Baseline and Exercise Predictors of VO2peak in Systolic Heart Failure Patients: Results from SMARTEX-HF

Abstract

Purpose To investigate baseline, exercise testing, and exercise training-mediated predictors of change in peak oxygen uptake (VO2peak) from baseline to 12-week follow-up (ΔVO2peak) 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 NYHA class II-III, who were randomized to either supervised high intensity interval training (HIIT) with exercise target intensity 90-95% of peak heart rate (HRpeak), supervised moderate continuous training (MCT) with target intensity 60-70% of HRpeak, or who received a recommendation of regular exercise on their own (RRE). Predictors of ΔVO2peak were assessed in two models; A logistic regression model comparing highest and lowest tertile (baseline parameters) and a multivariate linear regression model (test/training/clinical parameters). Results The change in VO2peak in response to the interventions (ΔVO2peak) 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 % 1.1 (1.0, 1.2), p = 0.005), age (OR per 10 years 0.5 (0.3, 0.8)), p=0.003) were associated with ΔVO2peak. In the multivariate linear regression, 34% of the variability in [INCREMENT]VO2peak was explained by the increase in exercise training workload, [INCREMENT]HRpeak between baseline and 12-wk post-testing, age, and ever having smoked. Conclusion Exercise training response (ΔVO2peak) correlated negatively with age, LVEF and NYHA class. The ability to increase workload during the training period, and increased ΔHRpeak between baseline and the 12-week test were associated with a positive outcome.