Inferior wall acute myocardial infarction with one-lead ST-segment elevation: Electrocardiographic distinction between a benign and a malignant clinical course

Background: In most clinical trials, ST-segment elevation in two contiguous leads is required for diagnosis of acute myocardial infarction (AMI). This study describes the clinical course of patients with inferior wall AMI with one-lead ST-segment elevation in lead L3 in the initial ECG. Methods: Of 394 consecutive patients with inferior wall AMI, 31 (7.8%) had an initial ECG showing ST-segment elevation (≥1 mm) only in lead L3 (ST < 1 mm in leads L2 and aVF) and upright T waves in inferior leads. Patients were categorized into three groups: (I) no precordial ST-segment depression (n=6), (II) maximal precordial ST-segment depression in leads V1-V3 (n = 4), and (III) maximal precordial ST-segment depression in leads V4-V6 (n= 21). Results: Patients in group III developed severe heart failure (pulmonary edema or cardiogenic shock) six times more frequently than those in groups I- II (62 versus 10%). Among patients who underwent coronary angiography, three- vessel coronary artery disease (>50% stenosis) was more common in group III. Five of six patients in group III who underwent emergency angioplasty of the right coronary artery because of cardiogenic shock survived. Conclusion: Patients with inferior wall AMI and an initial ECG with ST-segment elevation only in lead L3, and maximal precordial ST-segment depression in leads V4- V6, are at risk of severe complications, especially heart failure, but their clinical course may be ameliorated by employing an aggressive interventional strategy.