Background: Reperfusion delay in ST-segment elevation myocardial infarction (STEMI) predicts adverse outcome. We evaluated time from alarm call (system delay) and time from first medical contact (PCI-related delay), where fibrinolysis could be initiated, to balloon inflation in a pre-hospital organization with tele-transmitted electrocardiograms, field triage and direct transfer to a 24/7 primary percutaneous coronary intervention (PPCI) center.
Methods and results: This was a single center cohort study with long-term follow-up in 472 patients. The PPCI center registry was linked by person identification number to emergency medical services (EMS) and National Board of Health databases in the period of 2005-2008. Patients were stratified according to transfer distances to PPCI into zone 1 (0-25 km), zone 2 (65-100 km) and zone 3 (101-185 km) and according to referral by pre-hospital triage. System delay was 86 minutes (interquartile range (IQR) 72-113) in zone 1, 133 (116-180) in zone 2 and 173 (145-215) in zone 3 (p<0.001). PCI-related delay in directly referred patients was 109 (92-121) minutes in zone 2, but exceeded recommendations in zone 3 (139 (121-160)) and for patients admitted via the local hospital (219 (171-250)). System delay was an independent predictor of mortality (p<0.001).
Conclusions: Pre-hospital triage is feasible in 73% of patients. PCI-related delay exceeded European Society of Cardiology (ESC) guidelines for patients living >100 km away and for non-directly referred patients. Sorting the PPCI centers catchment area into geographical zones identifies patients with long reperfusion delays. Possible solutions are pharmaco-invasive regiments, research in early ischemia detection, airborne transfer and EMS personnel education that ensures pre-hospital triage.
Keywords: Acute myocardial infarction; STEMI; pre-hospital triage; primary PCI; reperfusion delay; telemedicine.