I am 65 and had a valve replacement ( along with aortic reconstruction , double bypass and maze procedure ) last August . I wanted a tissue valve but when they got in my aorta was too large and the surgeon was concerned that if failure occurred ( expectancy 10-15 yrs ) it would be too risky to install a replacement . I have not had any bad side effects from the warrfarin other than scratches and other minor injuries bleeding but it really is not any worse than with asprin . Testing weekly can be a challenge , but i now have a home test kit that makes it much more convienent .