Blood thinner or Watchman?
If you have AFib, you have probably heard of two ways to lower your stroke risk. This page explains both in plain language, what the research shows, and how we decide together.
From Dr. Kenneth Civello, MD, MPH, cardiologist and electrophysiologist
A drooping face, a weak arm or leg, trouble speaking, sudden vision loss, or a sudden severe headache. Note the time it started. Do not drive yourself.
Why AFib can cause a stroke
In AFib, the top chamber of your heart quivers instead of squeezing. Blood can pool in a small pouch off that chamber called the left atrial appendage.
Think of the pouch as a dead end street where traffic stalls. Clots can form there. If a clot breaks loose and travels to the brain, it causes a stroke.
Why the pouch matters so much
In people with AFib who do not have valve disease, most clots that cause stroke start in this pouch. That is why doctors came up with the idea of closing it off.
Some clots still form in other places. This is one reason closing the pouch does not protect you as fully as a medicine that works everywhere.
Your two options
Both lower your stroke risk. They do it in different ways.
A blood thinner pill
Medicines like apixaban (Eliquis) or rivaroxaban (Xarelto) keep clots from forming anywhere in the body.
- Taken every day
- Tested in four large trials of more than 70,000 patients
- The main downside is bleeding
A closure device
A small plug, such as the Watchman, is placed in the pouch through a vein in the leg. It seals the pouch off.
- One procedure, usually one night or less in the hospital
- Medicines are still needed afterward
- A small risk from the procedure itself
For more on stroke risk scores and the other parts of AFib care, see How AFib is treated.
What the research shows
In 2026, researchers combined all seven randomized studies that compared the device to blood thinners. That added up to 7,353 patients.
Strokes
Slightly more strokes from clots happened with the device than with the pill.
Bleeding
About the same either way. The device did not lower serious bleeding overall.
Brain bleeds
Possibly fewer with the device, but the studies were too small to be sure.
Why we trust these numbers, and their limits
These were randomized studies. Patients were assigned by chance to the device or the pill, which is the fairest way to compare two treatments.
Strokes are uncommon, so even 7,000 patients is a small number for this question. The pill studies each enrolled more than 10,000 people. Some doctors think newer devices may do better than older ones. That is still being studied.
The bleeding numbers include bleeding from the procedure. Some studies found fewer bleeds with the device after the first few months.
Many people choose the device hoping to stop all medicine. Most patients still take aspirin, or aspirin plus clopidogrel (Plavix), for months or for life after the procedure.
These medicines can cause bleeding too. In one large study, aspirin caused about as much serious bleeding as apixaban.
Which path fits you
Your bleeding history and your own wishes guide the choice.
You can take a blood thinner safely
The pill has the stronger evidence. For most people, this is the best choice.
You have serious bleeding again and again on a blood thinner
The device is a reasonable conversation. We have less research on people like you, so we will talk openly about what we know and what we do not.
You simply prefer not to take the pill
That is your choice to make. The trade is one less daily medicine for a small rise in stroke risk. It is not a safer path.
The 2023 national AFib guideline says the device is reasonable for people with a moderate or high stroke risk who cannot take a blood thinner long term. For people with a high risk of serious bleeding on a blood thinner, it says the device may be considered, based on what you prefer after we talk it through.
What counts as “can’t take a blood thinner”
Easy bruising or a nosebleed now and then is common and usually not a reason to stop. Bleeding that sends you to the hospital, needs a transfusion, or keeps coming back is different.
We can often fix the cause first. That might mean changing the dose, stopping another medicine that adds to bleeding, or treating a stomach problem.
Do not stop your blood thinner on your own. Call us first.
Questions to bring to your visit
- What is my stroke risk each year without any treatment?
- What is my bleeding risk on a blood thinner?
- Has my bleeding had a cause we could fix?
- What medicines would I take after a device, and for how long?
- What are the risks of the procedure in my case?
Common questions
Will I be off all blood thinning medicine after a Watchman?
Usually not. Most patients still take aspirin, or aspirin plus clopidogrel (Plavix), for months or for life. These medicines can cause bleeding too.
Is the Watchman safer than a blood thinner pill?
Not for stroke. When all seven studies were combined, slightly more strokes from clots happened with the device. Serious bleeding was about the same either way, once bleeding from the procedure was counted.
Does easy bruising mean I should get the device?
Usually not. Easy bruising or a nosebleed now and then is common on a blood thinner. Bleeding that sends you to the hospital, needs a transfusion, or keeps coming back is different, and we often can fix the cause first.
This page is general education for my patients. It does not replace advice from your own doctor. Every patient is different, and we will make this decision together.
Based on: Ruzieh M, Mandrola J, et al. Left atrial appendage closure versus oral anticoagulation in atrial fibrillation, a meta analysis of seven randomized trials. Trends Cardiovasc Med. 2026. Joglar JA, et al. 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation. J Am Coll Cardiol. 2024. Connolly SJ, et al. Apixaban in patients with atrial fibrillation (AVERROES). N Engl J Med. 2011. Ruff CT, et al. Comparison of the efficacy and safety of new oral anticoagulants with warfarin in patients with atrial fibrillation. Lancet. 2014.