Abstract 1717: Impact of Age on Aerobic Capacity in Patients With Systolic Heart Failure: The HF-ACTION Study
Background: Reduced exercise capacity is a chief complaint among systolic heart failure (SHF) pts, and indicates worse prognosis, especially for elderly pts. However, magnitude of an age effect on aerobic capacity (peak VO2), relative to other covariates, is unclear.
Methods: Baseline cardiopulmonary exercise test (CPX) data from SHF pts in the HF-ACTION exercise training trial were assessed. Linear regression analyses were used to clarify key covariates that predicted peak VO2. A comorbidity score was used to assess impact of aggregate comorbidity.
Results: There were 2331 NYHA class II-IV SHF pts age 19 –91 yrs, 28% women, 95% beta-blocker use. Mean peak VO2 was 14.9 ± 4.7 ml/kg/min and had a significant age-related decline of -0.14 mL/kg/min/yr (p < 0.0001) that was non-linear and by analysis of linear splines appeared to begin at about age 40 yrs (figure⇓). In a multivariable model with 34 other clinical/demographic variables, age was the strongest predictor of peak VO2 (partial R2 = 0.12), followed by BMI (partial R2 = 0.07), sex, race, and NYHA class (each partial R2 = 0.06); model R2 = 0.392, p < 0.0001. There was a strong, linear decline in peak exercise heart rate (HR) with age (−0. 69 beats/min/yr, R2 = 0.15, p < 0.0001), which persisted even after accounting for beta-blockers. However, age remained a strong predictor of peak VO2 even when peak HR was included in the multivariable model. Aggregate comorbidity increased with age, but did not significantly influence age effects on peak VO2.
Conclusions: Age is the strongest clinical/demographic predictor of peak VO2 in the HF-ACTION population. The effect is not explained by either age-related declines in HR or increases in comorbidities.