Influence of infarct artery patency on the relation between initial ST segment elevation and final infarct size.

Thirty seven patients with acute myocardial infarction were studied to determine the effect of perfusion of the infarct artery on the relation between the extent of initial ST segment elevation and final electrocardiographic infarct size. The sum of the initial peak ST elevations in all leads correlated with electrocardiographic infarct size in patients with anterior infarction and total occlusion of the infarct artery without collaterals. In patients with anterior infarction and subtotal occlusion of the infarct artery and in all patients with inferior infarction, infarct size was smaller than predicted from the extent of initial ST segment elevation. Collaterals to the infarct artery were present in eight of the 10 patients with inferior infarction and total occlusion. In patients with a persistently occluded infarct artery without collaterals the final infarct size correlated with the extent of initial peak ST segment elevation. This study provides further evidence that spontaneous reperfusion by anterograde flow or via collaterals may salvage jeopardized myocardium.