CLINICAL-SIGNIFICANCE OF INFERIOR ST ELEVATION DURING ACUTE ANTERIOR MYOCARDIAL-INFARCTION

Objectives - To clarify the genesis and clinical significance of infer ior ST elevation during acute anterior myocardial infarction. Patients and design - A total of 106 patients with first acute anterior myocar dial infarction (less than or equal to 6 h) were divided into two grou ps according to the presence (group A, n = 12) or absence (group B, n = 94) of ST elevation of greater than or equal to 1 mm in at least two of the inferior leads on the admission electrocardiogram. Results - O n admission electrocardiograms, group A had a smaller summed ST deviat ion in the lateral limb leads than group B. On emergency coronary arte riograms, the incidence of a wrapped left anterior descending artery w as higher in group A than in group B (100% v 27%, P < 0.01). The incid ence of occlusion of a left anterior descending artery distal to its f irst diagonal branch was higher in group A than in group B (100% v 46% , P < 0.01). Peak serum creatine kinase activity and in-hospital morta lity tended to be lower in group A than in group B. Group A had better left ventricular ejection fraction and regional wall motion in the an terobasal and anterolateral regions in the chronic phase than group B. In contrast, regional wall motion in the diaphragmatic region was red uced to a greater extent in group A than in group B. Conclusions-Infer ior ST elevation during acute anterior myocardial infarction appears o nly in the presence of a combination of a lesser degree of transmural ischaemic myocardium in the anterobasal and anterolateral wall togethe r with transmural ischaemic myocardium in the inferior wall; in all ca ses there was occlusion of a wrapped left anterior descending artery d istal to its first diagonal branch. Patients with such an ST elevation appear to have a better in-hospital prognosis than those without it.