The Value of Serum Aminopherase Determinations in Suspected Acute Myocardial Infarction

¹ The Montefiore Hospital Institute of Research, Pittsburgh, Pennsylvania and the Veterans Administration Hospital, Pittsburgh, Pennsylvania.
² The Montefiore Hospital Institute of Research, Pittsburgh, Pennsylvania and the Veterans Administration Hospital, Pittsburgh, Pennsylvania., VA Hospital.
³ Resident in Medicine., The Montefiore Hospital Institute of Research, Pittsburgh, Pennsylvania and the Veterans Administration Hospital, Pittsburgh, Pennsylvania.

The determination of the level of transaminase activity in the serum should not be used to replace the electrocardiogram, but to supplement it. It is of value when the diagnosis of acute myocardial infarction is suspected clinically but cannot be confirmed electrocardiographically. This situation frequently arises when a history suggestive of an acute coronary occlusion is obtained and the electrocardiogram is recorded too early for changes to appear. Or, the electrocardiogram, though abnormal, may not be completely diagnostic of recent myocardial injury but exhibits equivocal changes usually consisting of minor ST deviations or T wave inversions. Severe chest pain, particularly that following an operative procedure, will raise the question of a differential diagnosis between acute pulmonary embolism or an acute coronary occlusion and neither the. electrocardiogram nor chest x-ray film may be helpful in arriving at a decision. An elevated serum transaminase level, however, will clarify the issue by shifting the evidence in favor of the latter. Not uncommonly the electrocardiographer is confronted with a tracing that shows the pattern of left bundle branch block when acute myocardial infarction is suspected. Since conduction defects of this type can obscure the electrical signs of recent myocardial injury, the presence of an elevated serum transaminase level may prove of value. Another application of this laboratory test is in the identification of recent myocardial injury superimposed on the residual signs of old cardiac damage—a situation which may "neutralize" the characteristic changes produced by injury currents. The early appearance of an elevated serum transaminase value can confirm the clinical impression of additional myocardial damage. Also, serial serum transaminase determinations may help confirm or rule out recent myocardial damage when the electrocardiographic interpretation is complicated by an arrhythmia such as ventricular tachycardia where the contour resembles that of a recent infarct. Serial determination of the serum transaminase activity may also be of considerable value in assisting one to distinguish the electrocardiographic pattern of myocardial infarction from that of pericarditis or digitalis effect. Thus, we are of the opinion if serum transaminase levels are obtained early enough, and in a serial fashion following suspected myocardial infarction, a normal value is just as important in ruling out the presence of this lesion as an elevated value is in confirming the clinical impression.