I just saw these posts about Synthroid and arrhythmia. I have hypothyroidism and have been on Synthroid for over thirty years with no problems. Two years ago I started with PVCs. Of course, at the time I had no idea what it was and wondered if I'd make it to the next day. As you can see I did. Heart arrhythmia is scary. The doc said my thyroid levels were high. I stopped the Synthroid and I felt great. Now two years later, the same thing. My TSH is a whopping 27 but when I take Synthroid again, more PVCs. My doc is on vacation so I will see another doc and I'm going to want a scan too. After three decades of no problems, why now? Is it because I'm getting old (56), or being overweight? But nothing has really changed. I realize thyroid hormone is very important but I swear I don't want it anymore. Any and all advice is welcomed. I don't want afib.