Use of sequential cardiac enzyme analysis in stratification of risk for myocardial infarction in patients with unstable angina.

Patients presenting to the emergency room with unstable angina are a challenge to physicians whose responsibility it is to ration access to coronary care unit beds, a resource that is often in short supply. In this study, initial cardiac enzyme analysis was not helpful in identifying patients having an acute myocardial infarction. However, using two enzyme determinations, performed at least six hours apart, we were able to identify a large percentage of our patients with unstable angina who were at low risk for myocardial infarction. Patients with two consecutive normal creatinine kinase levels had only a 2% chance of having an acute myocardial infarction. We believe these data can assist physicians where monitored beds are in short supply to make judicious use of this limited resource; the subsequent reduction in critical care unit admissions and duration of stay could result in substantial monetary savings.