[Transient increase in ST-segment elevation immediately after reperfusion in acute myocardial infarction].

The significance of transient increase in ST-segment elevation immediately after reperfusion in acute myocardial infarction (AMI) was assessed by 12-lead electrocardiography. The study population consisted of 18 patients with initial anterior AMI, whose totally-occluded left anterior descending arteries were reperfused within 6 hours after the onset of symptoms. The ST-segment elevation was defined as that of more than 0.2 mV in the V3 lead immediately after reperfusion. Collateral circulation, timing of reperfusion, CPK release, left ventricular ejection fraction and mean % 201Tl uptake in the infarct regions were compared between patients with and without ST elevation. Eleven patients (61%) had ST-segment elevation (0.61 +/- 0.29 mV). Well-developed collaterals were observed in 43% of patients without ST-segment elevation (p < 0.05) but not in those with ST elevation. ST-segment elevations were accompanied by delays in timing of reperfusion (3.7 +/- 1.2 hrs vs 2.5 +/- 0.9 hrs, p < 0.05), higher peak CPK values (6,190 +/- 3,156 IU/l vs 3,222 +/- 2,053 IU/l, p < 0.05) and lower mean % 201Tl uptake (54.2 +/- 11.4% vs 73.9 +/- 11.3%, p < 0.01). We concluded that transient increase in ST-segment elevation immediately after reperfusion may relate to poorly-developed collaterals and prolongation of ischemia; i.e., severe ischemia before reperfusion, and therefore may reflect myocardial reperfusion injuries.