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

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 ( X® , 3.0, 95% confidence interval (CI), 2.4-3.7 ml/kg/min, p p = 0.16; I 2 = 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 ( X® , 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.