Use of rapid serial sampling of creatine kinase MB for very early detection of myocardial infarction in patients with acute chest pain.

To determine how early myocardial infarction can be detected, serial creatine kinase MB concentrations were sampled in 313 patients during triage of acute (less than 12 hours) chest pain. Serum was sampled on hospital arrival (baseline) and hourly for 3 hours (total of four samples). Creatine kinase MB concentrations were subsequently analyzed for their ability to detect infarction. Infarction was present in 70 patients (22%) and was diagnosable from the index electrocardiograms in 27 of these (39%). Sensitivity and specificity for detection of infarction were 76% and 72%, respectively, as determined from baseline MB values only and increased with each additional sample to a maximum of 92% and 96%, respectively, in all four samples. Analysis of two serum samples taken 2 hours apart showed a sensitivity of 94% and a specificity of 91%. If these results are confirmed, improved initial diagnostic accuracy with this rapid assay technique in acute chest pain may (1) conserve resources when initial suspicion of infarction is low, (2) identify patients with infarction appropriate for early intervention, and (3) avoid premature hospital discharge of patients with infarction.