Effects of high-intensity interval training on cardiorespiratory function in coronary artery disease: An overview of systematic reviews

Background: Exercise-based cardiac rehabilitation has been identified as a crucial component in mitigating all-cause mortality among individuals diagnosed with coronary artery disease (CAD). Nevertheless, the optimal exercise prescription remains elusive. Objective: The purpose of this overview is to conduct a systematic evaluation and synthesis of the evidence derived from systematic reviews/meta-analyses (SRs/MAs) regarding the effects on cardiorespiratory fitness and safety of high-intensity interval training (HIIT) compared to moderate-intensity continuous training (MICT) for CAD. Methods: SRs/MAs were searched across 5 databases from inception until March 22, 2023. We assessed methodological quality using the Assessing the Methodological Quality of Systematic Reviews 2 (AMSTAR-2). The risk of bias, reporting, and evidence were evaluated using the Risk of Bias in Systematic Reviews (ROBIS) tool, the Preferred Reporting Item for Systematic Review and Meta-analysis (PRISMA) 2020, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system, respectively. Results: In total, 9 SRs/MAs were included. Based on the AMSTAR-2 criteria, 4 and 5 studies were considered low- and critically-low quality, respectively. None of the studies reported all 27 items outlined in the PRISMA 2020 checklist. Regarding the ROBIS evaluation, 4 reviews were rated as low risk, 4 as high risk, and 1 as unclear risk. The GRADE evaluation indicated 3 high-level evidence, 20 moderate-level evidence, 28 lowlevel evidence, and 34 very low-level evidence studies based on 85 indicators. Moderate- to high-quality evidence supported that HIIT is superior to MICT in improving VO2peak for CAD. Conclusion: The efficacy and time cost of developing cardiorespiratory fitness support HIIT as an adjunct or alternative to MICT. The evidence does not permit a definitive decision regarding the adverse effects of HIIT compared to MICT. Because of the insufficient quality of the evidence, future studies should focus more on the quality of randomized controlled trials and evidence for SRs/MAs to provide scientific and robust evidence for conclusions. Trial Registration: The review was registered at PROSPERO: CRD42023420015 (c) 2024 Published by Elsevier Masson SAS.