INFERIOR ST SEGMENT DEPRESSION AS A USEFUL MARKER FOR IDENTIFYING PROXIMAL LEFT ANTERIOR DESCENDING ARTERY-OCCLUSION DURING ACUTE ANTERIOR MYOCARDIAL-INFARCTION

To determine whether or not ST segment deviation on admission electroc ardiograms can identify patients with anterior acute myocardial infarc tion due to proximal left anterior descending artery occlusion, the ma gnitude and location of ST segment elevation ol depression were compar ed between patients with proximal left anterior descending artery occl usion (group A, n=47) and those with distal left anterior descending a rtery occlusion (group B, n=59). ST segment depression in each of the inferior leads was significantly greater in group A than in group B. T he incidence of ST segment depression greater than or equal to 1 mm in each of the inferior leads (II; 81% vs 27%, III; 85% vs 54%, aVF; 87% vs 47%, P<0.01) was significantly higher in group A than in group B. In addition, the incidence of ST segment depression greater than or eq ual to 1 mm in all of the inferior leads was significantly greater in group A than in group B (77% vs 22%, P<0.01). In group A, maximal ST s egment elevation was mole frequent in lead V-2 alone (43% vs 14%, P<0. 01). Group A had greater ST segment elevation in lead aVL than group B , and the incidence of ST segment elevation greater than or equal to 1 mm in lead aVL was significantly higher in group A than in group B (6 6% vs 47%, P<0.05). ST segment depression greater than or equal to 1 m m in all of the inferior leads was Most valuable for identifying group A patients (77% sensitivity and 78% specificity). In contrast, the ma ximal ST segment elevation in lead V-2 alone or ST segment elevation g reater than or equal to 1 mm in lead aVL had a low diagnostic value (4 3% sensitivity and 86% specificity, 66% sensitivity and 53% specificit y, respectively). In conclusion, this study indicates that analysis of ST segment deviation in the inferior leads is useful for identifying patients with acute anterior myocardial infarction due to proximal lef t anterior descending occlusion.