Background: Obtaining a prehospital 12-lead ECG may improve triage and expedite care of patients with acute myocardial infarction (AMI). Whether the ECG should undergo physician review prior to activation of a percutaneous intervention (PCI) team is unclear.
Objective: To document the positive predictive value (PPV) of the prehospital 12-lead ECG when interpreted by paramedics versus emergency physicians.
Methods: This was a prospective, observational study. In November 2003, our local health care and emergency medical services (EMS) systems implemented a prehospital "cardiac alert" program in which patients suspected of having ST-elevation myocardial infarction (STEMI) based on the prehospital 12-lead ECG were diverted away from receiving facilities without emergent PCI capability and the PCI team was mobilized. For the first year, a cardiac alert was activated by paramedics (Phase I). After the first year, the ECG was transmitted to the ED, with the emergency physician (EP) responsible for activation (Phase II). The PPV for cardiac alerts in Phases I and II were compared by using three different "gold standards": cardiologist interpretation of the prehospital 12-lead ECG, disposition to emergent PCI, and coronary lesions on angiography or arrest prior to emergent PCI.
Results: A total of 110 patients were enrolled (54 in Phase I, 56 in Phase II). Cardiologist confirmation of a STEMI on the prehospital 12-lead EKG was 42/54 (78%) in Phase I and 54/56 (96%) in Phase II. Disposition to emergent PCI occurred in 38/54 (70%) Phase I patients and 51/56 (91%) Phase II patients. Lesions at catheterization or arrest prior to emergent PCI were observed in 41/54 (69%) of Phase I patients and 50/56 (89%) of Phase II patients. All of these comparisons achieved statistical significance (p < 0.01).
Conclusions: Transmission to the ED for EP interpretation improves the PPV of the prehospital 12-lead ECG for triage and therapeutic decision-making.