The Risk of Early Recurrent Venous Thromboembolism after Oral Anticoagulant Therapy in Patients with the G20210A Transition in the Prothrombin Gene

Abstract
A G20210A transition in the prothrombin gene is a common risk factor of venous thrombosis. The risk of recurrent venous thrombo-embolism in carriers of the 20210A allele is unknown and guidelines for secondary thromboprophylaxis in these patients are not available. In a prospective multicenter trial, 492 patients with a history of objectively documented venous thromboembolism were followed for a mean observation time of 24 ± 16 months after discontinuation of oral anticoagulants. Forty-two patients (8.5%) were carriers of the 20210A allele. Three of the 42 patients with the G20210A mutation (7%) and 54 of 450 patients without the mutation (12%) experienced recurrent venous thrombosis. At 24 months, the probability of recurrence was 8% (95% CI 0-16.7) in patients with the mutation and was 12.2% (95% CI 8.8-15.6) in patients without the mutation. In conclusion, the risk of early recurrent venous thromboembolism is not higher in patients with the G20210A mutation than in those without the mutation. Therefore, long-term secondary thromboprophylaxis with oral anticoagulants in heterozygous carriers of the 20210A allele is not justified.