Abstract 14931: Frailty Status Modifies the Efficacy of ICD Therapy Among Patients With Chronic Heart Failure With Reduced Ejection Fraction

Abstract

Introduction: Frailty is common in patients with heart failure with reduced ejection fraction (HFrEF) and is independently associated with mortality. Implantable cardiac defibrillator (ICD) therapy is recommended to reduce mortality risk in patients with HFrEF. Whether baseline frailty modifies the efficacy of ICD therapy in HFrEF is not known. Methods: Stable outpatients with HFrEF randomized to ICD vs. placebo in the SCD-HeFT trial were included. Baseline frailty was estimated using Rockwood’s Frailty Index (FI) by dividing the number of deficits present by the number of variables considered (n=37). Participants were categorized into tertiles of FI. Multivariable adjusted Cox proportional hazard models with multiplicative interaction terms (frailty*treatment arm) were constructed to evaluate whether frailty modified the treatment effect of ICD therapy on the primary outcome all-cause mortality and secondary outcomes of cardiovascular (CV) mortality and sudden cardiac death (SCD). Results: Among 1,673 participants (age: 59±12 y, 23% women), the median [IQR] FI ranged from 0.19 [0.14-0.23] in tertile 1 (lower frailty burden) to 0.51 [0.47-0.56] in tertile 3 (higher frailty burden). Baseline frailty significantly modified the treatment effect of ICD therapy (P-interaction: 0.03) ( Fig. A ). Specifically, ICD therapy was associated with a lower risk of all-cause mortality in tertile 1 [HR (95% CI) = 0.55 (0.37-0.80)] but not in tertile 3 participants [HR (95% CI) = 0.90 (0.67-1.22)] ( Fig. B ). Among secondary outcomes, frailty status modified the association of both CV mortality and SCD (P-interaction = 0.007 and 0.04, respectively). Similar results were observed in landmark analyses at 12 months. Conclusions: Among patients with chronic stable HFrEF, baseline frailty modified the treatment effect of ICD therapy with a greater reduction in the risk of CV mortality and SCD in patients with a lower burden of frailty.