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Inadequate use of anticoagulation therapies was common among atrial fibrillation patients who experienced a stroke, according to results from a retrospective, observational study.

Of nearly 95,000 patients with acute ischemic stroke who had a known history of atrial fibrillation (Afib), 84% did not receive guideline-recommended therapeutic anticoagulation before the stroke, wrote , of the Duke University Medical Center, Durham, N.C., and colleagues.

However, therapeutic anticoagulation with warfarin, non-vitamin K antagonist oral anticoagulants (NOACs), or antiplatelet therapy was associated with lower odds of moderate or severe stroke (adjusted odds ratio 0.56, 95% CI 0.51-0.60; adjusted OR 0.65, 95% CI 0.61-0.71; adjusted OR 0.88, 95% CI 0.84-0.92, respectively) and in-hospital mortality (adjusted OR 0.75, 95% CI 0.67-0.85, adjust OR 0.79, 95% CI 0.72-0.88, and adjust OR 0.83, 95% CI 0.78-0.88, respectively), they wrote online in .

"These findings highlight the human costs of atrial fibrillation and the importance of appropriate anticoagulation. Broader adherence to these atrial fibrillation treatment guidelines could substantially reduce both the number and severity of strokes in the U.S.," Xian told 番茄社区.

"Despite numerous international guideline recommendations, many patients fail to receive proper treatment for stroke prevention," he stated.

Xian's group examined data on 94,474 patients (mean age 79.9; 57% women) with acute ischemic stroke and a known history of Afib. All patients were admitted to 1,622 hospitals participating in the (GWTG-Stroke) Registry program, an ongoing national stroke registry and quality improvement initiative sponsored by the American Heart Association and American Stroke Association, from October 2012 to March 2015.

History of Afib or atrial flutter was defined as Afib or atrial flutter known to exist prior to the index acute ischemic stroke admission and documented in the medical record.

Antithrombotic treatments were categorized into five mutually exclusive groups:

• No antithrombotic therapy (none) as the reference
• Antiplatelet therapy only (aspirin, clopidogrel, or dual antiplatelet therapy with aspirin and clopidogrel)
• Subtherapeutic warfarin with an admission international normalized ratio (INR) less than 2
• Therapeutic warfarin with an INR of 2 or higher
• NOACs (dabigatran, rivaroxaban, or apixaban)

Multivariable logistic regression models were used to investigate the relationships between preceding antithrombotic therapies with stroke severity at admission, in-hospital mortality, and mRS score at discharge.

Xian's group found that 7,176 (7.6%) patients received therapeutic warfarin (INR 2) and 8,290 (8.8%) received NOACs preceding the stroke.

A total of 79,008 patients (83.6%) didn't receive therapeutic anticoagulation: 12,751 (13.5%) had subtherapeutic warfarin anticoagulation (INR<2) at the time of stroke, 37,674 (39.9%) received antiplatelet therapy only, and 28,583 (30.3%) didn't receive any antithrombotic treatment.

The unadjusted rates of moderate or severe stroke were lower among patients receiving therapeutic warfarin (15.8, 95% CI 14.8%-16.7%) and NOACs (17.5%, 95% CI 16.6%-18.4%) compared with those receiving no antithrombotic therapy (27.1%, 95% CI 26.6%-27.7%), only antiplatelet therapy (24.8%, 95% CI 24.3%-25.3%), or subtherapeutic warfarin (25.8%, 95% CI 25.0%-26.6%).

Additionally, unadjusted rates of in-hospital mortality also were lower for those receiving therapeutic warfarin (6.4%, 95% CI 5.8%-7.0%) and NOACs (6.3%, 95% CI 5.7%-6.8%) compared with those receiving no antithrombotic therapy (9.3%, 95% CI 8.9%-9.6%), only antiplatelet therapy (8.1%, 95% CI 7.8%8.3%), or subtherapeutic warfarin (8.8%, 95% CI 8.3%-9.3%]), the researchers reported.

Xian's group also reviewed documented reasons for not having oral anticoagulation at discharge. The most common reasons included risk of bleeding (16.3%), risk of falls (10.3%), terminal illness (6.2%), patient or family refusal (4.3%), mental status (1.1%), medication adverse effects (1.0%), or allergy (0.6%). Nearly 66% did not have a documented reason for not receiving oral anticoagulation.

The researchers concluded that although Afib is a highly treatable risk factor for stroke, many patients still fail to receive proper treatment for stroke prevention.

"We estimate that between 58,000 to 88,000 strokes might be preventable per year if the treatment guidelines are followed appropriately. These findings highlight huge missed opportunities for stroke prevention and provide compelling evidence to promote quality improvement efforts to optimize care and outcomes in high-risk AF patients," Xian explained to 番茄社区.

Study limitations included its retrospective, observational nature, which may have allowed for treatment selection and unmeasured confounding. Additionally, Afib patients who were treated with different antithrombotic regimens, and did not have a stroke, were not included in the registry.

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