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Background:As the representative of early reperfusion therapy (RT), thrombolytic therapy and percutaneous coronary intervention (PCI) which can open the infarction related artery (IRA) and limit infarct size (IS) is the main therapeutic measures of acute myocardial infarction(AMI). However, RT itself paradoxically induces myocardial injury named"ischemic reperfusion injury (IRI)". Among AMI patients having accepted successful revascularization,40%of myocardial IS stems from IRI. How to reduce IRI during RT is a focus in recent years.In1986, Murry proposed ischemic preconditioning (IPreC) concept and pointed out that IPreC could reduce IRI and IS, this effect was confirmed in a variety of ischemia reperfusion animal model, cardiac surgeon also observed protective role of IPreC in the elective cardiac operation. However, the AMI event’s unpredictability limit the application of IPreC in clinical. In2000and2003, Tao Ling and Zhao successively put forward the concept of ischemic postconditioning (IPostC) and found that IPostC could also reduce IRI and IS during RT. Since then, a number of basic study confirmed that IPostC can attenuate myocardial IRI in different ischemia reperfusion animal models and discussed the mechanism of myocardial protection deeply and broadly. Because IPostC can be easily implemented in AMI patients during PCI, people have high hopes for its clinical effect. The small sample "proof-of-concept" translational studies in AMI patients treated with direct PCI shows that IPostC can reduce IS, but the myocardial protection of IPostC in clinical application remains controversial.Objective:To assess the effects of IPostC on arrhythmias (RA), coronary artery and myocardial perfusion, IS, changes of left ventricular structure and function, markers of inflammation and clinical events in AMI patients accepting direct PCI. Also to explore the method of prevention of myocardial IRI.Methods:106acute ST segment elevation myocardial infarction patients presenting within 12hours and accepting direct PCI in Department of Cardiology, Baodi Clinical college of Tianjin Medical University from2010June to2012June, were randomly assigned to control group (56cases) or IPostC group (50cases). Two groups both received standard drug therapy, and control group was treated with standard PCI technology, IPostC group was given a3round of30seconds IPostC within30seconds of the IRA opening, then was treated prolonged reperfuision and completed PCI operation. In the process of PCI, record RA, coronary TIMI flow, corrected TIMI frame count (cTFC), myocardial blush grade (MBG) and immediate postoperative ST segment recovery (STR). Blood samples were obtained in the immediate admission and after the incidence of8hours,10hours,12hours,14hours,16hours,18hours,24hours,48hours, and serum creatine kinase isoenzyme-MB (CK-MB), high sensitivity troponin T (hs-TnT) and high sensitivity C reactive protein (hs-CRP) were determined. Transthoracic two dimensional echocardiography was performed in90days after onset and left ventricular end diastolic diameter(LVED), left ventricular ejection fractions(LVEF), wall motion score index(WMSI) were determined. At the same time, clinical events, such as death, reinfarction. stroke, angina and heart failure, were observed in90days.Results:The two study groups were well balanced in relation to baseline clinical characteristics and angiographic data, as well as PCI treatment. RA in group IPostC, such as premature ventricular complex, ventricular tachycardia, is less than that in control group (24%vs42.9%,P=0.041;14.3%vs2%, P=0.034). The NRF rate during PCI was significantly decreased in the IPostC group than in the control group (8.0%vs23.2%, P=0.033). After PCI, there was no significant difference in TIMI flow grade in the two groups, but the cTFC and MBG were improved in the IPostC group than in the control group PCI caused a significant increase in CK-MB after the procedure in both groups, the peak CK-MB value was lower in the IPostC group than in the control group (258.3±87.8U/L vs306.6±94.4U/L, P=0.008). Similar changes were also observed in hs-TnT (3582.08±1731.40ng/L vs 4501.34±1554.4ng/L, P=0.005)and hs-CRP(13.65(4.36,32.76) mg/L vs17.25(9.58,36.35) mg/L, P=0.048). The LVED90days after onset in IPostC group was smaller than the control group (52.02±3.28mm vs55.11±4.08mm, P<0.0001), and LVEF was higher than that of the control group (55.92%±2.87%vs48.96%±3.19%, P<0.0001), WMSI lower than that of the control group (1.34±0.21vs1.49±0.24, P=0.0001). Heart failure90days after onset in IPostC group is lower than that in the control group (10%vs25%, P=0.044).Conclusion:On the base of standard PCI operating, the3round of30seconds IPostC operation could reduce the myocardial IRI in patients with acute ST segment elevation myocardial infarction, limite the incidence of RA and coronary artery NRF during PCI, the level of myocardial necrosis markers afte operation, IS, ventricular remodeling after AMI, improve ventricular wall motion, LVEF and the heart’s ability to pump blood, and these effects contribute to the improvement of clinical prognosis.
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