Is remote ischaemic preconditioning worthwhile for patients undergoing cardiac surgery with cardiopulmonary bypass? A meta-analysis and systematic literature review

Background: Numerous randomized controlled trials (RCTs) investigated the clinical benefits of remote ischemic preconditioning (RIPC) prior to cardiopulmonary bypass (CPB). However, to date, there is still no consensus on the benefit of this procedure. Therefore, this meta-analysis aimed to evaluate the treatment outcomes of RIPC in patients treated with CPB. Methods: Databases were systematically searched for eligible RCTs comparing the delivery of RIPC with no treatment or sham RIPC (control) before CPB. Two authors individually screened studies and assessed the risk of bias. The primary outcome measure was mortality. The secondary outcome measures were length of intensive care unit (ICU) or hospital stay, the incidence of myocardial injury (MI), low cardiac output syndrome (LCOS) and so on. The relative risk (RR) and the population size mean difference (SMD) at the 95% confidence interval (95%CI) were compared between the 2 groups. Results: Forty-one RCTs met the eligibility criteria. RIPC did not reduce overall and in-hospital mortality compared with the control group (RR=0.99, 95%CI: 0.78-1.26, I 2 =12%). No remarkable difference was observed between the two groups regarding the length of ICU and hospital stay (SMD: -0.12, 95%CI: -0.29−0.06, I 2 =93%; SMD: -0.926, 95%CI: -2.103−0.251, I 2 =95.2%, respectively). However, RIPC reduced the incidence of MI and the ventilation duration slightly when compared to the control group (RR=0.86, 95%CI: 0.76−0.99, I 2 =22%; RR=-0.16 95%CI: -1.85−1.52, I 2 =0%, respectively). Conclusion: RIPC did not have an impact on mortality and length of ICU/hospital stay, however, it reduced the incidence of MI and the ventilation duration. This work does not recommend RIPC for patients underwent cardiac surgery.