Atrial fibrillation (AFib) is a type of irregular heartbeat (arrhythmia) that can lead to stroke and other serious health complications. It’s the most common type of arrhythmia. When a heart is in AFib, the upper chambers (atria) quiver and beat chaotically instead of in a regular, predictable rhythm. Blood doesn’t travel through the heart as well as it should. It can sometimes pool in the atria, forming a blood clot.
A blood clot in the heart can travel to the brain and cause a stroke. About 1 out of 5 people who have a stroke also have AFib. So, people with atrial fibrillation are usually prescribed a blood thinner (anticoagulant) to reduce the risk of clots in the heart. Direct thrombin inhibitors (DTIs) are a type of anticoagulant used to treat atrial fibrillation and other conditions that can lead to stroke.
How Do Direct Thrombin Inhibitors Work?
Direct thrombin inhibitors work by latching onto a type of protein in the blood called thrombin. Thrombin plays a key role in clotting. It switches on platelets, which clump together to help form a clot. Thrombin also converts another protein -- fibrinogen -- into fibrin, which helps clots form. DTIs turn off thrombin, which disrupts the clotting process.
DTIs come in several forms, including oral tablets taken daily and medications that are injected or given intravenously (in your veins) to prevent blood clots during certain medical procedures. For example, intravenous DTIs can be safe and effective alternatives to the drug heparin, a type of anticoagulant often used during surgery, when people with AFib are having catheter ablation to try to stop their AFib.
DTIs are among several types of anticoagulants used to treat AFib and other conditions involving clots, such as deep vein thrombosis (DVT) and pulmonary embolism (PE). DVT is the formation of a blood clot in one of the body’s deep veins, usually in a leg. PE is a blood clot in the lungs.
Most people with AFib are prescribed some type of anticoagulant. This includes people with the four basic types of AFib:
- Paroxysmal AFib. AFib episodes happen every now and then and may last a few minutes or a few hours. They usually end on their own. If you have paroxysmal AFib, you might not need anticoagulation therapy.
- Persistent AFib. AFib doesn’t end on its own and continues until you get medications or cardioversion.
- Long-standing persistent AFib. AFib continues for more than a year.
- Permanent AFib. The arrhythmia no longer responds to treatment or procedures aimed at restoring a normal rhythm.
If you have permanent AFib, you may be unable to regain a healthy heart rhythm. You should still take anticoagulants to lower your risk of blood clots and stroke. If you have been diagnosed with permanent AFib, be sure to ask your doctor whether you should be on a DTI or other anticoagulant.
What Are DTI Side Effects and Complications?
Like any drugs, DTIs can cause side effects and complications. Some of the more common side effects of oral DTIs include:
- Bloody stools
- Vomiting blood or something that looks like coffee grounds
More serious complications of DTIs and other anticoagulants are bleeding risks. Internal bleeding problems can happen. Cuts or scrapes on your skin may bleed much more than usual because the anti-clotting effects are so strong. If you’re already at high risk for bleeding complications or for falls that could lead to bleeding injuries, you may be advised not to take a DTI.
What Are Some Alternatives to DTIs?
DTIs are among a type of anticoagulant class of drugs called direct oral anticoagulants (DOACs). The other main type of DOAC is a direct factor Xa inhibitor. Dabigatran is one of the more widely used oral DTIs.
Direct factor Xa inhibitors include:
DOACs have become the cornerstone of stroke prevention treatment for AFib. For many years, warfarin (Coumadin) was the only anticoagulant prescribed for AFib. But in recent years, the American Heart Association and American College of Cardiology changed their AFib treatment guidelines to recommend DOACs over warfarin. Research suggests that DOACs are safer and more efficient.
But, because anticoagulants can lead to bleeding problems, some people with AFib don’t take blood thinners. One alternative to anticoagulants that can sometimes cut the blood clot risk is a procedure that closes off a small pouch attached to the atria called the left atrial appendage (LAA). It’s within this little pocket of tissue that blood clots are more likely to form.
Other drugs, such as those to restore healthy rate and rhythm, may be prescribed, depending on how serious your atrial fibrillation is. All of these medications are important to staying healthy, so it’s critical to follow your doctor’s recommendations and know what to do if you miss a dose or have any side effects.