Biochemical diagnosis of myocardial infarction within the thrombolytic time window

A demonstrated temporal change in the total activity of creatine kinase or mass measurement of the cardio-specific isoenzyme creatine kinase MB is currently used as the biochemical diagnosis of myocardial infarction. The isoforms of creatine kinase MB may provide an earlier diagnostic marker of myocardial infarction than the currently available biochemical markers. We compare the sensitivity and specificity of total creatine kinase activity, creatine kinase MB mass measurement and the muscle and heart specific isoforms of creatine kinase in the early diagnosis of myocardial infarction. Using current methodologies, neither CK isoform offered any advantage over CK mass measurement as an early marker of ischaemic myocardial damage.