Abstract
Painless thyroiditis is a variant of thyroiditis without the typical neck pain and is otherwise similar to subacute thyroiditis, which is a known post-viral condition and has been associated with coronavirus disease 2019 (COVID-19) infections. While it is usually self-limiting, it can lead to thyrotoxicosis that can predispose individuals to cardiac dysrhythmias, including atrial fibrillation. There has been a clear association between COVID-19 and subacute thyroiditis with a few case reports describing atrial fibrillation. We present a case of a healthy patient with new-onset atrial fibrillation secondary to painless thyroiditis. This report highlights the rare entity of painless thyroiditis leading to atrial fibrillation with rapid ventricular response in a patient who recently recovered from COVID-19. Physicians should consider the potential association of painless thyroiditis in patients with new-onset atrial fibrillation who recently recovered from COVID-19.