CE-452775-3 SCAR ARCHITECTURE AS A STRUCTURAL BIOMARKER OF VENTRICULAR ARRHYTHMIAS IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY: A CARDIAC MAGNETIC RESONANCE STUDY

Abstract

Hypertrophic cardiomyopathy (HCM) patients with extensive cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) are at greater risk of ventricular arrhythmias and sudden cardiac death (SCD). LGE-CMRs enable to identify dense fibrosis (core), diffuse fibrosis (border zone; BZ), and corridors of BZ tissue connecting areas of normal myocardium between core zones (BZ channels). These channels are essential components of reentry circuits and may promote VT/VF. We conducted a retrospective analysis of a cohort of consecutive HCM patients. We sought to describe scar architecture and assess scar composition as a predictor of VT/VF. We analyzed CMR images, generated LGE color-coded pixel signal intensity (PSI) maps using ADAS 3D software (Galgo Medical), and characterized hyper-enhanced areas as core zone, BZ, and healthy tissue. BZ channels were identified as corridors of BZ tissue surrounded by scar core or anatomical barriers. The study endpoint (VT/VF) was composed by SCD, cardiac arrest, prolonged VTs, or appropriate ICD therapy. Cox multivariable analyses were adjusted for major risk factors of SCD, including end-stage disease, apical aneurysm, and LV scar mass. 130 consecutive HCM patients (43±17 y; 73% males) were included. 15% had end-stage disease, 4.6% apical aneurysm and 58% had an ICD. Median LV mass was 147 g (IQR:108-201) and 86 patients (66%) had LGE. Median scar mass was 14.8g (IQR:6.3-32.8), or 9.7% (IQR:4.3-18.4) of LV mass. The scar was mainly composed of BZ tissue (median: 12.7g, IQR:5.5-28.0). Median core scar mass was 1.5g (IQR:0.2-3.8). 46 (35%) patients had BZ channels. During a median follow-up of 87 months (IQR:54-108), 18 (13.8%) patients had VT/VF. Scar mass (49.9 g, IQR:24.4-66.5 vs 12.3 g, IQR:3.3-26.7), BZ mass (37.7g, IQR:21.2-54.8 vs 10.7g, IQR:2.4-22.7) and core mass (5.7g, IQR:2.4-11.5 vs 1.3g, IQR:0.1-2.7) were significantly higher in VT/VF patients (p<0.01 for all comparisons) (Figure). BZ channels were observed in 83% of patients with VT/VF as compared with 28% of those without (p<0.01) (Figure). Median BZ channels mass was higher in VT/VF patients vs controls (1.9g, IQR:0.8-3.6 vs 0.0g, IQR:0.0-0.47; p<0.001). In multivariate analysis, BZ channels emerged as the best independent predictor of VT/VF (HR:7.0; 95%CI:1.9-25.4; p=0.003). In an unselected cohort of HCM patients, scar composition affected the risk of VT/VF. BZ channels emerged as a potent risk predictor beyond the magnitude of scar mass.