Treatments for Atrial Fibrillation (AF)

Atrial Fibrillation Treatment options

When deciding what treatment to have for your AF it is important to remember that no treatment is without risk associated with it. This includes tablets and operations. When doctors are advising on treatment we are trying help you assess what is the best option for you based on the risks and benefits of each therapy.

Doctors are trying to predict how things may turn out for you based on statistics, research and their experience of other patients but inevitably until doctors can see into the future we will not always get it right. Obviously the more patients with AF we see and the more research we do the better our advice is likely to be.

Essentially there are three problems associated with AF that need treating:

  1. Stroke risk
  2. Fast heart rate
  3. Abnormal irregular rhythm

1) Stroke risk

At the present time stroke risk can be managed with tablets that make the blood take slightly longer to clot. Aspirin is a commonly known tablet of this type but IS NOT RECOMMENDED FOR STROKE PREVENTION IN AF. This is because asprin works slightly differently than other anticoagulant drugs and is not effective in preventing stroke in AF but gives the same risks of bleeding as the other drugs. Examples of currently used drugs that are commonly used are Warfarin, Rivaroxaban, Dabigatran, Apixaban or Edoxaban. Warfarin for example differs from the others (collectively known as direct oral anticoagulants or DOACs) in that it interacts with other dietary and drug agents. Its therapeutic action is therefore not stable and the action has to be closely monitored with regular blood tests. There is some evidence that the latter drugs (DOACs) may be associated with a small reduction in intracranial hemorrhage when compared with warfarin. There is no reliable evidence at present that any one agent is better than another. Left atrial occlusion devices can also be used to prevent strokes.

The reason why people who have AF suffer with strokes is because blood clot breaks away from the left atrial appendage (LAA), a small blind ending pouch off the main left atrial chamber. This ‘appendix’ of the heart is not thought to be necessary for normal heart function and is routinely removed during certain types of heart surgery. With the LAA removed the chances of having a stroke are greatly reduced and patients do not need to take an anticoagulant.

A minimally invasive, local anaesthetic procedure has been developed to exclude the LAA from the heart. A purposefully designed plug, compressed within a long thin tube (catheter), is delivered into the heart via the leg. Once the catheter is in position, it can be withdrawn allowing the plug to expand and fill the LAA.

The Left Atrial occlusion device

Over the next 6 weeks the body reacts to the plug, causing new tissue to grow over it and therefore permanently occlude the LAA. A clinical trial of 700 patients has demonstrated that the Watchman is as effective as warfarin in preventing stroke.*

The Watchman is suitable for patients who have AF and have been advised to take warfarin because they have a high risk of stroke, but are unable to because either they have had a complication e.g. a dangerous bleed or it causes unpleasant side effects. Even after successful LAA occlusion it is recommended that patients take an antiplatelet  (aspirin, clopidogrel). which also have some small bleeding risks associated with it.

Advice to doctors on who to give warfarin to and how much to thin the blood has been very clearly defined and guidelines have been published by both American and European societies of cardiology.

watchman_device

2) Fast Heart Rate

The debate over rate (control heart rate and do nothing to the AF) versus rhythm control (trying to restore and maintain normal sinus rhythm) has been raging for sometime. Most experts in AF management agree that it is better for patients to be in sinus rhythm but this may be difficult to achieve. Some studies have shown that rate control is safer for patients than rhythm control but this has been for two reasons, firstly our techniques for controlling rhythm at the time of these trials was not good so many patients reverted to AF and secondly warfarin was stopped inappropriately in the rhythm control patients which meant that if and when they did revert to AF they frequently suffered a stroke.

It may be appropriate to simply control the heart rate and do nothing to get rid of the AF and many patients ask what they should do. The aim of this site and the London AF centre is to give you enough information and advice to help you make that decision yourself. Examples of patients who may opt for rate control are elderly, inactive patients without symptoms from their AF. It is important to remember that AF is a chronic condition and patients get used to it and forget what it is like to be in a normal rhythm. One simple way of assessing you symptoms is to exercise with someone in normal rhythm of similar age and fitness and to see how you compare to them. If you do badly it may be because of the AF.

If you do opt for heart rate control then there are two methods that can be used:

Drugs

Drugs are used to slow the conduction between the atria and the ventricles (at the AV node) so that the atria keep fibrillating at the same rate but the ventricles are activated less often. The most effective drugs are beta-blockers or calcium channel blockers like diltiazem or verapamil. Digoxin is now less commonly used drug for this purpose in the UK because it is only effective at controlling heart rate at rest, when you are in the doctors surgery, but may leave the heart rate too high when you walk out of the surgery.

