Objective   To evaluate the effect of prehospital electrocardiogram (ECG) on the door-to-balloon time for patients with ST-segment elevation myocardial infarction (STEMI).    Methods   We retrospectively analyzed the consecutive patients with STEMI who had accepted primary percutaneous coronary intervention (PCI) in the Emergency Department of our hospital from Jan 2006 to Dec 2006. The study group consisted of patients with prehospital ECG

while the control group included patients without prehospital ECG. Their door-to-balloon time and mortality were compared.    Results   Totally 147 consecutive patients who had recieved primary PCI for STEMI were evaluated. Among them

92 (62.6%) patients were hospitalized with prehospital ECG while the other 55 (37.4%) patients without ECG. Significant difference was seen in the door-to-balloon time in study group (92±17 min) compared with control group (110±33 min) (P0.01). There were more patients in study group meeting the 90 min door-to-balloon time recommended by 2007 Focused Update of the ACC/AHA 2004 Guidelines than in control (42% vs 23%

P0.01). Much more patients who came to hospital through ambulance in study group than in control group (95% vs 3%

P0.001). No difference was observed in mortality between the two groups (P0.05).    Conclusion   Prehospital ECG significantly reduces the door-to-balloon time in STEMI patients

but there are fewer patients with prehospital ECG than we expected.