Unless your blockage is causing symptoms and symptoms which cannot be controlled by medication, I believe the general opinion would be to leave it alone. If you have symptoms, not controllable, then you would be evaluated for surgery as a first option. They would have to make an incision in your neck and remove the blockage using an arterectomy. If they feel surgery is too risky, then they will usually fall back to plan B, using a stent. I know that a stent is far less invasive, but the long term success favours arterectomy. There is a risk with both procedures for stroke, heart attack and of course, death. The risks are getting smaller as new surgical techniques are being introduced. Do you have a blockage? if so do you know what percentage it is? I know someone with a 60% blockage and she kept passing out, but medication is doing a great job now.
lots of web sites for information - here's one -
http://www.nhlbi.nih.gov/health/dci/Diseases/carend/carend_what.html