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Which Is Safer, Blood Thinners or the WATCHMAN Implant?

Did you know that a person with AFib is 5 times more likely to have a stroke than a person with a regular heartbeat?1 For people living with atrial fibrillation (AFib), lowering the risk of stroke is an important part of long-term care. Blood thinners have been the standard treatment for many years. They can help reduce stroke risk, but they also come with risks and daily trade-offs.

The WATCHMAN Implant is a treatment option for people with AFib who need an alternative to blood thinners. It’s designed to permanently reduce stroke risk — without the ongoing bleeding risks tied to long-term blood thinners.

An orange shield icon with a heart in it.

What are blood thinners? What do blood thinners do?

Blood thinners are medications that reduce the blood’s ability to form clots. However, they do not actually thin the blood.2 Instead, they slow down the clotting process to lower the risk of stroke.

Blood thinners for AFib must be taken every day to remain effective. Missing just a few doses can quickly lower protection against stroke caused by blood clots. A study found that taking blood thinners as prescribed only 80% of the time makes a person 64% more likely to have a stroke.3

Blood thinners for AFib: Common options

Blood thinners for atrial fibrillation include a variety of medications, including:

  • Coumadin® (warfarin)
  • Eliquis® (apixaban)
  • Xarelto® (rivaroxaban)
  • Pradaxa® (dabigatran)
  • Savaysa® (edoxaban)

These medications differ in how they’re taken, whether blood monitoring is required, and how they interact with foods or other drugs. All must be taken consistently and long-term to effectively reduce stroke risk in people with AFib.

Blood thinners and stroke prevention

By reducing clot formation, blood thinners lower the risk of stroke. However, this protection depends on taking the medication daily and long-term. Blood thinners must be taken exactly as prescribed, often alongside other long-term medications, to maintain their benefit.

Side effects of blood thinners

The side effects of blood thinners go beyond the risk of bleeding. Other common side effects include:

  • Increased bruising
  • Nosebleeds or bleeding gums
  • Prolonged bleeding from small cuts or injuries
  • Blood in the urine or stool
  • Gastrointestinal (stomach or bowel) bleeding

People taking blood thinners long-term must be careful about falls, injuries, and medication interactions. Common medications for arthritis, pain (NSAIDs), depression (SSRIs), cancer, and COVID-19 can increase bleeding risk that comes with blood thinners. Some examples include ibuprofen (Advil®, Motrin®) and naproxen (Aleve®).4,5

Everyday activities — such as dental work, minor procedures, or travel — may require extra planning and care. These seemingly small changes can add up to a big impact on daily routines and quality of life.

Find out if you’re a candidate for the WATCHMAN Implant.  Take the quiz

Blood thinner risks increase over time

The longer a person takes blood thinners, the higher the risk of bleeding becomes. Bleeding risk rises year over year, creating a compound effect with prolonged use. People who take blood thinners for 10 years may be at a 6–9x higher risk of bleeding due to prolonged blood thinner use.+6 The risk is even greater for older adults and people with other health problems.

Can blood thinners cause strokes and bleeding in the brain?

While blood thinners reduce the risk of ischemic stroke, they also increase the risk of serious bleeding events. This includes bleeding in the brain as well as bleeding in the stomach or intestines.

The burdens of long-term blood thinners

It’s not uncommon for long-term blood thinner use to take an emotional toll. In fact, more than one-third of people taking them report feeling torn between the fear of having a stroke and the fear of bleeding complications.7 This type of concern can affect one’s confidence, activity levels, and peace of mind, especially during emergencies or unexpected medical events.

Blood thinners, multiple medications, and heart failure risk

Many people with AFib take several medications to manage heart rhythm, blood pressure, cholesterol, and other conditions. Studies show that AFib patients who take five or more medications have a 33% higher chance of developing heart failure.8 Long-term blood thinner use can add to this medication burden, increasing the complexity of care over time.

