Anti-arrhythmic medications work by helping to stabilise electrical impulses within the heart.
The type of medication used to treat atrial fibrillation (AF) will vary in every individual according to symptoms and heart function.
You may be asked to take your medication on a when-needed basis ('pill in the pocket approach'), or we may want you take it regularly. We will sometimes look at combining more than one medication to ensure your heart rate and/or rhythm is well controlled.
Regardless of your treatment strategy (rate or rhythm control), it is still important that you continue your anticoagulation medication to reduce your risk of stroke.
Learn more about the following medications:
- Beta-blockers (bisoprolol, atenolol, carvedilol)
- Calcium channel blockers ( diltiazem / verapamil )
- 'Pill in the pocket'
Beta blockers work by blocking the effects of adrenaline and other related hormones on the heart to slow your heart rate down.
They are used to treat AF and also other heart conditions, such as angina and following a heart attack. There are many different types of beta blockers, but they all end with "ol". Some beta blockers are more selective to the heart (such as carvedilol, bisoprolol, atenolol, metoprolol); others are less selective (propranolol) and can be used to treat other conditions, such as migraines and tremors. Sotalol has a beta blocker component but also works as a class III anti-arrhythmic.
Beta blockers are usually first line for treatment of AF regardless of whether we are planning a rhythm or rate control strategy. We may also use them in combination with other anti-arrhythmic drugs, such as calcium channel blockers (diltiazem/verapamil), amiodarone, flecainide, digoxin or dronedarone.
The dose will be dependent on the type of beta blocker you are prescribed. Bisoprolol is prescribed most commonly. This is taken once a day and the dose will vary between 2.5mg and 10mg.
Beta blockers should not be abruptly stopped unless under the direction of a healthcare professional as you may experience a recurrence in your arrhythmia symptoms.
To ensure that you are on an appropriate dose, we may suggest checking your heart rate and / or ECG after you have started a beta blocker. This will usually be done one to two weeks after starting the medication.
The most common side effect that people experience when taking beta blockers is fatigue and tiredness. This can occur in around one in 10 patients. Sometimes people tolerate one beta blocker better than another and sometimes they are only able to tolerate low doses.
Beta blockers can occasionally affect the lungs and cause breathlessness in people who have pre-existing lung conditions, such as asthma or chronic obstructive pulmonary disease (COPD).
Your doctor may want you to try a small dose of the beta blocker initially to make sure that you tolerate it. If you have a pre-existing lung condition we may recommend that you check your peak flow more regularly to ensure there is no deterioration in your breathing.
It is unusual for people who do not have an underlying lung problem to experience breathlessness with beta blockers. However, if you do experience breathlessness, you should seek medical attention.
As beta blockers reduce your heart rate and blood pressure they can sometimes make you feel dizzy and lightheaded. If you are finding this troublesome, you should seek medical attention.
Beta blockers can affect the circulation and cause your extremities (hands and feet) to be cold. In cold weather, you should wrap up warm and wear gloves and an extra pair of socks, if necessary.
In particularly susceptible people this can cause a temporary loss of circulation to the fingers and toes making them white and painful. This is called Raynaud’s phenomenon and is an indication to stop the beta blocker.
Calcium channel blockers can be used as part of a rate or rhythm control strategy for AF.
There are two types of calcium channel blockers, known as the dihydropyridines (amlodipine, nifedipine), which are used to control blood pressure or angina, and the non-dihydropyridine (diltiazem, verapamil), which are also used to control blood pressure or angina but can be used as part of a rate or rhythm control strategy as well.
Diltiazem and verapamil work by reducing the movement of calcium into the AV-node and in the arteries and veins. This causes the force and rate of the heart's contractions to decrease and the arteries to relax, leading to a reduction in blood pressure (BP). They can be used on their own or in conjunction with other anti-arrhythmic drugs to enhance their effects.
We will normally start you on a low dose of these medications and increase the dose as necessary. This usually means starting diltiazem at a dose of either 120mg once a day or 90mg twice a day.
With verapamil, the starting dose is 120mg once a day or a split dose of either 40mg twice or three times a day.
Your starting dose is dependent on your heart rate and blood pressure.
