Stenting technique, gender, and age are associated with cardioprotection by ischaemic postconditioning in primary coronary intervention: a systematic review of 10 randomized trials

Aims We sought to perform a systematic review and meta-analysis to evaluate the potential factors affecting ischaemic postconditioning (IPoC) for patients with ST-segment elevation acute myocardial infarction (STEMI) in primary percutaneous coronary intervention (PCI). Methods and results Ten randomized controlled trials (RCTs) on IPoC reporting myocardial enzyme levels or left ventricular ejection fraction (LVEF) in a total of 560 STEMI patients were identified in PubMed, EMBase, and Cochrane Library (up to February 2012). Compared with controls, IPoC significantly reduced elevated cardiac enzyme levels [standardized mean difference = -0.84; 95% confidential interval (CI): -1.26 to -0.43; P < 0.00001; heterogeneity test, I-2 = 81.0%] and improved LVEF [weighted mean difference (WMD) 3.98%; 95% CI: 1.27-6.70%; P = 0.004; heterogeneity test, I-2 = 87.1%]. The effect on LVEF remained significant after 1 year (WMD = 5.04%; 95% CI: 4.20-5.88%; P < 0.00001; heterogeneity test, I-2 = 0.0%). Univariate meta-regression analysis suggested that the major sources of significant heterogeneity (P < 0.1) were the use of direct-stenting technique (%) (coefficient = -0.886; P = 0.069; adjusted R-2 = 0.34) and male proportion (%) (coefficient = -0.022; P = 0.098; adjusted R-2 = 0.28) for myocardial enzyme levels, and age (coefficient = -1.34; P = 0.025; adjusted R-2 = 0.55) for LVEF (%). Subsequent multivariate regression and subgroup analysis confirmed these results. Conclusion Available evidence from this systematic review and meta-analysis of 10 RCTs suggests that IPoC may confer cardio-protection in terms of myocardial enzyme levels and LVEF for STEMI during primary PCI. These effects are more pronounced among young and male patients, and those in whom direct-stenting techniques were used. Future studies should focus on the mortality in high-quality, large-scale clinical trials with long-term follow-up.