Early diagnosis of acute myocardial infarction. A comparison between chemical predictors

Consecutive patients (n = 155) admitted to coronary care units at three different hospitals were investigated. The overall prevalence of acute myocardial infarction (AMI) was 0.45. The predictive potential with respect to AMI was tested for S-myoglobin, total S-creatine kinase (Tot-CK), and its MB isoenzyme as well as combinations of the different components. S-Myoglobin was determined by latex agglutination (MYO1) and radio-immunoassay (MYO2). The isoenzymes were determined as mass (CKMB1) and catalytic (CKMB2) concentrations. Biochemical tests were performed at arrival and at about 3h, 6h and 12h after the onset of symptoms (chest pain). Diagnostic performance of MYO1 was similar to MYO2 and CKMB2 similar to that of CKMB1. Single components did not show acceptable performance. In the period 6-12 h, combinations of total CK with CK-MB or myoglobin performed equally, with sensitivities of 0.96-0.98 and predictive values of a negative test (PV-) of 0.96-0.98. In view of increasing diagnostic performance for total CK and CKMB following 12 h after the onset of symptoms contrary to a decreasing performance for myoglobin combinations, total CK and CKMB should be used for the early diagnosis of AMI.