Interindividual response variation to exercise-based cardiac rehabilitation on changes in cardiorespiratory fitness in heart transplant patients: A secondary meta-analysis of randomized controlled trials

Abstract

Background: Determine whether true exercise-associated interindividual response differences (IIRD) occur in cardiorespiratory fitness as a result of exercise-based cardiac rehabilitation in heart transplant patients. Methods: Using data from a recent (2023) meta-analysis of 9 randomized controlled trials representing 296 patients (163 exercise, 133 control), an aggregate data meta-analysis of treatment effects (change outcome differences between exercise and control groups) was conducted as well as an IIRD meta-analysis using the inverse variance heterogeneity model. The primary outcome was cardiorespiratory fitness (VO2max) in ml/kg/min. Results: Statistically significant and clinically important increases equivalent to 14.5% were observed for VO2max in ml/kg/min (X̅, 3.0, 95% confidence interval (CI), 2.4-3.7 ml/kg/min, p < 0.001; Q = 11.8, p = 0.16; I2 = 32.0%, 95% CI, 0%-68.8%; τ2 = 0.4). The 95% prediction interval (PI) was 1.2-4.7 ml/kg/min. However, no statistically significant IIRD were observed (X̅, 0.6, 95% CI, −1.1 to 1.4 ml/kg/min; τ2 = 2.9). The 95% PI was −2.7 to 2.8 ml/kg/min. Conclusions: While exercise-based cardiac rehabilitation increases VO2max in ml/kg/min in heart transplant patients, a lack of true exercise-associated IIRD exists. A need exists for additional well-designed randomized controlled trials of longer duration to determine the long-term effects of exercise-based cardiac rehabilitation on VO2max in ml/kg/min heart transplant patients.

Keywords

• cardiac rehabilitation
• heart transplantation
• cardiorespiratory fitness
• meta-analysis
• response variation