Even though your valve may be working fine after your surgery, there is a small risk that, over time, the valve may not function correctly. This occurs in less than 1 out of 100 patients. This may be the result of a clot forming on the replacement valve, preventing it from opening and closing properly. The new mitral valve may develop a leak around the sutures that hold it in place. This can be the result of the valve tissue weakening or due to an infection. Again, this occurs rarely. Further tests will most likely be done, and another surgery can be performed to replace the valve.