Blood thinners and emergency medical procedures

Blood thinners can complicate urgent and emergency care. Research shows that 43% of urgent procedures are delayed for people taking blood thinners for AFib due to bleeding concerns.9 In emergency surgeries, 1 in 8 people on blood thinners experience serious bleeding complications.9

An orange WATCHMAN device icon.

The WATCHMAN Implant: An alternative to daily blood thinners

The WATCHMAN Implant is a one-time, permanent implant. It’s designed to lower stroke risk in people with AFib not caused by a heart valve problem. It works by closing off a small part of the heart called the left atrial appendage (LAAC). This is where more than 90% of stroke-causing clots form in people with AFib.10 The WATCHMAN does not rely on lifelong daily medication to reduce stroke risk.

There are risks associated with all medical procedures. Please talk with your doctor about the risks and benefits of the WATCHMAN Implant.

The WATCHMAN Implant provides a safe and effective alternative for people who have experienced bleeding in the past, have concerns about long-term bleeding risk, take multiple medications, or have other health conditions that make ongoing anticoagulant use more challenging. Find out if you’re eligible.

Safety of Blood Thinners vs. WATCHMAN

How stroke risk is managed over time matters. Blood thinners are effective but carry an ongoing risk of major bleeding that increases the longer a person takes them. Research also shows that many people stop taking blood thinners within a few years, despite ongoing stroke risk.11

Clinical studies show that the WATCHMAN Implant offers a different approach: 10

  • It provides stroke risk reduction similar to warfarin
  • After the initial healing period, it significantly lowers long-term bleeding risk compared to continued blood thinner use12
  • The procedure has a high implant success rate of 99%* and a low major complication rate of 0.5%**13

LAAC with the WATCHMAN Implant offers a one-time approach that doesn’t depend on lifelong daily medication to maintain protection.

Life on blood thinners vs. the WATCHMAN Implant

If you’re currently taking blood thinners for AFib, you already know that they require ongoing daily vigilance. Daily dosing, refill schedules, and coordination around medical or dental procedures are part of routine care. Some people also limit activities or travel plans out of concern for injury or unexpected bleeding.

Life with the WATCHMAN Implant offers a different path. Stroke risk reduction doesn’t need to depend on taking daily blood thinners for life. Because of this, some people report fewer treatment-related interruptions.

Many people report that this gives them more freedom in daily life. This may include getting back to long walks, riding a bike, or gardening, without the nagging fear of small cuts, bruises, or falls. While living with AFib still means ongoing care, the WATCHMAN Implant may offer more flexibility to enjoy everyday activities. 



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Say goodbye to blood thinners

The WATCHMAN Implant is an alternative to blood thinners to reduce NV-AFib stroke risk. See if you're eligible.

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+ Assumes constant risk despite increasing age, and bleeding risk is independent from bleeding risk in previous years.

*In a clinical trial, 96% of patients were able to discontinue their blood thinner 45 days after getting the WATCHMAN Implant.

**Procedure success defined as successful delivery and release of a WATCHMAN FLX device into the LAA.

References: 

