Treatment for CAD only deals with symptoms, there is no cure. Usually the symptom is chest pain (PECTORIS ANGINA) and therapy can be medication, stent implant, or by-pass. Open an occluded vessels provides sufficient blood to the area deficit of blood flow usually relieves the pain. What treatment is best for you depends on the severity of the lesions (number and size), location, general health, medication tolerance, etc.
That's a very difficult question because it all depends on the severity of the disease.
As well as the severity, it depends on which locations the worst of the disease exists in, and how much (if any) heart tissue is dead. Is this a general question or do you have heart disease? If you do it would really be useful to know your situation.