OBJECTIVETo explore the risk and protective factors for the occurrence of myocardial ischemia-reperfusion injury (MIRI) during primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI).

METHODSClinical and angiographic data of 228 AMI patients in whom the infarct-related arteries (IRA) were successfully revascularized by primary PCI were analyzed retrospectively. MIRI was defined if the following conditions existed after PCI: severe bradycardia with hypotension, or lethal ventricular arrhythmias requiring electrical cardioversion, or IRA antegrade flow < or = TIMI 2 grade flow without angiographic evidence of thrombus, emboli, dissection or spasm. Multivariate logistic regression was used to identify independent relative factors among 18 clinical and angiographic factors for occurrence of MIRI.

RESULTSMultivariate logistic regression analysis showed that independent risk factors for MIRI were the time intervals from AMI onset to IRA reflow < or = 6 h (P = 0.014), inferior infarction localization (P = 0.006), IRA antegrade flow prior to PCI < or = TIMI 1 grade (P = 0.028), multivessel lesions (P = 0.063) and renal insufficiency (P = 0.067). Pre-infarction angina was found to be an independent protective factor (P = 0.005).

CONCLUSIONSShort time intervals from AMI onset to IRA revascularization, inferior wall infarction location, low IRA antegrade flow prior to PCI, multivessel lesions and renal insufficiency may promote the occurrence of MIRI during primary PCI, whereas pre-infarction angina may be a cardioprotective factor attenuating MIRI.