Anticoagulation in patients with pulmonary arterial hypertension: An update on current knowledge.

Pulmonary hypertension is a severe clinical condition characterized by molecular and anatomic changes in pulmonary circulation. It is associated with increased pulmonary vascular resistance, which leads to right-sided heart failure if left untreated and, ultimately, death. Treatment of patients with pulmonary arterial hypertension (PAH) involves a complex strategy that takes into consideration disease severity, general and supportive measures, and combination drug regimens. Abnormalities of blood coagulation factors, anti-thrombotic factors, and the fibrinolytic system may contribute to a prothrombotic state in patients with idiopathic PAH. These physiologic changes, in concert with the presence of non-specific risk factors for venous thromboembolism such as heart failure and immobility, are thought to be the basis for oral anticoagulation in PAH. Several observational studies provide helpful information in favor of anticoagulation use in idiopathic PAH but not in other pulmonary hypertension etiologies. Guideline recommendations are based on the lack of prospective comparative trials in this regard. For that reason, large differences exist in the use of anticoagulants in different countries and centers. More studies should be carried out to clarify the risks and the potential benefits of anticoagulant use in a heterogeneous population of patients who are already at considerable life risk.