Early stage effect of ischemic preconditioning for patients undergoing on-pump coronary artery bypass grafts surgery: Systematic review and meta-analysis

Background: During the on-pump coronary artery bypass grafts surgery, ischemia/reperfusion injury would happen. Ischemia preconditioning could increase the tolerance against subsequent ischemia and reduce the ischemia/reperfusion injury. However the clinical outcomes of the available trials were different. Methods: We searched the Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 3, 2013), the Medline/PubMed and CNKI in March 2013. RevMan 5.1.6 and GRADEprofiler 3.6 were used for statistical analysis and evidence quality assessment. Heterogeneity was evaluated with significance set at P ≤ 0.10. Results: Eighteen randomized controlled trials were included. There were no differences on in- hospital mortality, postoperative myocardial infarction morbidity between ischemia preconditioning and control groups. The heterogeneity of creatine kinase-MB level 24 hours after surgery was obvious. The differences of 72 hours area under the curve of cardiac troponin T (mean differences of -14.50, 95% confidence interval of -21.71 to -7.28) and troponin I (mean differences -181.79, 95% confidence interval of -270.07 to -93.52) after surgery were observed. Conclusions: All the 18 trails, the positive and the negative results were equal. The meta-analysis results should be interpreted with caution due to limited effective data. Because of high cost-effectiveness, ischemia preconditioning could not be denied completely. Large-scale randomized studies are needed, with the operation procedures and included criteria being more specific.