Oral Anticoagulants in Atrial Fibrillation

The most recent issue of The Medical Letter (July 7, 2014) on Drugs for Atrial Fibrillation coincided with the publication in The Lancet (July 5, 2014) of several letters commenting on an article in The Lancet earlier this year on the use of new oral anticoagulants in this disorder. The earlier article was a meta-analysis that found the new oral anticoagulants generally had a favorable risk-benefit profile compared to warfarin. The letters questioned that conclusion on various counts, including the much higher cost of the new drugs and a concern that the patients on warfarin in the clinical trials were not as well controlled as they should have been.

Many articles on this subject have appeared in the medical literature and the lay press. Atrial fibrillation is common, and the number of people who take warfarin is probably in the millions. That is a big market, and the manufacturers of the new oral anticoagulants (Pradaxa, Xarelto, and Eliquis) have pursued it aggressively with television commercials and full-page advertisements in newspapers. One of them urged readers to “rethink warfarin”. We responded to that advertising blitz with a short article (September 30, 2013) that acknowledged the positives of the new drugs (equal to warfarin in stroke prevention, less intracranial bleeding, no monitoring), but concluded that patients who are taking warfarin and whose INR generally remains in the therapeutic range should probably stay on it.

Our new article spells out the advantages and disadvantages of all the drugs in this debate, leaving the choice to the individual practitioner treating the individual patient. We do emphasize one thing that is rarely spelled out in articles on this subject, that patients with atrial fibrillation associated with a mechanical valve, a bioprosthetic valve, prior mitral valve repair, or mitral stenosis should take warfarin. Perhaps we also should have mentioned that all the comparisons with warfarin that led to the approvals and favorable estimates of the new agents were sponsored by their manufacturers; comparative drug trials sponsored by one manufacturer that do not come out in favor of the sponsor’s drug are hard to find.

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  1. Many articles refer to relative similarities of effectiveness in embolic stroke prevention in AF by using several agents.
    Few (if any) refer to absolute effectiveness.
    If the risk of untreated embolic stroke in AF runs 2% per year, what does it run with these various therapies? I have read that the decrease may be from 2.0% to 1.5%. If that is true, then what are the adverse effects (mostly bleeding, but also hemorrhagic stroke or brain hemorrhage after embolic stroke ) in those MANY patients who have been anti coagulated to prevent that small difference?
    Worth it?
    george lundberg

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