Abstract: To evaluate the cardioprotection of remote ischemic postconditioning (RIPostC) in patients with acute ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI).Methods：Forty-six STEMI patients undergoing primary PCI at Peking University Third Hospital from January to April 2014 were randomized to RIPostC group (n=23) and control group (n=23).The RIPostC protocol was started within 1 min after reflow by thrombus aspiration or balloon inflation and consisted of 3 cycles of 5 min/5 min ischemia/reperfusion by cuff inflation/deflation of the lower left limb. The enzymatic infarct size, rate of complete ST segment resolution, corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) in infarct-related artery (IRA) and plasma levels of malondialdehyde(MDA), endothelin-1(ET-1), tumor necrosis factor α (TNFα) of the two groups were compared. Results：There was no significant difference in enzymatic infarct size between the two groups (P＞0.05). The rate of complete ST-segment resolution was significantly higher in RIPostC group than in control group (60.9%vs. 30.4%，P=0.04). There was a trend toward lower CTFC in RIPostC group than that in control group, but the difference was not statistically significant(28 ± 11 vs. 33 ± 11, P = 0.10). However, in the subgroup of anterior wall myocardial infarction CTFC in RIPostC group was significantly lower, compared with control group (25±9 vs. 39±10, P=0.01).There were lower plasma levels of MDA,ET-1,TNFα in RIPostC group than in control group at different time points after primary PCI (P<0.05). Conclusion：In STEMI patients undergoing primary PCI, RIPostC may improve myocardial perfusion and attenuate ischemia reperfusion injury with the underlying mechanisms involving reduction of oxidative stress, protection of endothelial function and inhibition of inflammatory response.

Key words: Ischemic postconditioning, Myocardial infarction, Percutaneous coronary intervention, Myocardial reperfusion injury