Anticoagulation for Bioprosthetic Aortic Valve
For patients with a bioprosthetic aortic valve in sinus rhythm without other indications for anticoagulation, aspirin 75-100 mg daily is recommended for the first 3 months, with warfarin (INR 2.5, range 2.0-3.0) being a reasonable alternative for 3-6 months in patients at low bleeding risk, followed by indefinite aspirin monotherapy. 1, 2
Early Post-Operative Period (First 3-6 Months)
Aspirin Monotherapy (Preferred for Most Patients)
- Aspirin 75-100 mg daily is the preferred initial therapy for patients with surgical bioprosthetic aortic valves who are in sinus rhythm and have no other indication for anticoagulation. 1, 2
- This recommendation is based on the 2017 ACC/AHA guidelines (Class IIa, Level B) and 2012 ACCP guidelines (Grade 2C). 1
- The evidence supporting aspirin over warfarin in the aortic position comes from small randomized trials showing no significant difference in thromboembolic events but a trend toward less bleeding with aspirin. 1
Warfarin as Alternative Option
- Warfarin targeting INR 2.5 (range 2.0-3.0) for 3-6 months is a reasonable alternative, particularly in patients at low bleeding risk. 1, 2
- The 2017 ACC/AHA guidelines upgraded this recommendation to Class IIa, Level B-NR, extending the duration up to 6 months based on Danish registry data showing lower stroke risk and mortality with warfarin for up to 6 months post-implantation. 1
- This warfarin recommendation is stronger for mitral bioprosthetic valves (Grade 2C) due to higher thromboembolic risk (up to 40 events per 100 patient-years in the first month). 1
Critical Caveat About the Danish Registry Data
The Danish registry study cited by ACC/AHA guidelines has a major limitation: fewer than 15% of patients in the "no-warfarin" group received any antiplatelet therapy, which may have artificially inflated event rates in that group and created selection bias. 1 Despite this limitation, the ACC/AHA incorporated this evidence to support extended warfarin use up to 6 months. 1
Long-Term Management (After 3-6 Months)
Indefinite Aspirin Therapy
- Aspirin 75-100 mg daily indefinitely is recommended for all patients with bioprosthetic aortic valves in normal sinus rhythm. 1, 2
- This is a Class IIa, Level B recommendation from ACC/AHA guidelines. 1
- Long-term thromboembolic risk with bioprosthetic aortic valves is low (0.2% per year) in patients with sinus rhythm. 1
No Role for Long-Term Anticoagulation
- Long-term warfarin is not indicated for bioprosthetic valves in patients who remain in normal sinus rhythm without other risk factors. 1
- Case series demonstrate very low event rates (no major thromboembolic events in 254 patient-years) with aspirin alone in patients with aortic bioprostheses in sinus rhythm. 1
Special Populations and Considerations
Patients with Atrial Fibrillation
- If atrial fibrillation develops, warfarin (INR 2.0-3.0) is indicated regardless of valve type, based on the AF itself rather than the bioprosthetic valve. 1, 3
- The thromboembolic risk in bioprosthetic valve patients with AF has been reported as high as 16% at 31-36 months. 1
Transcatheter Aortic Valve Replacement (TAVR)
- For TAVR patients, aspirin 50-100 mg daily is recommended, with dual antiplatelet therapy (aspirin plus clopidogrel) being reasonable for 3-6 months. 1, 2
- Rivaroxaban is contraindicated after TAVR based on the GALILEO trial, which was terminated early due to increased harm compared to antiplatelet therapy. 1, 2
High-Risk Features Favoring Warfarin
Consider warfarin over aspirin alone in the first 3-6 months for patients with: 1, 4
- Female gender (odds ratio 2.23 for thromboembolism) 4
- Small prosthesis size (19mm valve, odds ratio 2.22) 4
- NYHA Class III/IV symptoms (odds ratio 1.77) 4
- Advanced age 4
- Short stature 4
What NOT to Do
Direct Oral Anticoagulants (DOACs)
- DOACs are not recommended for bioprosthetic valves based on current evidence. 1, 2
- While small retrospective studies suggest similar safety profiles between DOACs and warfarin for bioprosthetic valves, these lack the power to detect differences and are not supported by guidelines. 5
- The GALILEO trial's negative results with rivaroxaban after TAVR have dampened enthusiasm for DOACs in this population. 1, 2
Dual Antiplatelet Therapy for Surgical Valves
- DAPT (aspirin plus clopidogrel) is not recommended for surgical bioprosthetic aortic valves - this is reserved for TAVR patients only. 2
- The PROACT trial demonstrated that DAPT was inferior to warfarin for mechanical valves, with excess thromboembolic events. 6
Practical Algorithm
For surgical bioprosthetic aortic valve patients in sinus rhythm: