If aortic dissection is missed, the EP’s assessment and tests ordered are going to be scrutinized. According to a recent literature review, neither an Aortic Dissection Detection Risk Score (ADD-RS) nor a negative D-dimer are enough to exclude acute aortic dissection.1
Aortic dissection is not common in the ED. “We are not going to see it on a very routine basis, but there’s a very high mortality rate if we miss it. As emergency physicians, one of our primary roles is to evaluate patients for life-threatening conditions, so we have to think about dissection,” says Brit Long, MD, the study’s lead author and a San Antonio-based EP.
EPs may err on the side of caution and order CT angiography, but this carries downsides, too. It slows the ED flow and increases patients’ radiation exposure. “We were looking for evidence to determine if there’s an easier way to potentially exclude aortic dissection in patients who are considered low risk,” Long says.
Long and colleagues reviewed literature about two tools: D-dimer and ADD-RS. “D-dimer is very non-specific. It is elevated in a number of conditions,” Long notes.
Many inflammatory conditions will result in an elevated D-dimer. “At the same time, though, it does have high sensitivity, and can potentially be used to exclude a disease if you use it the right way,” Long says.
Long and colleagues found D-dimer alone likely is not enough to rule out aortic dissection. The ADD-RS takes pre-existing conditions and physical exam findings into account, and gives a score of 0 to 3. A low-risk score or even a score of 0 alone also likely is not enough to rule out aortic dissection.
However, Long and colleagues found a negative D-dimer and risk score of 0 gives a high sensitivity to rule out aortic dissection without the need to obtain a CT scan of the chest. “There is a very, very low likelihood of a patient having a dissection with a negative D-dimer and score of 0,” Long explains.
Still, none of this discounts clinical judgment. A patient could present with focal arm weakness, chest pain, and hypertension, and end up with a ADD-RS score of 1. Despite the low score, “that’s a difficult situation. Clinically, it fits with the picture of dissection,” Long says.
This is where the EP’s clinical judgment comes into play. In this case, the patient needs further evaluation for dissection and management. “The D-dimer and the score should not trump any clinical judgment. They should only supplement decision-making,” Long offers.
If aortic dissection (or any dangerous condition) is a possibility and the patient is going to be discharged, a discussion is needed about returning to the ED if symptoms recur. “In the ED, the tricky thing is that we see the patient at one point in time, and diseases are evolving entities,” Long observes.
Many times, EPs do engage in the discussion, but just forget to document it. “You need to just take that extra 30 seconds and document that you had the discussion, the patient understood, and why you thought the condition was not present at the time,” Long stresses.
One obstacle to prevailing in malpractice litigation is the mortality rate for aortic dissections, especially abdominal aortic dissections, is high, even with timely diagnosis and surgical intervention. “Many patients die from strokes in the days following surgery. Plaintiffs’ attorneys have an uphill climb establishing proximate cause,” says Kenneth N. Rashbaum, JD, a partner at New York City-based Barton.
For EPs, aortic dissection is “one of the can’t-miss diagnoses,” says Mark Spiro, MD. “This is a very devastating disease, but is less common and, at times, we don’t think about it.”
Aortic dissection presents in a variety of ways. “Almost a quarter of people die before they even get to the ED. For every hour delayed, mortality goes up anywhere from 1% to 3%,” notes Spiro, chief medical officer of the Walnut Creek, CA-based The Mutual Risk Retention Group.
Some aortic dissection patients report knifelike pain in the chest and back; others report difficulty swallowing; in some patients, symptoms come and go. “We’re no different from anybody else. We have had missed diagnoses,” Spiro reports.
In two of those cases, the patients complained of feeling like they had to burp but being unable to — and the EP did not think of aortic dissection. “In both cases, the patient was discharged and died from the disease,” Spiro says.
Risk factors (e.g., cardiovascular disease, hypertension, Marfan syndrome, or family history) also must be factored in. Some aortic dissection cases have involved a sudden increase in blood pressure, which might make the EP incorrectly suspect cocaine use or a reaction to vigorous exercise such as weightlifting.
Some suspected aortic dissection patients undergo a chest X-ray, which may show a widened mediastinum — or not. “It’s not present all the time, but it’s present more than half the time,” Spiro says.
If it is present but subtle, and goes unappreciated by whoever is reading the X-ray, “that’s problematic,” Spiro says. “Anyone reviewing the chart will think, ‘Why didn’t they pick that up?’”
An abnormal blood pressure also raises the index of suspicion (e.g., someone whose typical blood pressure is 120/80 mmHg who records a reading of 160/50 mmHg). “Nothing is specifically diagnostic until you are getting the CT. Then, there it is,” Spiro says. “CT angio with IV contrast should pick it up, is quicker than MRI, and is usually where people go to get the diagnosis.”
Documenting equal pulses also is key. Are the right and left arms, or the upper and lower extremities, the same? Or is there a difference of 20 mm in the pulses? If the patient is going to be discharged and aortic dissection was on the differential during the ED visit, the chart should indicate why the EP believed it was unlikely: The neck veins were flat, the ECG was nondiagnostic, there were no risk factors, the blood pressure was normal, they recorded equal pulses, and the chest X-ray showed no widening of the mediastinum. “Even then, you can still miss it,” Spiro says. “It is not an easy diagnosis to make, and we can’t do advanced imaging on every single person who comes through the ED.”
The mere act of documenting why aortic dissection was thought to be unlikely could make the EP reconsider the decision to discharge. “It makes you think for another second,” Spiro says. “If you go through the thought process, that’s the main thing.”
REFERENCE
- Long DA, Keim SM, April MD, et al. Can D-dimer in low-risk patients exclude aortic dissection in the emergency department? J Emerg Med 2021; Sep 5:S0736-4679(21)00567-9. doi: 10.1016/j.jemermed.2021.07.028. [Online ahead of print].
Aortic dissection is not an easy diagnosis to make, and providers cannot order advanced imaging on every person who comes through the ED. But the mere act of documenting why aortic dissection was thought to be unlikely could make the provider reconsider the decision to discharge — and end up saving a life.
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