Comparative effectiveness of exercise training modalities in heart transplant recipients: a systematic review and network meta-analysis of randomized controlled trials

AIMS: Exercise training (ET) provides numerous benefits for heart transplant (HTx) recipients. However, direct comparisons between ET modalities remain limited. This study aims to compare the efficacy and safety of multiple ET modalities on peak oxygen consumption (peak VO2) and key secondary outcomes in HTx recipients. METHODS AND RESULTS: We systematically searched eight electronic databases from inception to September 2024. Traditional random-effects models and Bayesian network meta-analysis were employed. Confidence in the results was evaluated using the Confidence in Network Meta-Analysis (CINeMA) tool. Thirteen randomized controlled trials involving 473 HTx recipients were analysed. The network meta-analysis identified high-intensity interval training (HIIT) [mean difference (MD): 4.34 mL.kg⁻¹.min⁻¹; 95% credible interval (CrI), 1.41-5.6] and combined training (CT) (MD: 3.49 mL.kg⁻¹.min⁻¹; 95%CrI, 1.15-7.44) as the most effective interventions for improving peak VO2 compared to usual care. HIIT was also more effective than moderate-intensity continuous training (MICT) (MD: 2.09 mL.kg⁻¹.min⁻¹; 95%CrI, 0.05-4.03). No significant differences were observed between MICT, home-based MICT, home-based CT, and usual care. The certainty of evidence ranged from moderate to very low across comparisons. No significant differences were observed between ET modalities regarding heart rate response or ventilatory efficiency. ET was associated with improvements in specific quality of life subdomains. No exercise-related adverse events were reported. CONCLUSION: This review demonstrates that ET significantly improves peak VO2 in HTx recipients, with HIIT and CT outperforming usual care. HIIT also surpasses MICT in improving peak VO2. Overall, ET modalities are safe and effective for this population. LAY SUMMARY: This study compared different types of exercise training (ET) to determine which are most effective and safe for people who have received a heart transplant (HTx).High-intensity interval training (HIIT) and combined training significantly improved fitness levels, measured by peak oxygen consumption (peak VO2), in HTx recipients compared to usual care. Additionally, HIIT resulted in greater improvements in peak VO2 than moderate-intensity continuous training.No major differences in safety outcomes were observed between the ET modalities, suggesting that various exercise approaches may be safe for this population. REGISTRATION: PROSPERO number: CRD42020191192. DATA SHARE: Open Science Framework tool, available at: https://osf.io/3rwxb/.