Corinary Artery Disease

Three years ago my fiance' had a heart attack and had a stent put in the back side of his heart. On September 21st 2007, he had 2 more stents put in because of blockages of 80% and 90% but it was not a heart attack. When the stents were put in, I was told that he had damage to the lower part of the heart, scareing that wasn't there the first time they did a stent and that blood was not getting to the back part of his heart. They have done 2 stress test, recently, one to simulate running and an echo,  the other he actually ran on the thread mill and an echo.  The first stress test was inconclusive.
After having the stents put in and the test done, we are now being told that the blood flow has returned to the back part of his heart. Is that possible?  Also, they are saying he has a leaky valve, didn't have that before and we are told it is nothing to worry about. Is that something we should be worried about?  (He also has High Blood Pressure, Corinary Artery Disease, High Cholesterol, is managed, Unstable Angina and a Hyanal Hernia). He is being told that he can return to work only to lift 50lbs. (He is a truck driver, 18 Wheelers). I know with CAD he is at high risk for other blockages. Is it safe for him to return to that type of work and lifting? Should he have more tests?? Should we be concerned about his heart condition??   Thank you for your time.. concerned