There is no ONE treatment, it is basically a list of lifestyle changes. Things such as trying to avoid lots of stress, regularly exercising, eating healthily. Having blood pressure checks and ensuring it's in the normal range, even if it means taking medication. Having blood tests every year to check your cholesterol levels are normal.
The BEST treatments are yet to come, once they fully understand the chemical/physical processes involved with Atherosclerosis.
While I am NOT, repeat NOT an expert i would assume outside of stenting and bypass this is the most advanced form of treatment of corronary artery disease http://my.clevelandclinic.org/heart/disorders/cad/tmr.aspx. It's a procedure known as transmyocardial laser revascurilazation. The procedure sounds pretty innovative but it sounds like a last resort.