Risk of ischemic stroke after new-onset atrial fibrillation in patients with hyperthyroidism

• Published in: Heart rhythm Vol. 6; no. 2; p. 169
• Main Authors: Siu, Chung-Wah, Pong, Vincent, Zhang, Xuehua, Chan, Yap-Hang, Jim, Man-Hong, Liu, Shasha, Yiu, Kai-Hang, Kung, Annie W C, Lau, Chu-Pak, Tse, Hung-Fat
• Format: Journal Article
• Language: English
• Published: United States 01.02.2009
• Subjects: Adult; Atrial Fibrillation - complications; Brain Ischemia - epidemiology; Brain Ischemia - etiology; Case-Control Studies; Female; Humans; Hyperthyroidism - complications; Incidence; Male; Middle Aged; Proportional Hazards Models; Prospective Studies; Risk
• ISSN: 1556-3871
• DOI: 10.1016/j.hrthm.2008.10.023

Hyperthyroidism is one of the most common reversible causes of atrial fibrillation (AF); nevertheless, the risk of ischemic stroke in patients with hyperthyroidism who present with new-onset AF is unclear. This study sought to investigate the clinical outcome of hyperthyroidism-induced AF with regard to risk of ischemic stroke risk. We prospectively studied the incidence, time course, and clinical predictors for ischemic stroke in patients with hyperthyroidism-induced AF (n = 160). They were compared with age- and sex-matched cohorts of hyperthyroid patients without AF (n = 160) and AF patients without hyperthyroidism (n = 160). Baseline characteristics were comparable among the 3 groups. At 1 year, 86 hyperthyroid patients with AF (54%) and 92 patients with nonthyroid AF (58%) had spontaneous or pharmacological sinus conversion (P = .20). Ischemic stroke was observed in 15 hyperthyroid patients with AF (9.4%) versus 5 patients with nonthyroid AF (3.1%, P = .02), and 1 hyperthyroid patient without AF (0.6%, P < .001). Furthermore, the majority of ischemic stroke (>70%) in patients with AF occurred within the first 30 days of presentation, whereas AF was still present. Cox regression analysis showed that hyperthyroidism (hazard ratio [HR]: 3.5, 95% confidence interval [CI]: 1.15 to 10.42, P = .03) and persistent AF (HR: 13.0, 95% CI: 2.88 to 58.80, P < .01) predicted the occurrence of ischemic stroke; warfarin therapy reduced the risk of ischemic stroke (HR: 0.17, 95% CI: 0.04 to 0.79, P = .02). In hyperthyroid patients who presented with new-onset AF, there was an increased risk of ischemic stroke clustering during the initial phase of presentation. This should prompt early use of anticoagulation therapy in hyperthyroid patients with AF.