  1. FAQ About AFib. American Heart Association, Inc., 2023. Available at: www.heart.org/-/media/Files/Health-Topics/Atrial-Fibrillation/FAQ-About-AFib.pdf. Accessed June 10, 2024.
  2. Blood thinners. MedlinePlus. Accessed December 12, 2025. https://medlineplus.gov/bloodthinners.html
  3. Grymonprez M, Steurbaut S, Capiau A et al. Minimal Adherence Threshold to Non-Vitamin K Antagonist Oral Anticoagulants in Patients with Atrial Fibrillation to Reduce the Risk of Thromboembolism and Death: A Nationwide Cohort Study. Cardiovasc Drugs Ther. 2023; 39:107–117. https://doi.org/10.1007/s10557-023-07507-3
  4. UpToDate Inc. (2025). Drug interactions. In UpToDate. Retrieved July, 2025, from https://www.uptodate.com/drug-interactions
  5. Elsevier. Drug monograph. ClinicalKey. Retrieved June, 2025, from https://www.clinicalkey.com
  6. Turagam MK, Parikh V, Afzal MR, et al. Replacing warfarin with a novel oral anticoagulant: Risk of recurrent bleeding and stroke in patients with warfarin ineligible or failure in patients with atrial fibrillation (The ROAR study). J Cardiovasc Electrophysiol. 2017; 28: 853-861.
  7. Data on file with Boston Scientific. Atrial Fibrillation Patients survey. The Harris Poll on behalf of Boston Scientific and StopAFib.org; 2018:1-64.
  8. Chen N, Alam AB, Lutsey PL, et al. Polypharmacy, Adverse Outcomes, and Treatment Effectiveness in Patients ≥75 With Atrial Fibrillation. Journal of the American Heart Association. 2020;9(11). doi:10.1161/jaha.119.015089
  9. Godon A, Gabin M, Levy J et al. Management of urgent invasive procedures in patients treated with direct oral anticoagulants: An observational registry analysis. Thrombosis Research. 2022; 216:106-112. https://doi.org/10.1016/j.thromres.2022.06.005
  10. Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg. 1996;61:755-759
  11. Cleveland clinic-led trial finds heart implant may be effective alternative to blood thinners for those with atrial fibrillation. Cleveland Clinic. Published November 16, 2024. Accessed December 12, 2025. https://newsroom.clevelandclinic.org/2024/11/16/cleveland-clinic-led-trial-finds-heart-implant-may-be-effective-alternative-to-blood-thinners-for-those-with-atrial-fibrillation
  12. Price MJ, Reddy VY, Valderrábano M, et al. Bleeding outcomes after left atrial appendage closure compared with long-term warfarin. JACC Cardiovasc Interv. 2015;8(15):1925-1932.
  13. Kar S, Doshi SK, Sadhu A, et al. Primary Outcome Evaluation of a Next-Generation Left Atrial Appendage Closure Device: Results From the PINNACLE FLX Trial. Circulation. 2021;143(18):1754-1762.
Caution: U.S. Federal law restricts this device to sale by or on the order of a physician. 

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Content on this web page is for Informational Purposes only and does not constitute medical advice and should not be used for medical diagnoses. Boston Scientific strongly recommends that you consult with your physician on all matters pertaining to your health or to address any clinical/medical questions. 

WATCHMAN™ Left Atrial Appendage Closure Implant

Important Safety Information

The WATCHMAN FLX and WATCHMAN FLX Pro Devices are permanent implants designed to close the left atrial appendage in the heart in an effort to reduce the risk of stroke.

With all medical procedures there are risks associated with the implant procedure and the use of the device. The risks include, but are not limited to, accidental puncture of the heart causing fluid to collect around the heart possibly leading towards the need for an additional procedure, allergic reaction, anesthesia risks, altered mental status or confusion after procedure, arrhythmias (irregular heartbeats), bleeding or throat pain from the TEE (Trans Esophageal Echo) probe, chest pain/discomfort, congestive heart failure, renal failure, excessive bleeding, gastrointestinal bleeding, groin puncture bleed, bruising at the catheter insertion site, groin pain, anemia (reduced red blood cells requiring transfusion), hypotension, infection/pneumonia (example: in or around your heart or lungs), misplacement of the device, improper seal of the appendage or movement of device from appendage wall, clot formation on the device, blood clot or air bubbles in the lungs or other organs, stroke, transient ischemic attack (temporary stroke-like symptoms), cranial bleed (bleeding in or around your brain), thrombosis (blockage of a blood vessel or vein by a clot) and in rare cases death can occur.

Be sure to talk with your doctor so that you thoroughly understand all of the risks and benefits associated with the implantation of the device. SH-2109508-AA