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Have you eliminated AFIB by normalizing thyroid hormones?
Has anyone eliminated their AFIB by bringing their thyroid levels to the normal range. I was diagnosed with sub-clinical hyperthyroidism and Graves when my AFIB was discovered. Methimazole brought my TSH level to normal, and I went from being in AFIB 100 percent of the time to under 20 percent of the time. I'm considering an ablation, but I want to make sure I've reached the maximum effectiveness through the thyroid medication first.
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do they test your T3 and T4 and are they in the normal range?
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Location: Georgia
Posted December 3, 2025
after 2 hospitalizations for afib/flutter and an Trans Ultrasound which pinpointed an Atrial Septal Defect (effectively an exaggerated opening in wall between right and left atria) I had an ablation in 2017 and the ASD was plugged. After some short episodes during 'blanking period of approx 2 months) I didn't have any episodes until 2021. SInce then I routinley have an episode (Aflutter or AFIB?) on average every 2-4 mos which lasts about 2 hrs and then goes away. Hard to determine what triggers it although about for about half of the episodes, it's there when I wake up in morning. Anyway last year I began suffering from a lot of PVCs and PACs - with AFIB symptoms (Apple watch mistakenly labels these as AFIB episodes even though rate is low - 60-70 BPM). I referred to this condition as 'AFIB lite'. I consulted with cardiologist and he responmded that PVCs/PACs are no big deal, everybody has some from time to time. If I want treatment he recommended Multaq or another ablation even though the ASD plug presents a complication. He also told me to keep my thyroid hormone from being too high = THyroid Stimulating Hormone (TSH) being too low. SO I decreased the amount of Levothyroxine I'm taking (Cancerous Thyroid was removed over 35 yrs ago) and lo the PACs, PVCs ceased. However it's hard to find the right doseage to achieve the desired value of TSH. So my family doctor suggested that I take Synthroid as its quality control is better. In the process of moving from Levothyroxine (generic Synthroid) to name brand Synthroid he upped the doseage and my AFIB/Flutter and PVCs/PACs resumed in spades (4 episodes in a little over 2 mos). I subsequently obtained a lower doseage of Synthroid and the AFIB/Flutter sessions have ceased for almos 3 mos. I've done some reading and there is definitely a recognized link between Thyroid hormone and Heart Arrythmias. I am now working on a theory (and looking for expertise) that these PVCs and short AFIB episodes are a result of too much Thyroid hormone since they seem to have ceased when I lowered my Levothyroxine (generic Synthroid) doseage. Too little Thyroid hormone (high TSH) is also a problem as the symptoms are not unlike AFIB/Flutter. I need a 'goldilocks' solution. I'm looking for an endocrinologist who has knowledge and experience treating heart arrythmias. I'm looking locally but have struck out so far. can anyone recommend a specialist who might be able to help achieve the right balance between thyroid issues; perhaps I can work with him /her via Telehealth.
@chickenfarmer I can't help with expertise, but I can provide my interaction between hypothyroidism and Afib. In December 2024 I was being prepped for Cataract surgery on my right eye and was found to be in Afib. No symptoms that I could feel. 2 weeks before that I had Cataract surgery on my left eye, no Afib. Blood work then showed that my TSH levels were low. All my previous blood work for years and years showed no TSH problems. Levothyroxine was prescribed and my TSH levels are in the normal range. I had a cardioversion done in February 2025 which put me back in sinus rhythm and then a pulse field ablation in May 2025. Since then, no Afib episodes. I have autoimmune system problems, so I requested that I be tested for Hashimoto's Syndrome which is known to cause hypothyroidism. The test was positive for Hashimoto's. There is no cure for Hashimoto's all you can do his work on the impact, which is hypothyroidism. Since starting on Levothyroxine, I have never varied the dosage up or down. Did the Hashimoto's trigger hypothyroidism which in turn triggered the heart to go into Afib? Know way of really knowing. All I know is that my TSH, T4, T3 and T2 levels are in the normal range, and I have had no Afib episodes since February of 2025.
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1 ReactionThanks for sharing your experience. It’s somewhat different from mine in that my recent episodes seem to correlate with hyperthyroidism not hypo. What little reading I’ve been able to find cites a relationship between hyperthyroidism (low TSH) and arrhythmia which appears opposite to your experience. Confusing - yes. All the more reason for me to find an experienced medical type who has studied this narrow area of TSH and heart arrhythmias.
@tphome I’ve discovered a definite relationship between my TSH level and PVC occurrence. By reducing my synthroid I’ve virtually eliminated arrhythmias in 2025. AND I was able to reproduce the effect by increasing the Levothyroxine again then reducing it.
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1 Reaction@stan4745 in my case of hyperthyroidism, my TSH was all over the place while T4free and T3 were virtually unchanged. Yet lowering the synthroid dosage which increased TSH virtually eliminated my arrhythmias.
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1 Reaction@suerte yes thyroid hormones can cause Afib That’s why you should check regularly
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1 ReactionHello, @chickenfarmer My cardiologists, and the literature, have admitted for many years now that low thyroid (hypothyroidism) also causes heart arrhythmias, although it's not clearly understood why and how this occurs. Previously, it was believed that only high thyroid triggered atrial fib, and that was taught in med school for years. But it's a complex relationship between heart & thyroid. "Stop The Thyroid Madness" is a patient-centered website (and a book by that name) that has been compiling research on this and other thyroid questions and treatments for almost 25 years, and might be of interest to you. There are research studies discussed and other documentation of doctors who are studying the low-thyroid/afib connection. I found it helpful; I have low thyroid and AF episodes.
@merrychristmas I am well aware that hypothyroidism can cause arrythmia problems. My question and statement were about the complete daisy chain from Hashimoto's to hypothyroidism to Afib. Is this a valid sequence of events? There is no empirical data that proves there is or is not a linkage.
@drdianeschneider Studies and experts suggest that thyroid medication (levothyroxine) is frequently overprescribed, especially for mild or subclinical hypothyroidism, with many patients potentially taking it unnecessarily due to vague symptoms, lab reporting issues, or a lack of re-evaluation, leading to potential risks like heart palpitations and anxiety, particularly in older adults. Reassessment for continued need and exploring other causes for symptoms are crucial, say health professionals.
I have Hashimoto's Syndrome which is a known trigger for hypothyroidism so for me there is not much of an option. But if a real trigger cannot be found, it may be worth looking into whether it is necessary.