Study objective: Current recommendations indicate that emergency physicians should activate cardiac catheterization laboratory personnel by a single page for ST-segment elevation myocardial infarction (STEMI) patients. We assessed the accuracy of emergency physician cardiac catheterization laboratory activations, angiographic findings, outcomes, and treatment times among patients with and without STEMI. Methods: We classified the appropriateness and outcomes of consecutive emergency physician STEMI pages between June 2006 and September 2008. Emergency physician activations of the cardiac catheterization laboratory were classified according to the findings of the initial ECG compared with cardiology interpretation for the presence of STEMI and presence of coronary disease. Results: During a 27-month period, emergency physician activation of the cardiac catheterization laboratory occurred 249 times. There were 188 (76%) patients with a true STEMI, of whom 13 did not receive emergency angiography. Of the 37 (15%) patients who had ECG findings meeting STEMI criteria and who ultimately did not have myocardial necrosis and underwent emergency angiography, 12 had significant disease and 5 had revascularization performed. Eleven patients had ECGs concerning for but not meeting STEMI criteria; all had emergency angiography (n=11) or received a diagnosis of non-STEMI (n=6). Only 13 patients were considered as having received unnecessary cardiac catheterization laboratory activations (5.2%) in which emergency angiography was not performed and myocardial infarction was excluded. Conclusion: A significant number of emergency physician STEMI cardiac catheterization laboratory activations are for patients who did not meet standard STEMI criteria. However, most had ECG findings and symptoms that lead to emergency angiography, had significant disease, or were diagnosed with non-STEMI. Only a small percentage of patients received unnecessary cardiac catheterization laboratory activations. Our findings support current recommendations for emergency physician cardiac catheterization laboratory activation for potential STEMI patients. © 2009 by the American College of Emergency Physicians.