Inferior ST elevation during anterior acute myocardial infarction(AMI) was not widely investigated. We investigated the frequency, causes, angiographic and clinical significance of simultaneous precordial and inferior ST elevation.

We compared clinical, electrocardiographic and angiographic features of 49 patients with anterior AMI according to the presence(group A) or absence(group B) of inferior ST elevation.

1) ST segment elevation in inferior leads was found in 19(21%) of 89 patients with anterior AMI. The sum of ST elevation in precordial leads and lateral limb leads was smaller in group A than in group B(174 vs 248 mV, 01 vs 57 mV, respectively). 2) Wrapped left anterior descending artery(LAD)(94% vs 26%), 2-vessel disease(50% vs 19%), and collaterals to inferior wall(17% vs 0%) were more common in group A than in group B. Occlusion of middle or distal LAD(83% vs 58%) and patent diagonal or septal branches proximal to occlusion site(21 vs 10) were also more common in group A than in group B. 3) By left ventriculogram, anterolateral involvement was lower(38% vs 82%) and diaphragmatic involvement higher(56% vs 11%) in group A than in group B. 4) The two groups did not differ regarding cardiac enzymes and left ventricular ejection fraction.

Inferior ST elevation during anterior AMI results from a smaller mass of ischemic anterolateral myocardium combined with simultaneous inferior wall ischemia (i.e., a middle or distal occlusion of wrapped LAD) or multivessel disease. In patients with occlusion of wrapped LAD, deterioration of ventricular function is not worse than in anterior AMI without inferior ST elevation.