['We evaluated the impact of emergency physician (EP)-initiated primary percutaneous coronary intervention (PCI) via a single-group page on door to balloon (D2B) interval times in patients with ST-segment elevation myocardial infarction.', 'Consecutive ST-segment elevation myocardial infarction patients presenting to the emergency department between February 2004 and September 2008 were divided into 4 groups: group 1, PCI performed on an ad hoc basis after cardiology consultation; group 2, primary PCI activated via a single-group page only on-call cardiology consultation; group 3, primary PCI with EP cardiac catheterization laboratory (CCL) activation via the same page strategy; group 4, prehospital CCL activation based on prehospital diagnostic electrocardiogram. Composite D2B and relevant time intervals were measured for each time group.', 'A total of 295 consecutive patients undergoing emergent angiography were included. Times decreased for most time intervals from groups 1 to 4. Although there was no significant change in composite D2B or any measured interval time with the introduction of PCI after emergent cardiology consultation, each decreased significantly after implementing an EP-initiated PCI strategy except CCL2B (D2B 95 to 77 minutes, D2E 14 to 10 minutes, D2CCL 71 to 50 minutes). Further significant reductions in D2B time were achieved among all patients after the institution of emergency medicine services activation of the CCL (D2B 77 to 64 minutes, D2CCL 50 to 38 minutes, CCL2B 28 to 22 minutes).'] Does emergency physician-initiated cath lab activation reduce door to balloon times in ST-segment elevation myocardial infarction patients?