Emergency Medical Services
Background: Prehospital ST-elevation myocardial infarction (STEMI) detection relies upon accurate paramedic 12-lead electrocardiogram (ECG) interpretation. The emergency medical services (EMS) agency in rural Wilkes County, North Carolina began administering thrombolytics in 2001 for acute STEMI based on paramedic ECG interpretation. The objectives of this study were to describe the patient cohort that received prehospital thrombolytics and to assess the accuracy of paramedics in identifying STEMIs
Methods: We performed a retrospective chart review of Wilkes County EMS records over an 18-year period (1/2001-12/2018). We reviewed all patients who received thrombolytics for STEMI. Paramedic and ECG machine interpretations of the ECGs were recorded. Two board-certified EM physicians adjudicated the ECGs to determine if they met STEMI criteria, which was defined as at least 1 mm of ST-elevation in two or more contiguous leads. The EM physicians also described the myocardial infarction (MI) distributions. Descriptive statistics were performed.
Results: There were 73 thrombolytic administrations for paramedic-declared STEMIs with ECGs available for review. Mean patient age was 59.0 years (95%CI 56.3-61.7) and 69.9% (n=51) were males. ECG machine interpretation determined that 76.7% (n=56) met STEMI criteria. EM physician review determined that 91.8% (n=67) met STEMI criteria. Of the 6 cases that did not meet STEMI criteria, EM physician review determined that 33.3% (n=2) had a left bundle branch block and 66.6% (n=4) had non-specific ST-segment and T-wave changes. EM physician review for MI distribution determined that 61.2% (n=41) were inferior, 22.4% (n=15) anterior, 9.0% (n=6) septal, 6.0% (n=4) lateral, and 1.5% (n=1) posterior.
Conclusion: Paramedics accurately identified STEMIs in >90% of cases. While paramedics recognize more STEMIs than ECG machine interpretation, they tend to overcall STEMIs, particularly when left bundle branch blocks or non-specific ST-segment or T-wave changes are present. Further prehospital provider education is needed to ensure appropriate recognition of and care for STEMI patients, especially in rural prehospital systems that rely upon thrombolytics for reperfusion therapy.