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AF Diagnosis and treatment

Find out how doctors diagnose atrial fibrillation (AF) and learn about the treatments used to prevent complications and manage AF symptoms.

In this article

How is atrial fibrillation diagnosed?

A doctor and patient meet in the clinic. the doctor passes his patient a prescription.

If your doctor thinks you have atrial fibrillation (AF) he or she will:

  • review your symptoms and medical history
  • carry out a physical exam
  • do an ECG
  • order one or more diagnostic test. 

This information will be used to confirm an AF diagnosis, provide more information about the type of AF you have and indicate the best options for treatment. Tests may also be done to rule out other conditions which have similar symptoms.

The diagnostic tests you receive are likely to include one or more of the following:

Electrocardiogram (ECG)

An electrocardiogram(PDF), or ECG, is likely to be the first test you receive and, in most cases, it can be used to confirm an AF diagnosis.

The ECG records the rhythm and electrical activity of your heart, using sensors (electrodes) attached to your chest, arms and legs. It is a simple, painless test usually done at your GP practice.

Blood tests

Blood tests can be used to rule out any underlying conditions which could be associated with your AF and may also require treatment. These conditions include:

  • diabetes
  • hyperthyroidism
  • anaemia
  • problems with your kidneys
  • infections
  • high cholesterol.

Your doctor may also order blood tests to get information before starting anticoagulant treatment.

Chest x-ray

Your doctor may order a chest x-ray to help identify the cause of your AF.

Holter monitor

This may be performed when AF is suspected but not confirmed by an ECG. It may also be used to assess how well AF is controlled.

For a holter monitor test you wear a small, portable ECG machine for 24 to 48 hours. Electrodes will be fixed to your chest with leads attaching to the ECG machine, which can be worn around your neck, shoulder or your waist. During this time, your heart rate and rhythm are recorded, providing the medical team with information about your heart rhythm over a longer period.

For more information view our holter monitoring resource(PDF).


Once you've had your atrial fibrillation confirmed by an ECG, your doctor may refer you for a transthoracic echocardiogram(PDF), or echo test.

An echocardiogram (or Echo)is an ultrasound of the heart. This test uses sound waves to study your heart muscle and valves. A probe transmits and records these sound waves, producing a moving image of your heart.

Event recorder

If you don't get your AF symptoms very often, your doctor may order an event recorder which is also known as an event monitor.

The monitor is used over a period of two to four weeks to record your heartbeat when you experience symptoms such as dizziness, black outs, chest pain or palpitations.

For more information view our event monitoring resource(PDF).

Implantable loop recorder

The implantable loop recorder is a tiny monitor, about the size of a piece of chewing gum, which can be implanted under the skin and used to record heart rhythm abnormalities. It is inserted during a 15-20 minute minor surgical procedure performed under local anaesthetic.

It can be used for people whose AF episodes can't be captured by a holter monitor or external event recorder, because the gaps between the events are too long.

Atrial fibrillation treatment

There are two important reasons for treating atrial fibrillation.

Atrial fibrillation treatment differs from person to person depending on:

  • the underlying cause of your AF
  • your symptoms
  • the length of time you've had AF
  • any other health conditions.

If your AF is caused by an underlying health problem, such as hyperthyroidism, it's likely your doctor will want to treat that problem first. Once the underlying condition is being treated, the doctor will help you decide what further treatment you may need for the AF.

In most cases, atrial fibrillation can be managed successfully by your GP but sometimes hospital treatment is needed.

Dr Fraser Hamilton talks about the two main types of atrial fibrillation medications.

Preventing clots and reducing stroke risk

Your doctor may recommend an anticoagulant or “blood thinning” medicine to lower your risk of stroke by preventing the formation of blood clots.

The decision to start any blood thinning agents is considered very carefully for each individual. Your doctor will estimate your stroke risk and the risk of a serious bleed. Your doctor will weighup these risks and discuss which medication may be right for you.

There are two general classes of anticoagulant that can be taken in tablet form: non-vitamin K oral anticoagulants (NOACs) or warfarin. These medications reduce the chances of a stroke by about two-thirds.​

Aspirin is not recommended for reducing the risk of stroke in people with atrial fibrillation.

Non-Vitamin K Oral Anticoagulants (NOACs)

NOACs work by slowing down the body's natural clotting process. When compared with warfarin, NOACs have two main benefits:

  • they do not require regular blood testing
  • they don’t interact with food.

Common types of NOACs available in New Zealand include:

  • dabigatran
  • rivaroxaban
  • apixaban.

These drugs are also sometimes known as direct oral anticoagulants (DOACs).

You will need to tell your doctor about any other prescribed medication, complementary or herbal medicines, and or recreational drugs before starting a NOAC. You should avoid heavy drinking when taking NOACs.

