Percutaneous coronary intervention for ST-elevation myocardial infarction (STEMI) reduces morbidity and mortality if performed rapidly. We examined whether timely intervention in myocardial perfusion times achieved at NorthEast Medical Center (NEMC) using pre-hospital (PH) electrocardiography (ECG) could be maintained during a 3-year follow-up period, and whether a similar system could be implemented at 6 other larger hospitals in a prospective, multicenter study. We calculated median door-to-reperfusion times for emergency medical services (EMS) and self-transport patients. PH wireless ECG transmission was attempted by trained EMS personnel with transmission to an on-call cardiologist's hand-held device. A standardized "STEMI code system" was implemented to further improve door-to-reperfusion times. At NEMC, door-to-reperfusion times were similar in both the pilot study and follow-up periods, with a median time of 63 minutes. However, successful PH-ECG transmission was less frequent during the followup period (20% vs. 56%; p < 0.0001). At the 6 larger sites, both EMS and self-transport patients had lower door-to-reperfusion times in the study period compared to the pre-study period. However, successful PH-ECG transmission was rare in the EMS-transported patients (2%). Initial reduction of reperfusion time at NEMC using PH-ECG transmission to the cardiologist was maintained over time, however, there was a decrease in the PH-ECG transmission rate. PHECG transmission was difficult to achieve in larger-sized communities. Successful PH-ECG transmission to an on-call cardiologist, together with an effective STEMI code system, can markedly reduce door-to-reperfusion times.