Atrial fibrillation, stroke and the heart-brain link

In atrial fibrillation (AF), the upper chambers of the heart beat irregularly. The US National Heart, Lung, and Blood Institute (NHLBI) says blood may pool in the heart as a result, which increases the risk of forming clots and can lead to strokes. A clot that forms in the heart can break away, travel in the bloodstream and lodge in an artery supplying the brain. Doctors call this a cardioembolic stroke, meaning a stroke caused by a clot (an embolus) that came from the heart. The NHS makes a similar point about transient ischaemic attacks, saying the blockage is usually a clot that formed elsewhere in the body.

The US Centers for Disease Control and Prevention (CDC) states that AF increases a person's risk for stroke. When standard stroke risk factors were accounted for, it reports, AF was associated with an approximately fivefold increased risk of ischemic stroke, and it says AF causes about 1 in 7 strokes. The CDC also notes that strokes caused by complications from AF tend to be more severe than strokes with other underlying causes. These are figures from a US source, so they describe that population and should not be read as a personal forecast.

A stroke happens when blood flow to part of the brain is cut off or a vessel bleeds. A transient ischaemic attack (TIA), often called a "mini-stroke", is a brief disruption of blood supply with the same kinds of symptoms, such as weakness on one side, slurred speech or loss of vision. The difference is duration. The NHS says the effects of a TIA last from a few minutes to a few hours and fully resolve within 24 hours.

The American Stroke Association (ASA) calls a TIA a "warning stroke" and reports that nearly 1 in 5 people with a suspected TIA will have a stroke within 90 days. That is why symptoms that clear are still treated as an emergency. The NHS notes that early on it is not possible to tell a TIA from a stroke, and that you still need to be assessed in hospital. The warning signs themselves are covered in stroke signs and what to do.

After a stroke or TIA, doctors look for the cause. The NHS says tests can include blood tests, brain scans and an electrocardiogram (ECG) to check the heart, and the ASA says an ECG is often helpful after a TIA. An ECG records the heart's rhythm, which is how AF can come to light for the first time.

Preventing a second event is called secondary prevention. In outline it has three parts, according to the NHS. The first is medicines, which can include medicines to lower blood pressure, anticoagulants to stop blood clots forming, and statins to lower cholesterol. The second is controlling risk factors, and the World Health Organization (WHO) calls hypertension the leading contributor to stroke, which makes high blood pressure central. The third is lifestyle. The NHS lists not smoking, a balanced diet, regular exercise and less alcohol. Which medicines suit a person, and whether an anticoagulant is prescribed for AF, is decided by their clinician.

Care does not end when the first emergency treatment does. The NHS describes a recovery plan set by the healthcare team, which may include physiotherapy, speech and swallowing exercises, and help with memory and mood, and it says there should be a review of progress after about 6 months. The WHO states that rehabilitation should begin as soon as the person is medically stable.

Specialist neurological follow-up is part of this for many people. The ASA says that once a TIA is diagnosed, a follow-up visit with a neurologist is recommended to assess the risk of a future stroke, and that when a TIA occurs with no clear risk factors, a neurologist may carry out tests for other causes. Follow-up is usually led by a stroke or neurology clinic, and where a local service is hard to reach, a reader based in the Cayman Islands could start by looking for a neurologist in the Cayman Islands who sees people after a stroke or TIA, then ask their own doctor to share the hospital records.

A medicines review is the other regular item. People are usually asked to keep taking medicines for conditions such as high blood pressure or diabetes, and the NHS advises speaking to a GP if there are problems with them. Measuring blood pressure at home is one way some people keep track between appointments, if their clinician suggests it.

Sudden face drooping, arm weakness, speech difficulty, loss of balance or sudden vision changes need emergency help, even if they pass. Emergency numbers differ by country, so use your local one; the NHS gives 999 for the United Kingdom, and US sources give 911. Do not drive yourself to hospital. If you have AF or have had a stroke or TIA, ask your own clinician about your medicines and follow-up rather than changing anything yourself.

Atrial fibrillation can let clots form in the heart, and a clot that reaches the brain causes a cardioembolic stroke. A TIA is a brief version of the same event and is treated as a warning. After either, doctors look for causes such as AF, and prevention centres on blood pressure, prescribed medicines and lifestyle, followed by rehabilitation and specialist review.