Baseline and Exercise Predictors of V-O_2peak in Systolic Heart Failure Patients: Results from SMARTEX-HF

Purpose This study aimed to investigate baseline, exercise testing, and exercise training-mediated predictors of change in peak oxygen uptake (V-O_2peak) from baseline to 12-wk follow-up (ΔV-O_2peak) in a post hoc analysis from the SMARTEX Heart Failure trial. Methods We studied 215 patients with heart failure with left ventricular ejection fraction (LVEF) ≤35%, and New York Heart Association (NYHA) classes II-III who were randomized to either supervised high-intensity interval training with exercise target intensity of 90%-95% of peak heart rate (HR_peak) or supervised moderate continuous training (MCT) with target intensity of 60%-70% of HR_peak, or who received a recommendation of regular exercise on their own. Predictors of ΔV-O_2peak were assessed in two models: a logistic regression model comparing highest and lowest tertiles (baseline parameters) and a multivariate linear regression model (test/training/clinical parameters). Results The change in V-O_2peak in response to the interventions (ΔV-O_2peak) varied substantially, from-8.50 to +11.30 mL·kg^-1·min^-1. Baseline NYHA (class II gave higher odds vs III; odds ratio (OR), 7.1 (2.0-24.9); P = 0.002), LVEF (OR per percent, 1.1 (1.0-1.2); P = 0.005), and age (OR per 10 yr, 0.5 (0.3-0.8); P = 0.003) were associated with ΔV-O_2peak. In the multivariate linear regression, 34% of the variability in ΔV-O_2peak was explained by the increase in exercise training workload, ΔHR_peak between baseline and 12-wk posttesting, age, and ever having smoked. Conclusion Exercise training response (ΔV-O_2peak) correlated negatively with age, LVEF, and NYHA class. The ability to increase workload during the training period and increased ΔHR_peak between baseline and the 12-wk test were associated with a positive outcome.