Late reperfusion for acute myocardial infarction limits the dilatation of left ventricle without the reduction of infarct size

Abstract

Background. While previous clinical studies have shown a possible beneficial effect of the reperfusion performed at a relatively late phase of acute myocardial infarction ("late reperfusion") in preventing left ventricular enlargement, the mechanism has not been clarified. Methods and Results. Of 89 patients with an initial anterior myocardial infarction, reperfusion was successful in 69. These 69 were divided into three groups according to the time required to achieve reperfusion after the onset of symptoms: early-reperfused (<3 hours from the onset to reperfusion; n=22), intermediate-reperfused (3 to 6 hours from the onset to reperfusion; n=28), and late-reperfused (>6 hours from the onset to reperfusion; n=19). The 20 patients whose infarct-related artery were occluded in the acute phase as well as 1 month later was classified as nonreperfused. Infarct size, evaluated as defect volume by 201TI single-photon emission computed tomography 1 month after the onset, was 1593±652 units (mean±SD) in the late-reperfused group, significantly larger (P 6 hours after onset) did not limit infarct size or preserve left ventricular function. In contrast, the end-diastolic volume index did not differ significantly among the early-reperfused (50±15 mL/m2), intermediate-reperfused (54±14 mL/m2), and late-reperfused (53±19 mL/m2) groups; those were significantly smaller than that of the nonreperfused group (68±12 mL/m2; P