We evaluated the effect of prehospital triage (PHT) in the ambulance on infarct size and clinical outcome and studied its relationship to the distance of patient's residence to the nearest percutaneous coronary intervention (PCI) center.

All consecutive ST-segment elevation myocardial infarction patients who were transported to the Isala klinieken from 1998 to 2008 were registered in a dedicated database. Of these, 2,288 (45%) were referred via a spoke center and 2.840 (55%) via PHT.

PHT patients were more often treated within 3 hours after symptom onset (46.2% vs 26.8%, P < .001), more often had a post-procedural thrombolysis in myocardial infarction (TIMI) 3 flow (93.0% vs 89.7%, P < .001) had a smaller infarct size (peak creatine kinase 2,188 ± 2,187 vs 2,575 ± 2,259 IU/L, P < .001) and had a lower 1-year mortality (4.9% vs 7.0%, P = .002). After multivariate analysis, PHT was independently associated with ischemic time less than 3 hours (OR 2.45, 95% CI 2.13-2.83), a peak creatine kinase less than the median value (OR 1.19, 95% CI 1.04-1.36) and a lower 1-year mortality (OR 0.67, 95% CI 0.50-0.91). The observed differences between PHT patients and the spoke group were more pronounced in the subgroup of patients living >38 km from the PCI center.

PHT in the ambulance is associated with a shorter time to treatment, a smaller infarct size and a more favorable clinical outcome, especially with longer distance from the patient's residence to the nearest PCI center. Therefore, PHT in the ambulance may reduce the negative effect of living at a longer distance from the PCI center.