What is the frequency of a positive D-dimer (D-dimer) test in patients with aortic dissection?

D-dimer Positivity in Aortic Dissection

D-dimer is positive in approximately 94-99% of patients with acute aortic dissection, making it a highly sensitive marker for this condition. Based on the most recent evidence, a 2023 large retrospective cohort study found that D-dimer has a sensitivity of 94.9% using a cutoff of 400 ng/mL and 93.0% using a cutoff of 500 ng/mL for detecting acute aortic dissection 1.

Sensitivity of D-dimer in Aortic Dissection

The evidence consistently demonstrates high sensitivity of D-dimer for aortic dissection:

• The 2023 TriNetX database study analyzing 1,319 patients with confirmed aortic dissection found 94.9% sensitivity with a 400 ng/mL cutoff and 93.0% sensitivity with a 500 ng/mL cutoff 1
• A 2015 clinical guideline reported a meta-analysis of 11 studies showing pooled sensitivity of 94% (95% CI 91% to 96%) 2
• Ohlmann et al. (2006) found 99% sensitivity with a cutoff of 400 ng/mL 2
• Suzuki et al. (2009) reported 96.6% sensitivity (95% CI 90.3% to 99.3%) with a cutoff of 500 ng/mL 2, 3

Factors Affecting D-dimer Levels in Aortic Dissection

Several factors can influence D-dimer levels in aortic dissection, potentially leading to false negatives:

1. Chronicity of dissection: D-dimer levels are higher in acute versus chronic aortic dissections 2
2. Time from symptom onset: Significant negative correlation between D-dimer values and time from onset 2
3. Thrombosed false lumen: Patients with thrombosed false lumens exhibit significantly lower D-dimer levels 2
4. Intramural hematoma: D-dimer levels are lower in patients with intramural hematoma versus those with patent false lumen 2
5. Length of dissection: Short dissection lengths may result in lower D-dimer values 2
6. Patient age: Younger patients may have false-negative D-dimer results 2

Clinical Implications

While D-dimer is highly sensitive for aortic dissection, it has limited specificity (ranging from 34% to 73% across studies) 2, 4, 5. This means:

• A negative D-dimer test is useful to help exclude aortic dissection in low-risk patients
• A positive D-dimer is not specific for aortic dissection and can be elevated in many conditions including pulmonary embolism, myocardial infarction, and inflammatory conditions 2

Current guidelines suggest that D-dimer testing may be most valuable when combined with clinical risk assessment. The 2021 study found that combining a negative D-dimer with an Aortic Dissection Detection Risk Score (ADD-RS) < 1 provided a sensitivity of 99.9-100% for ruling out acute aortic syndrome 6.

Important Caveats

• D-dimer should not be used in isolation to rule out aortic dissection in high-risk patients
• False negatives can occur in specific circumstances (thrombosed false lumen, intramural hematoma)
• The 2010 ACC/AHA guidelines state they "cannot recommend serum D-dimer screening for all patients being evaluated for aortic dissection" due to limitations in its diagnostic accuracy 2
• D-dimer levels cannot reliably differentiate between aortic dissection and pulmonary embolism 2

In summary, while D-dimer is positive in the vast majority of aortic dissection cases (93-99%), its use as a standalone test has limitations, and clinical judgment remains essential in the diagnostic approach to suspected aortic dissection.