Exclusion of acute myocardial infarction. The value of measuring creatine kinase slope.

For the exclusion (and diagnosis) of acute myocardial infarction, we studied timed sequential (slope) measurements of creatine kinase and creatine kinase-MB catalytic activity concentration, creatine kinase-MB mass concentration, troponin T and myoglobin, using data from 242 patients consecutively admitted for evaluation of suspected acute myocardial infarction in the 12 hours before admission. Three biochemical strategies based on measurements in two consecutive samples obtained within 12 hours after admission were evaluated. The highest sensitivities were encountered for a biochemical strategy based on the sole measurement of creatine kinase mass concentration (98%) or troponin T (96%) and a strategy based on measurements of creatine kinase activity concentrations, which includes creatine kinase slope calculation and measurement of creatine kinase mass concentration (95%). Both strategies were applied in subgroups of patients based on the electrocardiographic findings. In patients with a normal electrocardiogram, the sensitivity of the strategy using sole measurements of creatine kinase mass concentration was 100%, but this was true for the strategy based on creatine kinase slope measurements, which is the cheaper and therefore preferred procedure for excluding myocardial infarction. This approach, however, does not account for detecting minor myocardial cell damage in patients not yet fulfilling the criteria of the World Health Organization for diagnosing acute myocardial infarction.