Unfortunately as with all treatments these drugs may have side effects and rarely these can be dangerous. Dangerous side effects are very rare but all heart rhythm controlling drugs can cause heart rhythm problems and sometimes can produce a fatal heart rhythm. It can often be difficult to get the heart rate down sufficiently without lowering it too much and so patients may find that their heart races at some times but is slow and makes them feel dizzy at others. Other common side effects are tiredness and loss of sex-drive for beta-blockers and constipation for verapamil.

Rate control is simple and low risk and will only take a few weeks to optimise, so it is not unusual for patients to try this and see if this eliminates their symptoms. If it does, great because the patient has got away with a good quality of life without having taken the risk of rhythm control.

Catheter ablation and pacing

If patients have decided on rate control but cannot be controlled on drugs either because they do not work well or they cause troublesome side-effects then the connection between the atria and the ventricles, the AV node can be destroyed by burning it with a catheter. A catheter is a small wire that is introduced with the help of local anaesthetic and passed up the leg to the heart.

You can see two videos of two wires being passed up to the heart from the leg. The videos are recorded using the NavX x-ray free imaging system that we often use at the London AF centre. In the first video the wire (coloured green) is passed up the main vein to the heart, the inferior vena cava (red tube) but then goes into a side branch. We leave this wire in the side branch and pass a second wire (coloured blue) up to the heart past the first one. We then pulled the green one back from the side branch and passed it up to the heart as well but this is not shown on a video. Video 1 (Click here to view Video 1)and Video 2 (Click here to view Video 2).

Once the wire is at the AV node we pass energy through it which heats the tissue and kills the cells immediately under the catheter tip. This causes a small 4mm scar to form which is electrically inert. The atria are then disconnected from the ventricles and cannot affect ventricular rate. Something is needed to keep the ventricle beating and so a pacemaker (for more about pacemakers click here) is used to replace the function of the AV node. This is an irreversible process and the patient is dependent on the pacemaker to stay alive.

The pacemaker is put in at least two weeks before the ablation (burning) of the AV node so that we can be sure that it is “bedded-in” and functioning properly before we render you dependent on it. After the procedure the AF remains and so does the stroke risk so the “turbo-charger” of the heart is not restored and the patient must continue to take appropriate stroke prevention medication. In addition some patient’s hearts do not like being paced and prefer being activated in the normal way by its own conduction system. This can result in the heart function deteriorating and causing more symptoms of shortness of breath. This is unusual but impossible to predict.

Benefits

This procedure can be extremely helpful to patients whose main problem is heart rate control and palpitation. It can be difficult to know how much the lack of atrial function causes symptoms and how much the abnormally fast heart rate contributes. In some patients it can therefore be difficult to predict your outcome after this procedure. One reason that we don’t perform this routinely as a first line therapy because it is irreversible, i.e. you cannot re-grow the AV node.

Success rates

The success rates of achieving control of the heart rate is 99%. This does not however mean that you would be free of symptoms for the reasons described above.

Risks

This is a very safe procedure and has been studied in a number of large trials. Pacemakers rarely fail and the mortality after this procedure is extremely rare. Complications occur in 4 to 5% of patients these include:

  • Bruising in the shoulder (after pacemaker) or leg (after ablation) which can be dramatic but resolves.
  • Infection requiring extraction of the pacing system and replacement with a new one.
  • Arm swelling because of blockage of the vein in the arm which usually resolves.
  • Haemo/pneumothorax. This is a complication of puncturing the subclavian vein so that pacing leads can be introduced to the heart.

In summary ablation and pacing is an irreversible procedure that hides the AF and doesn’t get rid of it, but it is a technically easy procedure to perform.

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3) Rhythm control

Rhythm control is used when patients have decided that their quality of life is inadequate with rate control. Rhythm control comes in 3 forms:

  1. Pill in the pocket – this describes using a drug or combination of drugs only when you get the AF. This is useful in patients who have infrequent episodes of AF lasting a few hours. This is because the drug takes a few hours to work therefore if the AF lasts less than this, it is unlikely the drug will have a chance to work. Clearly for patients getting AF more frequently then they may feel that they want to try and prevent or reduce the AF beforehand. In this case the next option may be preferred.
  2. Regular medication – this describes taking the same medication as one might for “pill in the pocket”, but regularly. Medication are simple to take and for most patients are safe, with a sudden cardiac death rate of less than 1:1000. However, many patients don’t want to take regular medication for the rest of their lives or find that the medication don’t work, or over time the AF becomes more troublesome and the medication fails.

Catheter ablation – this procedure is described in detail here.