I Am A 44 Yr. Old Female. I Have Just

I am a 44 yr. old female. I have just been diagnosed as having a 100% blockage and dissection of my carotid artery. Does this sound like a case where surgery will be needed? Also, the doctor mentioned my past use of cocaine may have contributed to my condition, but he did elaborate on this statement - can you please provide me with any details as to why past cocaine use is a possible factor? Thank you.