Differentiation Between Occlusion of the Left Circumflex Artery and Right Coronary Artery from the Admission Electrocardiogram in Inferior Acute Myocardial Infarction

This study compares the initial electrocardiogram (ECG) with coronary angiographic findings in patients having electrocardiographic criteria for inferior wall acute myocardial infaretion (AMI) in order to determine. whether the initial ECG can predict the infarcı related artery (IRA) and whether the extent of coronary artery disease alters the ability to predict the culprit artery. One-hundred and fifty one patients m et electrocardiographic criteria for inferi or AMI ( 1 mm ST-segment elevation in II, III, and/or aVF), with 137 undergoing coronary angiography within 14 days of infarction. One mm of ST-segment elevation or depression was considered significant including in the case of leads I, aVL, Vl to V6. Coronary ang.iography was performed in the standard fashion, with :2:50% stenosed arteries considered significant. Patients were divided into 2 main groups based on whether the IRA was circumflex (Cx) or the right coronary artery (RCA) and each group was subdivided into 4 additional groups in order to assess the influence of increasing extent of coronary disease. The first subgroup included patients in whom the IRA was the only significant stenosis of the Cx or RCA. The second subgroup included patients with one- or two-vessel disease. The third subgroup included patients with one-, two- or three-vessel disease. The fourth subgroup included patients with Cx+RCA or RCA+Cx. In the main group and all 4 subgroups, patients with Cx as IRA (rather than the right coronary) artery were significantly more likely to have ST depres s i on in V ı or V2 (p:0.044, p:0.04, p:0.045, p:0.048, respectively). The sensitivity of ST depression in leads VI or V2 for identifying the Cx as IRA w as 100%, 91%, 84% and 83% for groups I, Il, III, and IV, respectively, with specificities of 47%, 41%, 37%, and 36%, respectively. The negative predictive value of no ST depression in leads V 1 or V2 for the all groups were 100%, 96%, 88%, and 87%, respectively. In conclusion, in patients presenting with electrocardiographic criteria for inferior wall AMI the presence of concomitant precordial ST depression was a sensitive sign of Cx occlusion, although not specific. Absence of precordial ST depression had a high negative predictive value in excluding the Cx as a culprit vessel and was not affected by inercasing number of underlying coronary involvement.