There are many different preparations of verapamil (Securon SR, Half Securon SR, Univer) and diltiazem (Tildiem retard, Dilzem, Adizem XL, Adizem SR). It is important that you keep to the same brand of these medications as different preparations can have different effects. Changing brands may cause a reoccurrence of your arrhythmia symptoms. Check with your pharmacist if you do not think that you have been given the correct preparation.
We may suggest checking your heart rate and/or ECG after you have started on a calcium channel blocker to monitor that you are on an appropriate dose. This will usually be done one to two weeks after starting the medication.
The most common side effects experienced with calcium channel blockers include flushing, lightheadedness, headaches and swollen ankles.
Some people may experience a sensation of light-headedness or dizziness because the drugs can cause a drop in BP.
Due to their effect on widening the arteries and veins these medications can occasionally cause ankle swelling. This will return to normal when the medication is discontinued.
Verapamil, and to a lesser extent, diltiazem, can reduce the contraction of the heart and should not be used if you are known to have severe heart failure (known as left ventricular impairment). If you have mild or moderate heart failure we may use diltiazem cautiously if you are unsuitable for or unable to tolerate other anti-arrhythmics.
If you notice any of the following you should contact your GP as soon as possible:
- Any difficulties breathing, new breathlessness on exertion
- Severe ankle swelling
Digoxin is a medication extracted from the foxglove plant that is commonly used to treat AF
Digoxin works by slowing the electrical impulses through the AV-node so it helps to control how fast the ventricles contract.
We know that digoxin works effectively whilst you are resting but, if you are an active person, it is unlikely to control your heart rate adequately on exercise when used on its own. Therefore, we may use it in combination with other anti-arrhythmic medications, such as beta blockers or calcium channel blockers(diltiazem/verapamil) or amiodarone. If you also have severe heart failure, digoxin can be used to help your heart beat slightly stronger and may help to improve the symptoms of heart failure.
Digoxin is given as a once daily medication but you may find that you are recommended a higher “loading” dose initially which can be given either orally or as an intravenous injection.
The dose of digoxin will be between 62.5mcg and 250mcg daily and the dose which you are prescribed will depend on your symptoms, your heart function and kidney function.
Routine monitoring of digoxin is not usually necessary unless your doctor feels that your dose may be too low or you are suffering side effects and we think this may be related to your dose being too high.
If necessary we can do a blood test to check the level of the digoxin in the bloodstream. The best time to take the level is 6-10 hours after you have taken your dose. Therefore if you normally take your dose in the morning we will do the blood test in the afternoon. We may also want to periodically check your kidney function as the digoxin is not removed as effectively from the body if your kidney function is impaired.
Digoxin is usually well tolerated however if your dose is too high then you may develop signs of toxicity. These include loss of appetite, nausea, vomiting, diarrhoea, blurred vision, visual disturbances (yellow-green halos around people or objects, some people describe these as auras), confusion, drowsiness and dizziness.
If you are concerned that your digoxin may now be causing problems, it is important to seek medical advice promptly.
'Pill in the pocket' means taking a tablet when you realise an AF episode has just started
If you have paroxysmal AF, your episodes are infrequent and so a pill-in-the-pocket approach may be recommended.
You will be advised to take a dose of your anti-arrhythmic medication when you have an episode of AF to help stop it. Medications used for this indication include either flecainide or a beta blocker (or occasionally a calcium channel blocker).
The pill-in-the-pocket approach works well if you are able to identify when an episode starts, respond well to a dose of the above medication and are aware of how much to take and when.
If your symptoms do not improve and you feel very unwell, you should call an ambulance.
If your AF persists for more than 48 hours, you should see your GP or seek advice from your arrhythmia specialist as your AF treatment may need to be changed
If you are unsure when you need to take your medication, speak to your GP or your arrhythmia specialist pharmacist/nurse specialist.
If pill in the pocket fails, or if your AF episodes are becoming more frequent and/or more symptomatic, then the anti-arrhythmic can be taken on a regular (daily) basis.
There are a few anti-arrhythmics which can be used for the pill-in-the-pocket approach or used regularly. The choice of which anti-arrhythmic will best suit you depends on any underlying heart disease (i.e. coronary heart disease, heart failure and hypertension) the occurrence of side effects and how effective the drug(s) may be.
