Prompt detection of myocardial injury by assay of creatine kinase isoforms in initial plasma samples

To determine the sensitivity and specificity of assays of isoforms of the MM isoenzyme of creatine kinase (CK) and MB-CK for the diagnosis or exclusion of acute myocardial infarction in plasma samples obtained at the time of presentation to the emergency room of patients with suspected myocardial infarction, 50 patients in whom the diagnosis was ultimately established and 31 in whom infarction was ultimately excluded were evaluated. Of the 50 patients in whom infarction was ultimately established, 47 had an increased ratio of the MM3 to the MM1 isoform or elevated MB-CK in the plasma sample initially available. The specificity of the approach was 77%, sensitivity 94%. The availability of rapid assays for MM-CK isoforms and for MB-CK should facilitate determination of the presence or absence of acute myocardial injury sufficiently promptly so that decisions regarding treatment can be made optimally.