Clinical characteristics of precordial ST-segment depression in acute inferior myocardial infarction]

Assessments of the significance of precordial ST segment depression in acute inferior myocardial infarction (AIMI) have yielded conflicting results. Among 92 AIMI patients admitted within 6 hrs after the onset, 65 showed ST depression, and the remaining 27 showed no ST depression. These depressions were present in all of V1-4 (right type; 17), V2-5 (middle type; 10), V3-6 (left type; 13) and V1-6 (broad type; 25). The clinical severity was Forrester subset I in the majority (89%) of patients without ST change, while complications were prevalent in patients with ST depression, especially in the right type (44% were Forrester subset II-IV). Peak CK was 2,150 +/- 399 U/L in patients without ST depression, but it was elevated to 3,172 +/- 811 in patients with ST depression, especially in the right type (4,506 +/- 499). Wall motion evaluated by echocardiography and QRS scores on ECG also revealed greater abnormality in patients with ST change. The initial right coronary angiogram on admission revealed complete occlusion in 76% of these patients with ST depression of whom all of the right type had completely occluded artery. Abnormal motion of the anterior wall, which suggests remote ischemia associated with AIMI was proved neither by left ventriculography nor echocardiography. Hospital mortality in patients with ST depression (9.2%) was as twice as high as that in those without ST depression (4.6%). We concluded that ST depression in patients with acute inferior infarction may not be indicative of remote ischemia but manifests as a mirror image of a large infarction with a complicated clinical course.