Flecainide is a sodium channel-blocking drug, which slows the conduction (carrying the electrical impulses) within the heart. It mainly acts on the atria and also slows conduction through the AV-node.
Flecainide is very effective in treating episodes of AF and tends to be better tolerated than some of the other anti-arrhythmic medications. Its action is more pronounced at faster heart rates, which is why it is particularly useful to control fast episodes of AF.
This drug can only be given to people who have a normal functioning heart.
The dosage of flecainide can go up to 200mg twice a day. We would initially start you on a low dose (50mg twice a day) and will increase the dose according to your symptoms and your ECG.
If you are started on flecainide, you may also be prescribed either a beta blocker or a calcium channel blocker to protect the lower chambers of the heart (ventricles) from contracting too quickly.
Once you have started taking flecainide you will need to have regular ECGs performed. We know that flecainide slows the conduction in the heart and this change will be reflected on your ECG. However, we will want to ensure that the conduction has not slowed down too much.
You will usually be advised to have an ECG approximately one week after starting flecainide and after each dose increase.
The most common side effect is visual disturbances usually reported as blurred vision. Less common side effects include gastrointestinal symptoms (such as nausea) and dizziness.
Flecainide can also be proarrhythmic (cause arrhythmias) and this is why it is recommended that it is only given to patients that have a normal functioning heart.
Sotalol is a mixture of a beta-blocker and an anti-arrhythmic. At low doses its effect is similar to beta blockers, but at higher doses it also has anti-arrhythmic activity by blocking potassium channels and slowing conduction in the heart.
The dosage of sotalol can go up to 160mg twice a day. We will initially start you on a low dose (40mg twice a day) and will increase the dose according to your symptoms and your ECG.
When sotalol has been commenced you will need to have regular ECGs performed. We know that sotalol at higher doses slows the conduction within the heart and this change will be reflected on your ECG.
However, we will want to monitor that the conduction has not slowed down too much. It is especially important that we check this when your heart is in sinus rhythm.
Sotalol can also be pro-arrhythmic (causes arrhythmias). Therefore, if we see certain changes on your ECG you may be advised to reduce or stop your sotalol.
You will usually be advised to have an ECG approximately one week after starting sotalol and after each dose increase.
The most common side effect with sotalol is bradycardia (when the heart beats at a slow rate, usually less than 60 beats per minute).
Other side effects, which are associated with beta blockers, include:
- fatigue or tiredness
- cold extremities (cold hands and feet)
- exacerbation of asthma
Amiodarone works in a similar way to sotalol by blocking potassium channels and slowing conduction within the heart.
This drug has been shown to be very effective at maintaining sinus rhythm and we would consider using this medication for patients with structural heart disease or for patients where other medications have failed to control their AF.
Despite being a powerful and effective drug in restoring and maintaining the normal heart rhythm, it is associated with many side effects and, therefore, we may only want to use the medicine for a short duration.
Depending on the severity of your symptoms we may decide to start this medicine either orally or by an intravenous infusion over 24 hours.
Because of the structure of amiodarone it takes a long time (weeks to months) for levels of the drug to build up in the body. You will usually be asked to take a 200mg tablet three times a day for one week, then twice a day for one week and then once a day thereafter.
Although generally well tolerated, amiodarone can cause the following side effects:
When taking amiodarone the skin can take on a greyish / blue tinge when your skin comes into contact with sunlight. Your skin may also become more sensitive to sunburn. Wearing sunblock and hats will help to prevent this. As amiodarone remains in the body for a long time it may be necessary to continue using sun block for a few months after stopping it.
The thyroid gland produces a hormone, which controls the body’s metabolism. Amiodarone can affect this gland making it both overactive (this occurs in about 2 per cent of people taking amiodarone) or under active (this occurs in about 6 per cent of people taking amiodarone). Your doctor will take regular blood tests to check if either of these has developed.
If you experience symptoms of extreme tiredness or restlessness, you should contact your GP to discuss this further. Your doctor will arrange for you to have blood tests if these have not already been done. Both an underactive and an overactive thyroid can be treated with medications. If you develop an overactive thyroid it is likely that we will need to stop the amiodarone.
Small deposits can form on the cornea of the eye (the clear surface that covers the pupil, iris and white of the eye). These deposits are not harmful, but you may notice the effects when looking at bright lights at night time e.g. when driving a car. Around one in 10 people taking amiodarone will notice a bluish halo around their vision. Again, this is not harmful.
