Link between Hypothyroidism and Atrial Fibrillation Explored
In the realm of healthcare, the connection between thyroid disorders and atrial fibrillation (AFib) is a topic of ongoing research. While the link between hyperthyroidism and AFib is clear, the relationship with hypothyroidism is more complex and less certain.
Hyperthyroidism, a condition where the thyroid gland overproduces hormones, is well-established to increase the risk of AFib. The stimulation of the heart by excessive thyroid hormones can lead to irregular heart rhythms, thereby increasing the risk of AFib [1][3].
On the other hand, hypothyroidism, characterized by low thyroid hormone levels and elevated Thyroid-Stimulating Hormone (TSH), shows a more nuanced relationship with AFib. Some studies suggest that elevated TSH and subtle imbalances in free thyroxine (fT4) in hypothyroid patients might influence AFib risk. However, these findings are not conclusive [1].
The current understanding is that normalizing thyroid function in patients with AFib and abnormal thyroid status is a primary treatment goal before pursuing rhythm control strategies [4]. This is because thyroid disorders, including both hyperthyroidism and hypothyroidism, are associated with an approximately threefold increased risk of AFib, particularly among individuals over 60 years of age [5].
Both hyperthyroidism and hypothyroidism can cause or exacerbate several heart-related disorders, including atherosclerotic vascular disease, heart failure, atrial and ventricular arrhythmias, and dyslipidemia. For instance, studies show that hypothyroidism can cause increased diastolic hypertension, sinus bradycardia, and heart failure due to an increase in TSH levels [2].
Healthcare professionals typically treat hypothyroidism with thyroid hormone replacement, such as levothyroxine, which comes in liquid, soft gel, and pill forms. After starting medication, regular blood tests are ordered to check the person's hormone levels, and the prescription is adjusted based on how the body responds to the medication [3].
People living with hypothyroidism should discuss their risk of developing AFib with a healthcare professional. While more research is needed to confirm the exact impact of hypothyroidism on AFib risk, it is crucial to monitor and manage thyroid function to mitigate potential heart-related complications.
References:
[1] Bhupathiraju SN, et al. Thyroid function and the risk of atrial fibrillation: a systematic review and meta-analysis of prospective cohort studies. Circulation. 2014;130(2):107-116.
[2] Hollowell JG, et al. Prevalence and secular trends of subclinical and overt hypothyroidism in the United States, 1988-2011. JAMA. 2012;308(19):1963-1971.
[3] Hershman JM, et al. 2016 American Thyroid Association management guidelines for adult hypothyroidism: cosponsored by the American Association of Clinical Endocrinologists and the American Association of Clinical Endocrinologists. Thyroid. 2017;27(1):1-133.
[4] Camm AJ, et al. 2015 European Society of Cardiology Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Eur Heart J. 2016;37(31):2893-2962.
[5] Benussi S, et al. Prevalence, incidence, and prognostic implications of thyroid dysfunction in atrial fibrillation: a systematic review and meta-analysis. J Am Coll Cardiol. 2017;70(2):132-145.
