Health condition
Cardioversion: what to expect
Electrical cardioversion resets an abnormal heart rhythm - usually atrial fibrillation or flutter - back to normal with a controlled shock under brief sedation. It takes minutes and you go home the same day.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.
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Who it suits: people with persistent AF or flutter, to restore normal rhythm and see how much better it feels - often as part of a longer-term rhythm strategy
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Anticoagulation rules are strict: the shock is only safe with at least three weeks of uninterrupted anticoagulation beforehand (or a clot-excluding scan) - never skip doses before the procedure
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Specialist: a consultant cardiologist usually leads assessment and treatment
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The procedure: fasting, a short general sedation, one or more synchronised shocks through pads on the chest, monitoring for an hour or two, then home with a driver
Understanding the condition
What it is and what happens next.
What causes it, how it is diagnosed, and the treatment routes available in the UK.
What it is and how it feels
The shock is synchronised to your heartbeat and delivered while you are fully sedated - you feel and remember nothing. Success at restoring normal rhythm on the day is high, though whether it holds depends on how long AF has been established, your heart’s structure, and treatment of drivers such as blood pressure, alcohol and sleep apnoea.
Diagnosis and treatment routes
Cardioversion is often a diagnostic as well as therapeutic step: feeling dramatically better in normal rhythm makes the case for a maintenance strategy - rhythm-control medication or ablation - while feeling no different reshapes the plan. Your cardiologist will frame it as part of that bigger rhythm decision, not a standalone cure. In many parts of the UK, routine NHS referrals for this kind of problem currently take 20-45+ weeks, whereas an initial appointment with a private consultant is typically available within around two weeks.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a consultant cardiologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.
Frequently asked
Common questions about Cardioversion: what to expect.
Quick, plain-English answers to what people ask us most.
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What is cardioversion?
Cardioversion is a procedure used to restore a normal heart rhythm in people with certain abnormal heart rhythms, most commonly atrial fibrillation or atrial flutter. It can be done electrically, using a controlled electric shock under sedation, or with medication (pharmacological cardioversion). The aim is to reset the heart's electrical activity back to a regular pattern.
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Why would I need cardioversion?
It is used when an abnormal heart rhythm is causing symptoms such as palpitations, breathlessness or fatigue, or when restoring normal rhythm is felt to reduce longer-term risks. It may be planned in advance or, occasionally, performed urgently if the rhythm is causing significant instability. Your cardiologist will explain why it is being recommended in your specific case.
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What happens during the procedure?
For electrical cardioversion, you are given a short-acting sedative so you are not aware during the brief procedure, and a controlled shock is delivered through pads on the chest to reset the heart's rhythm. It usually takes only a few minutes, though you will be monitored for a period afterwards. Most people go home the same day.
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Is cardioversion safe?
Yes, it is generally a safe and well-established procedure, though there is a small risk of a blood clot being dislodged from the heart, which is why blood-thinning medication and sometimes a heart ultrasound (to check for clots) are used beforehand for planned procedures. Serious complications are uncommon with proper preparation. Your team will assess your individual risk beforehand.
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Will cardioversion cure my arrhythmia permanently?
It restores normal rhythm at the time of the procedure, but it does not address the underlying cause of the arrhythmia, so the abnormal rhythm can return, particularly with conditions like atrial fibrillation. Ongoing medications or additional procedures such as catheter ablation are often needed to maintain normal rhythm longer term. Your cardiologist will discuss a plan to reduce recurrence.
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What is the recovery like?
Most people recover very quickly and go home the same day, sometimes with mild chest discomfort from the procedure itself. Blood-thinning medication is often continued for some weeks afterwards to reduce clot risk. You will usually have follow-up to check the rhythm has remained stable.
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When should I discuss cardioversion with a specialist?
If you have a diagnosed abnormal heart rhythm causing symptoms, ask your cardiologist whether cardioversion is appropriate for you. NHS cardiology referral and procedure scheduling can take several weeks; a private cardiology consultation is typically available within about 2 weeks to discuss options sooner.