Q&A 027 : Atrial Fibrillation and Stroke

⏱ 10 min read

Dr. Hayes Q&A · No. 027

By Eleanor Hayes, M.D. · Hospitalist

How does a problem with the heart’s rhythm end up as a problem in the brain? The link between atrial fibrillation and stroke is one of the most important connections in medicine, and once you see it, the question of why someone who feels fine needs a daily pill starts to answer itself.

The Question

“My father was just admitted with a stroke, and they told us the cause was atrial fibrillation. He never once said anything felt wrong with his heart. How does a heart problem cause a stroke? And I get a flutter in my chest now and then myself. Should I be checked too?”

— Name withheld

The Short Answer

In atrial fibrillation, the upper chambers of the heart stop contracting in an orderly way and simply quiver. Blood slows and pools in a small pouch of the left upper chamber, a clot forms there, and a piece can break loose and travel to the brain. Atrial fibrillation raises the risk of stroke about fivefold, and the strokes it causes tend to be larger and more deadly. Because it often causes no symptoms at all, the first sign can be the stroke itself. With a flutter of your own, being checked is a reasonable step.

Atrial Fibrillation and Stroke: How the Heart Sends a Clot to the Brain

Where the blood pools. The left atrium has a small, blind-ended pouch called the left atrial appendage. When the atrium beats normally, blood keeps moving through it. When the atrium only quivers, flow in that pouch slows, and slow blood clots. A clot that forms there and breaks loose tends to travel to one of the large arteries of the brain, which is why these strokes are often severe. Atrial fibrillation is linked to about a fivefold higher risk of ischemic stroke and roughly twice the risk of death. (atrial fibrillation and ischemic stroke, clinical review)

The trap of feeling nothing. The father’s silence before his stroke is not unusual. Many people with atrial fibrillation never feel it. Here the evidence needs to be stated honestly: there is no proof yet that screening people with no symptoms improves outcomes. What is well supported is long-term heart monitoring after a stroke with no clear cause, to find a hidden rhythm problem. (same review, on screening and monitoring) So the message is not “everyone should be scanned.” It is “if you have symptoms, get them checked.” The reader has symptoms. That is the difference.

Aspirin is not the answer. This is where the father’s medication list matters. Aspirin works on platelets, and it is not the tool for the kind of clot that forms in a quivering atrium. The standard for preventing stroke in atrial fibrillation is an anticoagulant, a medicine such as warfarin or apixaban that works on the clotting system itself. The 2023 U.S. guideline does not support aspirin alone as a substitute, and it moved toward deciding on anticoagulation by a person’s overall stroke risk rather than by a single score. For people who cannot take anticoagulants because of bleeding risk, closing off the left atrial appendage with a device is an option the guideline now supports more strongly. (2023 ACC/AHA/ACCP/HRS guideline on atrial fibrillation) How that trade-off looks for a real patient is laid out in the case of a Watchman device and bleeding risk.

Most of the risk factors can be changed. Age cannot be undone. But high blood pressure, excess weight, alcohol, and sleep apnea all feed atrial fibrillation, and the 2023 guideline treats managing them as a pillar of care in its own right, not an afterthought. Alcohol can matter within hours, as I described in the previous question on palpitations. And the detail in the son’s own history that stood out to me was not his flutter. It was his wife’s comment about the snoring. Untreated sleep apnea is one of the conditions most often found alongside atrial fibrillation, and it is worth raising with a doctor directly.

What I See in the Hospital

The pattern I see most is atrial fibrillation discovered only after the stroke. The monitor in the stroke unit finds what no one had looked for. The other pattern is harder to watch: someone who already knew about the rhythm problem, stopped an anticoagulant out of fear of bleeding, or was left on aspirin alone, and then came in with the very stroke the medicine was meant to prevent. The question families ask me most is why no one knew. Sometimes the clot does not go to the brain at all, as in the case of a clot that blocked an arm artery. The source is the same.

Plain-Language Reference

What to Actually Do

· If a flutter feels irregular or lasts more than a few minutes, ask for an ECG and a wearable monitor.
· If you have been diagnosed with atrial fibrillation, ask directly: “Does my stroke risk call for an anticoagulant?”
· If bleeding worries you, do not stop the medicine on your own. Ask about alternatives, including appendage closure.
· Treat the snoring, the drinking, and the blood pressure as part of the rhythm problem, because they are.
· A drooping face, a weak arm, or slurred speech means call 911 immediately. Note the time it started.

This article is for general information only and does not constitute medical advice. Reading it creates no provider-patient relationship. The reader’s situation is a composite and does not represent any specific person. Anticoagulants carry real benefits and real bleeding risks, and the decision to start, stop, or change one belongs with a qualified licensed professional who knows your full history. Do not start or stop any medication based on this article. Signs of a stroke, such as facial drooping, arm weakness, or trouble speaking, call for 911 without delay.

Take care of yourself. Nobody else will do it for you.
— Eleanor Hayes, M.D.