The Cardioprotective Effect Of Ischemic Postconditioning In Patients Undergoing Primary Percutaneous Coronary Intervention

Objective: To investigate the cardioprotective effect of ischemic postconditioning(IPost) in acute ST-segment elevation myocardial infarction(STEMI) patients within 12 hours during primary percutaneous coronary intervention(PPCI).Methods: From December 2012 to December 2014, a total of 110 patients consented to PPCI due to first-time acute STEMI were selected from the cardiovascular department of the Third Hospital of Hebe Medical University.Inclusion criteria:(1)eligible for the 2010 Chinese society of cardiology guideline for the management of ST-elevation myocardial infarction: elevation of myocardial biomarkers(the best is troponin I) at least once exceed the upper reference value, accompanied with at least 1 of the following myocardial ischemia evidence: ①clinical symptoms of myocardial ischemia; ②the presence of new ST elevation in at least 2 contiguous leads or left bundle-branch block(LBBB) on the surface electrocardiogram(ECG); ③the presence of pathological Q-wave on ECG; ④radiographic evidence indicates newly myocardial viability lost or regional wall motion abnormalities;(2) between 18 to 75 years old;(3)presented within 12 hours after the onset of chest pain;(4)coronary angiography(CAG) indicates that the thrombolysis in myocardial infarction(TIMI) flow grade of the infarct-related artery(IRA) is 0 or 1.Exclusion criteria:(1)cardiac arrest or cardiogenic shock;(2)complicated by severe chronic heart failure, perforation of ventricular septum, chordae tendineae or papillary muscle rupture of mitral valve;(3)patients with previous valve replacement, cardiac transplantation, myocardial infarction, pereutaneous coronary intervention(PCI), coronary artery bypass grafting or angina within 48 hours before infarction;(4)patients treated with thrombolytic therapy;(5)coagulation disorders, hemophilia or thrombopenia;(6)severe hepatic, renal or respiratory insufficiency, tumor, severe infection or dissection of aorta;(7) hemorrhagic diseases such as intracranial hemorrhage, subhyaloid hemorrhage or active peptic ulcer;(8) patients allergic to aspirin, clopidogrel, heparin, low molecular heparin or contrast agents;(9)coronary collaterals(Rentrop grade≥1) to the IRA;(10)IRA is the left main coronary artery or others with severe left main stenosis;(11)women in pregnancy or lactation;(12) patients refused to participate in the study.The study protocol was approved by the ethics committee of our hospital, and all the patients were willing to participate and be followed-up on time. Patients were listed in order of presentation after they signed written informed consent. Odd numbered patients were allocated IPost group while even numbered ones allocated control group. All of them received monitoring and oxygen therapy. Patients had neither taken aspirin nor clopidogrel were given 300 mg aspirin and 600 mg clopidogrel, while those who had taken aspirin were given 100~300 mg aspirin. As with those who had taken clopidogrel 6 hours ago, more 300 mg should be given. Complete the measurement of blood pressure,heart rate, myocardial enzyme spectrum, cardiac troponin I(c Tn I), hepatic and renal functions, electrocardiogram and so on.Cardiovascular chief physicians with more than 10 years’ experience conducted PPCI within 90 minutes from admission with standard protocols. In the IPost group, within 1 minute of reflow the percutaneous transluminal coronary angioplasty(PTCA) balloon was positioned upstream of the lesion and reinflated 4 times for 30 s with 4 to 6 atm inflations, each separated by 30 s of reflow. Whether to implant in a stent is determined by the chief operator after these procedures. In the control group, no additional intervention was performed during the first 5 minutes of reperfusion, and then the routine practice.Record the baseline characteristics of the study population, including gender, age, smoking history, hypertension, type 2 diabetes mellitus, dys- lipidemia, heart rate, mean arterial pressure(MAP), body-mass index(BMI), c Tn I on admission, treatment on admission, time from symptom onset to reperfusion, door-to-balloon(DTB) time. Operative data, including IRA, number of vessels, reflow method, stent length, stent diameter, treatment during angioplasty, TIMI flow grade and TMPG after PPCI,and severe arrhythmias. Postoperative data, including treatment after operation and at discharge, ST-segment resolution(STR), c Tn I in the first and the seventh postoperative morning, the left ventricular ejection fraction(LVEF) and wall motion score index(WMSI) in 1 week, 1 month and 3 months after PPCI, major adverse cardiac events(MACE) in 3 months after PPCI.Results: 1 4 patients in the IPost group and 8 patients in the control group were excluded after CAG, thus 51 patients versus 47 at last. There were no significant differences in baseline characteristics(P>0.05),(Table1). No significant differences were found in treatment during angioplasty, IRA, number of vessels, reflow method, stent length or diameter(P>0.05),(Table2). Treatment after operation or at discharge were no significant differences(P>0.05).(Table3) 2 Cardiac reperfusion 2.1 TIMI flow grade The coronary no reflow(CNR) was significantly reduced in IPost patients compared to the controls(7.84% vs. 23.40%, P=0.033).(Table 3) 2.2 TMPG The TMPG was significantly increased in IPost patients compared to the controls(P=0.047).(Table 3) 2.3 STR The STR was significantly increased in IPost patients compared to the controls(60.78% vs. 40.43%, P=0.045).(Table 3) 3 Arrhythmias Less patients had fatal arrhythmias in IPost group compared to the controls(5.88% vs. 19.15%, P=0.045).(Table 3) 4 c Tn I c Tn I level in the first postoperative morning was significantly reduced in IPost patients compared to the controls(7.89±3.96 vs. 9.53±3.78 μg/L, P=0.038). c Tn I level in the seventh postoperative morning was also significantly reduced in IPost patients(0.13±0.16 vs. 0.23±0.23μg/L, P=0.016).(Table 3) 5 Cardiac function 5.1 LVEF There were no significant differences in LVEF in 1 week and 1 month after PPCI between the two groups(P>0.05), while a significant increase was observed in 3 months after PPCI in IPost patients(55.76±6.35% vs. 52.87±7.48%, P=0.041).(Table 3) 5.2 WMSI There were no significant differences in WMSI in 1 week after PPCI between the two groups(1.04±0.06 vs. 1.06±0.07, P>0.05), while a significant increase was observed in 1 month(1.07±0.08 vs. 1.11±0.12, P=0.048) and 3 months(1.04±0.06 vs. 1.07±0.10, P=0.030) after PPCI in IPost patients.(Table 3) 6 MACE The MACE was significantly reduced in IPost patients(3.92% vs. 17.02%, P=0.032).(Table 3)Conclusions:Patients within 12 hours STEMI can benefit from IPost during PPCI. It’s good for decreasing CNR, infarct size and arrhythmias, while improving cardiac reperfusion, cardiac function and prognosis. IPost is a safe and effective way to rescue myocardium and provid more benefits for STEMI patients in reperfusion therapies.