LAUSR

Prehospital activation of cardiac cath labs for potential ST‐elevation myocardial infarction (STEMI) reduces total ischemic time and door‐to‐ balloon (DTB) time and has become the standard of care in many industrialized nations. At the same time, interventional cardiologists (ICs) routinely experience being woken at 2:00 a.m. only to call off a cardiac cath lab activation (CCLA) for an obvious false‐positive electrocardiogram (ECG) in a patient without chest pain. False‐positive activations occur frequently (23%–65%) with computer interpretation alone, and would be expected to increase costs, staff and practitioner burnout, and patient morbidity from unnecessary procedural and anticoagulation risks. In this issue of Catheterization and Cardiovascular Interventions, Faour and colleagues from Liverpool hospital in Australia identified 1088 consecutive prehospital electrocardiograms (PH‐ECGs) transmitted for possible STEMI CCLA. Paramedics were obligated to systematically transmit any ECG with a computer diagnosis of STEMI regardless of symptoms. ECGs were transmitted directly to the hospital and the mobile device of the on‐call IC, who could discuss with the paramedics the options of prehospital CCLA or fibrinolysis or deferral of activation depending on the clinical presentation and whether the IC agreed with the interpretation. Among the 1088 PH‐ ECG transmissions that might have led to automatic CCLA in systems without IC input, there were instead 565 (52%) CCLA and 523 (48%) nonactivations in the authors' system. Each ECG was blindly adjudicated by two cardiologists for STEMI or equivalents according to University of Glasgow ECG criteria (ST‐segment elevation ≥1mm in ≥2 contiguous leads, and STEMI equivalents including left bundle branch block, posterior infarction, and aVR elevation). The appropriateness of the CCLA decision was adjudicated after review of the patient's clinical presentation, ECGs angiograms, and troponin values. The authors judged the CCLAs as 97% appropriate and 2.7% inappropriate, while the nonactivations were 96% appropriate and 3.6% inappropriate (missed STEMI). Appropriate nonactivations were due to nondiagnostic ST‐elevations (25%), artifact (14%), bundle branch blocks (26%), repolarization abnormalities (12%), among other causes. In short, about half of the automated PH‐ECG transmissions in this study were false‐positives and would have resulted in unnecessary CCLA without the interpretation of the IC. With IC involvement, the rates of inappropriate CCLA and missed STEMI were both very low. Prehospital CCLA, usually with PH‐ECG alone, has been highly successful in reducing DTB time in most hospitals to less than 90min and rightfully celebrated as an effective process improvement. However, reductions in DTB have not reduced mortality after STEMI and PH‐ECG activations are frequently false‐positives. This study demonstrates that incorporating IC interpretation of the ECG and discussion with the paramedics before CCLA would reduce inappropriate activations at the risk of a few minutes of clinically insignificant delay.