Background: Chronic thromboembolic pulmonary hypertension (CTEPH) is an important cause of severe pulmonary hypertension (PH). D-dimer, a degradation product of fibrin, has been used as a marker for various diseases. In patients with idiopathic pulmonary arterial hypertension there is evidence to suggest that D-dimer levels are associated with disease severity; however, data regarding D-dimer in patients with CTEPH are lacking.
Objective: To assess the significance of D-dimer in patients with CTEPH.
Patients and methods: Retrospective chart review of 618 patients seen at our PH clinic from 1991 to June 2008. Data collection focused on patients diagnosed with CTEPH, D-dimer levels, demographics, clinical, and hemodynamics. We compared D-dimer levels in CTEPH patients or World Health Organization (WHO) diagnostic group 4 with PH patients in WHO group 1.
Results: Thirty-four patients with confirmed CTEPH were identified, of these 19 had D-dimer levels and 7 were positive. Of the 234 patients in WHO group 1 excluding patients with portopulmonary hypertension (n = 54) and pulmonary venoocclusive disease (n = 2) 97 had D-dimer levels and 52 were positive. We found an estimated sensitivity of the D-dimer test in diagnosing CTEPH was 37% while the estimated specificity was 46%. The positive predictive value and negative predictive value were 12% and 79% respectively.
Conclusion: D-dimer is an insensitive and nonspecific test for the diagnosis of CTEPH. Despite a high negative predictive value D-dimer alone cannot be used to rule out CTEPH in patients with PH.