Background: Micro-vascular thrombus is a common pathological finding in pulmonary artery hypertension. The association between plasma D-dimer, a marker of thrombus formation, and pulmonary artery hypertension (PAH) in patients with systemic sclerosis is unknown.
Objective: To assess the correlation of the level of plasma D-dimer and pulmonary artery pressure in patients with systemic sclerosis.
Material and Method: One hundred and twenty nine patients with systemic sclerosis between 19 and 75 years of age (mean, 48 + 11.3) entered the study. Plasma D-dimer was determined using immunoturbidimetric assay (D-dimer plus, Dade Behring Inc., Newark, USA). Pulmonary artery pressure was estimated by Doppler echocardiography. PAH was considered present if the Doppler echocardiography-estimated right ventricular systolic pressure (RVSP) exceeded 36 mmHg.
Results: Forty-seven patients (36.4%) had PAH according to Doppler echocardiography including 32 (68.1%) mild (RVSP, 36-45 mmHg), nine (19.1%) moderate (RVSP, 46-55 mmHg), and six (12.8%) severe PAH (RVSP > 56 mmHg). No significant correlation was found between plasma D-dimer and RVSP (r = 0.02, p = 0.82).
Conclusion: The present study demonstrated that the D-dimmer level is not associated with the level of pulmonary artery pressure in patients with systemic sclerosis, indicating that microvascular thrombosis may not play a significant role in the pathogenesis of PAH in patients with systemic sclerosis.

Keywords: D-dimer, Pulmonary hypertension, Systemic sclerosis