Background: Although remote ischemic conditioning (RIC) by transient limb ischemia in percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) has shown favorable effects on myocardial (ischemia-reperfusion) injury, recent trials provide inconsistent results. The aim of the present study was to assess the effect of RIC in PCI or CABG.
Methods and results: Medline/Embase/conference reports were searched for randomized RIC trials and were included if they reported on biomarkers of myocardial injury (CK-MB/troponin T/I), after which, standardized mean differences (SMDs) were calculated (Hedges g statistic). Meta-analysis of 4 studies on PCI, involving 557 patients, indicated reduced biomarkers for myocardial injury with RIC compared to control (random effects model: SMD, -0.21; 95% confidence interval [CI]: -0.66 to 0.24). Analysis of primary PCI studies, involving 314 patients, indicated a highly significant positive effect of RIC on myocardial injury (SMD, -0.55; 95% CI: -0.77 to -0.32). The 13 CABG studies taken together, involving 891 patients, indicated a significant effect of RIC on myocardial injury (SMD, -0.34; 95% CI: -0.59 to -0.08). The statistical tests indicated moderate to high heterogeneity across the studies (Q-statistic: PCI, P=0.0006, I(2)=83%; CABG, P<0.0001, I(2)=69%).
Conclusions: In patients undergoing PCI or CABG, RIC with transient episodes of limb ischemia is associated with lower biomarkers of myocardial injury compared to control, but this effect failed to reach statistical significance in the overall PCI analysis.