Abstract 9970: Prevalence of ECG Abnormalities and Association with Arrhythmic Risk and Myocardial Fibrosis in a Large Cohort of Patients with Mitral Valve Prolapse

Abstract

Background: Inverted or biphasic T-waves (IBTWs) in the inferior leads on a 12-lead electrocardiogram (ECG) have been previously described in small, retrospective samples of MVP with sudden cardiac arrest (SCA) or sudden cardiac death (SCD). However, prior studies are limited by selection of bileaflet involvement, referral bias or targeted autopsies. Moreover, the association of IBTWs with focal fibrosis remains poorly defined. Objective: To assess the rates of IBTWs and their association with arrhythmic risk and late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) in an unselected, longitudinal MVP cohort. Methods: We reviewed available 12-lead ECGs from a cohort of 570 MVP patients with clinical and ambulatory ECG or telemetry monitoring evaluated at the University of California San Francisco between 2012 and 2020. IBTWs were considered clinically relevant if present in at least 2 of 3 inferior ECG leads. Complex ventricular ectopy (ComVE) was defined as >5% burden of premature ventricular contractions, bigeminy, or non-sustained ventricular tachycardia. SCD cases were identified through the National Death Index. In a subset of 86 (15%) patients with available contrast CMR, we assessed the presence and location of LGE. Results: Among 570 MVP patients (52% male, mean age 64±17), 86 (15%) had IBTWs, 160 (28%) had ComVE, and 26 (5%) had severe arrhythmic events (2 sustained VT, 13 SCA, and 11 SCD). Of these 26, 15 (58%) were bileaflet. Rates of IBTWs were similar between MVPs with severe arrhythmic events (9/26, 35%), ComVE (28/160, 18%), and no ventricular arrhythmia (58/410, 14%) ( p= 0.33). Among MVPs with contrast CMR, there were higher rates of IBTWs in those with LGE (papillary muscles or basal inferolateral wall in all) versus without LGE (7/22 vs 6/64, respectively, p = 0.01). Conclusions: In a large, unselected MVP sample inclusive of all arrhythmic presentations and leaflet subtypes, the prevalence of IBTWs is overall low and similar in those with and without ventricular arrhythmia, including SCA/SCD. In those with IBTWs, LGE in the papillary muscles or basal inferolateral wall is common, suggesting focal myocardial traction/fibrosis as the underlying anatomical substrate for repolarization abnormalities in the MVP population.