I have had pvc's for 30 years. They come, they go, Ive gotten kinda used to them by now. They have been sort of calm lately. I was just diagnosed with hyperthyroid and put on methimazole 10mg twice a day. Just before I started taking them, my pvc's came back with a fury. I started getting them every or everyother beat for about 6 or 7 beats and then go away a little bit (hour) then come back again. They are harder ones it seems. Both my Dr.s are out of town so talked with the on duty Dr. She said because of the hyperthyroid, I might feel these stronger and more of them until the medicine kicks in. Anyone ever have this problem and how long does it take for this medicine to start helping to block this overactive thyroid. Thanks if anyone can relate.