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Writer's pictureThe Review Course in Family Medicine

Are you missing patients with Acute Aortic Syndrome?

by Dr. Simon Moore MD CCFP






SNAP SAMP: List FIVE High Risk Features on physical exam for AAS (answer is below).


One out of every 2000 ER patients with chest or back pain have this life-threatening diagnosis.

ASSESSING FOR AAS IS AS EASY AS 1, 2, 3 . . .

In fact, 25% of patients with AAS have their diagnosis delayed by 24 hours. Don't miss it!

In a new Canadian guideline for AAS, your action depends on the patient's risk:

  1. LOW RISK - No testing for AAS

  2. MED RISK - D-dimer

  3. HI RISK - ECG-gated CT aorta


EXAM TIP: Most questions can be answered in 10 words or less, but use as many words as you need to be descriptive. Write "ECG-gated CT aorta" and NOT just "CT" as an answer. This key guideline fits perfectly into the CFPC’s 105 topics as Chest Pain and now Shortness of Breath are priority topics.


How do you determine who is high risk? See the scoring tool below.


NEGATIVE D-DIMER RULES OUT AAS

A negative DD-dimer rules out AAS (<0.5% probability). A positive D-dimer necessitates an ECG-gated CT scan.

WHY NOT ORDER A D-DIMER FOR EVERYONE?

D-dimer for all comers will excessively increase the number of false positive CT scans.

HOW DO YOU DETERMINE WHO IS MEDIUM OR HIGH RISK?

The guideline authors use a risk calculator that is almost identical to the Aortic Dissection Detection Risk Score (ADD-RS) - see the easy-to-use calculator here, with some key changes marked with a * below:

Risk factors for patients

(Score one point for each except as noted)

  • *Connective tissue disease

  • Aortic valve disease

  • Recent aortic manipulation

  • Family history of AAS

  • *Aortic aneurysm = 2 points

HISTORY - Pain features

(Score one point if 1-2 risk factors, two points if more)

  • Severe or worst ever

  • Thunderclap or abrupt

  • Tearing or ripping

  • Migrating or radiating*

EXAM – High risk features

(Score two points if any are present)

  • Hypotension*

  • Pulse deficit

  • Neurologic deficit

  • New murmur of aortic regurgitation

  • Aortic aneurysm

LOW RISK = 0 points = No further investigations

MED RISK = 1 point = D dimer

HI RISK = ≥ 2 points = ECG - gated CT aorta


References:

CMAJ 2020 July 20;192:E832-43.

Circulation. 2018;137(3):250-258.

* = indicates a difference between the ADD-RS and the guideline

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