Atrial fibrillation

What is Atrial Fibrillation?

This is an abnormal heart rhythm due to electrical short circuits in the upper chamber of the heart (left atrium) and adjoining pulmonary veins (connected to the back of the left atrium), resulting in a rapid and irregular heartbeat. Some people affected by Atrial Fibrillation may not feel any symptoms at all, while others can experience palpitations, breathlessness and/or tiredness. It can also cause heart failure, dizziness or blackouts in some people. Ineffective circulation of blood in the heart due to Atrial Fibrillation may lead to blood clot formation; blood clots can travel from within the heart to the brain, thus causing stroke.

Atrial Fibrillation from Khan Academy.

Atrial Fibrillation is a benign condition aside from the risk of stroke. There are rare exceptions where Atrial Fibrillation may be harmful. Your doctor will discuss this with you.

How does Atrial Fibrillation occur?

The majority of patients with Atrial Fibrillation will have an otherwise healthy heart on testing. There are some contributory factors to developing Atrial Fibrillation. Treating and/or reversing these risk factors may reduce the burden and symptoms of Atrial Fibrillation in affected people.

These factors include:

  • high blood pressure
  • previous heart attack
  • increasing age
  • thyroid abnormalities
  • alcohol
  • endurance sports
  • obesity
  • sleep apnoea (snoring)

What are the treatment priorities for Atrial Fibrillation?

There are two main issues to address in treating Atrial Fibrillation.

  • Stroke risk. This is minimised by using blood thinning medications, which act by preventing blood clots in the heart. A risk assessment for stroke due to Atrial Fibrillation will be calculated. If your risk is high, your doctor may recommend Warfarin or one of the newer agents (novel oral anticoagulant, or NOAC). This risk is independent of your symptoms or treatment choice for symptoms in Atrial Fibrillation.

  • Symptoms due to a fast and irregular heart beat. Some treatments act merely to slow the heart rate down (referred to as rate control), which is often sufficient to treat palpitations and dizziness. Some treatments aim to restore the heart to a normal rhythm (referred to as rhythm control), which can be more difficult to achieve, but is necessary in some people with severely symptomatic Atrial Fibrillation.

What are the treatment options for Atrial Fibrillation?

There are a number of options available to control the symptoms of Atrial Fibrillation.

  1. Medications. Tablet treatments can be used for either rhythm control or rate control strategies; the aim is to reduce the frequency and severity of your symptoms. Medications are effective in many patients but do not cure this condition. If you choose this option, it is likely that you will need medications lifelong. All medications come with side effects and your doctor will discuss these with you.

  2. DC Cardioversion. This is a treatment to revert Atrial Fibrillation back to a normal rhythm by delivering an electric shock under brief general anaesthesia. This is an effective treatment, although at least half of those who undergo an initially successful cardioversion will have another episode of Atrial Fibrillation over the next year. Therefore, many patients also require medication to prevent a recurrence of Atrial Fibrillation after this treatment.

  3. Radiofrequency ablation. This is a procedure performed by an Electrophysiologist to provide a potential "cure" for Atrial Fibrillation and is described in detail in the following sections.

  4. Pacemaker and AV Node Ablation. These two procedures are offered to patients who have debilitating symptoms where medications fail to work and radiofrequency ablation to cure Atrial Fibrillation is unsuitable. These two procedures do not cure Atrial Fibrillation but are very effective in controlling symptoms. This is usually undertaken in two separate procedures by an Electrophysiologist and is explained separately in the AV Node Ablation section.

How do I prepare for Atrial Fibrillation ablation?

Please refer to the section on EPS. You would usually continue your Warfarin uninterrupted before, during and after the procedure; you should clarify this with your Electrophysiologist, especially if you are taking a different blood-thinning medication.

Before the procedure, a CT scan of your heart may be performed. This will then be used during your ablation procedure.

You will need a trans-oesophageal echocardiogram to exclude the presence of any preformed clots within your heart. This may be done the day before the procedure or at the start of the procedure depending on whether your ablation is performed under general anaesthetic.

The procedure can be carried out under general anaesthetic or local anaesthetic with sedation. The approach to anaesthetic is tailored to individual patients.

How is Radiofrequency Ablation performed for Atrial Fibrillation?

Please refer to the section on EPS on how EPS is performed. Following the EPS, catheters would be placed in your left atrium because Atrial Fibrillation originates from the left atrium. A long needle will be used to cross from the right to the left side through a thin membrane. This is a routine procedure called transeptal puncture.

Cardiac Ablation for Atrial Fibrillation from Biosense Webster.

