Prognostic Value of Lead V1 ST Elevation During Acute Inferior Myocardial Infarction

Background-Lead V1 directly faces the right ventricle and may exhibit ST elevation during an acute inferior myocardial infarction when the right ventricle is also involved. Leads V1 and V3 indirectly face the posterolateral left ventricle, and ST depression ("mirror-image" ST elevation) in V1 through V3 may reflect concomitant posterolateral infarction. The prognostic significance of V1 ST elevation during an acute inferior myocardial infarction may therefore be dependent on V3 ST changes. Methods and Results-In 7967 patients with acute inferior myocardial infarction in the Hirulog and Early Reperfusion or Occlusion-2 (HERO-2) trial, V1 ST levels were analyzed with adjustment for lead V3 ST level for predicting 30-day mortality. V1 ST elevation at baseline, analyzed as a continuous variable, was associated with higher mortality. Unadjusted, each 0.5-mm-step increase in ST level above the isoelectric level was associated with 25% increase in 30-day mortality; this was true whether V3 ST depression was present or not. The odds ratio for mortality was 1.21 (95% confidence interval, 1.07 to 1.37) after adjustment for inferolateral ST elevation and clinical factors and 1.24 (95% confidence interval, 1.09 to 1.40) if also adjusted for V3 ST level. In contrast, lead V1 ST depression was not associated with mortality after adjustment for V3 ST level. V1 ST elevation 1 mm, analyzed dichotomously in all patients, was associated with higher mortality. The odds ratio was 1.28 (95% confidence interval, 1.01 to 1.61) unadjusted, 1.51 (95% confidence interval, 1.19 to 1.92) adjusted for V3 ST level, and 1.35 (95% confidence interval, 1.04 to 1.76) adjusted for ECG and clinical factors. Persistence of V1 ST elevation 1 mm 60 minutes after fibrinolysis was associated with higher mortality (10.8% versus 5.5%, P=0.001). Conclusion-V1 ST elevation identifies patients with acute inferior myocardial infarction who are at higher risk.