Impact of an Age-Adjusted Co-morbidity Index on Survival of Patients With Heart Failure Implanted With Cardiac Resynchronization Therapy Devices

Abstract

Age is an adverse prognostic factor in patients with heart failure. We aimed to assess the impact of age and noncardiac co-morbidities in the outcome of patients undergoing cardiac resynchronization therapy (CRT), and determine which of these two factors is the most important predictor of survival. The study involved a single-center retrospective assessment of 697 consecutive CRT implants during a 12-year period. Patient co-morbidity profile was assessed using the Charlson Co-morbidity Index (CCI) and the Charlson Age-Co-morbidity Index (CACI). Predictors of survival free from heart transplantation were assessed. CRT-related complications and cause of death analysis were assessed within tertiles of the CACI. During a mean follow-up of 1,813 ± 1,177 days, 347 patients (49.9%) died and 37 (5.3%) underwent heart transplantation. On multivariate Cox regression, female gender (HR = 0.78, 95% confidence interval [CI] 0.62 to 0.99, p = 0.041), estimated glomerular filtration rate (HR per ml/min = 0.99, 95% CI 0.98 to 0.99, p < 0.001), left ventricular ejection fraction (HR per % = 0.99, 95% CI 0.98 to 1.00, p = 0.022), New York Heart Association class (HR = 1.83, 95% CI 1.53 to 2.20, p < 0.001), presence of left bundle branch block (HR = 0.70, 95% CI 0.56 to 0.87, p = 0.001), and CACI tertile (HR = 1.37, 95% CI 1.18 to 1.59, p < 0.001) were independent predictors of all-cause mortality or heart transplantation. Compared with age and the CCI, the CACI was the best discriminator of all-cause mortality. Inappropriate therapies occurred less frequently in higher co-morbidity tertiles. In conclusion, patient co-morbidity profile adjusted to age impacts on mortality after CRT implantation. Use of the CACI may help refine guideline criteria to identify patients more likely to benefit from CRT.