Warfarin and coumadin were used in pulmonary hypertension therapy. But there is limited evidence for their effectiveness. Leading lung and heart disease expert explains. Anticoagulants are used in clinical practice in patients with pulmonary arterial hypertension. But blood thinners, as they are also known, have a lot of significant side effects. Dr. Aaron Waxman, MD. The major side effect is the risk of bleeding. It includes intracranial bleeding, gastrointestinal bleeding. How to balance risks and benefits of anticoagulants when they are used for pulmonary arterial hypertension? Dr. Anton Titov, MD. The whole role of anticoagulants in pulmonary arterial hypertension is now in question. Originally, anticoagulants were started because pathologically there was recognition of in-situ thrombosis in pulmonary hypertension. Thrombosis was noticed when pulmonary arterial hypertension was first described in the 1950s. As such, people started asking questions. We had no other treatment options for pulmonary arterial hypertension. Maybe we should put patients on coumadin. Will it have an impact on disease? Dr. Anton Titov, MD. That was a suggestion. Dr. Aaron Waxman, MD. Blood thinning had a small impact on survival in pulmonary arterial hypertension. Since that time and over the past five years, we have recognized that probably there is not a lot of clinical benefit from anticoagulants in pulmonary arterial hypertension. This doubt is based on studies that have been published out of the European registries, the US registries and even out of our own patient population here. Dr. Aaron Waxman, MD. We are not convinced anymore that the risks of anticoagulation outweigh the benefits in pulmonary arterial hypertension. Especially if it is a lifelong anticoagulation. For many of us, we have stopped using routine anticoagulation. For those patients with pulmonary arterial hypertension who might have chronic thromboembolic disease, or who have had known blood clots, obviously they will be anticoagulated. But now less and less we anti-coagulate patients with pulmonary arterial hypertension. Dr. Aaron Waxman, MD. We have no indication that there is a lot of benefit from it. It also speaks that there is a lot of research going on in the vascular lung diseases. New medications are becoming available to treat pulmonary arterial hypertension. Older medications were empirically used. Now they are being phased out, in a sense. In many ways this is true.