What is atrial fibrillation ablation?

We us atrial fibrillation ablation to treat arrhythmia (irregular heartbeats). By using a thin electrode catheter to burn heart tissue, we try to stop the faulty electrical signals which cause your arrhythmia. 

This is a keyhole technique (surgery performed through a tiny incision), which directs a small, flexible tube (or catheter) to a specific area inside the heart. Once there, it uses heat energy to damage (or ablate) the abnormally active heart muscle. We normally recommend this treatment if your AF is too difficult to control with medication, if you can't tolerate the medication or of you don't want to take it. 

Sometimes, we recommend atrial tachycardia (AT). It is a more regular, but complex, treatment which uses a similar approach. We only really suggest this procedure, however, if you've had heart surgery, were born with congential heart defects, or have already had an ablation procedure. 

After having a catheter ablation, many patients find their symptoms of AF are reduced or go completely.

Before your ablation

We will let you know before you come to the hospital if there are any medications that you need to stop taking before the procedure and when you leave. This advice varies between patients, but it is to make sure you understand what each of the drugs you need do.

If you are not currently taking warfarin, you will start taking it before your ablation.

If you are currently taking a NOAC, we will ask you to swap this to warfarin unless this is contra-indicated or you are unable to tolerate it. 

You will be taking warfarin for at least six weeks before your planned ablation. You should have weekly INR levels between two and three for at least four consecutive weeks leading up to the procedure. If your levels leading up to your ablation are above or below this range, contact your arrhythmia nurse specialist at once. 

Warfarin should not be stopped for your procedure and will continue following your ablation. We will review this at your outpatient appointment three months after your ablation. 

If you are unable to take warfarin and are taking one a NOAC, you will need to stop taking it before the ablation. You will stop taking it 24 to 36 hours before the ablation, depending on which NOAC you are using.

Continue on all your medications up to your admission date, unless instructed otherwise. On the day of your procedure, we will stop any anti-arrhythmics/beta blockers/calcium channel blockers. This is to avoid bradycardia following the procedure. We may also stop any blood pressure medications the evening before your procedure and on the day of the procedure. This is to avoid hypotension (low blood pressure) during your procedure. 

If you are having your ablation at Harefield Hospital, we may ask you to come to our pre-admission clinic. This is a nurse-led clinic run by the arrhythmia nurse specialist, who will assess that you are fit and ready for your procedure. They will do a routine blood test, physical examination (listening to your heart and lungs), ECG and MRSA swabs. One of the pharmacy team will also see you and check your medication.

Remember to bring details of your past medical history and a list of your current medications. 

We will prescribe you a drug called lansoprazole, if you are not already taking (or similar, such as omeprazole). We will ask you to start taking it one week before the ablation and to carry on taking it for six weeks after. Lansoprazole is a proton-pump inhibitor, which reduces the amount of gastric acid the stomach produces. The ablation takes place in the left atrium, which is very close to the oesophagus (food pipe). This can cause some irritation, which this drug helps to reduce.

When you come in

Regardless of whether you are asked to attend the pre-admission clinic or not, you will be admitted the night before your procedure. Contact the ward on the morning of your admission to check there is a bed available. 

A doctor/arrhythmia nurse specialist will see you and take a full medical history. You will also have a blood test, including your INR levels and make sure you are fit for the procedure. We will start you on lansoprazole if you have not already started taking it or something similar.

We will explain the procedure to you, including any associated and you to sign a consent form.

On the ward 

An anaesthetist will visit you on the ward before the procedure to discuss your anaesthetic. They will need to find out about:

  • your general health
  • prior experiences of anaesthesia
  • medicines you are taking
  • allergies you may have.

If you have caps or crowns on your teeth, tell the anaesthetist as these can anaesthesia can sometimes damage these.

Take your time to talk to them about any previous experiences you have had with injections, hospitals stays or any concerns you have. The anaesthetist who sees you on the ward may not be the same one who gives you the anaesthetic on the day of the procedure. But they will know about your medical history, past experiences and any concerns you may have.

If the anaesthetist finds something such as cold, rash or infection, it could increase the risks of anaesthetic or ablation. If this happens, we may delay your procedure and review the issue.

Eating and drinking

You will need to have an empty stomach before your anaesthetic, so we will not let you eat anything for six hours before you go to the catheter lab. But you will be able to drink clear fluids up to two hours before the anaesthetic.

The procedure

On the day of your procedure you will wait on the ward so you are ready for the ablation. We usually have two to three cases on any given day, but this is based on many factors and is decided by the consultant.

We may give you a sedative (pre-medication) to take before you go to the catheter lab. We give you this to help you relax before the procedure, and it is usually a tablet.

When the cath lab team are ready for you, a nurse from the ward will take you to the cardiology department. They will stay with you until you are taken into the cath lab.

At the cath lab, one of the team will greet and ask you to confirm your name and details, to make sure you are the right person.

In the cath lab

In the lab you will meet all the members of the team for your procedure. Make sure you talk to the members of the team. They understand that you may be anxious about the procedure and are happy to answer any questions you may have.

We will ask you to answer the same questions (name, date of birth, allergies) multiple times, and for female patients if there is any chance they could be pregnant. This is to avoid X-rays harming the fetus.

We will give you a blood-thinning medicine, known as heparin, at the beginning of the procedure to reduce the risk of blood clots forming during ablation. This is something that is done will any ablation procedure as it involved accessing the heart's left atrium.

Whilst the anaesthetic assistant checks your details, we will transfer you onto the cath lab bed. There will be large TV screens surrounding the bed, but this is part of the equipment the team use to carry out the procedure.

A cardiac physiologist will put some stick patches on your back and help you to lie down and get comfortable. These are part of the monitoring equipment we use for the procedure.

The anaesthetist may put a drip into a vein on your hand or arm if you don't have one already. This is how they will give you the anaesthetic to make your sleep during the procedure. You will also be given a local anaesthetic in your wrist, so that a small tube can go into an artery to help monitor your blood pressure.

We will then give you oxygen through a mask, and then the anaesthetist will give you the anaesthetic. Once you are asleep, a tube will be placed in your windpipe, which allows the anaesthetist to support your breathing during the procedure. We will also insert some more intravenous infusion lines (drips).

Under the anaesthetic

Once you are asleep, we will do a transoesophageal echocardiogram (TOE) to exclude a blood clot (thrombus) in the heart. This uses an ultrasound probe (a long thin tube) that placed in your oesophagus (food pipe), which helps with the procedure.

Using ultrasound we will make a detailed scan of your heart. If we see a thrombus, we will stop your procedure and reschedule it after you may had some more blood-thinning medication. The ultrasound probe will also check how well you heart is working during the procedure.

If you have any problems swallowing, make sure that you tell your doctor this before the procedure as it may affect whether we use the probe or not. The TOE may also give you a sore throat and, in very rare cases, may damage the oesophagus.

What happens?

We make small cuts (incisions) at the top of both legs and place three to five small tubes (less than 3mm) into the veins near the groin area. These tubes allow us to pass thin, flexible, specially shaped catheters (electrodes) and other slightly longer sheaths up to the heart. 

We cross the electrical catheters from the right atrium into the left atrium through a small punctured hole made by a special needle. The catheters allow us to take pictures of the pulmonary veins and deliver the radiofrequency energy to the area around the veins. We use an advanced computer system to create a 3D picture of the top of the heart.

We use X-rays, ultrasound images and electrical information coming from the electrodes to assess the electrical activity of each vein before and after ablation.

Ablation describes the process where we use the thin electrical catheter to 'burn' the heart tissue to prevent short circuits occurring. This is like creating "fire breaks" around a forest fire to prevent it from spreading. We continue to ablate until we are sure we have created intact lines of ablated tissue. Like in the forest, if the lines are not complete, the fire can spread. 

When the consultant is satisfied that the pre-planned ablation strategy has been achieved, we will ensure you are in a normal rhythm or reset your heart to sinus rhythm using cardioversion

Once in sinus rhythm, the catheters and sheaths are removed and manual pressure is applied to the entry site at the groin until any bleeding has stopped.

The length of your procedure will vary depending on factors such as how large your heart chambers are and whether you have paroxysmal or persistent AF. We usually find an ablation for paroxysmal AF takes two to four hours, whereas a procedure for persistent AF takes three to six hours.

After the procedure

When your procedure is complete, we will take you back to the recovery room. We will check on you until you are fully awake and ready to return to your ward. Once you are awake and your observations (blood pressure and heart rate) are stable, we will take you back to the ward, where you will spend the night. We will attach to a cardiac monitor to check your heart rhythm and blood pressure. 

We may apply a pressure dressing to the top of your leg, to reduce the risk of bleeding from the vein where the catheters were inserted. For the same reason, you will need to stay in bed for three to six hours being you will able to sit up, then stand and then walk after your procedure.

The following day we will do an ultrasound of your heart (transthoracic echo) in the morning. One of the team will then review this, and if the echo shows everything to be normal, you will be discharged. You will normally be discharged after lunchtime. 

Explain My Procedure: video animation to help guide you through your procedure 

Explain My Procedure uses video animation to help patients understand what their recommended cardiac procedure will involve, the associated risks and benefits, and possible alternatives. You can view this simple video animation on the Explain My Procedure platform to help you further understand what an AF ablation will involve, the associated risks and benefits, and possible alternatives. To find out more about Explain My Procedure, click here

Click on the 'Information' tab for more information about what to expect after your procedure, and other ablation procedures. 

Atrial tachycardia is an abnormal heart rhythm which is usually seen in patients that have undergone heart surgery, have congenital heart defects or have undergone previous ablation procedures.

Atrial fibrillation is an abnormal heart rhythm. It is the most common heart rhythm disorder in the UK.

What to expect

Immediately after your ablation

You may experience a:

  • sore throat
  • tenderness around the groin site
  • some chest discomfort
  • some AF or atrial tachycardia (AT). An AT is faster than normal heartbeat, which feels regular in nature and can occur following an AF ablation.

When you get home

  • You should not drive for two days and avoid any heavy lifting or strenuous exercise for at least two weeks.
  • You might feel tired after your ablation and for the first week or so. This is due to having a long procedure under a general anaesthetic. 
  • Your groin site may remain tender for a few days/weeks and you may develop some bruising around the puncture site. This bruising can spread up or down your leg and can take several weeks to go away. 
  • You have been through a procedure and your heart will need time to recover. Your heart will be inflamed and irritated. This is normal and means that you may experience episodes of AF/AT. It does not mean your ablation has been unsuccessful. 

The first three months of your recovery are called the "blanking period". You do not need to attend your local A&E unless you feel unwell, but contact the arrhythmia helpline in normal working hours to let us know.

We recommend that you treat your AF the way you did before your ablation or as you have been told when we discharged you.

The benefits

The main benefit is to attempt to abolish your AF/AT and symptoms associated with it. If this happens, it may be possible to reduce/stop some of the medicines you are currently taking. 

This is often a very personal decision and your doctor will discuss this with you before and after your procedure.

Success rate

Your success rate will depend on the type of AF you have (paroxysmal or persistent), how long you have had AF and factors such as the size of your left atrium.

Paroxysmal AF

If you have paroxysmal AF your success rates are around 60 to 70 per cent with one procedure. It increases to around 80-90% with multiple procedures (two, or, on rare occasions, three).

Persistent AF

If you have persistent AF your success rates are around 40 to 50 per cent with one procedure. This increases to around 80 per cent with multiple procedures (two or more).

Your success rates may be lower if you have been in AF for a long time and have a large left atrium.

In a small percentage of patients, it may be difficult to achieve long-term sinus rhythm and we may have to choose a rate control strategy.


Any medical procedure carries with it a certain amount of risk. Remember that your doctor would not have recommended this procedure to you unless they felt the benefits outweighed the risks.

The risk of suffering any complication from this procedure is around three to five per cent. Some complications are minor, such as bruising, while others may be more serious, such as bleeding around the heart, which we would treat.

As a comparison, the risk of life-threatening bleeding while on warfarin is around one to two per cent per year. This would mean that out of 100 people taking warfarin, one or two will suffer major bleeding which requires urgent treatment. The success and risks of the procedure will depend on individual factors and it is important to discuss your individual case.


Complications can include:

  • Bleeding or bruising in the area of the groin where the catheter was inserted
    This is the most common complication from the procedure and is not normally serious, affecting only 1 per cent of patients. You will need to keep your leg straight for a few hours after the procedure to minimise the risk of bleeding. When you leave hospital, avoid any strenuous physical activity or heavy lifting for at least one week. Sometimes the vessels in the legs can be damaged and need a procedure to repair them.
  • Atrial arrhythmia
    After ablation, you might have a faster but regular heart rhythm from the atria (atrial tachycardia). This may feel worse than AF but often settles in the first few months after an ablation. If not, you may need a cardioversion (electric shock treatment to restore a normal rhythm) or another ablation. 
  • Stroke
    This is an uncommon complication occurring in approximately 0.5 per cent of patients undergoing catheter ablation. This may occur during the procedure if a small blood clot or air bubble passes to the brain. You are given heparin during the procedure which helps to reduce the risk of blood clots. 
  • Phrenic nerve injury
    Catheter ablation next to the right upper pulmonary vein may occasionally result in damage to the nerve which runs near the heart. This nerve supplies part of the main breathing muscle, known as the diaphragm. If this occurs, it may lead to breathlessness, particularly when bending forward or swimming. Significant phrenic nerve injury happens to less than 1 per cent of patients. Full recovery of phrenic nerve function occurs without treatment in the vast majority of cases, but your doctor will follow up on this.
  • Bleeding around the heart
    Sometimes the catheters used for the ablation can make a small hole in the heart during the procedure and cause bleeding. This is usually drained under local anaesthetic with a needle. It occurs in around 1 to 2 per cent of patients having this procedure. Occasionally, surgery will be needed to remove blood which has collected around the heart and repair the hole.
  • Narrowing of the pulmonary veins
    Ablation is performed very close to the pulmonary veins and sometimes veins react to this and become severely narrowed or even blocked. This does not usually cause any symptoms immediately. But, it is possible to cause breathlessness, recurrent chest infections or a blood-stained cough. Although symptoms from this complication are rare (0.5 per cent), they can be very difficult to treat. This is usually treated by placing a stent in the vein. 
  • Damage to the native conduction system
    The risk of damage to your normal electrical system, resulting in the need for a pacemaker, is less than than 0.5 per cent. When the AF/AT stop, your heart's ability to pace itself naturally may not work as well. A pacemaker may be recommended but this is due to an underlying problem rather than a complication of ablation. 
  • Infection or damage to the valves inside the heart
    Infection or damage in the heart or heart valves (known as endocarditis) is a very rare yet recognised complication following catheter ablation. The estimated risk of this is approximately 1 in 10,000 patients (0.01 per cent). This is usually treated with antibiotics, but sometimes surgery is needed.  In rare cases, a valve in the heart may be damaged from the ablation or one of the catheters becoming entangled in the valve. This usually requires no treatment but may need surgery.
  • Damage to the food pipe
    Rarely, ablation from inside the heart can damage the food pipe, which is next to the heart. This can lead to infection, strokes or even death. Surgery is often needed to treat this problem. The ultrasound probe as its passed down can also damage the food pipe; it usually recovers on its own but rare in cases needs surgery. 
  • Collapsed lung
    If a tube is placed underneath the collarbone, sometimes the lung can be nicked by the needle leading to it deflating. This often gets better on its own but sometimes needs a drain to re-inflate the lung. 
  • Chest infection
    An associated chest infection or fluid on the lungs may develop after the procedure and could need treatment with medication.
  • Other risk
    It's not possible to list all possible complications but they are very rare. Please discuss any concerns you have with your doctor.

Other ablation procedures

For some patients, there may come a point where a rhythm control strategy (using tablets and/or AF ablation) has not worked. This means that the patient will have permanent AF, but this arrhythmia status can be lived with for many years.

Atrial fibrillation means you have an irregular heartbeat, but many of the symptoms are caused by electrical impulses from the atria to the ventricles transmitting too quickly.

The atrioventricular (AV) node is usually the only path which the electrical impulses can pass from the atria to the ventricles.

Medications can help control this by slowing down the transmission of electricity at the AV node, but is not always enough. One option is to perform an ablation at the AV node and permanently stop the transmission of electrical impulses from the atria to the ventricles. This means the atria will continue to be in fibrillation but that the ventricles will be beating too slowly. A pacemaker would be needed then.

In this situation, patients who already have a permanent pacemaker are protected from a very slow heartbeat because the pacemaker takes control. But for patients who don't have a pacemaker, an ablation will not be able to be done until a pacemaker is implanted. This can be done sometimes on the same day or a few weeks before the ablation is meant to take place. All patients who need AV-node ablation will need to have a pacemaker for the rest of their lives.

If you and your consultant decide that this is the right procedure for you, it will usually take place under a local anaesthetic. There will be a single sheath placed in the vein in your groin and an ablation catheter passed into your heart. The AV node is then found and the area will be ablated.

With this procedure, you will have a pacemaker for the rest of your life, but you will have a consistent and regular heartbeat. The staff at your pacing clinic will ensure there is no impact on pacemaker function during or after the procedure.

Other cath lab procedures

There are other procedures that happen in the cath lab, such as cardioversion. For example, if there is a problem with your anticoagulation medication and this makes you unwell, your consultant may place a small 'plug' in the left atrial appendage. This then prevents a blood clot forming in your heart.

These devices are placed in a similar procedure to an AF ablation. We use the same veins in the leg and cross from the right side to the left side of the heart in the atria.

Using transoesophageal echocardiogram (TOE), we place the plug in the appendage and check its stability. When it is securely in place, the catheter is removed leaving just the plug in position.

Contacting the arrhythmia nurse specialist

You should contact your arrhythmia nurse specialist if you have:

  • Hard swelling around your groin site that was not there before your discharge.
  • New or increased breathlessness.
  • New or increased chest pain.
  • If you are having frequent AF episodes and need a medication review
  • If you experience AF which does not settle after a few days. A small percentage of patients may need cardioversion within the first three months. But this does mean your ablation has been unsuccessful.

If you feel very unwell, see your GP or go to A&E. 

Stopping medications 

Your medication will be reviewed at your first follow-up appointment, three months after your procedure.

We will not stop you taking warfarinNOAC if we think the risk of you having a is significant. This is because an AF ablation is not a cure and, if your AF recurs at some point in the future, you are more protected from a stroke. 

We will reduce your anti-arrhythmic drugs and stop them at your first appointment if you have been well. We will also review your beta blockers and calcium channel blockers at three months. These will be reduced and/or stopped unless you have other indications to continue these long term. 

If you stop taking anti-arrhythmic medications after your first appointment, we will review it at your next appointment.

Follow up

You will have a follow-up appointment three months after your ablation either at Royal Brompton Hospital, Harefield Hospital or your local hospital. 

If your appointment is at Royal Brompton Hospital or Harefield Hospital you will see one of the members of the arrhythmia team.

Arrhythmia team

The arrhythmia team includes: 

  • EP consultants
  • clinical nurse specialists
  • an arrhythmia pharmacist 
  • catheter laboratory technicians.  


Clinical nurse specialists

  • Natalie Crump 
  • Sue King
  • Sarah Plowright 
  • Alex Wise 

Arrhythmia pharmacist


Harefield Hospital
01895 828979

Royal Brompton Hospital
020 7351 8364 

Useful links

If you want to know more about arrhythmia, here are some helpful organisations and websites: