MULTICENTER STUDY OF CREATINE KINASE-MB USE - EFFECT ON CHEST PAIN CLINICAL DECISION-MAKING

Objective: To determine whether creatine kinase-MB isomer (CK-MB) leve ls affect initial physician decisions regarding patients with potentia l cardiac chest pain. Methods: A prospective, multicenter, observation al cohort study was performed at seven university teaching hospital ED s. Hemodynamically stable chest pain patients greater than or equal to 25 years old and without ST-segment elevation on their ECGs were obse rved with one to two sets of CK-MB level determinations obtained three hours apart prior to disposition. The physicians committed to a dicho tomous (yes/no) absolute decision regarding the diagnosis of myocardia l infarction (MI), need for hospital admission, and need for coronary care unit (CCU) admission both before and after enzyme results were ob tained. The physicians ranked the perceived importance of initial hist ory and physical, serial clinical observation, initial ECG, and CK-MB level to their decision making (rank score: 1 = most important, 4 = le ast important). Results: Of the 1,042 patients enrolled, 777 (74.6%) w ere admitted to the hospital. For the 67 MI patients (8.6% of the admi ssions), changes in absolute decisions about the diagnosis of MI and p lanned CCU admission were associated with increased CK-MB importance ( p = 0.04 and p = 0.02, respectively). Of the 146 patients who had new- onset angina or unstable angina, changes in absolute decisions were no t associated with CK-MB importance. No patient who had MI or unstable angina was released from the ED. There were three of 67 (4%) MI patien ts and one of 146 (1%) unstable/new-onset angina patients initially sl ated for release home who were admitted to the hospital. Conclusions: For a minority of the patients who had subsequently proven MI, the CK- MB result helped guide disposition decisions. The CK-MB availability d id not adversely impact the disposition of the patients who had unstab le or new-onset angina.