Guidelines recommended that patients with bioprosthetic heart valves (BHV) only need 6 months oral anticoagulation therapy after operation. However, a small part of patients still suffered thrombotic events after withdrawal of warfarin, which means these patients may need extend anticoagulation therapy. D-dimer, a sensitive marker of thrombosis or prethromboembolism state. Previous studies have demostrated that patients with elevated D-dimer levels have significant more clinical outcomes than those with nagative D-dimer levels. The aim of this study was to evaluate whether D-dimer could guide the duration of oral anticoagulation therapy in patients with BHV.

Patients with BHV were screened and enrolled in this study. D-dimer levels were measured in the sixth months after BHV operation but before withdrawal of warfarin. Patients with elevated D-dimer were randomized to extend anticoagulation therapy group and routine stopping anticoagulation group.

Inclusion Criteria:

• Patients received BHV within 3 months

Exclusion Criteria:

• Recently throboemblism within 6 months
• Recently bleedings within 3 months
• Evaluated lifetime less than 2 years