Dear Dr. Roach: I am a 70-year old woman with a prior history of asymptomatic atrial fibrillation (AFib). I’ve been in normal sinus rhythm since having two catheter ablations in 2018. I take Eliquis since my CHA2DS2-VASc score is 2, but I would like to get off of it due to the bleeding risk. (I tripped and fell recently while traveling abroad, and a resulting minor injury caused excessive bleeding.) My doctor told me about the OPTION clinical trial and suggested that I consider a WATCHMAN device.

Can you comment on OPTION, for which results were published recently? I’ve read that about 90% of blood clots originate in the left atrial appendage (LAA). How is the percentage known? If about 10% of blood clots originate outside the LAA, does this not suggest that a WATCHMAN should be less protective than anticoagulation, in spite of the study results?

Do you think I am a good candidate for the WATCHMAN?

— L.M.

Answer: There’s a lot to explain here. The most important is that AFib, a common rhythm disorder, increases the risk of stroke. In asymptomatic people, the most important goal is managing stroke risk. You already had a catheter ablation to stop AFib, but your cardiologist is correctly continuing to ensure that you have the lowest possible stroke risk, since catheter ablation alone does not adequately reduce the risk of a stroke.

When choosing how to reduce the risk of stroke, a clinician uses tools to estimate the risk of stroke and serious bleeding without treatment. The CHA2DS2-VASc score is the most common way of estimating stroke risk, and you have 2 points just from being a 70-year-old woman, which gives you a 2.2% chance of a stroke per year without treatment.

The HAS-BLED bleeding risk score is then calculated and weighed against the stroke risk when considering anticoagulation with a medicine like Eliquis.

The WATCHMAN device is an LAA-occlusion device. It blocks the LAA (a small area within the left atrium) and prevents clots that form there from breaking off to the brain and causing a stroke. The proportion of clots that come from the LAA is known through many studies that identified the source of the clot by cardiac surgery, echocardiogram and autopsy studies.

Because 10% of clots come from outside the LAA, an LAA-occlusion device can’t prevent all clots. However, no medication can stop all clots either; studies estimate that anticoagulation is about 70% effective at reducing strokes compared to a placebo.

There is the potential for side effects during the placement of an LAA-occlusion device, and women are more likely to have one (6% versus 4% in men). Bleeding around the time of placement and fluid around the heart that required drainage were the most common adverse effects.

Basing your decision on the OPTION trial won’t give you a straightforward answer, since the subjects in the trial were at a much higher risk for stroke than you are. The major benefit for you will be a lowered risk of bleeding with a reduction in the risk of stroke. It is a very reasonable option.

Contact Dr. Roach at ToYourGoodHealth@med.cornell.edu.