We have known for a long time that atrial fibrillation, a common heart rhythm disorder, is a risk factor for having a stroke. We have also known that anticoagulation therapy can prevent strokes in people with atrial fibrillation. So, the results of a study by researchers at the Duke Clinical Research Institute published in the March 14 issue of the Journal of the American Medical Association should shock all of us who believe in evidence-based medicine:

More than 80% of stroke patients with a history of atrial fibrillation either got no anticoagulation therapy or received too little prior to having a stroke, despite the drugs’ proven record of reducing stroke risk.

The study’s lead author Ying Xian, M.D., Ph.D., assistant professor of neurology at Duke and member of the Duke Clinical Research Institute, also pointed out that “in those rare cases where anticoagulation failed to prevent a stroke, patients who were taking the therapy showed a tendency to have less severe strokes, with less disability and death.


Get with the guidelines

The study included more than 94,000 patients with atrial fibrillation from the American Heart Association’s “Get With The Guidelines-Stroke” registry who had had an acute ischemic stroke. Only 16% of patients with atrial fibrillation had received the recommended anticoagulation medication prior to having a stroke. These medications include therapeutic levels of warfarin or a non-vitamin K antagonist oral anticoagulant (NOAC).

According to Xian,

“Treatment guidelines call for these patients to receive an anticoagulant such as warfarin at a therapeutic dose or a non-vitamin K antagonist oral anticoagulant (NOAC), so it’s surprising that this is not occurring in the vast majority of cases that occur in community settings.”

A total of 84% of patients were not treated according to the guidelines prior to their stroke:

  • 30% were not taking any antithrombotic treatment at all;
  • 40% were taking an antiplatelet drug such as baby aspirin or clopidogrel;
  • 13.5% percent were on warfarin, but at a level that was not considered therapeutic at the time of their stroke.

Xian notes that some of these patients may have had medical reasons that made it too risky to prescribe anticoagulants, like a high risk of bleeding or falls. However, he says, “more than two-thirds had no documented reason for receiving inadequate stroke prevention therapy.

His conclusion:

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. We estimate that between 58,000 to 88,000 strokes might be preventable per year if the treatment guidelines are followed appropriately.

The analysis was sponsored by the Patient-Centered Outcomes Research Institute to inform patients, physicians, and others about optimal stroke care.


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