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

BACKGROUND: Most randomized trials on implantable cardioverter-defibrillator (ICD) use for primary prevention of sudden cardiac death in heart failure with reduced ejection fraction enrolled patients >20 years ago. We investigated the association between ICD use and all-cause mortality in a contemporary heart failure with reduced ejection fraction cohort and examined relevant subgroups. METHODS: Patients from the Swedish Heart Failure Registry fulfilling the European Society of Cardiology criteria for primary-prevention ICD were included. The association between ICD use and 1-year and 5-year all-cause and cardiovascular (CV) mortality was assessed by Cox regression models in a 1:1 propensity score-matched cohort and in prespecified subgroups. RESULTS: Of 16 702 eligible patients, only 1599 (10%) had an ICD. After matching, 1305 ICD recipients were compared with 1305 nonrecipients. ICD use was associated with a reduction in all-cause mortality risk within 1 year (hazard ratio, 0.73 [95% CI, 0.60-0.90]) and 5 years (hazard ratio, 0.88 [95% CI, 0.78-0.99]). Results were consistent in all subgroups including patients with versus without ischemic heart disease, men versus women, those aged <75 versus ≥75 years, those with earlier versus later enrollment in the Swedish heart failure registry, and patients with versus without cardiac resynchronization therapy. CONCLUSIONS: In a contemporary heart failure with reduced ejection fraction population, ICD for primary prevention was underused, although it was associated with reduced short- and long-term all-cause mortality. This association was consistent across all the investigated subgroups. These results call for better implementation of ICD therapy.