Pre-hospital diagnosis and transfer of patients with acute myocardial infarction--a decade long experience from one of Europe's largest STEMI networks

Early reperfusion in patients with ST-segment elevation myocardial infarction (STEMI) is essential. Although primary percutaneous coronary intervention (pPCI) is the preferred revascularization technique, it often involves longer primary transportation or secondary inter-hospital transfers and thus longer system related delays. The current ESC Guidelines state that PCI should be performed within 120 minutes from first medical contact, and door-to-balloon time should be <60 minutes in order to reduce long term mortality. STEMI networks should be established with regionalization of pPCI treatment to address the challenges regarding pre-hospital treatment, triage and transport of STEMI patients and collaborations between hospitals and Emergency Medical Services (EMS). We report on a regional decade long experience from one of Europe's largest STEMI networks located in Eastern Denmark, which serves a catchment area of 2.5 million inhabitants by processing ~4000 prehospital ECGs annually transmitted from 4 EMS systems to a single pPCI center treating 1100 patients per year. This organization has led to a significant improvement of the standard of therapy for acute myocardial infarction (MI) patients leading to historically low 30-day mortality for STEMI patients (<6%). About 70-80% of all STEMI patients are being triaged from the field and rerouted to the regional pPCI center. Significant delays are still found among patients who present to local hospitals and for those who are first admitted to a local emergency room and thus subject to inter-hospital transfer. In the directly transferred group, approximately 80% of patients can be treated within the current guideline time window of 120 minutes when triaged within a 185 km (~115 miles) radius. Since 2010, a Helicopter Emergency Medical Service has been implemented for air rescue. Air transfer was associated with a 20-30 minute decrease from first medical contact to pPCI, at distances down to 90 km from the pPCI center and with a trend toward better survival among air transported patients. The pPCI center also serves a small island in the Baltic Sea, where STEMI patients are rescued via air force helicopters. Based on data from more than 100 patients transferred over the past decade, we have found a similar in-hospital and long term mortality rate compared to the main island inhabitants. In conclusion, with the optimal collaboration within a STEMI network including local hospitals, university clinics, EMS and military helicopters using the same telemedicine system and field triage of STEMI patients, most patients can be treated within the time limits suggested by the current guidelines. These organizational changes are likely to contribute to the improved mortality rate for STEMI patients.