Cardioprotective role of ischemic postconditioning in acute myocardial infarction: A systematic review and meta-analysis

Background Evidence suggests that ischemic postconditioning (IPoC) may reduce the extent of reperfusion injury. We performed a meta-analysis of randomized controlled trials, which compared the role of IPoC during primary percutaneous coronary intervention (PCI) to PCI alone (control group) in ST-segment elevation myocardial infarction. Methods Several databases were searched, which yielded 19 studies. The outcomes of interest were measures of myocardial damage (serum cardiac enzymes and infarct size by imaging) and left ventricular function (left ventricular ejection fraction and wall motion score index). Mean difference (MD) and standardized mean difference (SMD) were used to assess the treatment effect. An inverse variance method was used to pool data into a random-effects model. Results Ischemic postconditioning demonstrated a decrease in serum cardiac enzymes (SMD -0.48, 95% CI -0.92 to -0.05, I-2 = 92%), reduction in infarct size by imaging (SMD -0.30, 95% CI -0.58 to -0.01, I-2 = 80%), wall motion score index (MD -0.19, 95% CI -0.29 to -0.09, I-2 = 44%), and showed improvement in left ventricular ejection fraction (IPoC 52 +/- 0.4, control 49.7 +/- 0.4) (MD 2.78, 95% CI 0.66-4.91, I-2 = 69%). All included studies were limited by high risk of performance and publication bias. Conclusions Ischemic postconditioning during PCI in ST-segment elevation myocardial infarction appears to be superior to PCI alone in reduction of both myocardial injury or damage and improvement in global and regional left ventricular function. The effect seems to be more pronounced when a greater myocardial area is at risk. Given the limitations of the current available evidence, additional data from large randomized controlled trials are warranted.