Abstract 8128: Clinical Implications of ST-Segment Elevation in Leads V5-6 in Patients with Reperfused Inferior Wall Acute Myocardial Infarction

Abstract

Background: During inferior wall acute myocardial infarction (IWMI), ST-segment elevation (ST↑) often occurs in leads V5-6, but its clinical implications remain unclear. Methods: We examined admission ECG in 357 patients with a first IWMI who had TIMI 3 flow of the right coronary artery (RCA) or left circumflex artery (LCX) within 6 h after symptom onset. Patients were divided according to the presence (n=76) or absence (n=281) of ST↑ of >2 mm in leads V5-6. Patients in the former group were divided into the 2 subgroups according to the degrees of ST↑ in leads III and V6: ST↑ III>V6 (n=53) and ST↑ III<V6 (n=23). The perfusion territory of the culprit artery was assessed on the basis of the angiographic distribution score, and mega-artery was defined as a score of >0.7. Results: Both ST↑ in leads V5-6 with ST↑ III>V6 and that with ST↑ III<V6 were associated with mega-artery occlusion, impaired myocardial reperfusion as defined by myocardial blush grade 0/1 on the final angiogram, and a larger infarct size. RCA occlusion was most common in the former, whereas LCX occlusion, especially proximal LCX occlusion, was most common in the latter. Multivariate analysis showed that both ST↑ in leads V5-6 with ST↑ III>V6 (odds ratio 4.81, 95%CI 2.10-11.0, p<0.001) and that with ST↑ III<V6 (odds ratio 5.96, 95%CI 3.28-27.6, p<0.001) were independent predictors of impaired myocardial reperfusion; but ST↑ in leads II, III, and aVF was not. Conclusions: In patients with reperfused IWMI, ST↑ in leads V5-6 on admission ECG was associated with mega-artery occlusion with a larger infarct size; furthermore, it was a strong predictor of impaired myocardial reperfusion. In addition, by comparing the degree of ST↑ in lead V6 with that in lead III, we could differentiate between RCA occlusion and LCX occlusion.