The value of the initial electrocardiogram in the evaluation of an acutely ischaemic area in anterior myocardial infarction

Background : The aim of the study was to evaluate the importance of admission electrocardiography (ECG) in predicting the extent of acute ischaemia in anterior acute myocardial infarction (AMI). Methods : In 56 patients with anterior AMI electrocardiographic, echocardiographic and angiographic images, troponin I concentration and CK-MB activity were analysed. Results : In 55 cases the artery responsible for infarction was the left anterior descendent (LAD). In the group with proximal occlusions the number of leads with ST elevation was greater (6.6 ± 1.4 vs. 5.3 ± 1.8; p = 0.02) and the level of ST elevations in all leads was higher (18.3 ± 9.9 vs. 11.6 ± 7.2; p = 0.01). The mean height of ST elevation in I, aVL, V3 and V5, ST-segment depression in inferior leads and CK-MB activity, was higher in proximal LAD disease. The height of ST elevation in I and aVL correlated with a low ejection fraction and high CK-MB activity. The higher the total ST-segment elevation in all leads, the higher CK-MB activity level. Conclusions : ECG is useful in identifying the site of a LAD occlusion in an anterior AMI. The total ST-segment elevation correlates with the AMI size measured as the maximal CK-MB activity. The height of the ST-segment elevation in leads I and aVL reflects the degree of left ventricle dysfunction. The traditional terminology used to define the localisation of ST-segment shifts in ECG does not take account of the regional wall motion abnormalities observed in echocardiographic examination in an anterior AMI.