Significance of ST segment elevations in posterior chest leads (V7 to V9) in patients with acute inferior myocardial infarction:: Application for thrombolytic therapy

Objectives. This study was designed to examine whether ST segment elevation in posterior chest leads (V-7 to V-9) during acute inferior myocardial infarction ((MI) identifies patients with a concomitant posterior infarction and whether these patients might benefit more from thrombolysis. Background. Because the posterior wall is faced by none of the 12 standard electrocardiographic (EGG) leads, the ECG diagnosis of posterior infarction is problematic and has often remained undiagnosed, especially in the acute phase. Methods. Eighty-seven patients with a first inferior infarction who were treated with recombinant tissue-type plasminogen activator were stratified according to the presence (Group A [46 patients]) or absence (Group B [41 patients]) of concomitant ST segment elevation in posterior chest leads V-7 to V-9. Results. Patients in Group a had a higher incidence of posterolateral wall motion abnormalities (p < 0.001) on radionuclide ventriculography, a larger infarct area (as evidenced by higher peak creatine kinase levels) (p < 0.02) and a lower left ventricular ejection fraction (LVEF) at hospital discharge (p < 0.008) than those in Group B. ST segment elevation in leads V-7 to V-9 was associated with a higher incidence of at least one of the following adverse clinical events: reinfarction, heart failure or death (p = 0.05). Although patency of the infarct-related artery (IRA) in Group A resulted in an improved LVEF at discharge (p < 0.012), LVEF was unchanged in Group B, regardless of the pateneg status of the IRA. Conclusions. ST segment elevation in leads V-7 to V-9 identifies patients with a larger inferior MI because of concomitant posterolateral involvement, Such patients might benefit more from thrombolytic therapy. (C) 1998 by the American College of Cardiology.