Bypass surgery does not fix blockages in the way stenting does, it simply bypasses them with new grafts. Some blockages are not bypassed, for instance if they are not severe, or if the artery is small and does not supply a large area of the heart, or if the artery has no good runoff and is small distally. I am not sure why it was not done in your case, since I am not aware of all the details in your case. The question is what symptoms are you having that are attributable to this blockage: arrhythmias, chest pain, CHF or shortness of breath? If any of thee are present and clearly implicated by a severe blockage in that part of the heart, then you may be a candidate for stenting.
before the doctors answers your question, maybe you can add a reply with more details,,,i only say this in trying to help you get the best answer - where is the blockage specifically etc