If there is one heart rhythm problem worth taking the time to understand, it is atrial fibrillation: the most common sustained arrhythmia, increasingly frequent as we get older, and one many people have without knowing it. Today I want to explain what it is, why we cardiologists take it so seriously — the key word is "stroke" — and everything we can do so that it doesn't rule your life.

What is atrial fibrillation?

It helps to remember how a healthy heart beats: the atria (the two upper chambers) contract in an orderly way and pass blood into the ventricles, which pump it around the body, keeping a steady beat, like a well-conducted orchestra.

In atrial fibrillation that order is lost: the atria stop contracting effectively and "quiver", driven by disorganised electrical impulses. The result is an irregular pulse, with no pattern, often fast. It may come and go in episodes (paroxysmal) or settle in for good.

The likelihood rises clearly with age, and high blood pressure, some valve diseases, an overactive thyroid, alcohol, excess weight and sleep apnoea all make it more likely.

How it shows itself — and why it sometimes doesn't

The classic symptoms are irregular palpitations — the feeling that your heart is "doing its own thing" — disproportionate tiredness, breathlessness on efforts that never used to trouble you, or dizziness.

Here is the crucial part: atrial fibrillation can be silent. Many cases are picked up by chance — at a routine check-up, during pre-operative tests — or, sadly, after a stroke. That is why I recommend one simple habit: checking your pulse from time to time and noticing whether it feels regular. And it is why smartwatches and fitness bands have become useful allies: when they flag an irregular rhythm they give us a valuable clue. A clue, mind you — not a diagnosis: confirmation always requires an electrocardiogram (ECG, the electrical tracing of the heart).

What it means: far more than an irregular beat

The risk of stroke

When the atria fibrillate they no longer empty properly, and blood pools inside them, particularly in a small pouch called the atrial appendage; stagnant blood tends to form clots. If one breaks free and travels to the brain, it can block an artery and cause a stroke. That is why it concerns us well beyond its symptoms.

The risk is not the same for everyone: we assess it individually using clinical scores that weigh up age, blood pressure, diabetes and previous cardiovascular disease, and we decide with you the best way to protect yourself.

In atrial fibrillation we are never just treating a rhythm: we are protecting a brain.

A heart that wears itself out

If the arrhythmia runs fast for weeks or months, the heart muscle can weaken — like an engine kept permanently at high revs — and heart failure may develop (the heart loses pumping capacity). Nobody should simply "get used to" living with a racing pulse.

Memory matters too

Several studies describe an association between this arrhythmia and a higher risk of cognitive decline over the years, even without an obvious stroke. Research is ongoing, but the message is the same: it is well worth diagnosing and treating properly.

What we can do: from treatment to lifestyle

We have more tools than ever, and the plan is always tailored to each person:

Anticoagulation. Medicines that make the blood less likely to clot, to prevent those clots that travel to the brain. Not everyone needs it: it is an individualised decision, weighing the risk of stroke against the risk of bleeding, reviewed over time.
Rhythm control or rate control. In some people we try to restore and maintain a normal rhythm (with medication or a cardioversion, which "resets" the heartbeat); in others we accept the arrhythmia but slow it down so the heart can work comfortably. It depends on your symptoms and your preferences.
Ablation. A catheter-based procedure that isolates the areas where the arrhythmia usually starts, around the pulmonary veins. It is a useful option in selected cases, particularly when symptoms persist despite treatment.
Lifestyle — the great ally. Its role is enormous: keeping blood pressure under control, cutting down on or cutting out alcohol, losing excess weight, identifying and treating sleep apnoea, and taking regular, moderate exercise. Looking after all of this reduces recurrences and improves the results of every other treatment.

When to book an appointment — and when to call 112

Book an appointment, without letting it drift, if you notice repeated irregular palpitations, if your watch flags a possible irregular rhythm, or if tiredness or breathlessness have changed without explanation.

Call 112 or go straight to the emergency department if you develop:

Sustained palpitations and feeling generally unwell.
Chest pain or tightness.
Severe breathlessness.
Loss of consciousness (syncope).
Signs of a stroke: weakness down one side of the body, difficulty speaking or a drooping mouth. Here, every minute counts.

The role of your cardiologist: when to get in touch

In my clinic we study atrial fibrillation calmly and with the right tests: an electrocardiogram to confirm it, a Holter monitor (a continuous recording of your rhythm over 24-48 hours) to see how it behaves in everyday life, and an echocardiogram (an ultrasound scan of the heart) to assess the atria, the valves and the strength of the muscle. With all this we build a plan around you — protection against stroke, control of the arrhythmia and of the factors that feed it — and follow it up together over time.

I see patients by appointment in Valencia and Dénia, in English and Spanish; remember that my clinic is not an emergency service: with acute symptoms, the call is always to 112. If atrial fibrillation is already part of your life, or you suspect it might be, don't put it off: diagnosing it early and treating it well is one of the best investments in your heart and your brain. After all, the best medicine is good prevention.

Sources and further reading

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This article is for information only and does not replace individual assessment or advice from a healthcare professional. For acute symptoms such as severe chest pain, call 112.

Atrial fibrillation: what it is and what it means