The relationship of ST elevation to eventual QRS loss in acute inferior myocardial infarction

Abstract

The electrocardiographic changes of ST-segment elevation in acute myocardial infarction are related to the region of infarction. The authors examined body surface map data in 70 patients with acute inferior infarction to determine the exact relationship of the initial ST elevation to the eventual loss of QRS. The patients had no evidence of previous myocardial infarction and no subsequent infarction and did not receive thrombolytic therapy or other acute interventions, such as surgery. Maps were recorded on admission to the hospital, during the hospital admission and again at follow-up examination 6–48 months after infarction. The region of ST elevation of the initial body surface map was compared to a QRS loss region derived by subtracting the follow-up map, integrated over the 80 msec after the onset of the QRS, from a “QRS loss region” derived from 381 normal patients using the same interval. In 76% of patients there was a direct relationship between the position of the ST elevation and the QRS loss region (mean correlation coefficient, 0.49). In a further 15% of patients there was a general relationship without specific features, and in the remaining 8% the difference maps were not related to the position of ST elevation. The region of ST elevation predicts the eventual QRS loss in the majority of patients and may be useful for monitoring interventions in acute myocardial infarction.