Right Ventricular Dysfunction and the Effect of Defibrillator Implantation in Patients With Nonischemic Systolic Heart Failure

Background Patients with nonischemic systolic heart failure are at an increased risk of sudden cardiac death, but more discriminating tools are needed to identify those patients likely to benefit from implantable cardioverter-defibrillator (ICD) implantation. Whether right ventricular (RV) ejection fraction (RVEF) can identify patients with nonischemic systolic heart failure more likely to benefit from ICD implantation is not yet known. Methods In this post hoc analysis of the DANISH trial (Danish Study to Assess the Efficacy of ICDs in Patients with Nonischemic Systolic Heart Failure on Mortality), patients with nonischemic systolic heart failure randomized to ICD or control underwent cardiovascular magnetic resonance. RV systolic dysfunction was defined as RVEF ≤45%. Cox regression assessed the effects of RV function and ICD implantation on all-cause mortality, sudden cardiac death, and cardiovascular death. Results Overall, 239 patients had interpretable images of RV volume. Median RVEF was 51%, RV systolic dysfunction was present in 75 (31%) patients, and 55 (23%) patients died. RVEF was an independent predictor of all-cause mortality, hazards ratio 1.34 per 10% absolute decrease in RVEF (95% CI, 1.05-1.70), P=0.02. There was a statistically significant interaction between RVEF and the effect of ICD implantation (P=0.001). ICD implantation significantly reduced all-cause mortality in patients with RV systolic dysfunction, hazards ratio 0.41 (95% CI, 0.17-0.97), P=0.04 but not in patients without RV systolic dysfunction, hazards ratio 1.87 (95% CI, 0.85-3.92), P=0.12, (P=0.01 for the difference in effect of ICD between RV groups). Conclusions In this post hoc analysis of the DANISH trial, ICD therapy was associated with survival benefit in patients with biventricular heart failure. These findings need confirmation in a prospective study.