Anterior ST segment depression in inferior myocardial infarction: effect on complications and long-term survival.

The effect of anterior ST segment depression in inferior myocardial infarction on early complications and long-term prognosis was studied. A modification of the Minnesota Code was used for grading the extent of ST segment depression in leads V2 to V4 on the first hospital electrocardiogram. In 267 patients with acute inferior myocardial infarction, 107 had isoelectric anterior ST segments, 84 had minor (less than or equal to 0.5 mm) depression, and 76 had major (greater than 0.5 mm) depression. Patients with anterior ST segment depression had higher serum enzyme levels, higher Norris coronary prognostic indices, and more frequent cardiac failure during the acute stages, but similar 28 day case fatality rate (11.1%) compared with patients without anterior ST segment depression (12.6%). In the subsequent four years total cardiac death rates were not significantly different and the pattern of survival was not influenced, but there was a higher fatal re-infarction rate in patients with major anterior ST segment depression. Thus, anterior ST segment depression in inferior myocardial infarction was associated with more severe infarction in the early phase but was not a reliable marker of high risk after recovery. Selection of patients for further investigation should not be based on this observation alone.