Abstract
OBJECTIVES: We examined the appropriateness of prehospital cardiac catheter laboratory activation (CCL-A) in ST-segment elevation myocardial infarction (STEMI) utilizing the University of Glasgow algorithm (UGA) and remote interventional cardiologist consultation. BACKGROUND: The incremental benefit of prehospital electrocardiogram (PH-ECG) transmission on the diagnostic accuracy and appropriateness of CCL-A has been examined in a small number of studies with conflicting results. METHODS: We identified consecutive PH-ECG transmissions between June 2, 2010 and October 6, 2016. Blinded adjudication of ECGs, appropriateness of CCL-A, and index diagnoses were performed using the fourth universal definition of MI. The primary outcome was the appropriate CCL-A rate. Secondary outcomes included rates of false-positive CCL-A, inappropriate CCL-A, and inappropriate CCL nonactivation. RESULTS: Among 1088 PH-ECG transmissions, there were 565 (52%) CCL-As and 523 (48%) CCL nonactivations. The appropriate CCL-A rate was 97% (550 of 565 CCL-As), of which 4.9% (n = 27) were false-positive. The inappropriate CCL-A rate was 2.7% (15 of 565 CCL-As) and the inappropriate CCL nonactivation rate was 3.6% (19 of 523 CCL nonactivations). Reasons for appropriate CCL nonactivation (n = 504) included nondiagnostic ST-segment elevation (n = 128, 25%), bundle branch block (n = 132, 26%), repolarization abnormality (n = 61, 12%), artefact (n = 72, 14%), no ischemic symptoms (n = 32, 6.3%), severe comorbidities (n = 26, 5.2%), transient ST-segment elevation (n = 20, 4.0%), and others. CONCLUSIONS: PH-ECG interpretation utilizing UGA with interventional cardiologist consultation accurately identified STEMI with low rates of inappropriate and false-positive CCL-As, whereas using UGA alone would have almost doubled CCL-As. The benefits of cardiologist consultation were identifying "masquerading" STEMI and avoiding unnecessary CCL-As.