B-PO05-174 CORE SCAR BURDEN ON CARDIAC MAGNETIC RESONANCE IMAGING IS ASSOCIATED WITH CLUSTERED VENTRICULAR ARRHYTHMIA AND LONGER CYCLE LENGTH IN NONISCHEMIC CARDIOMYOPATHY

Abstract

Patients with ≥2 ventricular arrhythmia (VA) events within three months (clustered VA) have higher mortality than patients without frequent VA. However, the association between myocardial scar and clustered VA in nonischemic (NICM) and ischemic cardiomyopathy (ICM) is unknown. The type of VA (MMVT, PMVT, VF) and relationship of scar burden and VA cycle length has also not been well characterized in these subgroups. To study the association of core and gray zone scar on cardiac magnetic resonance imaging (CMR) with clustered VA and VA cycle length in NICM and ICM, and characterize the type of VA present. We retrospectively analyzed data from 331 primary prevention ICD recipients (mean age 57 years, 26% female, 29% black) in the LV Structural Predictors of Sudden Cardiac Death study (NCT01076660). VA was defined as an adjudicated appropriate ICD shock for VT or VF. After stratifying by cardiomyopathy etiology (47% NICM, 53% ICM), we performed Fine and Gray competing risk and multinomial logistic regression analysis to evaluate the association of core and heterogeneous gray zone scar by CMR with the occurrence of clustered vs. unclustered VA. We further examined the association of VA cycle length with myocardial scar burden in stratified multivariate regression analysis. 69 participants developed ≥1 VA event (48 unclustered, 21 clustered). Time to clustered VA was 3.6±3.1 years. While accounting for competing risk of death, each 1-gram increase in core scar was associated with greater clustered VA in NICM (HR 1.19; 95% CI: 1.07-1.32). Gray scar did not increase the likelihood of clustered VA in NICM or ICM. The NICM and clustered VA subgroup had the highest overall mean VA cycle length (297±40 ms). In regression analysis, higher core scar burden was associated with longer VA cycle length in NICM (p=0.002). Higher BMI was associated with shorter VA cycle length in ICM (p=0.02). Type of VA was similar between cardiomyopathy subgroups and MMVT was more common in the clustered VA subgroups. In patients with NICM, CMR imaging may help identify those at risk for clustered VA and slower VA. BMI may be inversely associated with VA cycle length in ICM.