Retrospective description and analysis of consecutive catheterization laboratory ST-segment elevation myocardial infarction activations with proposal, rationale, and use of a new classification scheme.

BACKGROUND Rapid activation of a cardiac catheterization laboratory (CCL) has reduced door-to-balloon times in ST-segment elevation myocardial infarction (STEMI), leading to lower mortality. This process is accelerated with prehospital electrocardiography and notification. False activations of the CCL occur at an unknown rate and have been poorly described. METHODS AND RESULTS We analyzed 345 consecutive CCL activations for suspected STEMI over 18 months (March 2009-August 2010). We retrospectively reviewed the ECGs that prompted activation, as well as the clinical course and final diagnoses. Among all CCL activations, STEMI was not confirmed in 28%. On review, 301 (87.2%) had appropriate ECG criteria for activation. However, even among the ECG-appropriate patients, only 247 (82%) had a final diagnosis of STEMI. The inclusion of clinical characteristics did not improve the ability to identify patients with STEMI. Activations were modestly more accurate when made by emergency department physicians than by emergency medical service personnel, but door-to-balloon time was noticeably shorter when emergency medical service personnel requested prehospital activation. CONCLUSIONS If all CCL activations are considered, the occurrence of false activations is surprisingly high. Although still the gold standard for diagnosis, these data reveal the inherent limitations of clinical evaluation and the ECG in identifying patients with STEMI. Within our retrospective review, we used a 2-tiered classification for STEMI activations based on ECG appropriateness and final clinical diagnosis to give a complete picture of false activations and assist in quality improvement.