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Coumadin and Stroke Prevention

What is Coumadin?


Updated May 28, 2014

Hispanic doctor talking with older patient
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Coumadin, also known as warfarin, is a medication originally extracted from coumarin, a chemical found in some plants. It suppresses the body's ability to form blood clots, by blocking the function of vitamin K.

How Does Coumadin Prevent Strokes?

Coumadin is an excellent medication for stroke prevention as a result of its potent blood thinning properties (i.e., it prevents the abnormal formation of blood clots in the body). An example of a disease in which abnormal blood clot formation leads to stroke is atrial fibrillation, a disease in which an erratic beating of the heart leads to the formation of unwanted blood clots inside the heart chambers. Other instances in which coumadin is used for stroke prevention include:
  • When someone had a defective heart valve replaced surgically with a mechanical prosthetic valve
  • When someone is found to have a blood clot inside the heart after they suffered a heart attack
  • When someone is found to have a blood clot inside the deep veins in the legs (also known as deep venous thrombosis or DVT. DVTs can cause strokes in people who have a small hole between the right and left sides of the heart. This small hole is known as patent foramen ovale or PFO.
  • When someone has an abnormal tendency to form blood clots as a result of an autoimmune disorder, such as lupus.
    Related: Lupus and Stroke
  • When someone has a genetic predisposition to form blood clots due to a deficiency in one or more of the body’s mechanisms that normally prevent abnormal blood clot formation.

Coumadin Treatment and the International Normalized Ratio (INR)

Blood clotting is measured using the International Normalized Ratio (INR) which attributes a value of 1.0 to people with a normal ability to form blood clots. When people take coumadin, their INR increases, an indication that they are less likely to form blood clots. The desirable INR for sroke prevention is between 2-3. The INR is measured with a blood test. If the INR goes too high (more than 3) this can cause unwanted bleeding. This is the reason why people who take coumadin must have their blood taken every few weeks or months.

Coumadin Treatment and Blood Pressure Control

People who suffer from high blood pressure and who also take coumadin for stroke prevention must always keep in mind that high blood pressure increases the risk of hemorrhagic strokes, or strokes caused by bleeding in the brain. As coumadin decreases the body’s mechanisms which normally stop bleeding, people who take coumadin must always keep their blood pressure in check. In fact, a study has shown that even small reductions in systolic blood pressure (as low as 12 points) can decrease the risk of bleeding in the brain by almost 80%.

If You Take Coumadin Follow These Tips

  • Take only medicines prescribed by your doctor (coumadin interacts with multiple medications)
  • Take your coumadin at the same time every day (usually before bed time)
  • Eat the same amount of vitamin K containing food every day (e.g., fish, broccoli, spinach, cabbage, kale, cauliflower)
  • Avoid excessive alcohol
  • Avoid activities which might cause you to fall
  • Never stop coumadin without your doctor's knowledge
  • Never take double doses of coumadin, unless specifically asked by your doctor to do so
  • Call your doctor if your stool changes in color

    Barker Fiebach, and Zieve, Principles of Ambulatory Medicine, Seventh Edition, Baltimore, Williams and Wilkins.

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