Spontaneous course of ST-segment elevation in acute anterior myocardial infarction

Abstract

The spontaneous course of ST-segment elevation (ST) in 24 patients with acute anterior myocardial infarction (AMI) was studied by precordial ST-segment mapping, which was recorded at 2-hr intervals during the first 48 hr after admission. Change of ST between two registrations was expressed as mV/hr, and was compared with clinical and hemodynamic parameters, course of MB-CK curve, calculated infarct mass and arrhythmias. After an initial rapid increase, there was a decrease of ST, which reaches a plateau-like curve approximately 12 hr after the onset of chest pain. A second new increase of ST exceeding a value of 0.6 mV/hr correlates well with extension of necrosis, verified by re-elevation of MB-CK. During the first 2 days, extension of necrosis could be detected in 50% of the patients. As new ischemic episodes and extension of necrosis in AMI occur frequently and are promptly indicated by an increase of ST, the physician should, while monitoring therapeutic interventions, concentrate on such a second increase rather than on a decrease of ST (which may occur spontaneously), as has been suggested in previous reports.