Calling STEMI

ekgHow good are physicians at calling STEMI? After reading Dr. Smiths “Can’t miss ECGs” in EM Resident Dec/Jan 2013 vol. 39, issue 6, I decided to look further into the accuracy of physicians to call STEMI.

Jayroe et al presented 116 ECGs with ST elevation and asked 15 cardiologists to determine if emergent PCI was needed, and alternative diagnosis if indicated. All cases were to be assumed that the patient had compatible symptoms with myocardial infarction, age and ethnicity was withheld. Important to this study design was that the ECGs came from any patient with ST elevation, chest pain was not an inclusion criteria. Sensitivity for correct identification was 50% to 100%. Specificity ranged from 73% to 97%.¬† This study’s “findings reflect the diagnostic limitations encountered by cardiologists when the ECG is used as the sole diagnostic tool for STEMI.”

In a study by Tran et al., there were 84 patient presentations and electrocardiograms reviewed by interventional cardiologists. 40 were true STEMIs. The recommendation for immediate PCI ranged from 33-75% and the sensitivity for true STEMI was 53-83%.

A review of emergency medicine physicians interpretation of 202 patients with ST elevation showed a rate of ECG ST elevation misinterpretation of 5.9%. Most frequently misdiagnosed was left ventricular aneurysm, followed by benign early repolarization. There were 2 cases of missed acute myocardial infarction. Many other articles assess the ability of the emergency physician in calling STEMI. There are none to very few misses but the specificity is low. This can likely be explained by the ED Docs mindset of 100% sensitivity for bad disease. It is known that 2-4% of acute myocardial infractions are inappropriately sent home from the ED with the great minority of these being ST elevation in nature.

What we can take from these articles is that we can become better at ECGs and become advocates for our patients in unclear cases. This advocacy and intellectual debate is bolstered with thorough knowledge. Coronary catheterization is not a benign procedure. False activation with subsequent catheterization can lead to patient harm including stroke, dissection, and bleeding.

For a start check out Dr Smith’s ECG blog,

Jayroe JB, et al. Differentiating ST elevation myocardial infarction and nonischemic causes of ST elevation by analyzing the presenting electrocardiogram. Am J Cardiol. 2009 Feb 1;103(3):301-6. doi: 10.1016/j.amjcard.2008.09.082.
Tran V, et al. Differentiating ST-elevation myocardial infarction from nonischemic ST-elevation in patients with chest pain. Am J Cardiol. 2011 Oct 15;108(8):1096-101. doi: 10.1016/j.amjcard.2011.06.008.
Kontos MC, et al. An evaluation of the accuracy of emergency physician activation of the cardiac catheterization laboratory for patients with suspected ST-segment elevation myocardial infarction. Ann Emerg Med. 2010 May;55(5):423-30. doi: 10.1016/j.annemergmed.2009.08.011.
Brady WJ, et al. Electrocardiographic ST-segment elevation: correct identification of acute myocardial infarction (AMI) and non-AMI syndromes by emergency physicians. Acad Emerg Med. 2001 Apr;8(4):349-60.
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