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Warfarin Initiation Negatively Linked to Stroke in Atrial Fibrillation Patients

 
FRIDAY, Jan. 3, 2014 (HealthDay News) -- Patients with atrial fibrillation are at higher risk of having a stroke in the first month after initiating treatment with the anti-clotting drug warfarin, according to a study published online Dec. 18 in European Heart Journal.

Noting that previous studies have observed a link between warfarin treatment and stroke among patients with atrial fibrillation, Laurent Azoulay, Ph.D., from McGill University in Montreal, and colleagues analyzed data on stroke incidence in 70,766 adults newly diagnosed with atrial fibrillation. Each case of incident stroke was randomly matched with 10 controls.

During 275,987 person-years of follow-up, the researchers found that 5,519 patients had a stroke. After adjusting for various factors, compared with no use of any antithrombotic therapy for at least one year, the risk of stroke was significantly higher within 30 days of initiating warfarin treatment (relative risk, 1.71). The risk of stroke was lower when warfarin treatment was initiated more than 30 days earlier (relative risks: 0.50 for 31 to 90 days earlier and 0.55 for >90 days earlier).

"Patients initiating warfarin may be at an increased risk of stroke during the first 30 days of treatment, supporting the biological plausibility of a transient hypercoagulable state at the start of the treatment, although additional studies are needed to confirm these findings," Azoulay and colleagues conclude.

The study was funded by Bristol-Myers Squibb and Pfizer. More than one author disclosed financial ties to pharmaceutical companies, including Bristol-Myers Squibb.

Abstract
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Further Reading
Total number of hospitalizations increased by more than 23%, while associated treatment costs rose but mortality declined.
Patients treated with too much or too little warfarin for atrial fibrillation (AF) are significantly more likely to develop dementia than patients who maintain proper medication levels.
Subanalysis of a study comparing warfarin and apixaban in patients with atrial fibrillation found that uncontrolled hypertension increased the risk of stroke or systemic embolism in these patients.
Changes to the recommended use of various medications and catheter ablations rank among the highlights of comprehensive new guidelines for the treatment of patients with atrial fibrillation.
Nearly half of patients treated with warfarin for atrial fibrillation fail to optimally reduce their risk of stroke or bleeding. Physician experience with warfarin therapy plays a major role in successful management.
For older patients with atrial fibrillation starting on warfarin, the rates of hemorrhage are highest within the first 30 days, according to a study published online Nov. 26 in CMAJ, the journal of the Canadian Medical Association.
Although they offer an alternative to warfarin for preventing stroke in patients with atrial fibrillation, effective use of the new anticoagulants requires careful patient selection.
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