Ask the doctor: Is it okay to take aspirin, Plavix, and warfarin?

I am 85. I had an angioplasty with a stent and I’m on aspirin and Plavix. Now I have atrial fibrillation, and my doctor wants me to take Coumadin. Is this dangerous? Should I stop taking aspirin and Plavix? Or could I just take them without the Coumadin?