Implantable Cardioverter-Defibrillators Effective, Underused for HFrEF

Despite being associated with decreased mortality in both the short and long term, primary prevention implantable cardioverter-defibrillators (ICDs) are consistently underused in treating heart failure with reduced ejection fraction (HFrEF), according to study results recently published in Circulation.

This prospective analysis included 16,702 individuals with physician-judged HF (mean age, 73±11 years; 73% men), which, after propensity score matching, was limited to 1305 individuals with ICDs and 1305 without ICDs. Researchers extracted data from the Swedish Heart Failure Registry (SwedeHF) and included enrollees who registered between May 2000 and December 2016. Other inclusion criteria were ejection fraction <40%, complete data on ICD use, and HF lasting ≥3 months. Primary outcomes were all-cause mortality at 1 and 5 years. Investigators estimated survivor functions among the propensity score-matched cohort using the Kaplan-Meier method.

Among patients with ICDs vs without, crude 1-year mortality risk was 12.7% (95% CI, 10.8-14.5) compared with 16.9% (95% CI, 14.8-19), respectively, whereas 5-year mortality risk was 47.4% (95% CI, 43.0-49.5) compared with 49.5% (95% CI, 46.2-52.6), respectively. Researchers did not identify any significant differences between subgroups according to sex, age, current ischemic heart disease status, earlier vs later SwedeHF enrollment, or use of cardiac resynchronization therapy.

Limitations to this study included potential unmeasured confounding and interactions between the covariates, reduced generalizability because of better outcomes for SwedeHF enrollees, the possibility of later implantation in patients classified as non-ICD, and an inability to determine ischemic/nonischemic drivers for HFrEF.

The study researchers concluded that “primary prevention ICD was associated with reduced short-term and long-term all-cause mortality,” indicating that this lends support for current guidelines for ICD.

Reference

Schrage B, Uijl A, Benson L, et al. Association between use of primary prevention implantable cardioverter-defibrillators and mortality in patients with heart failure: a prospective propensity-score matched analysis from the Swedish Heart Failure Registry [published online September 3, 2019]. Circulation. doi:10.1161/CIRCULATIONAHA.119.043012