Abstract
Background:Patients with hyperthyroidism have higher risk of atrial fibrillation (AF). However, the risk of thromboembolic event in patients with hyperthyroidism-related AF is controversial.Objectives:The aim of the study was to examine the risk of thromboembolic events in AF patients with/without hyperthyroidism.Methods: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 CHA2DS2-VASc level was treated as a stratum variable. The outcomes were ischemic stroke and systemic thromboembolism.Results: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 CHA2DS2-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).Conclusion:Patients with HT AF had lower incidence of thromboembolic events as compared to non-thyroid AF patients. The threshold of CHA2DS2-VASc score for anticoagulation in AF patients with clinical hyperthyroidism should be further evaluated.HighlightsThe incidence of thromboembolic event was different between hyperthyroidism-related atrial fibrillation (HT-AF) and non-thyroid AF patients.Hyperthyroidism did not confer additional risk of thromboembolic event at CHA2DS2-VASc of ≤ 4.The benefit of anticoagulation strategy in patients with hyperthyroidism-related AF should be further evaluated, especially at low CHA2DS2-VASc score.
Highlights
Atrial fibrillation (AF) is a complication of hyperthyroidism [1, 2], and up to 13% of patients with new-onset atrial fibrillation (AF) have biochemical evidence of hyperthyroidism [3]
The CHA2DS2-VASc score is used to predict the risk of stroke/systemic embolism in non-valvular AF patients: Anticoagulation therapy is recommended in patients at CHA2DS2-VASc score ≥ 2 [8]
When the incidence of thromboembolic events were assessed separately, the incidence of ischemic stroke was lower in the HT AF group than in the non-thyroid AF group (1.4 versus 1.8 events per 100 person-years; HR, 0.74; 95% CI, 0.64–0.84) (Figure 2B), and the trend was the same in the comparison of systemic thromboembolism (0.3 versus 0.5 events per 100 personyears; HR, 0.71; 95% CI, 0.55–0.93) (Figure 2C)
Summary
Atrial fibrillation (AF) is a complication of hyperthyroidism [1, 2], and up to 13% of patients with new-onset AF have biochemical evidence of hyperthyroidism [3]. A few studies have reported that individuals with hyperthyroid AF have a higher risk of stroke than those with non-thyroid AF [5, 9, 10]. 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 personyears; 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. 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 CHA2DS2-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). The threshold of CHA2DS2-VASc score for anticoagulation in AF patients with clinical hyperthyroidism should be further evaluated
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