Amiodarone can cause problems with thickening (fibrosis) of the lungs, which may be irreversible. The risk of this occurring increases if you have been on the medication for a long time. If you experience shortness of breath, you should arrange to see your GP as soon as possible.
Amiodarone causes problems with the function of the liver in rare cases. Your doctor will perform regular blood tests to check that your liver function is normal. If you experience jaundice (yellowing of the skin) or new nausea and vomiting, you should arrange to see your GP as soon as possible.
Other side effects
You may notice that when you are first started on amiodarone it causes some gastrointestinal disturbances, such as nausea and vomiting. This should settle within a few days, but if you continue to have problems, you should contact your GP. It is also not unusual for people to get taste disturbances and a metallic taste in the mouth. Again, if this is causing you concern, you should see your GP.
When you are first started on amiodarone you will have a blood test performed to check your liver and thyroid function. You will also have a chest X-ray if you have not had one recently. Your GP will then recheck your liver and thyroid function every six months.
Amiodarone can interact with many medications and herbal medicines. Therefore, it is very important that your GP and pharmacist are aware of all the medicines you are taking (including herbal products).
We may recommend that your statin dose and digoxin is reduced and, if you are taking warfarin, the addition of amiodarone will cause your INR to increase and your warfarin dose will need to be reduced accordingly.
If you notice any of the following you should contact your GP as soon as possible:
- Any difficulties breathing, or if you develop an unexplained cough.
- Extreme tiredness or restlessness.
- Jaundice (any yellowing of your skin or the whites of your eyes). These could be signs of a problem developing in your liver.
- A severe skin rash. This could be a sign of an allergic reaction.
Dronedarone has a similar structure to amiodarone. It is not considered to be as effective as amiodarone. However, the advantage of dronedarone is that it seems to be better tolerated and has fewer side effects.
We normally reserve this medication for people who either unsuitable or unable to tolerate other anti-arrhythmic medications. It is only suitable for patients who have paroxysmal or persistent AF to maintain sinus rhythm.
The dose of dronedarone is 400mg twice a day and it should be taken with food.
There have been some reports of dronedarone causing liver damage and you will need to have a blood test to check your liver function every month for the first six months of your treatment, at nine months, 12 months and periodically thereafter.
You will also need to have a blood test seven to 10 days after starting dronedarone to check your kidney function and an ECG at least every six months. If your ECG shows that you have remained in persistent AF, this indicates that the medication is not working adequately and it will be stopped.
The most common side effects that people experience are gastrointestinal disturbances, such as nausea, vomiting, diarrhoea or abdominal discomfort. It may also cause skin rashes, bradycardia and, rarely, changes in the ECG.
Most side effects disappear within the first two weeks of starting the drug, but in some patients, dronedarone will need to be discontinued because of these side effects.
You should contact your GP if you experience any of the following:
- Any difficulties breathing
- Swollen ankles
- New onset abdominal pain
- Jaundice (any yellowing of your skin or the whites of your eyes)
These could be signs of a problem developing in your liver.
Dronedarone can interact with many medications and herbal medicines. Therefore, it is very important that your GP and pharmacist are aware of all the medicines you are taking (including herbal products).
We may recommend that your statin dose, verapamil/diltiazem or digoxin dose is reduced, because dronedarone interacts with them and may increase the circulating levels of these drugs in the body. You should also avoid grapefruit whilst taking dronedarone.
Getting further supplies of dronedarone
You may find that your GP is unable to continue to provide you with further supplies of dronedarone tablets due to funding restrictions by the Clinical Commissioning Groups (CCGs).
However, your GP may prescribe dronedarone for you if they have an agreement from the hospital, known as a shared care document. This details the responsibilities of both the GP and the hospital.
If you are having difficulties obtaining a regular supply of your tablets, please contact Sally Manning, senior arrhythmia pharmacist.
Meet the team
The arrhythmia team includes:
- EP consultants
- clinical nurse specialists
- an arrhythmia pharmacist
- catheter laboratory technicians.
Clinical nurse specialists
Contact the team
Harefield Hospital: 01895 828979
Royal Brompton Hospital: 020 7351 8364