Hello there, I can understand your concern for your father s health. Diabetic patients tend to have higher chances of having multiple artery blockages. Considering his previous angioplasty and the recurrence of blockage in multiple arteries it seems that your treating cardiologist is weighing the risk versus benefit ratio of a surgery. It would have helped to know your father s age. Every surgery especially on the heart is a big risk to the patient. Doing bypass surgery on your diabetic father may be more risky than trying to reduce the clot with medicines. I cannot say that this will work and prevent any problems but this looks like the best course. If you feel uncomfortable you should take your father s reports to another cardiologist and get a second opinion. Without seeing the Angiography report it is difficult to tell you the right course of action. But let me assure you that if your doctor has refrained from suggesting a bypass maybe with the bigger picture in mind. So do continue to give him the medicines as prescribed and keep tight control on his diet. Hope this helps. Take care.