Is d-dimer (D-dimer) useful in the workup for aortic dissection?

D-dimer in the Workup for Aortic Dissection

D-dimer should not be used as the sole screening test to rule out aortic dissection due to significant limitations in sensitivity and specificity, particularly in certain patient populations. 1

Diagnostic Performance of D-dimer in Aortic Dissection

Sensitivity and Specificity

• D-dimer shows high sensitivity (94-98%) but poor specificity (40-56%) for acute aortic dissection 1, 2
• Using the standard cutoff of 500 ng/mL (used for PE), D-dimer has:
  • Negative likelihood ratio of 0.07 3
  • Positive likelihood ratio of only 2.11 2

False Negative Results

Several conditions can result in false-negative D-dimer results in patients with confirmed aortic dissection:

• Chronicity (longer time from symptom onset) 1
• Thrombosed false lumen or intramural hematoma 1, 4
• Short dissection length 1, 4
• Younger patient age 1
• Higher platelet count 4

Clinical Implications

Risk of Missed Diagnosis

• Even patients with negative D-dimer can have life-threatening aortic dissection:
  • 44% of patients with negative D-dimer had Type A dissection in one study 4
  • 33% of patients with negative D-dimer required emergency surgery for cardiac tamponade 4

Guidelines Position

The American College of Cardiology Foundation/American Heart Association guidelines state:

• "A lack of large prospective studies precludes a recommendation regarding D-dimer use" 1
• "The negative likelihood ratio provided by the most sensitive D-dimer assay is not of sufficient magnitude to provide useful information in high-risk individuals" 1
• "The writing committee cannot recommend serum D-dimer screening for all patients being evaluated for aortic dissection" 1

Recommended Diagnostic Approach

Risk Stratification

• Use validated clinical tools like the Aortic Dissection Detection (ADD) risk score 1
• Even with an ADD score of 0, the prevalence of aortic dissection is still 5% 1

Definitive Imaging

• For high-risk patients: Proceed directly to definitive imaging (CTA, TEE, or MRA) 1
• For intermediate-risk patients: Chest X-ray first, followed by definitive imaging if indicated 1
• For low-risk patients: Chest X-ray may help establish alternative diagnosis 1

Role of D-dimer

• May be helpful as an adjunct in low-risk patients 2
• Cannot be relied upon as the sole screening test 1, 5
• Should not delay definitive imaging in high-risk patients 1

Pitfalls to Avoid

• Relying solely on D-dimer to exclude aortic dissection 1, 5
• Failing to recognize that a negative D-dimer does not rule out fatal aortic dissection 4
• Using D-dimer to differentiate aortic dissection from pulmonary embolism (both conditions show similar elevations) 1
• Delaying definitive imaging in high-risk patients while waiting for D-dimer results 1

D-dimer testing may be useful as part of a comprehensive assessment, but its limitations make it unsuitable as a standalone rule-out test for aortic dissection, particularly in high-risk patients.