176-72: Diffuse Ventricular Fibrosis on Cardiac Magnetic Resonance Imaging Associates with Ventricular Tachycardia in Patients with Hypertrophic Cardiomyopathy

Abstract

Purpose: Non-sustained ventricular tachycardia (NSVT) is a risk factor for sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM). We aimed to assess whether diffuse ventricular fibrosis on cardiac magnetic resonance (CMR) imaging could be a surrogate marker for ventricular arrhythmias in patients with HCM. Methods: 100 patients with HCM (mean age 51 ± 13years, septal wall thickness 20 ± 5mm) underwent CMR with a 1.5T scanner to determine the presence of ventricular late gadolinium enhancement (LGE) for focal fibrosis, and post-contrast T1 mapping for diffuse ventricular fibrosis. The presence of NSVT was determined by holter monitoring and a subset of high risk patients received an implantable cardioverter-defibrillator (ICD). Results: NSVT was detected in 23 of 100 patients with HCM. Focal ventricular fibrosis (by LGE) was observed in 87%, with no significant difference between patients with (96%) or without NSVT (86%, p = 0.19). However LGE mass was greater in patients with (16.5 ± 19.1g) versus without NSVT (7.6 ± 10.2g, p < 0.01). NSVT was associated with a significant reduction in ventricular T1 relaxation time (422 ± 54ms) versus patients without NSVT (512 ± 115ms; p < 0.001). There was significant reduction in ventricular T1 relaxation time in patients with (430 ± 48ms) versus without aborted SCD (495 ± 113ms; p = 0.01) over a mean follow-up of 40 ± 10 months. On multivariate analysis post-contrast ventricular T1 relaxation time and septal wall thickness were the only predictors of NSVT.