Comparison of 3 and 6 Months of Oral Anticoagulant Therapy After a First Episode of Proximal Deep Vein Thrombosis or Pulmonary Embolism and Comparison of 6 and 12 Weeks of Therapy After Isolated Calf Deep Vein Thrombosis - DTAVK Study
Comparison of 3 and 6 Months of Oral Anticoagulant Therapy After a First Episode of Proximal Deep Vein Thrombosis or Pulmonary Embolism and Comparison of 6 and 12 Weeks of Therapy After Isolated Calf Deep Vein Thrombosis
What is the optimal duration of anticoagulant therapy after a first episode of venous thromboembolism (VTE)?
Patients Enrolled: 736
An open-labeled randomized trial comparing short-term oral anticoagulation defined as 12 weeks for pulmonary embolism (PE) and proximal deep vein thrombosis (P-DVT) and 6 weeks for calf DVT, with a longer course of therapy defined as 6 months for P-DVT and PE and 12 weeks for calf DVT. Outcome measures included recurrences over at least 12 months after treatment end and bleeding complications during therapy. The anticoagulant was fluindione, a vitamin K antagonist, titrated to an INR of 2.0 to 3.0 while the patient was on fractionated or low molecular weight heparin.
A total of 736 patients were enrolled with an average age of 58 years, 47% were male, 34% had calf DVT (7% with PE), 62% P-DVT (18% with PE) and a total of 30% had a PE of whom 4.5% had no DVT. At least one temporary risk factor was present in 52% (majority being surgery or immobilization) and at least one permanent risk factor was present in 55% including venous insufficiency in 30% and obesity in 32%. Forty-five percent were considered to have idiopathic VTE. In the 15 months of follow-up, there were 23 recurrences with short-term therapy (6.4%) and 26 with long-term treatment (7.4%). The recurrence rate was about 3% with calf DVT and 8.5% with PE and P-DVT. There was an insignificant increase in major and minor bleeding with longer therapy. There was no impact of duration of treatment or the effectiveness of heparin or fluindione” on outcome in any group. Patients without risk factors, idiopathic VTE, had nearly twice (9% vs. 5%) the recurrence rate (p<0.03).
After isolated calf DVT, 6 weeks of oral anticoagulation appears to be sufficient. For first episodes of proximal DVT and pulmonary embolus 3 and 6 months of treatment appear to be equivalent. Patients with temporary risk factors have a low risk of recurrence, and 12 weeks of therapy may be sufficient. For patients with idiopathic DVT or permanent risk factors, further trials are necessary to assess the efficacy of therapy prolonged beyond 6 months.
It is reasonable to assume the same results would have been obtained with warfarin (rather than fluindione) targeted to an INR of 2.0 to 3.0. The NHLBI PREVENT trial is testing the effectiveness of long-term low-dose warfarin (INR 1.5–2.0) vs placebo in idiopathic DVT in patients with and without evidence of inherited traits promoting thrombosis (e.g., factor V Leiden).
1. Pinede L, Ninet J, Duhaut P, et al., for the Investigators of the Duree Optimale du Traitement AntiVitamines K (DTAVK) Study. Circulation 2001;103:2453–60.
Keywords: Vitamin K, Pulmonary Embolism, Heparin, Low-Molecular-Weight, Warfarin, Venous Thromboembolism, Risk Factors, Thromboembolism, Recurrence, Venous Insufficiency, Obesity, Venous Thrombosis
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