The effect of comorbidity on the competing risk of sudden and nonsudden death in an ambulatory heart failure population

Background: Sudden death (SD) and non-sudden cardiac death are responsible for the majority of deaths in patients with heart failure. We sought to identify the influence of comorbid illness (Charlson Comorbidity Index [CCI]) on competing modes of death in heart failure. Methods: A retrospective analysis of 824 patients followed in a tertiary care heart failure clinic was performed. We analyzed the cumulative incidence of sudden and nonsudden death. Competing risk regression was used to examine the association between medical comorbidities and mode of death. The outcomes of interest were overall mortality, SD, SD and/or appropriate implantable cardioverterdefibrillator therapy (ICD), and non-SD. Results: Mean age of the study population was 64.1 ± 14.7 years, 68.6% were male, and mean ejection fraction was 32.8% ± 13.5%. Over a mean follow-up of 4.4 years, 229 patients (27.8%) died. SD accounted for 33 deaths (14.4%), whereas SD/appropriate ICD therapy occurred in 56 patients (24.5%). The risk of non-SD and total mortality increased (P <.0001) as the CCI increased, whereas the risk of SD decreased (P =.03). The cumulative incidence of SD, SD and/or ventricular tachycardia/fibrillation, and non-SD at 5 years was 5.6%, 9.1%, and 27.8%, respectively. In multivariate competing risk analysis, advancing age, New York Heart Association class, and a CCI >4 were significantly associated with non-SD, Conclusion: Patients with heart failure with significant comorbidities are much more likely to sustain non-SD. These findings may have implications in optimal selection of patients with heart failure for interventions such as prophylactic ICD therapy.