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


OBJECTIVE
This study sought to investigate the clinical outcome of hyperthyroidism-induced AF with regard to risk of ischemic stroke risk.


METHODS
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).


RESULTS
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).


CONCLUSIONS
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.
Siu
Chung-Wah
CW
Cardiology Division, Department of Medicine, Queen Mary Hospital, the University of Hong Kong, Hong Kong SAR, China.
Pong
Vincent
V
Zhang
Xuehua
X
Chan
Yap-Hang
YH
Jim
Man-Hong
MH
Liu
Shasha
S
Yiu
Kai-Hang
KH
Kung
Annie W C
AW
Lau
Chu-Pak
CP
Tse
Hung-Fat
HF
D000328:Adult; D001281:Atrial Fibrillation / Q000150:complications*; D002545:Brain Ischemia / Q000453:epidemiology / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk