Abstract 18906: Differences in Coronary Anatomy Between Patients With Anteroseptal and Extensive Anterior ST Elevation Myocardial Infarction
Objective: To assess whether there are distinct coronary angiographic characteristics that differentiate between anteroseptal (AS-STEMI) and extensive anterior (EA-STEMI) ST elevation myocardial infarction (A-STEMI).
Background: AS-STEMI (A-STEMI with ST elevation limited to V1-V3) is usually conceived as A-STEMI limited to the basal and mid anterior and septal walls, sparing the apex; whereas EA-STEMI (ST elevation extending to leads V4-V6) is considered to extend more apically and distally. However, it was previously reported that AS-STEMI affects mainly the apex and others suggested that AS-STEMI may occur in extensive A-STEMI due to proximal occlusion of a wrapping left anterior descending (LAD) artery leading to cancellation effects of the basal anterior and inferoapical injury vectors.
Methods: The index admission 12-lead electrocardiogram (ECG) and coronary angiogram performed during primary percutaneous coronary intervention were evaluated in 101 consecutive patients (age 60 ±12 years) presenting with A-STEMI. Patients were classified into two groups: 1) AS-STEMI (n=39); 2) EA-STEMI (n=62). On coronary angiography, the length of the LAD and its site of occlusion, and the presence of large diagonal branches proximal to the site of occlusion, or obtuse marginal (OM) or ramus intermedius (RI) branches reaching the apex were identified.
Results: AS-STEMI (82.1%) was seen more often than EA-STEMI (46.8%) in patients with a large OM branch (p=0.0009) and significantly more patients with AS-STEMI had ≥1 branches reaching the apex (84.6% vs. 53.2% p=0.0054). Patients with occlusion proximal to the first septal branch of a wrapping LAD were more likely to have AS-STEMI (35.9%) than EA-STEMI (11.3%) pattern (p=0.0066).
Conclusions: The results of this study suggest two opposing explanations for AS-STEMI pattern. Lack of ST segment elevation in leads V4-V6 during A-STEMI can occur if apical segments are supplied by large diagonal branches proximal to the site of occlusion, or large OM or RI. Alternatively, our findings suggest AS-STEMI pattern can also occur due to a cancellation effect by the injury vector directed anteriorly and superiorly in patients with pre-septal occlusion of a wrapping LAD artery, as the chest leads V1 and V2 oppose V5 and V6.
- © 2010 by American Heart Association, Inc.