The combined Antiplatelet and Anticoagulant treatment decreased thrombus formation and overall mortality. Also the initiation of an efficacious early anticoagulation protocol is important because of its potential impact on the rate of early thromboembolic complications after mechanical valve implantation. An important question that remains to be answered is whether the combination would be cost effective than Warfarin alone, with a reduction in major bleeding. In addition, the knowledge about its cost-effectiveness has not yet been established in Egypt. The aim of this trial based economic evaluation is to conduct a cost-effectiveness analysis for combination of low-dose Aspirin and Warfarin versus Warfarin alone in prosthetic valve patients from the medical provider perspective specially that a misconception is still existed between the physicians in Egypt that the cost of complications is not worthy so our main aim is to test the cost of complications.

The measurements will be assessed:

A- Number of patients improved during follow up:

1. Demographic data
2. Diagnosis
3. Laboratory tests (CBC, Prothrombin Time, liver and renal function tests)
4. Echocardiography profile

B-Costs:

Direct medical costs will be assessed directly from hospital's records and tender lists.

Inclusion Criteria:

Patients operated in Ain Shams University Hospitals for aortic and/ or mitral valve replacement.

Exclusion Criteria:

• Congenital blood disorders, Hemophilia.
• Advanced liver disease
• Advanced renal disease (dialysis patients)
• Aspirin sensitivity
• Autoimmune diseases
• Biological bioprosthesis valves
• Non-compliant & Drop out patient
• Pregnant women
• Caucasians.