Effect of ischemic postconditioning on two-dimensional structure and left ventricular contractile function after acute myocardial infarction

Objective To investigate the two-dimensional structure and left ventricular contractile function 7 days and 6 months after percutaneous coronary intervention(PCI) in patients with acute myocardial infarction to evaluate the effect of ischemic postconditioning on ischemic myocardium by echocardiography. Methods A total of 62 patients with ST-elevation myocardial infarction undergoing direct percutaneous coronary intervention were randomly assigned to ischemic postconditioned group(n=32) or control group(n=30). In the control group, no additional intervention was performed during the first 8 min of reperfusion. In the ischemic postconditioned group, within 1 min of reflow, the angioplasty balloon was reinflated four times for 1 min using low-pressure(4-6 atm) inflations, each separated by 1 min of reflow. At 7 days and 6 months after angioplasty, two-dimensional structure and left ventricular global and regional contractile function were evaluated by echocardiography, the evaluated parameters including left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-diastolic volume, cardiac output, left ventricular ejection fraction(LVEF) and wall motion score index(WMSI). Results There were no significant intergroup differences in age, sex, body mass index or clinical characteristics, including ischaemia time, culprit artery and drug treatment(P0.05). At 7 days, there were no significant differences in left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-diastolic volume, cardiac output, LVEF or WMSI between the two groups. At 6 months, compared with the control group, LVEF was significantly improved in the ischemic postconditioned group(P0.05) and WMSI was significantly reduced in the ischemic postconditioned group(P0.01). However, there were no significant differences between the two groups in the other measured parameters including left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-diastolic volume and cardiac output. In the control group, left ventricular end-diastolic diameter significantly increased(P0.05) and WMSI significantly decreased(P0.01) at 6 months than at 7 days. However, there was no significant difference in the decreased LVEF at different time. In the ischemic postconditioned group, left ventricular end-diastolic volume(P0.05) and cardiac output(P0.05) significantly increased, WMSI significantly decreased(P0.01) at 6 months than at 7 days. However, there was no significant difference in the increased LVEF at different time. Conclusions Ischemic postconditioning is associated with improved left ventricular global and regional contractile function contractile function detectable 6 months after reperfusion following acute myocardial infarction. However, further studies with larger sample sizes and longer term follow-up are necessary to more fully investigate and understand the protective benefits of ischaemic postconditioning before widespread use of this technique in patients with acute myocardial infarction.