Blood Thinners for Heart Disease - Warfarin (Coumadin)

What is warfarin?

Warfarin (Coumadin) is an anticoagulant that interferes with the blood's ability to clot.

What is it used for?

Warfarin is approved to reduce the risk of death, another heart attack or stroke after a heart attack, and to treat or prevent blood clots in the deep veins of the lower legs (deep vein thrombosis, or DVT) and in the lung ( pulmonary embolism). Warfarin also prevents blood clots in people with a rapid, irregular heartbeat ( atrial fibrillation) or those who have a mechanical heart valve.

Warfarin is not routinely prescribed after a heart attack. There is some evidence that warfarin combined with aspirin is better than aspirin alone at preventing another heart attack or stroke after a heart attack.⁸ However, some studies found no additional benefit for the combined treatment.^{9, 10} Warfarin is taken orally as a pill — everyone responds a little differently, so drug doses are tailored for each patient. If you are prescribed warfarin, you will need to have regular blood tests to ensure you are not taking too much or too little.¹ Because of this inconvenience, many people prescribed long-term warfarin stop taking it. It is much easier to take aspirin alone for preventive purposes. Research is now focused on combining aspirin with the newer antiplatelets such as clopidogrel (Plavix). These newer antiplatelet drugs are taken in pill form without the need for monitoring tests. Although warfarin may be used to prevent future heart attacks or strokes in women who cannot take daily aspirin — because of allergy, for example — physicians prefer to prescribe the newer antiplatelets instead.

Women who have had a heart valve replacement may need to take warfarin for the rest of their lives.

What are the risks of warfarin use?

Warfarin can cause excessive bleeding from even minor cuts such as a razor nick. If you have to take warfarin, you'll be advised to avoid activities that might cause injury. Your diet can affect how well warfarin works. You should restrict foods that contain vitamin K, a vitamin involved in blood clotting. These foods include green vegetables (such as lettuce and broccoli), avocado and egg yolks. People taking warfarin for 3 to 10 weeks or longer may develop purple toe syndrome. The toes and feet turn a dark, purple, or mottled color that fades if you raise your legs. This side effect can be reversed, but if left untreated, it may cause gangrene.

Warfarin Quick Reference Table