Conference Coverage

Aspirin May Not Prevent Stroke in Patients With Atrial Fibrillation


 

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SNOWMASS, CO—Aspirin should no longer be prescribed for stroke prevention in patients with atrial fibrillation and a CHA2DS2-VASc score of 1, according to a presentation given at the Annual Cardiovascular Conference at Snowmass.

“The European guidelines have done away with aspirin for stroke prevention in atrial fibrillation. It barely made it into our current US guidelines. I don’t think aspirin should be in there and I don’t think it will be there in the next guidelines. The role of aspirin will fall away,” said Bernard J. Gersh, MB, ChB, DPhil, Professor of Medicine at the Mayo Clinic in Rochester, Minnesota. “It’s not that aspirin is less effective than the oral anticoagulants, it’s that there’s no role for it. There are no good data to support aspirin in the prevention of stroke in atrial fibrillation.”

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Bernard J. Gersh, MB, ChB, DPhil

Questions About SPAF Data

“The use of aspirin has probably been misguided, based upon a single trial which showed a profound effect and was probably just an anomaly,” said N.A. Mark Estes III, MD, Professor of Medicine and Director of the New England Cardiac Arrhythmia Center at Tufts University in Boston, and a past president of the Heart Rhythm Society.

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N.A. Mark Estes III, MD

The sole positive clinical trial of aspirin versus placebo, the 25-year-old Stroke Prevention in Atrial Fibrillation (SPAF) study, found an unusually high stroke protection benefit for aspirin, a result made implausible by multiple other randomized trials that showed no benefit, said the cardiologists.

“In our current guidelines for atrial fibrillation, aspirin can be considered as a Class IIb, level of evidence C recommendation in patients with a CHA2DS2-VASc of 1. But I would just take it off of your clinical armamentarium because the best available data indicate that it doesn’t prevent strokes. I’m certainly not using it in my patients. Increasingly in my patients with a CHA2DS2-VASc of 1, I’m discussing the risks and benefits of a novel oral anticoagulant,” said Dr. Estes.

Dual Therapy Entails Risks

Dr. Gersh criticized another common practice in stroke prevention in atrial fibrillation: concomitant use of aspirin with an oral anticoagulant. “We use too much aspirin in patients on oral anticoagulation. Aspirin is perhaps the major cause of bleeding in patients on an oral anticoagulant. Other than in people with a drug-eluting stent, there’s no role at all for aspirin in stroke prevention,” he asserted.

Dr. Gersh coauthored an analysis of 7,347 participants in the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF) who were on an oral anticoagulant. Approximately 35% of participants were also taking aspirin. In a multivariate analysis, concomitant aspirin and oral anticoagulation were independently associated with a 53% increased risk of major bleeding and a 52% increase in hospitalization for bleeding, compared with an oral anticoagulant alone, in patients with atrial fibrillation.

Moreover, the widespread use of dual therapy in this real-world registry did not always appear to be justified. Thirty-nine percent of participants on aspirin plus an oral anticoagulant had no history of atherosclerotic disease, the presence of which would be an indication for considering aspirin. And 17% of patients on dual therapy had an elevated Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) risk score of 5 or more, which generally indicates that dual therapy is risky.

This clinically important interaction between aspirin and oral anticoagulation was recently underscored in an analysis of rivaroxaban-treated patients in the ROCKET AF trial, Dr. Gersh observed. Long-term use of aspirin at entry into this pivotal randomized trial of rivaroxaban versus warfarin in patients with atrial fibrillation proved to be an independent predictor of a 47% increase in the risk of gastrointestinal bleeding, compared with use of rivaroxaban alone.

No evidence indicates that combining aspirin and oral anticoagulation enhances stroke prevention beyond the marked benefit achieved with oral anticoagulation alone, Dr. Gersh concluded.

Bruce Jancin

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