A map of your left atrium with the pulmonary veins will be created using a 3-dimensional navigation system. The system also helps identify the location of the catheters used to perform the ablation inside the left atrium. Atrial Fibrillation usually starts from the pulmonary veins (usually 4) connected to the back of the left atrium. Radiofrequency ablation is performed in continuous lines to encircle and therefore electrically isolate the pulmonary veins. If you have persistent Atrial Fibrillation, further ablation may be required within your atria. Usually 30-60 minutes of ablation is required.

The entire procedure may take 3-4 hours.

What is the success rate for ablation for Atrial Fibrillation?

The success rate of ablation for paroxysmal Atrial Fibrillation (which starts and stops by itself within 7 days) is approximately 80-90%. In up to 1 in 3 patients, it may be necessary to perform a second procedure to achieve that result. 10-15% of patients may continue to experience Atrial Fibrillation even after 2 procedures.

The success rate for ablation for persistent Atrial Fibrillation (which continues for more than 7 days) is approximately 70%. In up to half of patients, it may be necessary to perform a second procedure to achieve that result. 30% of patients may continue to experience Atrial Fibrillation even after 2 or even 3 procedures. If you have been in Atrial Fibrillation continuously for more than a year, the success rates may be lower.

Your Electrophysiologist will usually ask you to resume the medications you were taking from before the procedure as ablation success may not be apparent for several months.

You would usually be asked to continue to take your blood thinning medications if you were on them before the procedures regardless of the success of the procedure. The decision to continue or cease blood thinning medications are discussed on an individual basis. With this in mind, the decision to undertake ablation for Atrial Fibrillation is primarily for symptom control.

What are the risks of Atrial Fibrillation ablation?

Ablation for Atrial Fibrillation is a common procedure and has been routinely performed for over two decades. Most patients who undergo ablation for Atrial Fibrillation do not experience any complications but you should be aware of the following risks. In general, it has been estimated that the risk of any complications is between 4 and 6%. This includes:

  • Blood vessel problems: bleeding, bruising, damage to the vessel wall, abnormal connections and blood clots can form in the blood vessel in your groin or higher up near or in the heart. Usually these settle by themselves, but sometimes medications, injections or small operations are required to fix them.
  • Abnormal heart rhythms: these are deliberately provoked during the procedure, but can become unstable requiring an electric “shock” to restore a normal heart rhythm. There is a very small risk of requiring a pacemaker if the normal and necessary electrical system of the heart is damaged.
  • Perforation: there is a very small chance of causing a leak of blood around your heart. This usually settles without treatment but can also be dealt with by inserting a drain from the chest wall.
  • Pulmonary vein narrowing: This is very rare using modern technology and techniques. Nonetheless, it can cause breathlessness if severe and affects multiple pulmonary veins.
  • Phrenic nerve damage: This nerve controls breathing muscles, though damage to this usually causes no symptoms at all and the damage usually recovers within 1 year in any case.

Major and life-threatening complication risks are quoted as up to 1%, which includes:

  • Stroke: Most affected by stroke have only transient symptoms, though 0.3% of all people undergoing Atrial Fibrillation ablation have persistent symptoms.
  • Heart attack: This is exceedingly rare, affecting less than 0.1%.
  • Gullet damage: This can be damaged either directly by the trans-oesophageal probe, or by ablation injury due to the close proximity of the gullet to the left atrium and pulmonary veins. This is an exceedingly rare life-threatening complication affecting 0.1%.

What happens after the Atrial Fibrillation ablation?

You will be required to lie flat for 4-6 hours. You may have a compression clamp over your groin area during this time. Your nurse will check on you to see if there is bleeding or swelling at the groin site. Most people can start eating and drinking water within 4-6 hours after the procedure. Most patients stay in the hospital for either one or two nights and their heart rhythm may be monitored. Your Electrophysiologist may stop, switch or commence you on new medications after the procedure. Your blood thinner will be recommenced and you may receive an additional blood-thinning medication as an injection in your belly. In many instances, your Electrophysiologist may advise you to stay on blood thinning medications lifelong.

You should avoid strenuous physical activity and sports for 2 weeks after the procedure. Most people take approximately 1 week off work. It is not uncommon to experience abnormal or irregular heart beats for up to 4 weeks after the procedure. Rarely, Atrial Fibrillation may be worse for a few weeks after the procedure while the inner lining of your heart heals from irritation caused by the ablation. Any recurrence or deterioration of symptoms in the first few weeks does not mean the ablation has not been successful; arrhythmias may settle as the irritation settles. Some patients may experience minor chest discomfort for several days after the procedure. If this persists, please consult your Electrophysiologist. You should not drive for at least 48 hours although we usually recommend that you do not drive for a week.

Your groin site might be sore for several days. A small bruise at the groin site is normal but if it starts to bleed, you can contact your local doctor or the Electrophysiologist.