Clinical Benefits of Aortic Cross-clamping Versus Limb Remote Ischemic Preconditioning in Coronary Artery Bypass Grafting with Cardiopulmonary Bypass: a Meta-analysis of Randomized Controlled Trials

Background: We assessed whether aortic cross-clamping or limb remote ischemic preconditioning improved postoperative outcomes, reduced myocardial injury and incidences of postoperative complications in patients undergoing on-pump coronary artery bypass grafting (CABG).

Materials And Methods: PubMed, EMBASE, the Cochrane Library, and ClinicalTrials databases were searched for studies comparing the effects of ischemic preconditioning with no preconditioning in adult patients undergoing on-pump CABG. The primary end points were mechanical ventilation time, the length of stay in intensive care unit and hospital, whereas the secondary end points were peak values of myocardial biomarkers and postoperative complications. Mean differences were estimated for the primary end points, as well as standard mean differences and odds ratios for the secondary end points.

Results: A total of 29 randomized controlled trials with 1791 patients were included. Compared with control group, aortic cross-clamping preconditioning reduced mechanical ventilation time (mean difference [95% confidence interval {CI}]) (-5.59 h [-9.21 to -1.96]), whereas limb remote ischemic preconditioning was not associated with improvement of postoperative outcomes. For myocardial biomarkers, both aortic cross-clamping and limb remote ischemic preconditioning reduced peak values of myocardial biomarkers (standard mean difference [95% CI]) (-0.48 [-0.81 to -0.14]; -0.19 [-0.36 to -0.02], respectively). Subgroup analysis showed that aortic cross-clamping preconditioning protocols with ischemia episodes <5 min did reduce the release of biomarkers (-0.69 [-1.04 to -0.34]) but those with 5 min ischemia episodes elevated them (0.40 [0.04-0.75]). Cardiovascular, cerebrovascular, renal, and intestinal complications were reported, and aortic cross-clamping preconditioning seemed to reduce the incidences of cardiac arrhythmia (odds ratio [95% CI]) (0.46 [0.27-0.80], P = 0.006).

Conclusions: Cardiac surgeons could consider aortic cross-clamping or limb remote ischemic preconditioning to reduce myocardial injury during CABG. Moreover, aortic cross-clamping preconditioning is associated with a decreased risk of postoperative respiratory failure and cardiac arrhythmia.