Remote ischemic preconditioning and cognitive dysfunction following coronary artery bypass grafting: A systematic review and meta-analysis of randomized controlled trials

Introduction: Postoperative cognitive dysfunction (POCD) is a common neurological issue following cardiopulmonary bypass (CPB)-assisted heart surgery. Remote ischemic preconditioning (RIPC) increases the tolerance of vital organs to ischemia/reperfusion injury, leading to reduced brain injury biomarkers and improved cognitive control. However, the exact mechanisms underlying RIPC’s neuroprotective effects remain unclear. This systematic review aimed to explore the hypothesis that RIPC lowers neurocognitive dysfunction in patients undergoing CPB surgery. Method: All relevant studies were searched in PubMed, ScienceDirect, EBSCOhost, Google Scholar, Semantic Scholar, Scopus, and Cochrane Library database. Assessment of study quality was carried out by two independent reviewers individually using the Cochrane Risk of Bias (RoB-2) tool. Meta-analysis was performed using a fixed-effect model due to low heterogeneity among studies, except for those with substantial heterogeneity. Results: A total of five studies with 1,843 participants were included in the meta-analysis. RIPC was not associated with reduced incidence of postoperative cognitive dysfunction (five RCTs, odds ratio [OR: ] 0.79, 95% confidence interval [CI]: 0.56–1.11) nor its improvement (three RCTs, OR: 0.80, 95% CI: 0.50–1.27). In addition, the analysis of the effect of RIPC on specific cognitive function tests found that pooled SMD for RAVLT 1-3 and RAVLT LT were −0.07 (95% CI: −0.25,012) and −0.04 (95% CI: −0.25–0.12), respectively, and for VFT semantic and phonetic were −0.15 (95% CI: −0.33–0.04) and 0.11 (95% CI: −0.40–0.62), respectively. Conclusion: The effect of RIPC on cognitive performance in CABG patients remained insignificant. Results from previous studies were unable to justify the use of RIPC as a neuroprotective agent in CABG patients.