NOACs are not suitable for:

  • people with mechanical heart valves
  • pregnant women and nursing mothers
  • severe kidney disease.


Warfarin works by blocking the body's clotting process. Normally the body uses vitamin K to produce 'clotting factors' (substances which help the body control bleeding). Warfarin interferes with this use of vitamin K, which in turn stops the blood from clotting so quickly.

Warfarin needs to be taken once a day at the same time every day.

One downside of warfarin is that other medications and diet can reduce its ability to work. This means you'll need to talk to your doctor about any other prescription or recreational drugs you're taking and any complementary medicine or herbal remedies.

You may also have to be careful with some foods, particularly those high in vitamin K, such as green leafy vegetables like spinach, kale and broccoli. These greens may reduce the blood thinning effect of taking Warfarin. 

Although you can eat these foods, it may need to be in moderation. This is something you can discuss with your doctor or nurse.

Large quantities of alcohol may also have a negative effect.

You will need to have regular blood tests to monitor the time it takes for your blood to clot (your INR level). Often it takes a while, for your body to adjust and or the doctor to get the right dose, so you may need more frequent blood tests when you start on the medication. If you make changes to your diet or start taking other drugs, this may have an impact on your INR levels.

Warfarin can't be prescribed for:

  • people at high risk of internal bleeding such as those with a stomach ulcer
  • people with a blood disorder such as haemophilia
  • pregnant women or nursing mothers.

Anticoagulant side effects

The main side effect of starting any type of anticoagulant is increased bleeding and bruising. Patients taking NOACs may also experience stomach side effects such as indigestion (heartburn).

You should contact your doctor if you:

  • have blood in your urine or faeces
  • have black faeces
  • cough or vomit blood
  • have nosebleeds that last more than 10 minutes
  • have bleeding gums
  • have very bad bruising
  • have unusual headaches
  • have increased bleeding during your period or other bleeding from your vagina.

It is very important that you tell your dentist or surgeon that you're taking an anticoagulant before you receive any kind or dental or surgical treatment.

While anticoagulants lower your risk of stroke, they don't remove all risk. It's important that you are aware of the signs of a stroke and if you notice any, you call 111 immediately.

Left atrial appendage closure

Sometimes your doctor may recommend a surgical procedure called a left atrial appendage closure to reduce your risk of stroke.

During the procedure, doctors close off a small sac in the left atrium (upper chamber of the heart), called the left atrial appendage. The procedure reduces your risk of stroke because many blood clots caused by atrial fibrillation form in the left atrial appendage.

This procedure may be suitable for people without heart valve problems who have an increased risk of bleeding and are aren't able to take anticoagulants.

Managing your atrial fibrillation symptoms

As well as reducing your risk of stroke, AF treatment may be needed to help manage your symptoms. This may be done by:

Slowing down your heart rate

Slowing down your heart rate can relieve symptoms even if you still have an irregular heart rhythm. 

Heart rate control medications

Dr Fraser Hamilton discusses common rate control medication’

In the first instance doctors will usually try medication to slow your heart rate down. Common types include:

  • beta blockers
  • calcium channel blockers
  • digoxin.

Beta blockers

Beta blockers are the most common type of rate control medication. Beta blockers prevent adrenaline speeding up your heart and lower your blood pressure. If you have heart failure, beta blockers can stop it from getting worse. Usually your doctor will start you on a low dose of beta blocker and increase it slowly. You should only change the dose if your doctor tells you to.

You will need to have your blood pressure and heart rate checked regularly at your GP practice.

You may experience some side effects when taking beta blockers such as:

  • cold hands and feet
  • tiredness
  • dizziness or light headedness
  • skin rash
  • pins and needles
  • trouble getting an erection (erectile dysfunction)
  • worsening asthma in those who suffer from asthma.

Often these side effects will reduce as your body gets used to the medication. But if you're experiencing erectile dysfunction or other side effects lasting longer than a few weeks, talk to your doctor about changing the medication.

Do not stop taking a beta blocker without first consulting your doctor. It is also important you don't run out of medication or forget to take your pills on holiday. Stopping beta blockers suddenly can cause:

  • palpitations
  • a rise in blood pressure
  • angina pains.

If you need to stop taking a beta blocker, your doctor may advise a gradual reduction in dose.

Calcium channel blockers

Calcium channel blockers are commonly used to treat high blood pressure. Two of these medications, diltiazem and verapamil, are also used to help slow down the heart rate in patients with atrial fibrillation. They do this by reducing the number of electrical impulses that pass through the atrioventricular (AV) node into the lower heart chambers (ventricles).

Serious side effects of calcium channel blockers are rare. Common side effects include:

  • constipation
  • headaches
  • swollen ankles
  • tiredness.

You should avoid grapefruit or grapefruit juice while taking diltiazem, because a chemical in the fruit prevents the absorption of the drug which can cause side effects. You should have your blood pressure and heart rate monitored regularly at your GP practice.

