Predictors of improved physical performance during cardiac rehabilitation
M Kurpaska, P Krzesinski, J Aftyka, M Kubiak, K PiotrowiczAbstract
Introduction
Cardiac rehabilitation (CR) focuses on improving exercise capacity, that could be assessed as oxygen uptake at peak exercise (peak VO2). Despite CR being performed according to the recommended program, patients achieve different degrees of improvement in peak VO2. A change in peak VO2 (Δ peak VO2) from baseline to post-CR of at least 2 ml/min/kg is associated with better long-term prognosis.
Aim
The aim of this study was to identify predictors of improvement in VO2 ≥2 ml/min/kg in patients undergoing CR.
Methods
A single-center, retrospective registry of 518 patients who underwent CR was conducted. Exclusion criteria included history of cardiac surgery, inpatient rehabilitation, and the absence of cardiopulmonary exercise testing performed twice during CR. The clinical reasons for CR, demographic data, comorbidities, and hemodynamic parameters at rest (assessed via impedance cardiography (ICG)) were analyzed. The analysis included 271 patients who were divided into two subgroups according to Δ peak VO2: Δ peak VO2 ≥ 2ml/min/kg (95 patients, 76 men, median age 60 years) and Δ peak VO2 < 2ml/min/kg (176 patients, 133 men, median age 63 years). Variables that significantly differed between the two subgroups with a p-value < 0.1 were selected for the logistic regression analysis.
Results
In the univariate logistic regression, the following parameters were identified as predictors of Δ peak VO2 ≥ 2ml/min/kg: age (OR 0.96, p=0.007), number of previous percutaneous coronary intervention (OR 1.25, p=0.039), total fluid content (TFC) (OR 1.08, p=0.032), and Karvonen upper training heart rate range (OR 1.02, p=0.042). In multivariate regression analysis as independent predictors revealed: baseline predicted value of peak VO2 (baseline peak VO2 % pred. - OR 0.91, p<0.001) and Karvonen upper training heart rate range (OR 1.03, p=0.004). Other variables, including comorbidities, left ventricular ejection fraction, reason of CR, other than TFC parameters via ICG were not associated with improvement in peak VO2 during CR.
Conclusions
The improvement of Δ peak VO2 ≥ 2ml/min/kg after CR has complex background. Lower exercise capacity before CR and higher training intensity revealed independent predictors of this positive effect. Individual comprehensive assessment is crucial for the qualification to CR, planning of intervention and prediction of the effects regarding exercise performance.