Emergency Medical Services Utilization among Patients with ST-Segment Elevation Myocardial Infarction: Observations from the Singapore Myocardial Infarction Registry.

Objective: Early activation of emergency medical services (EMS), rapid transport, and treatment of patients experiencing ST-segment elevation myocardial infarction (STEMI) can improve outcomes. The Singapore Myocardial Infarction Registry (SMIR) is a nation-wide registry that collects data on STEMI. We aimed to determine the prevalence, predictors, and outcomes of EMS utilization among STEMI patients presenting to Emergency Departments (ED) in Singapore.
Methods: We analyzed STEMI patients enrolled by SMIR from January 2010 to December 2012. We excluded patients who were transferred, developed STEMI in-hospital or suffered cardiac arrest out-of-hospital or in the ED. Primary outcome was process-of-care timings. Secondary outcomes included the occurrence of cardiac complications. Multivariate analysis was used to examine independent factors associated with EMS transport.
Results: 6412 patients were enrolled into the study; 4667 patients were eligible for analysis. 49.8% of patients utilized EMS transport. EMS transport was associated with higher rate of reperfusion therapy (74.3% vs. 65.1%, p < 0.01), shorter median symptom-to-door time (119 vs. 182 minutes, p < 0.01), door-to-balloon time (59 vs. 70 minutes, p < 0.01), and symptom-to-balloon time (185 vs. 233 minutes, p < 0.01). EMS transport had more patients with Killip Class 4 (7.5% vs 4.0%, p < 0.01) and was associated with greater presentation of heart failure, arrhythmias, and complete heart block. Independent predictors of EMS transport were age, syncope and Killip score; after-office-hour presentation was a negative predictor.
Conclusion: Less than half of STEMI patients utilized EMS and EMS patients had faster receipt of initial reperfusion therapies. Targeted public education to reduce time to treatment may improve the care of STEMI patients.