Emergency Medical Services as a Strategy for Improving ST-Elevation Myocardial Infarction System Treatment Times

Background

Reducing delays in time to treatment is a key goal of ST-elevation myocardial infarction (STEMI) emergency care. Emergency medical services (EMS) are a critical component of the STEMI chain of survival.

Study Objective

We sought to assess the impact of the careful integration of EMS as a strategy for improving systemic treatment times for STEMI.

Methods

We conducted a study of all 747 nontransfer STEMI patients who underwent primary percutaneous coronary intervention (PCI) in Dallas County, Texas from October 1, 2010 through December 31, 2011. EMS leaders from 24 agencies and 15 major PCI receiving hospitals collected and shared common, de-identified patient data. We used 15 months of data to develop a generalized linear regression to assess the impact of EMS on two treatment metrics—hospital door to balloon (D2B) time, and symptom onset to arterial reperfusion (SOAR) time, a new metric we developed to assess total treatment times.

Results

We found statistically significant reductions in median D2B (11.1-min reduction) and SOAR (63.5-min reduction) treatment times when EMS transported patients to the receiving facility, compared to self-transport. In addition, when trained EMS paramedics field-activated the cardiac catheterization laboratory using predefined specified protocols, D2B times were reduced by 38% (43 min) after controlling for confounding variables, and field activation was associated with a 21.9% reduction (73 min) in the mean SOAR time (both with p < 0.001).

Conclusion

Active EMS engagement in STEMI treatment was associated with significantly lower D2B and total coronary reperfusion times.