T1 Mapping Tissue Heterogeneity Provides Improved Risk Stratification for ICDs Without Needing Gadolinium in Patients With Dilated Cardiomyopathy

Abstract

ObjectivesThis study sought to determine whether myocardial tissue heterogeneity scanned by native T1 mapping could improve risk stratification in patients with nonischemic dilated cardiomyopathy (NICM) evaluated for primary prevention by ICD. BackgroundThe benefit of insertable cardiac-defibrillator (ICD) as primary prevention ICD in patients with NICM remains to be fully clarified. MethodsA total of 115 NICM candidates for primary prevention and 55 healthy controls with similar distributions of age and sex were prospectively enrolled. Imaging was performed at 1.5-T using a protocol that included cine magnetic resonance for left ventricular function, late gadolinium enhancement (LGE) for focal scarring, and 5-slice native T1 mapping for diffuse fibrosis and heterogeneity. The last method was assessed by mean absolute deviation of the segmental pixel-SD from the average pixel-SD (Mad-SD). The primary endpoint was a composite of appropriate ICD therapy and sudden cardiac death. ResultsDuring a median follow-up of 24 months, 13 patients (11%) experienced the primary endpoint. Dichotomized Mad-SD >0.24 provided a comparable outcome to the presence of LGE for the primary endpoint (annual event rate: 9.8% vs. 10.9%). The integration of Mad-SD to global native T1 showed excellent arrhythmic event-free survival (annual event rate: 0%), and high sensitivity of 85% (95% confidence interval [CI]: 55% to 98%) and moderate specificity of 72% (95% CI: 62% to 80%), with a C-statistic of 0.76 (95% CI: 0.64 to 0.87), which was comparable to the presence, location, or extent of LGE in its ability to predict arrhythmic events. ConclusionsCombined myocardium tissue heterogeneity and interstitial fibrosis assessment by native T1 mapping is an important predictor of ventricular tachycardia and ventricular fibrillation and provides additive risk stratification for primary prevention ICD in NICM patients without the need for gadolinium contrast.