Verapamil should not be used with a beta blocker as this combination may make the heart go too slowly.


Digoxin is used to slow the heart rate and increase the pumping force (contraction) of the heart. It can help to reduce symptoms of atrial fibrillation, such as breathlessness and palpitations.

Side effects of digoxin are not that common but may include:

  • loss of appetite
  • fainting
  • nausea and vomiting
  • painful, enlarged breasts (in both men and women).

You may need to have blood tests to check the levels of digoxin in your blood.

Restoring your heart rate to its normal rhythm

If you have severe AF symptoms, or if it's your first episode of AF, your doctor may attempt to restore your heart rate to its normal rhythm (sinus rhythm). To do this, doctors use a procedure called cardioversion.

There are two types of cardioversion.

  • Electrical cardioversion, which uses a machine to restore the rhythm.
  • Pharmacological cardioversion, which uses medicine to restore the rhythm.

Electrical cardioversion

Electrical cardioversion also called direct current cardioversion (DCC), is a short procedure which uses a defibrillator to provide an electrical shock to the heart. It is performed in hospital under sedation or anaesthetic.

The defibrillator sends an electrical impulse through your chest wall, via pads or electrodes which are placed on your chest. This impulse disrupts the abnormal rhythm for a split second, allowing your heart to resume a normal rhythm. The procedure takes a few minutes and because of the sedation you shouldn't feel any discomfort. Most people are able to go home from hospital the same day.

Pharmacological cardioversion

Pharmacological cardioversion, also known as chemical cardioversion, uses medicines called antiarrhythmics to restore a normal heart rhythm. Your healthcare professional may give you these antiarrhythmics as a tablet or intravenously (through a vein). This procedure will also be carried out in hospital and your heart rhythm will be monitored closely throughout. 

Unfortunately, cardioversion doesn't always work. For some people, their heart won't return to a normal rhythm. Others may slip back into atrial fibrillation at a later date. 

Even if your heart does return to a normal rhythm, you may still need to take medication to prevent blood clots because you are still at a higher risk of having a stroke. 

Antiarrhythmic medications

After cardioversion, you may be prescribed antiarrhythmic medication to keep you heart rate in a normal rhythm. Common antiarrhythmics include:

  • sotalol
  • flecainide
  • amiodarone.

Catheter and surgical procedures to control heart rate

If cardioversions and medications fail to control your AF symptoms, your doctor may recommend a procedure, designed to interrupt the abnormal electrical circuit.

There are three different kinds of procedure designed to do this:

  • AF ablation
  • pacemaker and atrioventricular node ablation
  • surgical maze procedure.

Dr Fraser Hamilton talks about treatment for severe AF.

AF ablation

Atrial fibrillation ablation, also known as AF ablation or AF catheter ablation, is a procedure that destroys the area inside the heart that is causing the abnormal rhythm. 

During the procedure, the doctor will insert a long thin tube (catheter) through your groin, shoulder, or neck and guide it into your heart using an X-ray camera. The tip of this tube uses energy - either radiofrequency (hot) or cryoablation (cold) - to create tiny scars in the heart that block faulty electrical signals and restore a normal heart rhythm from the area of your heart that triggers the irregular rhythm.  

This type of treatment is for people with symptomatic AF. If your doctor thinks you may benefit from an ablation, they will discuss the benefits and risks with you. 

Atrioventricular node ablation

If other ablations have been unsuccessful or you're not suitable for them, your doctor may suggest implanting a pacemaker, followed by an atrioventricular node ablation (AV node ablation).

During this ablation procedure, your specialist will use a catheter to ablate the AV node (the gateway between the upper and lower chambers of the heart). This will stop the irregular impulses generated in the atria (upper chambers of your heart) reaching the ventricles (lower chambers of your heart). You will need a permanent pacemaker inserted to help your heart maintain a regular rhythm.

Surgical maze procedure

Unlike catheter ablation, a surgical maze procedure involves open heart surgery to create the scar tissue within the heart. Because it involves open heart surgery, which carries a higher risk than a catheter ablation, maze procedures are usually carried out if you're already scheduled for other heart surgery, such as coronary artery bypass surgery or valve replacement.

Shared decisions about your treatment plan

Treatment for AF will be personalised for you and it is important that you have your say about your treatment plan. Your plan will be influenced by the type of AF you have, how severe your symptoms are, other health conditions and your assessed level of stroke risk, as well as your values and preferences.

There may be several treatment options to choose from. You may need to try a series of different treatments before finding the best management approach for you. You may also find that your treatment changes over time as your disease progresses or sa new options become available.

Together with your doctor or nurse, you can weigh the pros and cons of each treatment, compare options and make a decision that is best for you.


Adjusting to life with atrial fibrillation