Prehospital electrocardiographic computer identification of ST-segment elevation myocardial infarction.
BACKGROUND
Identifying ST-segment elevation myocardial infarctions (STEMIs) in the field can decrease door-to-balloon times. Paramedics may use a computer algorithm to help them interpret prehospital electrocariograms (ECGs). It is unknown how accurately the computer can identify STEMIs.


OBJECTIVE
To Determine the sensitivity and specificity of prehospital ECGs in identifying patients with STEMI.


METHODS
Retrospective cross-sectional study of 200 prehospital ECGs acquired using Lifepak 12 monitors and transmitted by one of more than 20 emergency medical services (EMS) agencies to the emergency department (ED) of a Summa Akron City Hospital, a level 1 trauma center between January 1, 2007, and February 18, 2010. The ED sees more than 73,000 adult patients and treats 120 STEMIs annually. The laboratory performs 3,400 catheterizations annually. The first 100 patients with a diagnosis of STEMI and cardiac catheterization laboratory activation from the ED were analyzed. For comparison, a control group of 100 other ECGs from patients without a STEMI were randomly selected from our Medtronic database using a random-number generator. For patients with STEMI, an accurate computer interpretation was "acute MI suspected." Other interpretations were counted as misses. Specificity and sensitivity were calculated with confidence intervals (CIs). The sample size was determined a priori for a 95% CI of ±10%.


RESULTS
Zero control patients were incorrectly labeled "acute MI suspected." The specificity was 100% (100/100; 95% CI 0.96-1.0), whereas the sensitivity was 58% (58/100; 95% CI 0.48-0.67). This would have resulted in 42 missed cardiac catheterization laboratory activations, but zero inappropriate activations. The most common incorrect interpretation of STEMI ECGs by the computer was "data quality prohibits interpretation," followed by "abnormal ECG unconfirmed."


CONCLUSIONS
Prehospital computer interpretation is not sensitive for STEMI identification and should not be used as a single method for prehospital activation of the cardiac catheterizing laboratory. Because of its high specificity, it may serve as an adjunct to interpretation.
Department of Emergency Medicine, Summa Health System, Akron, Ohio 44304, USA. mcmcquown@yahoo.com
Mary Colleen
MC
Bhalla
Francis
F
Mencl
Mikki Amber
MA
Gist
Scott
S
Wilber
Jon
J
Zalewski
D000328:Adult; D000465:Algorithms; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003936:Diagnosis, Computer-Assisted; D004562:Electrocardiography; D004632:Emergency Medical Services; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis*; D009820:Ohio; D012189:Retrospective Studies; D012680:Sensitivity and Specificity