The use of anticoagulant therapy in patients with pulmonary arterial hypertension (PAH) has been controversial for decades. Recommendations for anticoagulation in these patients are often derived from small, retrospective, and single centre studies without any placebo-controlled randomized study. Furthermore, selleck product uncertainties exist regarding a number of issues such as patient selection, risk stratification

for bleeding, the intensity of anticoagulation, appropriateness of anticoagulation in different types of PAH, and the potential use of new oral anticoagulants. Recently, the database of the Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) has been analyzed to assess the effect of anticoagulation on the long-term outcome of patients with various forms of PAH. This analysis is the largest

to date to assess anticoagulant therapy in PAH patients in a prospective design with long observation period. The results of COMPERA lend support to current recommendations for the use of anticoagulant therapy in patients with idiopathic PAH, but not in other forms of PAH. Also, the study confirmed the previously reported concern that anticoagulant therapy may be harmful in patients with scleroderma-associated PAH. Background The exact role of chronic thrombosis in the pulmonary arteries in patients with pulmonary arterial hypertension (PAH) is controversial. One view suggests that thrombosis is an epiphenomenon related to stasis and endothelial dysfunction. Another view holds that chronic organized thrombotic pulmonary vascular lesions are an integral part of pulmonary vascular remodeling leading to progressive luminal narrowing with increased pulmonary vascular resistance and progression of PAH. 1–2 Irrespective of whether thrombosis is a cause or consequence of PAH,

anticoagulants have been used for decades in PAH patients. The main rationales for the use of anticoagulant therapy in PAH are: (1) Pathological evidences that thrombi are a common finding in idiopathic PAH patients. In two retrospective studies Dacomitinib evaluating histopathology in idiopathic PAH patients (formerly called primary pulmonary hypertension), the prevalence rates for chronic organized pulmonary vascular thromboses were 56% and 57%. 3–4 (2) Evidence that PAH is associated with prothrombotic abnormalities, causing in situ thrombosis. These abnormalities include all components of coagulation cascade: coagulation factors, platelet function, and fibrinolytic system (for a review, see 2 ). (3) Evidence from observational studies that showed better outcomes in idiopathic PAH patients receiving anticoagulant therapy. In a systematic review of seven observational studies, survival benefit was demonstrated in five studies, while two did not support these findings.