Serum Enzyme Assays in the Diagnosis of Acute Myocardial Infarction Recommendations Based on a Quantitative Analysis

Abstract

In the last 20 years, serum enzyme and isoenzyme levels have become the final arbiters by which acute myocardial infarction is diagnosed or excluded. We review the characteristics of these enzymes, the methods and limitations of commonly used assays, and data on diagnostic accuracy and clinical implications of enzyme levels in various settings and offer recommendations on their optimal use. Because of the poor sensitivity of single measurements of cardiac enzyme levels, these assays should not be used in the emergency room to exclude myocardial infarction. If myocardial infarction is suspected, levels of creatine kinase and its MB fraction should be measured at admission and about 12 and 24 hours later. If a myocardial infarction may have occurred more than 24 hours before evaluation, then lactate dehydrogenase isoenzyme measurements may increase diagnostic accuracy. Used properly, these assays are remarkably sensitive, but like all tests, optimal interpretation requires insight into technical pitfalls and other causes of misleading results.

Development and Evaluation of a New Canine Myocardial Infarction Model Using a Closed-Chest Injection of Thrombogenic Material

“…In the present study, serum CK-MB, m-GOT and HBD transiently increased 1 day after coronary artery occlusion. The changes in the serum enzyme levels with time after coronary artery occlusion were in agreement with previously reported clinical data in patients with AMI, [15][16][17][18] which would seem to confirm infarction. Indeed, extensive transmural anteroinferior myocardial infarction was observed.…”

Diagnostic markers of acute myocardial infarction

“…In the year 1959, the total CK level was assessed for AMI, as it was a good indicator of skeletal muscle injury (14). Following this, in the year 1960, LDH was used for diagnosis of AMI (15). Finally in the year 1979, WHO recommended the panel of CK, AST and LDH for the diagnosis of AMI (2).…”

Impact of European Society of Cardiology/American College of Cardiology guidelines on diagnostic classification of patients with suspected acute coronary syndromes

“…2^5 Most laboratories in the UK have used measurement of creatine kinase (CK) alone or in combination with daily measurement of aspartate transaminase (AST) and/or lactate dehydrogenase (LDH). This is despite the diagnostic superiority of the MB isoenzyme of creatine kinase (CK-MB) 6 and recommendations made by professional bodies. 7 The advent of the cardiac-speci¢c markers cardiac troponin T (cTnT) and cardiac troponin I (cTnI) has meant that the laboratory can o¡er a completely cardiac-speci¢c diagnosis and prognostic risk strati¢cation.…”