Risk of Thromboembolism in Non-Valvular Atrial Fibrillation With or Without Clinical Hyperthyroidism
Yu‐Sheng Lin, Hsin-Yu Tsai, Chia-Ying Lin, Victor Chien‐Chia Wu, Tien‐Hsing Chen, Teng‐Yao Yang, Victor Aboyans, Mien‐Cheng Chen
Abstract
<strong>Background:</strong> Patients with hyperthyroidism have higher risk of atrial fibrillation (AF). However, the risk of thromboembolic event in patients with hyperthyroidism-related AF is controversial. <strong>Objectives:</strong> The aim of the study was to examine the risk of thromboembolic events in AF patients with/without hyperthyroidism. <strong>Methods:</strong> The national retrospective cohort study enrolled AF population was derived from the Taiwan National Health Insurance Research Database. The comparison between the AF patients with clinical hyperthyroidism (HT-AF group) and AF patients without hyperthyroidism (non-thyroid AF group) was made in a propensity score matched cohort and in a real-world setting, of which, the CHA<sub>2</sub>DS<sub>2</sub>-VASc level was treated as a stratum variable. The outcomes were ischemic stroke and systemic thromboembolism. <strong>Results:</strong> There were 3,880 patients in HT AF group and 178,711 in non-thyroid AF group. After propensity score analysis, the incidence of thromboembolism event and ischemic stroke were lower in HT AF patients than non-thyroid AF patients (1.6 versus 2.2 events per 100 person-years; HR, 0.73; 95% CI, 0.64–0.82 and 1.4 versus 1.8 events per 100 person-years; HR, 0.74; 95% CI, 0.64–0.84, respectively) in the 4.3 ± 3.2 year follow up period. The differences persistently existed in those receiving anticoagulants or not. In AF patients without anticoagulants, the incidence densities of ischemic stroke/systemic thromboembolism were significantly lower in HT AF group than those in non-thyroid AF group at CHA<sub>2</sub>DS<sub>2</sub>-VASc scores ≤ 4 (HR, 0.41; 95% CI, 0.35–0.48, p < 0.001), while the differences disappeared in case of score ≥ 5 (HR, 0.80; 95% CI, 0.63–1.02, p = 0.071). <strong>Conclusion:</strong> Patients with HT AF had lower incidence of thromboembolic events as compared to non-thyroid AF patients. The threshold of CHA<sub>2</sub>DS<sub>2</sub>-VASc score for anticoagulation in AF patients with clinical hyperthyroidism should be further evaluated. <strong>Highlights</strong> <ul><li>The incidence of thromboembolic event was different between hyperthyroidism-related atrial fibrillation (HT-AF) and non-thyroid AF patients.</li><li>Hyperthyroidism did not confer additional risk of thromboembolic event at CHA<sub>2</sub>DS<sub>2</sub>-VASc of ≤ 4.</li><li>The benefit of anticoagulation strategy in patients with hyperthyroidism-related AF should be further evaluated, especially at low CHA<sub>2</sub>DS<sub>2</sub>-VASc score.</li></ul>