Outcomes in African Americans undergoing cardioverter-defibrillator implantation for primary prevention of sudden cardiac death: findings from the Prospective Observational Study of Implantable Cardioverter-Defibrillators (PROSE-ICD)

Abstract

Background: Implantable cardioverter-defibrillators (ICDs) reduce the risk of death in patients with left ventricular dysfunction. Little is known regarding the benefit of this therapy in African Americans (AAs).

Objective: The purpose of this study was to determine the association between AA race and outcomes in a cohort of primary prevention ICD patients.

Methods: We conducted a prospective cohort study of patients with systolic heart failure who underwent ICD implantation for primary prevention of sudden cardiac death. The primary end-point was appropriate ICD shock defined as a shock for rapid ventricular tachyarrhythmias. The secondary end-point was all-cause mortality.

Results: There were 1189 patients (447 AAs and 712 non-AAs) enrolled. Over a median follow-up of 5.1 years, a total of 137 patients experienced an appropriate ICD shock, and 343 died (294 of whom died without receiving an appropriate ICD shock). The multivariate adjusted hazard ratio (95% confidence interval) comparing AAs vs non-AAs were 1.24 (0.96-1.59) for all-cause mortality, 1.33 (1.02, 1.74) for all-cause mortality without receiving appropriate ICD shock, and 0.78 (0.51, 1.19) for appropriate ICD shock. Ejection fraction, diabetes, and hypertension appeared to explain 24.1% (10.1%-69.5%), 18.7% (5.3%-58.0%), and 13.6% (3.8%-53.6%) of the excess risk of mortality in AAs, with a large proportion of the mortality difference remaining unexplained.

Conclusion: In patients with primary prevention ICDs, AAs had an increased risk of dying without receiving an appropriate ICD shock compared to non-AAs.

Keywords: African American; All-cause mortality; Implantable cardioverter-defibrillator; Sudden cardiac death; implantable cardioverter-defibrillator shock.

Figure 1. Multivariable adjusted hazard ratios (95% CI) for mortality comparing African-Americans (AA) with non-AA, by pre-specified subgroups

Hazard ratios were adjusted for age, sex, enrollment center, education, smoking status, body mass index, ejection fraction, NYHA class, ischemic cardiomyopathy, atrial fibrillation, diabetes, hypertension, and chronic kidney disease. Deviation to the right of 1 indicates higher mortality in AAs in the indicated subgroup.