papillary muscle.

Learning Points from this Case: MAD is an important arrhythmogenic entity, especially associated with myocardial fibrosis. CMR demonstrated with the cine sequences and LGE the correlation between MAD with localized fibrosis and progressive ventricular electrical instability, allowing differentiation from other arrhythmogenic cardiac diseases and underscoring the role of tissue characterization in diagnosis and risk stratification. This case illustrates the natural history of arrhythmic MAD, characterized by increasing arrhythmic burden despite optimized medical therapy and prior ablation. As in the present report, and in accordance with current consensus, ICD indication should be considered in the context of MAD, given the presence of NSVT episodes with heart rate above 180bpm and syncope, along with the CMR findings.

Panels A, B, and C. Cine cardiac magnetic resonance images in the left ventricular outflow tract view demonstrating mitral annular disjunction (14 mm), prolapse of the anterior mitral leaflet, and a valvular regurgitant jet. Panel D. Late gadolinium enhancement image demonstrating subtle fibrosis of the papillary muscle.
Panel E. Late gadolinium enhancement (PSIR sequence) in the left ventricular outflow tract view demonstrating basal inferolateral fibrosis adjacent to the mitral annular disjunction/curling motion area.
Panel F. Late gadolinium enhancement (PSIR sequence) in a short-axis basal view demonstrating inferior segment fibrosis adjacent to the mitral annular disjunction area.