Prognostic Significance of Thyroid Disease in Atrial Fibrillation

Background Thyroid disease (THD) has often been associated with atrial fibrillation (AF) triggering, through endocrine mechanisms. Still, data on the impact of hypothyroidism on AF are contradictory. Our aim was to correlate the THD profile with the incidence of hard clinical endpoints in AF patients. Methods This post- hoc analysis of the MISOAC-AF RCT included hospitalized patients with AF and available history of THD. Patients were classified by categories of thyroid disease history (hyperthyroidism, hypothyroidism, euthyroidism). Unadjusted and adjusted hazard ratios (aHRs) were calculated using Cox regression models. Comparison groups included euthyroid compared to hypothyroid and hyperthyroid AF patients, respectively. All-cause mortality, cardiovascular death (CVD) and hospitalizations were the outcomes of interest. Survival analysis with the Kaplan-Meier curves was performed to analyze time-to-event data. Results A total of 496 AF patients followed-up for a mean of 2.7 years period, had available THD history and were included in the study. Of them, 16 patients (3.2%) were hyperthyroid, 141 (28.4%) hypothyroid, and 339 (68.4%) euthyroid. Patients with hypothyroidism had higher hospitalization rates during follow-up (aHR: 1.57, 95% CI: 1.12 to 2.20, p=0.008, p=0.025) compared to the euthyroid group. Higher TSH levels were correlated with an increased risk of CVD (aHR: 1.03, 95%CI: 1.01 to 1.05, p=0.007) and hospitalizations (aHR: 1.06, 95%CI: 1.01 to 1.12, p=0.03), while lower T3 levels were correlated with higher all-cause mortality rates (aHR: 0.51, 95%CI: 0.31 to 0.82, p=0.006) and CVD risk (aHR: 0.42, 95%CI: 0.23 to 0.77, p=0.005). Conclusions In AF patients, hypothyroidism was associated with increased hospitalizations, while elevated TSH levels and decreased T3 levels were associated with increased CVD and all-cause mortality respectively.Hypothyroidism and clinical outcomes