When is long-term anticoagulation with warfarin indicated in the treatment of pulmonary arterial hypertension (PAH)?

Updated: Apr 25, 2018
  • Author: Kristin E Schwab, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Long-term anticoagulation with warfarin should be considered in selected patients with PAH. These include patients with pulmonary venoocclusive disease as well as those with low bleeding risk in who the benefit outweighs the risk (eg, those with cor pulmonale or immobility secondary to severe dyspnea).

Warfarin interferes with hepatic synthesis of vitamin K–dependent coagulation factors. It is used for prophylaxis and treatment of deep venous thrombosis, pulmonary embolism, and thromboembolic disorders. It is also used to decrease the risk of embolic stroke in patients with atrial fibrillation. The practitioner typically tailors the dose to maintain an international normalized ratio in the range of 2-3. Recurrence of deep venous thrombosis and pulmonary embolism increases dramatically when the international normalized ratio drops below 2 and decreases when it is kept between 2 and 3. Serious bleeding risk (including hemorrhagic stroke) is approximately constant when the international normalized ratio is between 2.5 and 4.5, but rises dramatically when it exceeds 5.

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