The effect of remote ischemic preconditioning on cardiac injury in adults undergoing cardiac surgery: a systematic review with quantitative synthesis

BACKGROUND: To evaluate the association between remote ischemic preconditioning and postoperative hs-TnT levels in patients undergoing cardiac surgery. METHODS: We systematically searched PubMed, Cochrane Central, Scopus, Embase, and Web of Science library databases for original RCTs (randomized controlled trials) articles that looked at the effect of RIPC on cardioprotection undergoing Cardiovascular Surgery. The outcome assessed was high-sensitivity troponin T (hs-TnT). Random-effects-analyses were conducted using standardized mean differences (SMDs) or mean differences (MDs) with 95% confidence intervals, applying the Hartung-Knapp-Sidik-Jonkman (HKSJ) method with restricted maximum likelihood estimation (REML). Risk of bias was assessed using the Cochrane Risk of Bias 2 (RoB 2) tool, certainty of evidence was graded using GRADE. RESULTS: Four randomized controlled trials were included in the quantitative synthesis. Using a random-effects model with restricted maximum likelihood estimation (REML) and HKSJ, the pooled analysis showed no significant difference in hs-TnT levels between the RIPC and control groups (Hedges' g = - 0.13, 95% CI - 0.83 to 0.56; p = 0.59). Substantial heterogeneity was observed among studies (I² = 84.6%, τ² = 0.16). Leave-one-out sensitivity analyses demonstrated that the pooled estimate was highly sensitive to the inclusion of individual studies, indicating limited robustness of the available evidence. Exploratory subgroup analyses suggested that effect estimates varied according to postoperative hs-TnT measurement timing; however, these findings were based on very small numbers of studies and should be interpreted cautiously. CONCLUSION: Remote ischemic preconditioning was not associated with a significant overall reduction in postoperative hs-TnT levels in adult cardiac surgery. The available evidence is limited by the small number of trials, substantial heterogeneity, and reliance on a surrogate biomarker outcome. Consequently, current evidence is insufficient to support or refute a clinically meaningful cardioprotective effect of RIPC in this setting.