August 9, 2014 at 1:00 am

To Your Health

Warfarin is a necessary medicine for some

Dear Dr. Roach: My brother had his aortic valve replaced by a mechanical heart valve. He says the warfarin he takes causes him problems, such as head pain, stomach pain, nausea, and joint and muscle aches and pains. Are serious side effects common on warfarin, and how serious can they be?

D.J.M.

Dear D.J.M.: Warfarin (Co­umadin) is among the most pow­erful medicines we use, and it can have life-threatening side effects. Warfarin, an anticoagulant, works by inhibiting Vitamin K-1, and it prevents the body from making several of the proteins involved in blood clotting and regulation. It also has the potential to interact with many medications, and thus needs careful monitoring. Excess warfarin commonly causes bleeding, but in some people warfarin can cause paradoxical blood clotting when it is first started.

It would be reasonable to wonder why such a potentially harmful medication is ever used. After all, there were 29,000 em­ergency visits per year just due to adverse bleeding events from warfarin, according to a study. The answer is that, as potentially dangerous as warfarin is, there are many situations where NOT being on it is EVEN WORSE than being on warfarin. I’ve written about a common one, atrial fibrillation, where many (but not all) people with A fib should be on some kind of anticoagulation. There are newer alternatives in A fib, such as dab­igatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eli­quis). Unfor­tunately, as in your brother’s case, there is no good alternative to warfarin for anticoagulation due to a mechanical heart valve. A 2013 trial on dabigatran found it had no benefit and more risk than warfarin for mechanical heart valves.

Mechanical heart valves put people at a very high risk for blood clot and stroke. The risk of a stroke from a serious bleed into the brain is approximately 4 percent per year without anticoagulation, and there is an added 4 percent per year risk of a blood clot in the lungs or deep veins. Your brother’s doctor is quite right: Not taking the medicine is exceedingly dangerous.

Since there isn’t a good alternative medication, your bro­ther should try to find ways to minimize side effects. For example, stomach pain and nausea often can be managed with diet.

A bioprosthetic heart valve usually doesn’t require long-term anticoagulation: People with known poor reaction to warfarin probably should be given this kind of valve, and not a mechanical one.

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