Warfarin (brand name Coumadin) various dosages

Stop Taking Warfarin―Produces Arterial Calcification

The blood thinner, warfarin (Coumadin) is a “vitamin K-antagonist” which works by blocking vitamin K (i.e., K-2, menaquinone), thereby affecting several steps in the anticoagulation pathway and decreasing clotting proteins in the blood.

But vitamin K is also essential for heart and bone health. Vitamin K determines whether we maintain strong bone density and soft pliable tissues. Without enough K-2, osteocalcin, a protein that binds calcium to bone, doesn’t function. This vascular calcification produces plaque and reduces aortic and artery elasticity.

“When calcium doesn’t stay in bones, it can end up clogging your arteries, causing a heart attack or stroke.”

Vitamin K chemical structure

Warfarin Blocks Vitamin K: Deposits Calcium in Arteries

By blocking vitamin K (K-2), warfarin deposits calcium in our arteries and progressively turns them into stone. In the absence of vitamin K, bony structures form in soft tissues. When you hear the term “hardening of the arteries,” this means that previously flexible blood vessels are turning into rigid (calcified) bony structures.

In a study of 451 women using mammograms to measure arterial calcification, after just one month of warfarin use, arterial calcification increased by 50% compared to untreated women. After five years, arterial calcification increased almost 3-fold.

Why You Should You Stop Taking Warfarin

If you are taking warfarin (Coumadin), you should talk to your doctor about switching to Eliquis (apixaban) which tested the best of the NOACs and is the safest. (See my article, Warfarin and New Anticoagulants.)

Eliquis (Apixaban) is one of the new NOACs

The new oral anticoagulants (NOACs) do not block vitamin K. But the NOACs do have drawbacks. In the case of severe bleeding, there is currently no antidote or reversal agent like there is for warfarin (a reversal agent for the direct factor Xa inhibitors Xarelto and Eliquis is close to FDA approval).

Added 2015: The FDA approved a reversal agent Praxbind for the NOAC Pradaxa Oct. 16, 2015. In clinical trials, 5gs of Praxbind (idarucizumab) administered by IV reversed the anticoagulant effect of Pradaxa within minutes (which is significantly faster than the current antidotes for warfarin).

Added 2018: The FDA approved the reversal agent AndexXa for Xarelto and Eliquis.

Whether or not to be on an anticoagulant and which one to take is the most difficult decision you and your doctor have to make (and your initial decision may change over time as your body changes.)

If you aren’t happy with your doctor’s response, get a second opinion. You need to feel confident and at peace with this decision.