Introduction: Activation of the cardiac catheterization laboratory prior to patient arrival at the hospital, based on a prehospital 12-lead electrocardiogram (ECG), reduces door-to-balloon time by 10-55 minutes for patients with ST-segment elevation myocardial infarction (STEMI). In emergency medical services (EMS) systems where transmission of the ECG to the emergency department (ED) is not feasible, the ability of paramedics to accurately read 12-lead ECGs is crucial to the success of a prehospital catheterization laboratory activation program. Objective. To determine whether paramedics can accurately diagnose STEMI on a prehospital 12-lead ECG and decide to activate the cardiac catheterization laboratory appropriately.
Methods: Five chest pain scenarios were generated, with standardized prehospital ECGs accompanying each: three STEMI cases that should result in catheterization laboratory activation and two non-STEMI cases that should not. A convenience sample of paramedics in an urban/suburban EMS system examined each scenario and ECG, and indicated whether the patient had STEMI and whether they would activate the catheterization laboratory. A series of demographic and operational questions were also asked of each participant. We report diagnostic statistics, agreement (kappa), and 95% confidence intervals (CIs).
Results: A convenience sample of 103 of 147 eligible paramedics (70%) was enrolled. For STEMI diagnosis, paramedics' sensitivity was 92.6% (95% CI 88.9-95.1) and specificity was 85.4% (79.7-89.8); for catheterization laboratory activation, sensitivity was 88.0% (83.8-91.3) and specificity was 88.3% (83.0-92.2). False-positive activation of the catheterization laboratory occurred in 8.1% (5.4-12.0) of cases. Of the STEMI cases, 94.1% were correctly read as STEMI, and 91.0% had the catheterization laboratory appropriately activated. Of the non-STEMI cases, 14.9% were incorrectly read as STEMI, and 12.0% had the catheterization laboratory inappropriately activated. The paramedics' comfort with calling a "chest pain alert" with no resulting catheterization laboratory activation (the current practice in this system) was not statistically different from their comfort with calling a chest pain alert if that call were to automatically result in catheterization laboratory activation (p > 0.05).
Conclusions: Paramedics in an urban/suburban EMS system can diagnose STEMI and identify appropriate cardiac catheterization laboratory activations with a high degree of accuracy, and an acceptable false-positive rate, when tested using paper-based scenarios.