Objective: Postconditioning is a novel approach to myocardial protection during ischemia reperfusion. Our study observed the effect of postconditioning on coronary blood flow velocity and endothelial function in patients who underwent emergency percutaneous coronary intervention (PCI).
Methods: Ninety-four patients with their first acute myocardial infarction who underwent revascularization within 12 hours of onset by primary PCI were recruited in the study. All the patients were randomized to two groups, IR group (PCI without postconditioning) and Postcond group (PCI with postconditioning). Corrected TIMI frame count (CTFC) was used to evaluate velocity of coronary blood after PCI. Creatine phosphokinase (CK), CK-MB, and malondialdehyde (MDA) were measured before and after PCI. Arterial endothelial function was studied noninvasively by examination of brachial artery responses to endothelium-dependent and endothelium-independent stimuli by echo Doppler technique. Wall motion score index (WMSI) was assessed by two-dimensional echocardiography before and 8 weeks after angioplasty.
Results: There were no significant differences between the two groups with regard to age, sex, presence of angiographically visible collaterals, and elapsed time from the onset of symptoms until perfusion. Patients with postconditioning had much faster CTFC than patients without postconditioning (25.38 +/- 5.35 vs 29.23 +/- 5.54). After 8 weeks, the WMSI improved significantly in both groups, but the DeltaWMSI in Postcond group was significantly larger than that of IR group (1.20 +/- 0.30 vs 1.04 +/- 0.36, P < 0.05). There was a significant negative correlation between DeltaWMSI and CTFC in IR group and Postcond group (r = -0.9032, P < 0.01; r = -0.7884, P < 0.01). The peaks of CK and CK-MB of Postcond group were much lower than that of IR group (1236.57 +/- 813.21 U/L vs 1697.36 +/- 965.74 U/L; 116.92 +/- 75.83 U/L vs 172.41 +/- 92.64 U/L), and MDA-reactive products were significantly lower than that in the IR group at any same time after PCI. All patients with acute myocardial infarction had a depressed endothelium-dependent vasodilation function, while the endothelium-dependent vasodilation function was improved in Postcond group.
Conclusion: Postconditioning is a simple, operative procedure for salvaging the coronary endothelial function and cardiomyocyte. It could be used widely in clinic and to better the prognosis of acute myocardial infarction.