The guidelines below are based on the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines for Antithrombotic Therapy and Prevention of Thrombosis (ninth edition, 2012).[1]
Acute pulmonary embolism (PE)[2, 3]
International normalized ratio (INR) target (range)
Standard: 2.5 (2.0-3.0)
Unprovoked, infrequent INR checks: 1.5-1.9 after 3 months of standard therapy
Duration of therapy
Transient, reversible risk factor: 3 months
First episode, unprovoked
Low/moderate bleeding risk: Extended therapy
High bleeding risk: 3 months
Recurrent, unprovoked
Low/moderate bleeding risk: extended therapy
High bleeding risk: 3 months
Cancer: Extended therapy
Acute deep venous thrombosis (DVT) of the lower extremity
INR target (range)
Standard: 2.5 (2.0-3.0)
Duration of therapy
Transient, reversible risk factor: 3 months
First episode, unprovoked, proximal
Low/moderate bleeding risk: Extended therapy
High bleeding risk: 3 months
First episode, unprovoked, distal: 3 months (guidelines suggest serial imaging for 2 weeks rather than early anticoagulation for patients with isolated distal lower-extremity DVT who do not have severe symptoms or risk factors for extension)
Recurrent, unprovoked
Low/moderate bleeding risk: Extended therapy
High bleeding risk: 3 months
Cancer: Extended therapy
INR target (range): 2.5 (2.0-3.0)[4]
Duration of therapy
Axillary or more proximal: 3 months or more
Distal: 3 months
Central venous catheter (CVC) related: Until catheter is removed, or a minimum of 3 months
INR target (range)[5]
Standard: 2.5 (2.0-3.0)
CVC related: 1.5-1.9 after 3 months of standard therapy
Duration of therapy
Idiopathic, first episode: 6-12 months
Idiopathic, recurrent: Lifelong therapy
Reversible risk factor: Until risk factor has resolved, or a minimum of 3 months
Cancer, thrombophilia: Until risk factor has resolved, or a minimum of 3 months
CVC related: Until CVC is removed, or a minimum of 3 months