It is well known that primary percutaneous coronary intervention (PPCI) is the gold standard in STEMI treatment and that decreased door-to-balloon time has better patient outcomes. Guidelines recommend that the interval between arrival at the hospital and intracoronary balloon inflation (door-to-balloon time) should be 90 minutes or less.
One strategy to help decrease this time is activating the cath lab based on information from pre-hospital ECGs while the patient is still en route to the hospital. Bradley EH et al showed that an average decrease of 15.4 minutes could be possible with this strategy.1
What does this mean for emergency physicians?
- We now have to correctly activate the cath lab with just an ECG.
- Due to HIPAA, often times patient information cannot be transmitted with an ECG, therefore no prior ECGs can be obtained for comparison.
- Emergency medicine physicians already get a lot of push back, for false activations; this could potentially increase that number.
How good are EM physicians at correctly identifying STEMI on ECG alone?
- At the low end: 86%2
- At the high end: 94.9%3
How good are interventional cardiologists at correctly identifying STEMI on ECG alone?
- A 2009 study showed: specificity 73 – 97% (avg 85%) 4
- A 2011 study showed: specificity 32 – 86% (avg 66%) 5
What is the acceptable false activation rate of the cath labs?
- Based on a literature review, the range was 5 – 25% 5
What does all this mean?
- It remains difficult for even, experienced interventional cardiologists to determine by ECG alone if patients have true STEMI.
- While wireless prehospital ECG transmission does decrease door-to-balloon time, no one knows the difference in clinical outcomes, cost benefit, and false activations.
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1.
Bradley E, Herrin J, Wang Y, et al. Strategies for reducing the door-to-balloon time in acute myocardial infarction. N Engl J Med. 2006;355(22):2308-2320. [PubMed]
2.
Larson D, Menssen K, Sharkey S, et al. “False-positive” cardiac catheterization laboratory activation among patients with suspected ST-segment elevation myocardial infarction. JAMA. 2007;298(23):2754-2760. [PubMed]
3.
Brady W, Perron A, Chan T. Electrocardiographic ST-segment elevation: correct identification of acute myocardial infarction (AMI) and non-AMI syndromes by emergency physicians. Acad Emerg Med. 2001;8(4):349-360. [PubMed]
4.
Jayroe J, Spodick D, Nikus K, et al. Differentiating ST elevation myocardial infarction and nonischemic causes of ST elevation by analyzing the presenting electrocardiogram. Am J Cardiol. 2009;103(3):301-306. [PubMed]
5.
Tran V, Huang H, Diez J, et al. Differentiating ST-elevation myocardial infarction from nonischemic ST-elevation in patients with chest pain. Am J Cardiol. 2011;108(8):1096-1101. [PubMed]
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