Anticoagulants

Many people with heart failure (HF) also have atrial fibrillation (AF). AF is an irregular heart rhythm. In AF, the upper chambers of the heart contract too often, causing the upper and lower chambers to be unable to coordinate effectively. People with HF and AF have a higher risk of thromboembolism. This happens when blood clots travel through the bloodstream and cause a blockage.^1,2

Anticoagulants may be used to treat people with HF and AF. They can prevent blood clots from forming or becoming larger. This can reduce the risk of stroke and other serious problems. Anticoagulants can cause excessive bleeding and other side effects. Talk to your doctor about whether anticoagulants are right for you.^1,3,4

How do anticoagulants work?

Anticoagulants are often called blood thinners. They reduce the ability of blood to clot (coagulate). Clotting is important to reduce bleeding when a blood vessel is injured.^3,5

Blood clots that form and grow inside blood vessels can be dangerous. They can block veins and cause strokes, heart attacks, and other life-threatening conditions. Anticoagulants work in different ways to prevent clots from forming or growing. Types (classes) of these drugs include:^1-5

• Coumarins (also called vitamin K antagonists) are drugs you take by mouth (orally). They block the activity of vitamin K in the clotting process.
• Direct oral anticoagulants (DOACs) are newer drugs that block proteins involved in clotting. Examples of these proteins are thrombin and factor Xa.
• Heparins are injected (given with a needle). Heparin drugs come from proteins that activate antithrombin. They keep the clotting process from working normally.

DOACs tend to work faster and better than vitamin K antagonists. They also require less monitoring and dose changes. This is because their ability to block clotting is easier to predict.^2,6-8

Examples

Several anticoagulants are prescribed for people with HF. Some reduce the risk of blood clots in people with AF. Others reduce this risk for people with other heart problems. Examples of anticoagulants include:^2,3,5-7,9

• Coumadin® (warfarin)
• Generic (unfractionated) heparin as well as synthetic heparin derivatives like Arixtra® (fondaparinux) and low-molecular-weight heparins like Fragmin® (dalteparin), and Lovenox® (enoxaparin)
• DOACs like Pradaxa® (dabigatran), Xarelto® (rivaroxaban), Eliquis® (apixaban), Savaysa® (edoxaban), Bevyxxa® (betrixaban)

There is not yet enough evidence to know which anticoagulant is the most effective. The decision depends on a number of personal factors. These include cost, side effects, other drugs you take, and personal preference.^1,4

What are the possible side effects?

Side effects can vary depending on the specific drug you are taking. The most common side effect of any anticoagulant is bleeding. Warfarin has the highest risk of bleeding. Other risks include:^5-8

• Skin necrosis (death of skin tissue)
• Blue or purple toes
• Low numbers of platelets (blood cells that help clotting)
• Osteoporosis (low bone density and mass)
• Indigestion and upset stomach
• Nausea and vomiting

These are not all the possible side effects of anticoagulants. Talk to your doctor about what to expect when taking anticoagulants. You also should call your doctor if you have any changes that concern you when taking anticoagulants.

Other things to know

Take anticoagulants as your doctor prescribes. Do not stop taking anticoagulants without talking to your doctor. Prematurely stopping can increase the risk of blood clots.⁶

People taking warfarin must have regular blood tests. This includes a test called international normalized ratio (INR). INR measures how long it takes blood to clot, and is used to measure if your warfarin dose may be too high or too low. Your doctor will adjust your dose of warfarin to maintain a certain INR target.^2,7

Before beginning treatment for HF, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

Several health conditions make anticoagulants too risky to use. Other conditions may affect your risk of side effects. Many anticoagulants are not safe to take while pregnant.^5,7

Other medicines you take can interfere with anticoagulants. Many foods and drinks have blood thinning or clotting effects. Talk to your doctor about a safe and healthy diet. DOACs tend to have fewer drug and diet restrictions than warfarin and require fewer tests for monitoring.^5,7,10