New AAN Guidelines on Stroke Prevention in AF

February 24, 2014

The American Academy of Neurology has issued new guidelines on the prevention of stroke in patients with nonvalvular atrial fibrillation (NVAF).

The guidelines, published in the February 25 issue of Neurology, have particular emphasis on clinical judgment, lead author, Antonio Culebras, MD, from SUNY Upstate Medical University, Syracuse, New York, commented to Medscape Medical News.

"We may possibly make less strong recommendations on the use of oral anticoagulants compared to other AF guidelines," he added. "While we do strongly encourage the use of oral anticoagulants we still want physicians to use their clinical judgement so we give level B recommendations rather than level A. We prefer to issue recommendations rather than commandments."

The guidelines also break with convention in recommending anticoagulation for the elderly, even in those prone to falling or who have dementia.

Dr. Culebras noted that the guidelines, which he describes as "shorter and crisper" than some others, are written for the perspective of the clinical neurologist, but they will also be of interest to cardiologists, internists, primary care doctors, and nurse practitioners. "These guidelines are based on evidence from clinical trials in each area. We did not include opinion or review type articles."

Whom to Treat?

On treatment with antithrombotic medication, the guidelines make the following recommendations:

Level B:

  • Patients with NVAF should be counseled that the decision to use antithrombotics must be made only after the potential benefit from the stroke risk reduction has been weighed against the potential harm from the increased risk for major bleeding, and clinicians should emphasize the important role of judgment and preferences in this decision.

  • Clinicians should routinely offer anticoagulation to patients with NVAF and a history of transient ischemic attack or stroke.

  • Clinicians should use a risk-stratification scheme to inform their judgment as to which patients with NVAF might benefit more from anticoagulation, but they should not rigidly interpret anticoagulation thresholds suggested by these tools as being definitive indicators of which patients require anticoagulation.

Level C:

  • Clinicians might not offer anticoagulation to patients with NVAF who lack additional risk factors. These patients might reasonably be offered aspirin or no antithrombotic therapy at all.

Which Anticoagulant?

On which anticoagulant to select, the guidelines make the following recommendations:

Level B:

  • For patients at higher risk for intracranial bleeding, clinicians should administer dabigatran, rivaroxaban, or apixaban to patients who require anticoagulant, as they have a lower risk for intracranial bleeding compared with warfarin.

  • Clinicians should offer dabigatran, rivaroxaban, or apixaban to patients unwilling or unable to submit to frequent periodic international normalized ratio (INR) testing.

Level C:

  • For patients already taking warfarin who are well controlled, clinicians might recommend continuation of warfarin treatment rather than switch to treatment with a new oral anticoagulant.

  • For patients at increased gastrointestinal bleeding risk who require anticoagulation, clinicians might offer apixaban.

For patients unsuitable for warfarin, apixaban is the first choice, then one of the other new anticoagulants (Level B). If none of these new drugs are available, then a combination of aspirin and clopidogrel could be used (Level C).

Anticoagulation Recommended for the Oldest Old

What may also be different from other guidelines on the same subject are some specific recommendations for special groups. For example, the guidelines come out in favor of treatment with anticoagulants for the elderly who may be prone to falling.

"The conventional approach is to take these patients off anticoagulants because of the risk of bleeding if they fall, but the risk of AF and stroke increases with age and this is precisely the population who need these medications," Dr. Culebras commented. He cites one study that suggests that a patient would have to fall 295 times per year to cancel out the stroke prevention benefit of taking anticoagulants.

For the elderly, the guidelines state:

Level B:

  • Clinicians should routinely offer oral anticoagulants to elderly patients (aged > 75 years) with NVAF if there is no history of recent unprovoked bleeding or intracranial hemorrhage.

  • Clinicians might offer oral anticoagulation to patients with NVAF who have dementia or occasional falls. However, clinicians should counsel patients or their families that the risk-benefit ratio of oral anticoagulants is uncertain in patients with NVAF who have moderate-to-severe dementia or very frequent falls.

Specific Advice for Developing Countries

Dr. Culebras also emphasized the global reach of the American Academy of Neurology, so these guidelines have included treatment of NVAF in developing countries where the new oral anti-coagulants may not be available or affordable.

For these countries, they recommend the use of a combination of triflusal and acenocoumarol, which Dr. Culebras said was available in most developing countries and its use as recommended is supported by a high-quality conducted study.

The recommendation for patients in the developing world is:

Level B:

  • For patients at moderate stroke risk, the combination of triflusal 600 mg/day plus moderate-intensity anticoagulation (INR 1.25–2.0) with acenocoumarol is likely more effective than acenocoumarol alone at the higher INR (2.0-3.0) for reducing stroke risk.

Outpatient Monitoring for AF

On screening for AF, the guidelines recommend longer-term monitoring in patients with cryptogenic stroke. The recommendation is:

Level C:

  • For patients who have suffered a cryptogenic stroke without known AF, clinicians might obtain cardiac rhythm studies for prolonged periods (eg, for one or more weeks) instead of shorter periods (eg, 24 hours).

Dr. Culebras told Medscape Medical News that the guidelines were formulated on the basis of small studies showing suggestive evidence in favor of monitoring for longer periods. But the CRYSTAL-AF study, presented at the recent American Stroke Association International Stroke Conference last week and reported by Medscape Medical News at that time, shows this much more clearly.

"These results were not available when we reviewed the literature so we could not give a level A or B recommendation. But if they had been available, the current level C recommendation would have definitely been upgraded," he said.

Neurol. 2014;82:716-724. Abstract.

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