Association Between Comorbidities and Outcomes in Heart Failure Patients With and Without an Implantable Cardioverter-Defibrillator for Primary Prevention.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) therapy is associated with improved outcomes in patients with heart failure (HF), but whether this association holds among older patients with multiple comorbid illnesses and worse HF burden remains unclear. METHODS AND RESULTS: Using the National Cardiovascular Data Registry's ICD Registry and the Get With The Guidelines-Heart Failure (GWTG-HF) registry linked with Medicare claims, we examined outcomes associated with primary-prevention ICD versus no ICD among HF patients aged ≥65 years in clinical practice. We included patients with an ejection fraction ≤35% who received (ICD Registry) and who did not receive (GWTG-HF) an ICD. Compared with patients with an ICD, patients in the non-ICD group were older and more likely to be female and white. In matched cohorts, the 3-year adjusted mortality rate was lower in the ICD group versus the non-ICD group (46.7% versus 55.8%; adjusted hazard ratio [HR] 0.76; 95% CI 0.69 to 0.83). There was no associated difference in all-cause readmission (HR 0.99; 95% CI 0.92 to 1.08) but a lower risk of HF readmission (HR 0.88; 95% CI 0.80 to 0.97). When compared with no ICD, ICDs were also associated with better survival in patients with ≤3 comorbidities (HR 0.77; 95% CI 0.69 to 0.87) and >3 comorbidities (HR 0.77; 95% CI 0.64 to 0.93) and in patients with no hospitalization for HF (HR 0.75; 95% CI 0.65 to 0.86) and at least 1 prior HF hospitalization (HR 0.69; 95% CI 0.58 to 0.82). In subgroup analyses, there were no interactions between ICD and mortality risk for comorbidity burden (P=0.95) and for prior HF hospitalization (P=0.46). CONCLUSION: Among older HF patients, ICDs for primary prevention were associated with lower risk of mortality even among those with high comorbid illness burden and prior HF hospitalization.