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Anticoagulation benefit varies in hyperthyroidism-related AF based on stroke-risk score
Substantial risk for ischemic stroke exists for patients with hyperthyroidism-related atrial fibrillation, with the exception of those with a CHA2DS2-VASc score of 0 who have a risk on par with nonthyroid atrial fibrillation, according to research published in Clinical Cardiology.
Warfarin therapy appears to improve stroke prevention in patients with a CHA2DS2-VASc score of at least 1 and non–self-limiting AF, results from a single-center observational study of Chinese patients showed; however, this was not seen in self-limiting AF.
“Although current international guidelines based on well-validated risk scores for ischemic stroke and bleeding recommend long-term oral anticoagulation for AF patients with CHA2DS2-VASc score … ≥ 1, there is much less consensus on the need for anticoagulation in patients with hyperthyroidism-related AF,” the researchers wrote.
Pak-Hei Chan, MBBS, of Queen Mary Hospital, University of Hong Kong, Hong Kong Special Administrative Region, China, and colleagues studied 9,727 Chinese patients with nonvalvular AF from July 1997 to December 2011; 642 (6.6%) were concurrently diagnosed with hyperthyroidism.
The investigators recorded patient characteristics, AF duration and type of antithrombotic therapy; self-limiting AF was defined by a duration of less than 7 days. To prevent stroke, 136 patients (21.1%) were treated with warfarin and 243 patients (37.9%) with aspirin; the remaining patients (41%) received no treatment. The main outcomes sought were hospitalization with ischemic stroke and intracranial hemorrhage in the first 2 years.
Fifty patients (7.8%) experienced ischemic stroke, and none experienced hemorrhagic stroke. Further, there were no patients with CHA2DS2-VASc score of 0 among those who had ischemic stroke.
Compared with aspirin or no treatment, warfarin lowered the rate of stroke in patients with a CHA2DS2-VASc score of at least 1 and non–self-limiting AF, but not in those with self-limiting AF or a CHA2DS2-VASc score of 0.
No additional ischemic stroke risk was observed among patients with hyperthyroid-related vs. non–thyroid-related arrhythmia.
“The threshold to initiate anticoagulation therapy … as recommended by current guidelines seems appropriate in patients with hyperthyroidism-related AF,” the researchers wrote. “Transient, self-limiting AF during the early phase of hyperthyroidism may not impose additional risk of ischemic stroke … thus long-term warfarin therapy may not be necessary.” – by Allegra Tiver
Disclosure: Chan reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.