Metoprolol in acute myocardial infarction. Enzymatic estimation of infarct size. The MIAMI Trial Research Group.

The maximum serum activity for aspartate aminotransferase (s-ASAT) during the first 3 days was recorded in 5,507 patients with suspected or definite acute myocardial infarction. The s-ASAT activity was corrected for the normal range from each center. The median s-ASAT activity was 4.9 arbitrary units in the placebo group versus 4.6 arbitrary units in the metoprolol group (p = 0.072). Univariate analyses indicated that the delay time between onset of symptoms and randomization and sympathetic activity at entry significantly influenced the effect of metoprolol. A similar decrease in serum enzyme activity after metoprolol treatment was observed independent of signs of infarct localization on the entry electrocardiogram.