Benefit of Anticoagulation Therapy in Hyperthyroidism‐Related Atrial Fibrillation

Abstract

Background: Existing data on the risk of ischemic stroke in hyperthyroidism-related atrial fibrillation (AF) and the impact of long-term anticoagulation in these patients, particularly those with self-limiting AF, remain inconclusive. Hypothesis: Risk of stroke in hyperthyroidism-related AF is the same as nonhyperthyroid counterparts. Methods: This was a single-center observational study of 9727 Chinese patients with nonvalvular AF from July 1997 to December 2011. Patients with AF diagnosed concomitantly with hyperthyroidism were identified. Primary and secondary endpoints were defined as hospitalization with ischemic stroke and intracranial hemorrhage in the first 2 years. Patient characteristics, duration of AF, and choice of antithrombotic therapy were recorded. Self-limiting AF was defined as <7 days' duration. Results: Out of 9727 patients, 642 (6.6%) had concomitant hyperthyroidism and AF at diagnosis. For stroke prevention, 136 and 243 patients (21.1% and 37.9%) were prescribed warfarin and aspirin, respectively, whereas the remaining patients (41.0%) received no therapy. Ischemic stroke occurred in 50 patients (7.8%), and no patient developed hemorrhagic stroke. Patients with CHA 2 DS 2 -VASc of 0 did not develop stroke. Warfarin effectively reduced the incidence of stroke compared with aspirin or no therapy in patients with CHA 2 DS 2 -VASc ≥1 and non-self-limiting AF, but not in those with self-limiting AF or CHA 2 DS 2 -VASc of 0. Presence of hyperthyroidism did not confer additional risk of ischemic stroke compared with nonhyperthyroid AF. Conclusions: Patients with hyperthyroidism-related AF are at high risk of stroke (3.9% per year). Warfarin confers stroke prevention in patients with CHA 2 DS 2 -VASc ≥1 and non-self-limiting AF. Overall stroke risk was lower in hyperthyroid non-self-limiting AF patients compared with nonhyperthyroid counterparts.

Atrial fibrillation and hyperthyroidism: A literature review

“… 30 In a large recent trial conducted in China by Chan et al, of 9727 Chinese patients with nonvalvular AF from July 1997 to December 2011, hyperthyroidism with atrial fibrillation was not known to independently increase the risk of thrombotic events with the risk for thrombosis based of the traditional risk factors outlined in the CHA2DS2-VASC score. 31 Two major recommendations are present regarding anticoagulation in those with atrial fibrillation and hyperthyroidism. As per the American College of Chest Physicians, hyperthyroidism was not found to be an independent risk factor of thrombosis in those with atrial fibrillation and anticoagulation should be based of the traditional CHA2DS2-VASC score.…”

“…As per the American College of Chest Physicians, hyperthyroidism was not found to be an independent risk factor of thrombosis in those with atrial fibrillation and anticoagulation should be based of the traditional CHA2DS2-VASC score. 31 , 32 According to the American College of Cardiology however, hyperthyroidism independently increases the risk for development of stroke or thrombosis and patients should receive anticoagulation during the hyperthyroid phase regardless of CHA2DS2-VASC score. 33 In a study performed by de Souza and colleagues, in patients with hyperthyroidism and atrial fibrillation, a traditional CHADS2 score was used to predict who would benefit from anticoagulation with a subsequent TEE performed to assess the efficacy of the score in identifying possible thrombogenic milieu.…”

Thyrotoxic Atrial Fibrillation: Factors Associated with Persistence and Risk of Ischemic Stroke

“…The same investigation group also recently reported a beneficial effect of anticoagulation (in terms of ischemic stroke free survival) for those who had persistent atrial fibrillation and a CHA 2 DS 2 -VASc score equal to or more than 1 in 642 patients who had concomitant hyperthyroidism and atrial fibrillation. On the contrary, the same effect was not observed in those who had self-limiting atrial fibrillation [ 13 ].…”

Bleeding heart: a case of spontaneous hemopericardium and tamponade in a hyperthyroid patient on warfarin

“…The patient's hyperthyroid state was another factor which had earlier inclined us to pursue anticoagulation. However, a closer look at the literature reveals that even though data regarding the relative risk of stroke in hyperthyroidism-related atrial fibrillation were conflicting in the past, two recent studies show that hyperthyroidism is not an independent risk factor for stroke in atrial fibrillation 25 26. In fact, hyperthyroidism increases the bleeding risk associated with vitamin K antagonists 27.…”