Introduction: Few systems worldwide have achieved the benchmark time of less than 90 minutes from emergency medical services (EMS) contact to balloon inflation (E2B) for patients sustaining ST-segment elevation myocardial infarction (STEMI). We describe a successful EMS systems approach using a combination of paramedic and 12-lead electrocardiogram (ECG) software interpretation to activate a STEMI bypass protocol.
Objectives: To determine the proportion of patients who met the benchmark of E2B in less than 90 minutes after institution of a regional paramedic activated STEMI bypass to primary PCI protocol.
Methods: We conducted a before-and-after observational cohort study over a 24-month period ending December 31, 2009. Included were all patients diagnosed with STEMI by paramedics trained in ECG acquisition and interpretation and transported by EMS. In the "before" phase of the study, paramedics gave emergency departments (EDs) advance notification of the arrival of STEMI patients and took the patients to the ED of the PCI center. In the "after" phase of the study, paramedics activated a STEMI bypass protocol in which STEMI patients were transported directly to the PCI suite, bypassing the local hospital EDs. Transmission of ECGs did not occur in either phase of the study.
Results: We compared the times for 95 STEMI patients in the before phase with the times for 80 STEMI patients in the after phase. The proportion for whom E2B was less than 90 minutes increased from 28.4% before to 91.3% after (p < 0.001). Median E2B time decreased from 107 minutes (interquartile range [IQR] = 30) before to 70 minutes (IQR = 24) after. Median D2B time decreased from 83 minutes (IQR = 34) before to 35 minutes (IQR = 19) after. Median E2D time increased from 21 minutes (IQR = 8) before to 32 minutes (IQR = 17) after. Median differences between phases were significant at p < 0.001. The rate of false-positive PCI laboratory activation during the after phase of the study was 12.4%.
Conclusions: The proportion of patients with E2B times less than 90 minutes significantly improved through the implementation of a paramedic-activated STEMI bypass protocol. Further study is required to determine whether these benefits are reproducible in other EMS systems.