PREFER in AF: Stroke Prevention Therapy in AF Suboptimal

September 26, 2013

AMSTERDAM — New data from a registry of patients with atrial fibrillation (AF) shows that stroke prevention therapy is far from optimal in clinical practice.

The latest information from the PREvention oF thromboembolic events – European Registry in Atrial Fibrillation (PREFER in AF) was presented at the recent European Society of Cardiology (ESC) meeting in Amsterdam, the Netherlands.

Presenting one analysis, Luis Miguel Rincon, MD, from the University Hospital Ramon y Cajal, Madrid, Spain, noted that a large proportion of patients are still not getting anticoagulant therapy but should be, and other patients who are at very low risk and therefore not indicated for anticoagulants are receiving them.

In a separate presentation, Harald Darius, MD, from the Vivantes Neukolln Medical Center, Berlin, Germany, reported that a high proportion of patients taking both antiplatelet agents and anticoagulants did not need to be taking the antiplatelet agent. "We are both undertreating and overtreating AF — undertreatment with anticoagulants and overtreatment with antiplatelets," he commented to Medscape Medical News.

Chair of the session, Alexander Parkhomenko, MD, PhD, National Institute of Cardiology, Ukraine, added: "There is a huge gap between the guidelines and clinical practice, in both undertreatment and overtreatment. Much more work on education needs to be done."

Not on Anticoagulants

The PREFER in AF registry recruited 7243 unselected patients with AF in Austria, France, Germany, Italy, Spain, Switzerland, and the United Kingdom from January 2012 to January 2013. Data reported here were those collected at study enrollment. The mean age of patients was 71 years, 60% of patients were male, and the average CHA2DS2-VASc score was 3.4 (4.8% had a score of 0). Average HAS-BLED score was 2.0, and 70% of patients had a dilated left atrium.

Dr. Rincon noted that 66% of patients were taking vitamin K antagonists and 6%, one of the new oral anticoagulants. About 11% of patients were taking antiplatelets, and 6.5% were not receiving any treatment at all. "So 17% of patients were not on anticoagulants and therefore were being undertreated," he said.

Patients who received antiplatelets or no preventive treatment had a lower prevalence of left atrial dilation and more frequently had paroxysmal AF than the overall study population. Those taking no antithrombotic treatment tended to be younger than the average, but no age difference was seen for the antiplatelet group.

In addition, of the group with a CHA2DS2-VASc score of 0, 60% were receiving anticoagulant therapy when not needed, Dr. Rincon noted.

"There remains about 15%-20% of patients with CHA2DS2-VASc scores of 2 to 8 who are not receiving any anticoagulant therapy, and a significant proportion of those with scores of 0 who are being inappropriately treated," he concluded.

Inappropriate Dual and Triple Therapy

In his presentation, Dr. Darius looked at the appropriate versus inappropriate use of antiplatelet therapy in patients also taking anticoagulants for AF. He noted that the latest ESC guidelines state that antiplatelet therapy has not shown benefit for more than 1 year after an event if the patient is receiving anticoagulation.

"Warfarin is a good antithrombotic as well as an anticoagulant. It is cardioprotective. You don't need aspirin for more than a year if warfarin is on board. Using antiplatelets as well as anticoagulants when not necessary is exposing patients to bleeding risk without proven clinical benefit," he commented.

He reported that 720 (9.9%) of the PREFER in AF patients were receiving both a vitamin K antagonist anticoagulant and an antiplatelet drug, and 94 of these patients were receiving dual antiplatelet therapy. Antiplatelets were aspirin (in 88% of patients), clopidogrel (21%), and others in 3%.

Compared with patients only prescribed a vitamin K antagonist, patients receiving combination treatment had a higher mean CHA2DS2-VASc score (3.8 vs 3.5), and a higher mean HAS-BLED score (2.8 vs 1.9).

But Dr. Darius noted that most of the combination treatments were judged inappropriate, not being given because of recent stenting or acute coronary syndrome event. He reported that 96% of patients taking aspirin plus an anticoagulant had no indication for aspirin, and of the patients receiving dual antiplatelet therapy, 67% did not have an appropriate indication.

"For patients on warfarin, efficacy of lifelong aspirin has not been proven. If the patient had an event 10 years ago, it is especially questionable. The need to treat AF patients with warfarin is greater than the need for antiplatelet therapy. There is a lot of overtreatment here," he said.

He suggested this was probably happening because the interventionalist starts the antiplatelet therapy and the general practitioner doesn't know to stop it, so the patient ends up on both antiplatelet and anticoagulant long term. "More education is needed to explain to doctors which patients really need to be on dual or triple therapy," he concluded.

European Society of Cardiology (ESC) Congress 2013. Abstracts 1075 and 1077. Presented September 1, 2013.


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