We use 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

You will have a video or telephone appointment booked with one of the arrhythmia clinical nurse specialists who will assess that you are fit and ready for your procedure. In advance of this appointment you will be asked to watch a video and to read the procedure specific consent form. Please write down any questions and we will go through them during your appointment. You will also have to attend the hospital for routine blood tests, echocardiogram (ECG) and swabs a few days before admission.

If you are not currently taking warfarin, you will be asked to start this before your ablation. You should be taking warfarin or a direct oral anticoagulant (DOAC) for at least 4 to 6 weeks before your planned ablation.

If you are taking warfarin, we recommend that you have weekly INR levels between 2 and 3 for at least 4 consecutive weeks leading up to your ablation. If your levels leading up to your ablation are above or below this range, you should immediately contact your anticoagulation clinic and the arrhythmia nurse specialist.

Warfarin / DOAC should not be stopped for your procedure and will continue following your ablation. This will be reviewed at your outpatient appointment 3 months after your ablation.

You should continue all your medications up to your admission date, unless instructed otherwise. On the day of your procedure we will omit medication such as your antiarrhythmics / beta blockers / calcium channel blockers. This is to avoid bradycardia following the procedure. We may also withhold any blood pressure medications on the evening before your procedure and on the day of procedure. This is to avoid hypotension (low blood pressure) during your procedure.

Your admission

You will be asked to contact the ward the day before your admission to check there is a bed available. If there is a bed available, you will be admitted the morning of your procedure.

On the morning of the procedure, you will be seen by a doctor or arrhythmia nurse specialist who will ensure that you remain fit for your procedure. The procedure will be explained to you in detail, including the associated risks, and you will be asked to sign the consent form if this hasn’t been done in your pre-admission appointment.  

You should bring with you all the medications you are taking, ideally in their original packaging.

The procedure

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 atrial fibrillation. We usually find an ablation for paroxysmal AF takes around two hours, whereas a procedure for persistent AF can take 3 to six 6 hours.

The procedure will take place in a catheter lab (cath lab). The 'catheter' in cath lab refers to the small tubes we pass into the body to perform some procedures. If you have any concerns, please talk to a member of the catheter lab team. They will be happy to answer any questions you have.

In the cath lab

In the lab you will meet all the members of the team for your procedure. If you have any questions, the team will be happy to answer them. 

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 involves accessing the heart's left atrium.

While we check your details, we will transfer you onto the cath lab bed. There will be large TV screens surrounding the bed, which are part of the equipment the team uses to carry out the procedure.

A cardiac physiologist will put some sticky 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 will explain what they are going to do. They will place a small needle (cannula) into the back of your hand or in your arm which will allow them to deliver the medication needed for a general anaesthetic. A small needle will also be inserted into one of the arteries in your wrist to closely monitor your blood pressure during the procedure.

Under the anaesthetic

Once you are asleep, we will do a transoesophageal echocardiogram (TOE) to exclude a blood clot (thrombus) in the heart. The TOE uses a long thin tube that is placed in your oesophagus (food pipe). If we see a blood clot, we will be unable to carry out the procedure and it will be rescheduled. 

During the ablation

During the procedure, we place 3 to 4 small tubes into the veins at the top of your leg, near the groin area. These tubes allow us to pass thin flexible electrical catheters and other slightly longer sheaths up to the heart. 

We cross the electrical catheters from the right side of your heart into the left side through a small punctured hole and use a computer system to create a 3D picture of the top chamber (atrium) on the left side of the heart.

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. Just 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, if required.

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.

After the procedure

When your procedure is complete, you will be taken to the recovery room. Once you are awake and your blood pressure and heart rate are stable, you will be taken back to the ward. You will be attached to a cardiac monitor to check your heart rhythm and blood pressure.

You may require an ultrasound of your heart (transthoracic echo) before you are discharged, which will be on the same day or the next day. 


Immediately after your ablation, you may experience:

  • a sore throat
  • tenderness around the groin site
  • some chest discomfort
  • some atrial fibrillation 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 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. The 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. 

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

You do not need to attend your local A&E unless you feel unwell. 

When to contact your arrhythmia nurse specialist

  • hard swelling around your groin site that was not there prior to discharge
  • new or increased breathlessness
  • new or increased chest pain
  • if you are having frequent AF/AT episodes and need a medication review
  • if you experience AF/AT which does not settle after a few days. A small percentage of patients may require a cardioversion within the first three months, but this does not mean your ablation has been unsuccessful.

Your medication

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

Your warfarin or direct oral coagulant will not be stopped if your stroke risk is considered significant. This is because an AF ablation is not a 100 per cent curative treatment, and, if your AF recurs at some point in the future, medication will help prevent a stroke.

Your anti-arrhythmic drugs may be reduced and stopped at your first appointment if you have been well. Beta blockers and calcium channel blockers will also be reviewed at three months and will be reduced and / or stopped, unless you have other indications to continue these long term. If you stop taking antiarrhythmic medications after your first appointment, this will be reviewed at your next appointment.

Further information

Click on the 'Information' tab above to find out about:

  • the benefits of an ablation
  • the risks and complications associated with an ablation
  • other ablation procedures
  • the arrhythmia team


Harefield Hospital
01895 828979

Royal Brompton Hospital
020 7351 8364 

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.

Benefits of an ablation 

An ablation attempts to stop your AF/AT and any 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:

  • (1-2 in 100) risk of tamponade (bleeding around the heart) that needs urgent drainage and may require a blood transfusion
  • (1 in 200) risk of stroke
  • (1 in 100) risk of peripheral vascular damage (damage to the veins in your groin), as we have to access your heart through your femoral veins.
  • (1 in 200) risk of pulmonary vein stenosis (narrowing of the veins we treat during the procedure), which may cause breathlessness
  • (1 in 200) risk of AV nodal damage (your natural pacemaker that stimulates the heart to pump) that requires an artificial pacemaker
  • (1 in 200) risk of phrenic nerve palsy (the nerve that is responsible for our diaphragms) which may cause breathlessness
  • (1 in 500) risk of cardiac surgery
  • (1 in 1000) risk of death
  • (1 in 1000) risk of damage to the oesophagus (food pipe)
  • (1 in 10,000) risk of endocarditis (infection of the heart valves) or damage to valves
  • 5–10 per cent risk of developing an atrial tachycardia (abnormal fast regular rhythm from the atria)

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 cannot be carried out until a pacemaker is implanted. This can sometimes be done on the same day or a few weeks before the ablation is due to take place. All patients who need AV-node ablation will need to have a pacemaker for the rest of their lives.

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.

Find out more about pacemaker implantation

Arrhythmia team

The arrhythmia team includes: 

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


Clinical nurse specialists

  • Beatrice Moloce, Royal Brompton Hospital
  • Harriet Fisher, Royal Brompton Hospital
  • Sue King, Harefield Hospital
  • Sally Deane, Harefield Hospital

Arrhythmia pharmacist

  • Carol Hayes


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: