Elective Cardioversion

What is cardioversion?

Cardioversion simply means getting your heart back into normal rhythm. It can be done as an emergency procedure, with medication, or as a planned (elective) procedure. This leaflet will focus on cardioversion as a planned procedure (Elective Cardioversion) for people with atrial fibrillation/flutter (AF). Elective cardioversion is a simple procedure using an electric (defibrillation) shock across the chest to re-establish the heart’s normal rhythm.

Why do I need cardioversion?

When your heart is beating irregularly in AF, its pumping action may be reduced, which can lead to symptoms such as breathlessness, reduced exercise tolerance and tiredness. Cardioversion is an option if your heart is beating irregularly as it may restore your heart to a regular rhythm.

What are the benefits?

Restoring a regular rhythm can improve symptoms connected to AF.

What are the chances of success?

The success of the procedure varies from person to person. We have the greatest chance of success if you have been in AF for a short time. Your doctor may feel it is worth trying even if it has been irregular for longer. The highest success rates are seen in patients with normal heart structure. The lowest success rates are seen in patients with physical heart abnormalities (e.g. leaking valves or enlarged heart chambers). These aspects should be discussed with your doctor or arrhythmia nurse specialist.

There are no absolute guarantees that the procedure will be successful. Even if the procedure is initially successful, there are no guarantees that your heart will remain in normal rhythm. Generally, we quote a 50:50 chance of you remaining in a normal rhythm one year after the cardioversion treatment.

What are the alternatives?

Some people decide not to proceed with cardioversion if they are not too troubled by symptoms of AF. In these circumstances, heart rate control medication and anti-coagulation is used to manage the condition.

If cardioversion is successful, but AF returns within a short period of time, we may discuss using stronger medication (anti-arrhythmic medication) or referring you for more invasive procedures such as ablation.

What are the risks?

We must by law obtain your written consent to this procedure beforehand. Staff will explain all the risks, benefits and alternatives before asking you to sign a consent form. If you are unsure about any aspect of the treatment proposed, please do not hesitate to speak with a senior member of staff.

• There is a small risk (approximately one in 100) of a major complication, such as a stroke, occurring as a result of the procedure. This risk of a major complication is minimised by ensuring that your blood is adequately ‘thinned’ before the procedure by taking medication such as warfarin, apixaban, rivaroxaban, edoxaban or dabigatran.
• There is a small risk of complication with slow or fast heart rhythms during or after the treatment. The clinicians who carry out the procedure can deal with these. On very rare occasions, some patients require a temporary ‘pacemaker wire’ to be inserted if the heart rate becomes too slow.
• Most patients experience some soreness where the defibrillator pads have been on their chest/back. This is usually minor – similar to sun burn.

The risks of this procedure may be higher in some cases, and this should be discussed with the cardiologist or arrhythmia nurse specialist. You will speak with an anaesthetist prior to the procedure to discuss the anaesthetic and, in some cases, will have an appointment with them before the treatment day if there are specific concerns about anaesthetic.

Before scheduling for the procedure

You will have had a ‘Heart Tracing’ (ECG), an echocardiogram scan (heart ultrasound scan) and been reviewed by the arrhythmia nurse specialist. You will have a chance to discuss any questions you may have about your heart condition and cardioversion before your name is placed on the waiting list. We will aim to keep the amount of time that you are waiting for this procedure to a minimum (weeks rather than months).

Why do I have to be anti-coagulated for the procedure?

When your heart is in AF, it is possible for small clots to form in the heart’s chambers. To reduce the possibility of dislodging these clots when normal rhythm is restored, we need to ensure that you have been taking anti-coagulant medication (warfarin, apixaban, rivaroxaban, edoxaban or dabigatran) without having missed any doses, for a minimum of three full weeks.

It is important to take your medication as prescribed and not miss any doses. If a dose has been missed prior to the cardioversion being undertaken, it is important to inform the arrhythmia nurse specialists via telephone on 01305 254920 (voicemail available).

A missed dose before the cardioversion will increase your risk of a stroke during the procedure so the cardioversion may need to be postponed; this is for your safety.

On the day of the procedure, you will be asked to confirm that you have taken your medication correctly and that you have not missed any doses. If you use warfarin, your INR clinic will measure how thin your blood is by taking a blood test for ‘INR’ on a weekly basis.

Planning ahead

• Cardioversions can be carried out under general anaesthetic or sedation; this is decided with you by the arrythmia nurse specialist at your pre-assessment appointment at Dorset County Hospital. You will need to come in as a day case (overnight stay is rarely needed).
• You will need to arrange for a responsible adult to escort you home and stay with you for 24 hours after the cardioversion.
• Digoxin tablets (not everyone is on this medication) are usually stopped one day before your planned cardioversion date. For example, if the day for cardioversion is a Friday, then the last dose of digoxin will be taken on the Wednesday.
• A letter from the Day Surgery Unit/ Cardiology catheter lab co-ordinator confirming your procedure date. We ask that you have the blood test one week prior to your cardioversion and a blood request form will be given to you at the pre-assessment appointment along with the date to book your blood test
• You will receive a telephone call from the arrhythmia nurse specialist in the week leading up to the procedure. This will be to confirm that your blood tests are satisfactory and to talk through with you preparation for the procedure.

On the day of the procedure (cardioversion)

• Do not apply lotions or ointments to your chest or back. If you have a hairy chest or back, we may need to clip the hair beforehand. If you can arrange for someone to shave your chest and back (left side) that would be helpful.
• Do not eat any food (including chewing gum) for six hours before the procedure time. You can drink clear (preferably water). fluids up to the time of your   procedure
•  Your medications will be discussed with you when the arrhythmia nurse calls you the week leading up to the procedure. Please ensure you have pen and paper to hand to make notes if you wish.
• If you use inhalers for a respiratory condition, please take these at the usual time.
• Bring all medication (including inhalers, if using) and your warfarin book (if you take warfarin) in with you on the day.

If you are diabetic

The arrhythmia nurse specialist with give you specific instructions about your diabetic tablets and/or insulin and what you should do with these on the day you come in. This will depend on what you take and whether the procedure takes place in the morning or afternoon.

Arriving in the Day Surgery Unit/ Cardiac catheter lab

When you arrive you will have a ‘Heart Tracing’, (ECG), be seen by the arrhythmia nurse specialist and day surgery nurses who will check that you are ready for the procedure. You will also be reviewed by the anaesthetist who will describe and discuss the anaesthetic you will receive and consent you for this.

The procedure

The actual cardioversion procedure itself takes very little time. You will be wheeled on a trolley into the theatre and introduced to the team who will be looking after you. The defibrillation pads will be placed on your chest (front and back). The anaesthetic or sedation drugs will be given, usually as an injection through a drip into one of your veins (usually in the back of your hand). you may require some extra oxygen through a mask. If you have any concerns about the anaesthetic or sedation let us know before you attend or discuss with the anaesthetist or the arrythmia nurses before the procedure.

Once the anaesthetic or sedation is working fully, we will attempt to shock your heart back to normal rhythm, using the defibrillation pads on your chest. We will deliver up to a maximum of three to four shocks in total, to try and restore your normal heart rhythm. We sometimes need to change the position of the pads.

What happens afterwards?

You will be taken to the recovery ward and monitored until you wake up. Generally, people wake up within 15 minutes. As soon as you feel able to, and providing your nurse is happy with your condition, you will be allowed to eat and drink.

Another ECG will be taken. We will be able to inform you whether the procedure has been successful or not.

Your medication will be reviewed, and you will be advised if any medication might need to be stopped or reduced. Anti-coagulation must not be interrupted for a minimum period of four weeks following the procedure as this will help to reduce your risk of having a stroke. Continuation of anticoagulation after the 4-week period following your cardioversion will be discussed with you fully on an individual basis at your follow-up appointment but more often than not, it is recommended lifelong

Following the procedure, you may develop superficial soreness where the adhesive pads have been on the chest. The day surgery staff can issue ointment for this but placing cool damp towels on the chest and taking mild painkillers can help ease the discomfort.

Going home

You will usually be allowed to go home once you have fully recovered from the procedure. You will need to plan for someone to drive you home and stay with you for 24 hours. We strongly advise you to spend the remainder of the day quietly at home.

For the next 24 hours you should not drive a car, operate heavy machinery, make any important decisions, or sign any documents.

What about follow-up arrangements?

An appointment will be arranged for you to see the arrhythmia nurse specialist six to eight weeks after the procedure. your need for follow-up will be discussed and arranged for you on an individual basis.

Contact numbers

We hope that you have found this information useful. If you have any questions or are worried about anything, please speak to the arrhythmia nurse specialists on 01305 254920 (voicemail available) or email dch.arrhythmianursespeci@nhs.net

About this leaflet

Authors: Arrythmia nurses
Written June 2017
Updated and approved: Juliet Quick, Arrhythmia Nurse Specialist, July 2026
Review date: July 2029
Edition: v3

If you have feedback regarding the accuracy of the information contained in this leaflet, or if you would like a list of references used to develop this leaflet, please email dch.patientinformation.leaflets@nhs.net.