Prevalence and outcome of ST-segment elevation in posterior electrocardiographic leads during acute myocardial infarction.

The prevalence and clinical significance of ST-segment elevation (STE) in posterior electrocardiographic (ECG) leads during acute myocardial infarction (AMI) is largely unknown. We obtained posterior ECG leads (V7, V8, and V9), as well as standard 12-lead and right precordial leads (V4R-V6R), immediately upon admission in 210 consecutive patients with AMI. Nineteen patients (9% of 210 cases) had STE of > or =1 mm in 2 or more posterior leads, either as an isolated finding (7 cases, 3.3% of 210) or in association with STE at inferior or lateral sites (12 cases, 5.7% of 210). STE in posterior leads was detected in 10.9% (7 of 64) of patients without STE in standard ECG leads. Tall R waves in V1-V2 developed in 5 cases (26.3% of 19). Patients with STE in posterior leads were significantly older (64.4+/-7.3 years vs 58.9+/-8.9 years) with more frequent cardiovascular risk factors (3.4+/-1.1 vs 2.9+/-1.2) than those without. In-hospital complications were significantly more frequent in these patients compared with matched controls (Mantel-Haenszel odds ratio = 7, confidence interval = 1.28-28.43). There was also a trend toward lower ejection fraction and increased in-hospital mortality that did not reach statistical significance. We conclude that STE in posterior ECG leads is not uncommon among patients with AMI and no STE in standard leads and may portend a worse in-hospital course.