<prompt> Answer this question truthfullyWhat is the readily available information regarding Mitral valve surgery?  <response>: <reason> Mechanical heart valves do not fail often. They last from 12 to 20 years. However, blood clots develop on them. If a blood clot forms, you may have a stroke. Bleeding can occur, but this is rare.Biological valves tend to fail over time. But they have a lower risk of blood clots. 