Atrial Fibrillation Specialist in London

What is atrial fibrillation?

Atrial fibrillation (AF) is the most common sustained heart rhythm disturbance, affecting more than a million people in the UK. Instead of beating in a regular, coordinated way, the upper chambers of the heart quiver chaotically, producing an irregular and often rapid pulse. Some people feel this clearly; others discover it only on a routine check or after a stroke, which AF makes around five times more likely if untreated.

AF can be paroxysmal (coming and going), persistent (lasting more than a week) or permanent. While it is rarely immediately dangerous, untreated AF increases the risk of stroke, heart failure and reduced quality of life. The good news is that modern treatment, including catheter ablation, can restore normal rhythm in the majority of suitable patients and dramatically reduce long-term risk.

Symptoms and when to see a specialist

Symptoms vary widely. Some patients are floored by breathlessness and palpitations at the slightest exertion, while others have no symptoms at all. Any irregular pulse, unexplained tiredness, breathlessness or episodes of a racing heart deserve specialist assessment, particularly if you have high blood pressure, sleep apnoea, diabetes or a family history of heart disease.

• An irregular or "fluttering" heartbeat at rest
• Sudden episodes of a racing pulse, sometimes with dizziness
• Shortness of breath on exertion or when lying flat
• Unusual fatigue or reduced exercise tolerance
• Chest discomfort, light-headedness or near-fainting episodes
• An irregular pulse detected by a smartwatch, GP or routine ECG

Our approach

Dr Ahran Arnold is a consultant cardiologist and electrophysiologist with a specialist interest in atrial fibrillation, atrial flutter and supraventricular tachycardias. He performs catheter ablation and device implantation at Hammersmith and Charing Cross Hospitals, and at OneWelbeck Heart Health on Welbeck Street. As a senior academic at Imperial College London, his practice is built on the latest evidence in rhythm control, stroke prevention and contemporary ablation techniques, including pulsed-field ablation where appropriate.

Every consultation begins with listening carefully to your story, reviewing your ECGs and any wearable data, and explaining the options in plain English. For some patients, careful medication and lifestyle change is the right path; for others, early ablation offers the best chance of long-term freedom from AF. Decisions are always shared, and you will leave with a clear written plan.

Tests we may recommend

A thorough AF work-up confirms the diagnosis, looks for reversible causes and quantifies the risk of stroke. Most tests can be arranged on the same visit at OneWelbeck, and results are usually available within a few days.

• 12-lead ECG and ambulatory rhythm monitoring (24-hour, 7-day or implanted loop recorder)
• Echocardiogram to assess heart structure and function
• Cardiac MRI where additional detail of the atria or ventricles is needed
• Blood tests including thyroid function, kidney function and lipids
• Exercise testing where exertional symptoms predominate
• Formal stroke-risk (CHA2DS2-VASc) and bleeding-risk assessment