Indications for Anticoagulation in Patients With Prosthetic Heart Valves

All patients with mechanical valves require warfarin therapy. The risk of embolism is greater with a valve in the mitral position (mechanical or biological) than in the aortic position. With either type of prosthesis or valve location, the risk of emboli is higher in the first few days and months after valve insertion. Low-dose aspirin is recommended for all patients with prosthetic valves (see Table 1. For patients with mechanical valves, the addition of low-dose aspirin (80 to 100 mg/d) to warfarin therapy (INR 2.0 to 3.5) not only further decreases the risk thromboembolism but also decreases mortality due to other cardiovascular diseases. A slight increase in risk of bleeding with this combination should be kept in mind.
Recommendations for Antithrombotic Therapy in Patients With Prosthetic Heart Valves
Class I
1.First 3 months after valve replacement: Warfarin- INR 2.5 to 3.5
2.3 or more months after valve replacement:
A. Mechanical valve
AVR and no risk factor*:
Bileaflet valve or Medtronic Hall valve, Warfarin- INR 2 to 3
Other disk valves or Starr-Edwards valve, Warfarin- INR 2.5 to 3.5
AVR and risk factor,* Warfarin- INR 2.5 to 3.5
MVR, Warfarin- INR 2.5 to 3.5

B. Bioprosthesis
AVR and no risk factor,* Aspirin- 80 to 100 mg/d
AVR and risk factor,* Warfarin- INR 2 to 3
MVR and no risk factor,* Aspirin- 80 to 100 mg/d
MVR and risk factor,* Warfarin- INR 2.5 to 3.5

Class IIa
1.Addition of aspirin to warfarin: Aspirin- 80 to 100 mg daily
2.High-risk patients for whom aspirin cannot be used: Warfarin- INR 3.5 to 4.5
Class IIb
Starr-Edwards AVR and no risk factor,* Warfarin, INR 2 to 3

Class III
1.Mechanical valve, no warfarin therapy.
2.Mechanical valve, aspirin therapy only.
3.Bioprosthesis, no warfarin and no aspirin therapy.