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.