Moving Beyond Aspirin for Atrial Fibrillation

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The MD Magazine Peer Exchange “Novel Anticoagulation Options: Target-Specific Oral Agents and Their Antidotes” features leading physician specialists discussing key topics in anticoagulation therapy, including the clinical characteristics of current and emerging agents and criteria for use in specific patient populations.

This Peer Exchange is moderated by Peter Salgo, MD, professor of medicine and anesthesiology at Columbia University and an associate director of surgical intensive care at the New York-Presbyterian Hospital in New York City.

The panelists are:

• Scott Kaatz, DO, MSc, Chief Quality Officer at Hurley Medical Center in Flint, Michigan, and clinical associate professor at Michigan State University
• Seth Bilazarian, MD, clinical and interventional cardiologist at Pentucket Medical and instructor of medicine at Harvard Medical School
• Gerald Naccarelli, MD, Bernard Trabin Chair in Cardiology, professor of medicine and chief of the Division of Cardiology at Penn State University School of Medicine, and associate clinical director at Penn State Heart and Vascular Institute in Hershey, Pennsylvania
• Christian T. Ruff, MD, associate physician in the cardiovascular medicine division at Brigham and Women’s Hospital, and assistant professor of medicine at Harvard Medical School in Boston

In this segment of the Peer Exchange, the panelists discuss the use of warfarin, aspirin, and newer anticoagulants in patients with valvular disease, atrial fibrillation, and venous thromboembolic disease.

In terms of what anticoagulation therapy is for and which patients will require it, Dr. Kaatz noted that typically in an anticoagulation clinic, 15 percent of the patients will have valvular disease, 50-6- percent of patients with have atrial fibrillation, and 30-40 percent of patients will have venous thromboembolic disease, both in the acute phase and then in the extended phase.

As our population ages, atrial fibrillation is becoming more prevalent, underscoring the need for more effective therapies. Dr. Ruff said warfarin is “one of the most difficult and potentially dangerous drugs we use in clinical practice” in patients with atrial fibrillation, with aspirin used for a long time as a second option in patients who cannot tolerate warfarin.

However, emerging data has shown that aspirin “is much less effective for stroke prevention than we thought it was. So, when a patient has atrial fibrillation, if you want to reduce strokes, you need to use an anticoagulant, and aspirin has really fallen out of favor for that,” said Dr. Ruff.

Dr. Kaatz agreed that aspirin only “works a little bit, and the anticoagulants work a lot better” in these patients. He also said that several old head-to-head trials and systematic reviews comparing aspirin and warfarin have given clinicians a fairly good picture of their relative efficacy. “But, I think with the new agents… at least with apixaban, we have a direct trial comparing one of these newer drugs to aspirin. And that efficacy was so strong that the trial was actually stopped early,” Dr. Kaatz said.

Dr. Bilazarian said it was important to make sure patients understand that aspirin is not very effective for atrial fibrillation, and that he is “very concerned” that many patients who are on long-term aspirin therapy for prevention of other coronary events think that the reason they’re taking aspirin is because of their atrial fibrillation. Patients need to understand that aspiring “cannot benefit [them], and then we have also to dispel many notions about anticoagulants in general and safety,” he said.

Dr. Ruff agreed, saying, “That’s a critical point, especially now that these newer agents are much safer with respect to the serious bleeding. And we have the data from AVERROES with apixaban where for major bleeding, these new agents, at least in that particular case, had a similar safety profile. So why use a drug that is much, much less effective and not any safer?”

Dr. Naccarelli also concurred, noting that the AVERROES trial comparing apixaban to aspirin was halted early because the aspirin group experienced 55% more strokes, and the ACTIVE A trial comparing aspirin and clopidogrel against warfarin was also stopped prematurely because of 50% more strokes.

He said we “just need to say no” and get over the idea that aspirin “works” as an effective treatment in this patient population. “This mixed message is confusing the physicians and it’s confusing the patients,” he said.