January 4, 2022Open Access
Challenges in the Management of Atrial Fibrillation With Subclinical Hyperthyroidism
Key Result
Subclinical hyperthyroidism is associated with an increased risk of incident atrial fibrillation (HR 1.68) compared to euthyroidism.
Structured PICO
P
Population
Patients with atrial fibrillation and subclinical hyperthyroidism
I
Intervention
Management strategies including screening, rate/rhythm control, and anti-thyroid treatment
This review highlights the association between subclinical hyperthyroidism and atrial fibrillation, emphasizing the need for TSH screening in new-onset AF and considering anti-thyroid treatment in high-risk patients to prevent AF complications.
Limitations
- Lack of large randomized controlled trials for the treatment of subclinical hyperthyroidism.
- Most human studies on the topic have been observational or small physiological studies.
- Previous randomized controlled trials failed to recruit enough participants.
Abstract
Subclinical thyroid disorders have a high prevalence among older individuals and women. Subclinical hypothyroidism is diagnosed by elevated serum levels of thyroid-stimulating hormone (TSH) with thyroxine levels within the reference range, and subclinical hyperthyroidism is diagnosed by low TSH in conjunction with thyroxine and triiodothyronine levels within reference ranges. Atrial fibrillation is the most commonly diagnosed cardiac arrhythmia and has been associated with an increased risk of mortality, heart failure, stroke, and depression. Mechanistic data from animal and human physiology studies as well as observational data in humans support an association of subclinical hyperthyroidism with atrial fibrillation. Guidelines recommend the measurement of TSH in the evaluation of new-onset atrial fibrillation. All patients with overt hyperthyroidism should be treated, and treatment of subclinical hyperthyroidism should be considered in patients older than 65 years with TSH < 0.4 mlU/L, or in younger patients with TSH < 0.1 mlU/L. Guidelines also recommend screening for AF in patients with known hyperthyroidism. Wearable devices that measure the heart electrical activity continuously may be a novel strategy to detect atrial fibrillation in patients at risk. In this review, we explore the interplay between thyroid hormones and atrial fibrillation, management controversies in subclinical hyperthyroidism, and potential strategies to improve the management of atrial fibrillation in patients with subclinical hyperthyroidism.