Acute myocardial infarction with isolated ST-segment elevation in posterior chest leads V7-9 - "Hidden" ST-segment elevations revealing acute posterior infarction

OBJECTIVES This study was done to determine whether electrocardiographic (E CG) isolated ST-segment elevation (ST up arrow) in posterior chest leads ca n establish the diagnosis of acute posterior infarction in patients with is chemic chest pain and to describe the clinical and echocardiographic charac teristics of these patients. BACKGROUND The absence of ST up arrow on the standard 12-lead ECG in many p atients with acute posterior infarction hampers the early diagnosis of thes e infarcts and thus may result in inadequate triage and treatment. Although 4% of all acute myocardial infarction (AMI) patients reveal the presence o f isolated ST up arrow in posterior chest leads, the significance of this f inding has not yet been determined. METHODS We studied 33 consecutive patients with ischemic chest pain suggest ive of AMI without ST up arrow in the standard ECG who had isolated ST up a rrow in posterior chest leads V-7 through V-9. All patients had echocardiog raphic imaging within 48 h of admission, and 20 patients underwent coronary angiography. RESULTS Acute myocardial infarction was confirmed enzymatically in all pati ents and on discharge ECG pathologic Q-waves appeared in leads V-7 through V-9 in 75% of the patients. On echocardiography, posterior wall-motion abno rmality was visible in 97% of the patients, and 69% had evidence of mitral regurgitation (MR), which was moderate or severe in one-third of the patien ts. Four patients (12%), all with significant MR, had heart failure, and on e died from free-wall rupture. The circumflex coronary artery was the infar ct related artery in all catheterized patients. CONCLUSIONS Isolated ST up arrow in leads V-7 through V-9 identify patients with acute posterior wall myocardial infarction. Early identification of t hose patients is important for adequate triage and treatment of patients wi th ischemic chest pain without ST up arrow on standard 12-lead ECG. (J Am C oll Cardiol 1999;34:748-53) (C) 1999 by the American College of Cardiology.