Remote ischemic conditioning and cardioprotection: a systematic review and meta-analysis of randomized clinical trials

Remote ischemic conditioning (RIC) represents an innovative cardioprotective method that has been investigated in numerous clinical studies providing miscellaneous results. This systematic review and meta-analysis sought to assess RIC-induced effects on myocardial injury biomarkers and clinical outcomes in clinical situations at risk of myocardial ischemia/reperfusion damage. PubMed and Cochrane databases were searched for randomized clinical trials testing any RIC protocol versus a control in a situation or procedure at risk of cardiac ischemia/reperfusion damage, including coronary angioplasty and cardiac or major vascular surgery. Data were collected from publications reporting biological markers of myocardial injury or clinical events, including major adverse cardiovascular and cerebral events (MACCE), all-cause mortality, myocardial infarction incidence, and repeat revascularization. Standardized mean difference (SMD) (continuous outcomes) and odds ratios (OR) (dichotomous outcomes) were compared between groups. Heterogeneity was investigated by means of meta-analysis regression. A total of 53 articles (44 studies) were identified by the search, with 5,317 patients included in the systematic meta-analysis. RIC significantly reduced troponin area under curve (AUC) (SMD −0.27, 95 % confidence interval (CI): [−0.36, −0.18]; p < 0.01) and troponin peak (SMD: −0.22, 95 % CI: [−0.30, −0.15]; p < 0.01). The same reduction was observed with creatine kinase MB (CK-MB) AUC and peak. Long-term MACCE and all-cause mortality were significantly lower in the RIC group (OR: 0.42, 95 % CI [0.28, 0.64]; p < 0.01 vs. OR: 0.27, 95 % CI [0.13, 0.58]; p < 0.01, respectively), as was myocardial infarction incidence (OR: 0.54, 95 % CI [0.40, 0.73]; p < 0.01). We observed no difference regarding repeat revascularization. RIC appears to be an effective method for reducing ischemia/reperfusion myocardial injury, and our findings suggest that it may reduce long-term clinical events.