Incidence, Risk Factors, and Outcomes of Incident Atrial Fibrillation in Patients With Graves Disease

Objective: To describe the incidence, risk factors, and outcomes of incident atrial fibrillation (AF) in Graves disease (GD). Patients and Methods: Patients with GD between January 1, 2009, and December 31, 2019, were included retrospectively. We defined GD-related AF as AF diagnosed less than or equal to 30 days before or any time after GD. Late-onset AF was defined as incident AF diagnosed more than 90 days after GD. Results: Of 1371 patients with GD, AF occurred in 139 patients. Late-onset AF occurred in 32 (23.0%) of AF cases, of which 16 (50.0%) had attained euthyroidism. Independent risk factors were age (HR, 1.05; 95% CI, 1.03-1.06 per year), overt hyperthyroidism (free T4 >1.7 ng/dL; HR, 2.75; 95% CI, 1.38 to 5.46), and male sex (HR, 2.30; 95% CI, 1.54 to 3.43) for early AF. These were age (HR, 1.08; 95% CI, 1.05 to 1.119 per year), chronic obstructive pulmonary disease (HR, 3.47; 95% CI, 1.36 to 5.54), and heart failure (HR, 5.86; 95% CI, 2.39 to 14.38) for late AF. Atrial fibrillation in GD was associated with higher mortality (HR, 16.32; 95% CI, 4.66 to 56.58), acute coronary syndrome/stable angina events (HR, 3.89; 95% CI, 1.23 to 12.31), and cardiac hospitalizations (HR, 15.39; 95% CI, 8.17 to 29.00) when adjusted to age, sex, and pre-existing AF. Conclusion: Late-onset AF comprised one-quarter of GD-related AF cases requiring surveillance even after restoring euthyroidism. Risk factors for AF in GD are similar to those in the general population although overt hyperthyroidism conferred the highest risk, especially for early AF. Treatment with thionamide was associated with late AF.