The positive predictive value of paramedic versus emergency physician interpretation of the prehospital 12-lead electrocardiogram

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.