Isolated inferior wall ST segment depression as an early sign of acute anterior wall myocardial infarction.

BACKGROUND Reciprocal changes may accompany ST segment elevation in the ischemic territory during acute myocardial infarction (AMI). We examined the hypothesis that isolated inferior ST segment depression on admission is an early sign of anterior wall infarction. METHODS 49 patients admitted to the coronary care unit between January 1996 and June 2008 who presented with inferior ST segment depression in the absence of ST segment elevation. Electrocardiograms (ECGs) obtained on admission and at 24-48 h were reviewed. Culprit artery was determined based on angiographic and echocardiographic data. RESULTS All patients had ST segment depression in the inferior leads on admission. A subgroup (55%) presented with concomitant ST segment depression in V5-V6. Follow-up ECG showed that 35% developed ST segment elevations and/or T wave inversions in anterior wall leads over 24-48 h. The left anterior descending (LAD) artery or one of its branches was the culprit in 60% of the patients. Sum of ST segment depression, V5-V6 involvement or presence of 'hyperacute' T waves did not predict LAD involvement. CONCLUSION Isolated ST segment depression in the inferior wall leads during ACS is usually an early sign of anterior wall AMI, in which the LAD or one of its branches is the culprit artery.