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.”
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.)
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).
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.
ATRIA Findings: Anticoagulants for Stroke Prevention Versus Risk of Intracranial Hemorrhage
Anticoagulants are prescribed for Atrial Fibrillation patients to reduce the risk of clots and stroke. But anticoagulants can also increase the risk of intracranial hemorrhage. So, who benefits and who may be harmed?
The “AnTicoagulation and Risk Factors in Atrial Fibrillation” Study (ATRIA) has contributed significantly to better understanding which A-Fib patients will benefit most from anticoagulant therapy.
A-Fib and Stroke Risk
As a consequence of atrial fibrillation, the pooling of blood in the atrial chambers of the heart significantly increases the risk of formation of blood clots. If a piece of a blood clot breaks off and travels to the brain it can occlude (block) a blood vessel and prevent blood from reaching the affected area of the brain. This condition is known as an ischemic stroke and can cause severe disability including the inability to walk or talk.
Ischemic Stroke Versus Intracranial Hemorrhage
In order to reduce the risk of ischemic stroke in people with atrial fibrillation, anticoagulant (blood thinner) medications are often prescribed. The most commonly used blood thinner is warfarin (Coumadin) although aspirin may also sometimes be used. While blood thinners can prevent ischemic stroke in people with atrial fibrillation, paradoxically, they can also cause bleeding into the brain, a condition known as intracranial hemorrhage.
Unfortunately, doctors don’t have a fool-proof method of determining which patients with atrial fibrillation will benefit from blood thinners (prevention of ischemic stroke) and which patients may be harmed by blood thinners (cause an intracranial hemorrhage).
Clearly, more research is necessary to more accurately identify those patients who would benefit the most from taking blood thinners as opposed to those who are more likely to be harmed by taking blood thinners.
The “AnTicoagulation and Risk Factors in Atrial Fibrillation” Study (ATRIA)
The “AnTicoagulation and Risk Factors in Atrial Fibrillation” Study (ATRIA) published in 2009, by a collaborative group of researchers from the Massachusetts General Hospital, the University of California at San Francisco, and Kaiser Permanente of Northern California, has contributed significantly to better understanding which patients with atrial fibrillation would benefit most from receiving anticoagulants for stroke prevention.
The study population consisted of 13,559 people with atrial fibrillation with a median age of 73 years. Twenty (20) percent of the subjects had no major risk factors for ischemic stroke. The major risk factors for ischemic stroke include older age (75 years or older), previous history of stroke, diabetes, hypertension, and congestive heart failure. This stroke-risk classification system is known as the CHADS2 grading system and is used by doctors as a basis for classifying patients with atrial fibrillation into stroke risk categories (low, intermediate, or high).
The researchers followed the clinical course of these 13,559 patients for a median of 6 years. At the time of enrollment into the study, 53% of the subjects were receiving warfarin (Coumadin) as prophylaxis for stroke prevention. During the follow-up period, the researchers identified a total of 1,092 thromboembolic events (occlusion of a blood vessel by a blood clot) among the study subjects, the overwhelming majority of which (1,017 cases or 93%) were ischemic strokes. Of the patients who experienced a thromboembolic event, 37% were receiving warfarin and 63% were not receiving warfarin.
The researchers also identified 299 patients among the study cohort who experienced an intracranial hemorrhage, of which 193 patients (65%) were receiving warfarin.
ATRIA Study Key Findings
The major findings of the study can be summarized as follows:
• The greatest benefit of anticoagulation therapy for the prevention of ischemic stroke was observed among patients with a history of ischemic stroke and those in the highest stroke risk category as determined by the CHADS2 stroke-risk grading system.
• In general, the net benefit of receiving warfarin anticoagulation therapy increased with advancing age. Patients with atrial fibrillation in the oldest age group (85 years of age or older) derived more benefit from warfarin prophylaxis than patients in the 75 to 84 year age group, although the benefits of warfarin prophylaxis was apparent in this age group as well.
• This finding strongly suggests that elderly people with atrial fibrillation who are not taking warfarin are at increased risk for ischemic stroke, however, adding warfarin for prevention of ischemic stroke in elderly people does not significantly increase the risk of intracranial hemorrhage.
• Younger people with atrial fibrillation (64 years or younger) who are considered at low risk for developing an ischemic stoke as measured by the CHADS2 stroke-risk grading system, appear to derive little benefit from warfarin prophylaxis and, indeed, adding warfarin may do more harm (intracranial hemorrhage) than good (prevention of ischemic stroke).
Who Will Benefit, Who May Be Harmed
In summary, this study has contributed significantly to more clearly identifying which patients with atrial fibrillation will derive the most benefit from warfarin anticoagulation therapy and which patients may be harmed by this treatment.
If you have atrial fibrillation, talk to your doctor about the risks and benefits of taking blood thinner medications. In general, older people and those at highest risk for ischemic stroke as determined by the CHADS2 stroke-risk grading system will gain the most from anticoagulation therapy.
Blood thinners, however, may not be advantageous and may cause more harm than good in younger patients with atrial fibrillation who are considered to be at low risk for developing an ischemic stroke.
Last updated: Sunday, February 15, 2015