Why Doctors Use Blood Thinners for Stroke Prevention

Blood thinners are medications used to prevent blood clots from forming and to stop blood clots from getting bigger. They do this by interfering with the body’s natural coagulation mechanisms. Coagulation is the physiological process of blood clot formation.​

There are a number of different blood thinners and they have similar effects but each individual blood thinner also has its own individual set of health benefits and side effects.

Use After a Stroke

Blood vessel with blood cells, illustration

Most strokes start when a buildup of blood cells, cholesterol and other fats and debris clump together to form a clot, interrupting the usual flow of blood within a blood vessel. Some blood clots form in the brain, particularly when someone has cerebrovascular disease. Some blood clots form in the heart and travel to the brain, lodging in one of the blood vessels of the brain to cause a stroke. The formation of such a clot takes time and blood thinners are taken over time to prevent another blood clot from forming in someone who is known to have a tendency to excessive blood clot formation. It is very important to prevent recurrent strokes because, while a stroke survivor may be able to recover from one stroke, it is even more taxing to recover from the cumulative brain damage caused by more than one stroke. Blood thinners are scientifically proven to prevent recurrent strokes—especially in stroke survivors who have heart disease such as atrial fibrillation.

Use Before a Stroke

Stroke risk is a double-edged sword. While it is fortunate to learn of stroke risk before a stroke happens, lifestyle adjustments are necessary to reduce, and hopefully eliminate, the chances of having a stroke. If you are at a known risk of stroke, you might need to take a blood thinner to prevent a stroke from happening.

Common Blood Thinners and Their Side Effects

Acetylsalycilic Acid (Aspirin, Ecotrin): the only over-the-counter blood thinner comes in regular strength and baby aspirin strength. Aspirin has been around for a while. It inhibits platelet aggregation- meaning that it restricts the ability of the small cells that clump together to heal a wound from clumping together. Aspirin is often recommended for stroke prevention because it has been scientifically proven to be effective. Side effects include bleeding, particularly in the stomach and colon. When stool (poop) appears bright red or dark and tarry, this can be a sign of bleeding in the stomach or colon.

Warfarin (Coumadin): a blood thinner that interferes with the action of vitamin K, a vitamin necessary for proper blood clotting. Coumadin prevents recurrent stroke and is often recommended for patients with heart problems that may lead to stroke such as heart valve replacement. Coumadin action must be monitored carefully with a blood test called International Normalized Ratio (INR) because an overdose of Coumadin can cause severe bleeding anywhere in the body. Patients who take Coumadin must be careful, as falls can lead to serious, life-threatening bleeding.

Clopidogrel (Plavix): a blood thinner that alters platelet activity. It is often recommended for stroke prevention, but the side effects include bleeding, low white blood cell count, and an unusual disorder called thrombotic thrombocytopenic purpura, characterized by tiny blood clots.

Aggrenox (a combination of aspirin and dipyridamole): dipyridamole is a blood thinner that inhibits platelet activity by blocking enzymes associated with platelets. It is combined with aspirin in one pill to reduce the risk of stroke. Side effects may include bleeding, bruising, and headaches.

Dabigatran (Pradaxa): a newly approved blood thinner that inhibits thrombin, which is involved in blood clotting. This medication has been proven to reduce the risk of stroke in individuals with atrial fibrillation but may cause bleeding or interfere with proper wound healing.

Apixaban (Eliquis): a blood thinner that interferes with activation of a protein called thrombin. It is approved for stroke prevention for people who have atrial fibrillation. Like other blood thinners, it increases the risk of bleeding.

Rivaroxaban (Xarelto): a blood thinner that inhibits blot clot formation by interfering with 2 different steps in the clotting cascade. Xarelto only needs to be taken once daily and it is approved for stroke prevention in people who have atrial fibrillation. As with other blood thinners, it can cause bruising and bleeding.

Bottom Line

Blood thinners are some of the simplest medications, yet they pose some of the most difficult decisions in stroke care. While they have been proven to reduce stroke, the risk of bleeding can cause annoying problems such as slow healing from a cut or small areas of bruising to serious life-threatening hemorrhage.

The decision about whether or not you should take a blood thinner requires consultation with your regular doctor who will thoroughly evaluate your stroke risk in combination with your bleeding risk.

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