295Myocardial fibrosis and the effect of defibrillator implantation in patients with non-ischemic systolic heart failure - DANISH-MRI

Abstract

Background: Patients with non‐ischemic systolic heart failure have an increased risk of sudden cardiac death (SCD) and implantation of an Implantable Cardioverter‐Defibrillator (ICD) is recommended. However, the ICD puts patients at risk of complications and most patients do not live longer. Hence, there is a need for better identification of patients likely to benefit from the ICD. Myocardial fibrosis, detected by late gadolinium enhancement (LGE) with cardiac magnetic resonance (CMR), has been shown to predict arrhythmic events and all‐cause death. LGE may thus be able to identify patients more likely to benefit from an ICD. Purpose: The purpose of this study was to investigate the impact of LGE on outcomes in patients with non‐ischemic systolic heart failure who were randomized to receive ICD or not. Methods: In this substudy of the Danish Study to Assess the Efficacy of ICDs in Patients with Non‐ischemic Systolic Heart Failure on Mortality (DANISH), we performed CMR on 237 patients with systolic heart failure (left ventricular ejection fraction [LVEF] ≤35%) not caused by ischemic heart disease. Two readers blinded to treatment allocation analysed volumes and LGE. LGE was quantified by the 2 standard deviations method. Median follow‐up time was 5.4 years. The primary outcome was all‐cause death and a secondary composite arrhythmic outcome consisted of SCD, resuscitated cardiac arrest, sustained ventricular tachycardia, or appropriate ICD shock. Results: Patients were on average 61 years old with a median duration of heart failure of 13 months; 102 (45%) received cardiac resynchronization therapy, and 105 (46%) were randomised to an ICD. In all, 50 patients died and 37 experienced a composite arrhythmic event. Ninety‐eight (46%) patients had LGE of any kind, 58 (27%) had classic mid‐wall fibrosis and 23 (11%) had fibrosis compatible with a previous myocardial infarction. The presence of any LGE was predictive of both all‐cause death (HR 2.2, CI 1.2‐3.9, p=0.008) and the composite arrhythmic outcome (HR 2.4, CI 1.2‐4.8, p=0.01). For every percent increase in LGE, the risk of all‐cause death increased by 4.0% (CI 1.3‐6.7%), p=0.003, and the risk of the composite arrhythmic outcome by 3.5% (CI 0.2‐6.9%), p=0.04. LGE remained an independent predictor for all‐cause death after controlling for age, LVEF, left ventricle end‐systolic volume, left ventricle end‐diastolic volume and right ventricular ejection fraction (HR 2.2, CI 1.2‐4.0, p=0.01). However, despite the correlation between LGE and clinical outcome, there was no impact of LGE on the effect of ICD implantation on the primary outcome, whether LGE was considered as any presence (p for interaction between any LGE and ICD implantation 0.8) or as percent of left ventricular mass (p=0.5). Conclusions: In patients with non‐ischemic systolic heart failure, LGE predicts all‐cause death and ventricular arrhythmic events. However, LGE does not identify patients who will survive longer by receiving an ICD.