Atrial fibrillation (AF) is one of the most common heart rhythm problems in the UK, affecting around 1.4 million people. Many live with it for years without a diagnosis. If you have been told you have AF, or you think you might, this article explains what it is, what causes it, and how you may be able to take part in a clinical trial to help develop better treatments.
What Is Atrial Fibrillation?
Your heart beats regularly because of a controlled electrical system. In a healthy heart, signals travel in an orderly way, causing the upper chambers (the atria) and lower chambers (the ventricles) to contract in sequence. This keeps blood moving efficiently around the body.
In atrial fibrillation, the electrical signals in the atria become disorganised and fire off randomly. Instead of contracting properly, the atria quiver rather than pump. The lower chambers still receive signals, but they arrive irregularly, leading to an uneven heartbeat that is often faster than normal.
AF is not always dangerous on its own, but it raises the risk of serious complications, particularly stroke and heart failure. Because the atria are not pumping properly, blood can pool inside them and form clots. If a clot travels to the brain, it can cause a stroke. For this reason, it is important to get AF diagnosed and managed as early as possible. You can read more about symptoms, diagnosis, and treatment on the NHS atrial fibrillation page.
Types of Atrial Fibrillation
AF is described in three main ways depending on how long episodes last and whether the rhythm returns to normal on its own.
| Type | What it means |
| Paroxysmal AF | Episodes come and go, usually stopping within 48 hours without treatment. |
| Persistent AF | The irregular rhythm lasts longer than seven days and needs treatment to correct. |
| Permanent AF | The irregular rhythm is ongoing and is managed rather than corrected. |
Symptoms and Causes
Some people with AF have no symptoms at all and only discover the condition during a routine check-up. Others notice palpitations (a fluttering, pounding, or racing heartbeat), unusual tiredness, shortness of breath, dizziness, or chest discomfort. Symptoms can come and go, which is one reason AF is often missed for a long time. If you experience any of these, speak to your GP, who can carry out an electrocardiogram (ECG) to check your heart rhythm.
There is not always a single clear cause. Common risk factors include older age, high blood pressure, other heart conditions such as coronary heart disease or heart valve problems, an overactive thyroid, and lifestyle factors such as heavy alcohol use or being overweight. In some cases, particularly in younger people, no clear cause is found at all.
How Is AF Treated?
There is currently no cure for AF, but several treatments can help to control symptoms and reduce the risk of complications. The right approach depends on the type of AF, how much it affects daily life, and a person’s overall health.
Rate control medication slows the heartbeat to a safer level, usually using beta blockers or calcium channel blockers. Rhythm control aims to restore a normal heart rhythm, either with medication or a procedure called cardioversion, which uses a controlled electrical shock to reset the heart. Anticoagulants (blood thinners) are often prescribed alongside these treatments to reduce the risk of blood clots and stroke. For some people, catheter ablation is an option, where the areas of the heart causing the abnormal signals are targeted directly.
Ongoing research is exploring whether new approaches can improve outcomes, particularly for people whose AF is not well controlled by existing treatments.
Why Clinical Trials Matter
Clinical trials are how researchers find out whether new treatments are safe and effective. Without people willing to take part, new medicines and procedures cannot be tested, developed, or approved for wider use.
For AF specifically, researchers are still working to understand how to better predict who will develop the condition, how to choose the most effective treatment for each individual, and how to lower the long-term risk of stroke and heart failure. Every person who takes part in a trial helps to move that research forward.
Taking part gives you access to a new treatment before it becomes publicly available, with careful monitoring from an experienced medical team at every stage. Trials at 4MCS are unpaid, though reasonable travel expenses to and from our facilities are covered.
At 4MCS, we have over 130 years of combined experience in clinical research and a database of over 35,000 participants. We are MHRA-approved and run trials from our sites in Ilford (London) and Swinton (Manchester).
Could You Qualify?
Each trial has its own eligibility criteria, which are the specific conditions a person must meet in order to take part. For an AF trial, typical requirements include a confirmed AF diagnosis and either not currently taking medication for it, or having tried medication that has not provided enough relief. Age and general health will also be taken into account.
You can find full details about our current atrial fibrillation clinical trial, including eligibility criteria and how to register your interest. If you are not sure whether you qualify, the best thing to do is get in touch and our team will talk you through it.
- If you would like to understand more about how trials work before making contact, our guide on how to take part in clinical research in the UK explains the full process from first contact through to screening and participation.
