Atrial fibrillation (AF)

What is it about ?

Atrial fibrillation (AF) is a heart rhythm disorder in which the heart beats irregularly and usually too fast.

Anatomy of the heart

The heart consists of a left atrium, a right atrium, a left ventricle, and a right ventricle. The right atrium contains a bundle of nerve cells that produce a small electric current. This mechanism works like a natural pacemaker, which sends electrical impulses through the muscle of the heart (myocardium). These impulses stimulate this muscle, which contracts. This system runs on its own, without any intervention on our part.

A normal heart rate is between 50 and 100 beats per minute at rest. In AF, the system is out of order and the heartbeat becomes irregular and usually too fast.

Blood clots

As the electrical current conduction is no longer as good through the heart muscle, the atria no longer contract properly. As a result, the heart can no longer pump blood properly. However, if the blood remains still, it can clot and form clots. These clots can travel to the brain and cause a stroke. This is why it is often indicated to take anticoagulants in case of AF. Without this treatment, the risk of stroke is about 5% per year.

Temporary or permanent atrial fibrillation

Atrial fibrillation can happen suddenly (acute), sometimes with symptoms and sometimes not. The atrial fibrillation episode may go away as it started or may persist.

• If you have an episode every now and then, this is Paroxysmal AF.
• When an episode lasts longer than seven days, it is a question of Persistent AF.
• Finally, if nothing more is tried to normalize the heart rate, we talk about Permanent AF.

Causes of atrial fibrillation

In some cases, a specific factor triggers AF. Some examples :

• a fever ;
• a heart attack (infarction);
• anemia;
• an overactive thyroid (hyperthyroidism).

Coffee, alcohol, drugs, and stress can also trigger the heart rhythm disorder.

When the cause is treated, AF usually goes away.

What is its frequency?

Atrial fibrillation is the second heart rhythm disorder, after extrasystoles (extra heartbeats). The number of new cases increases with age.

AF affects less than 0.5% of people under 50, while 5 to 15% of people over 80 have it.¹ It is estimated that 25 to 35% of people with AF are unaware of their disease.

How to recognize it?

AF does not cause symptoms in 1 in 3 people, which is why the condition has sometimes been present for (too) a long time before it is detected. In addition, the possible symptoms are often not specific to AF, but can also occur in other conditions.

The following symptoms can suggest AF:

• palpitations;
• irregular heartbeat;
• shortness of breath ;
• tired abnormal;
• reduced effort capacity;
• (tendency to) fainting ;
• dizziness ;
• pain or tightness in the chest.

How is the diagnosis made?

Your doctor may already suspect AF by auscultating your heart or in measuring your blood pressure. If necessary, he will systematically prescribe a electrocardiogram (ECG). This examination will allow him to establish the diagnosis with certainty.

If you are found to have AF, your doctor will also do a blood test in order to identify possible underlying causes.

In some cases, a heart specialist (cardiologist) will perform various Additional tests, such as :

• a heart ultrasound (echocardiogram);
• a chest x-ray;
• a 24 hour ECG (Holter);
• a stress test.

What can you do ?

• If you sometimes suffer from palpitations, note when they occur and how long they last. AF can occur in episodes or be present continuously.
• Check your pulse.
  • To do this, ideally feel your pulse at the base of the thumb, between the first tendon and the lateral aspect of the wrist bone.
  • Pay attention to the regularity of the pulse.
  • Count the number of beats per minute. If your heart rate is above 120 or below 40 at rest, contact your doctor.
• If you have AF and are showing signs of stroke (e.g. deformed mouth, paralyzed arm), contact your doctor immediately.

What can your doctor do?

The treatment of AF covers different aspects.

Treatment of arrhythmia

In 50 to 70% of cases, the heart rate spontaneously normalizes within 48 hours. If your symptoms are mild, then you may choose to wait a bit. Often you will be given medication to slow your heart rate.

If the arrhythmia does not go away on its own, the doctor will always start treatment. Various types of support are possible. The doctor will choose a strategy after discussing it with you. Its choice will take into account the symptoms of AF, its duration, other ailments from which you are affected, your risk of thrombosis, etc.

Heart rate control

In almost all cases of symptomatic AF, the doctor will first try to regulate the heartbeat. This is called a cardioversion. This is the preferred strategy if you are young and active, and if AF has been present for less than 6 months. Cardioversion can be done in two ways:

• by means of a defibrillator (electrical cardioversion);
  • The operation takes place under a general anesthesia of short duration and consists in giving an electrical impulse (electroshock) to the muscle of the heart using a defibrillator.
  • It is literally resetting the electrical system of the heart.
• by the administration of medications (pharmacological cardioversion).
  • This method involves taking a medicine that can restore the heartbeat (antiarrhythmic).
  • It is easier to perform than electrical cardioversion because it does not require general anesthesia, but it is less effective.

One of the risks of cardioversion is that a blood clot has already formed in the heart. This clot can indeed be sent to the brain and cause a stroke when the heart regains its full power. The risk is especially present in the case of an episode of AF that lasts for more than 48 hours or of which we do not know when it started. In this type of situation, a anticoagulant therapy is always administered beforehand. The cardiologist can also check the heart for clots using a CT scan or a trans-phagic ultrasound.

Heart rate monitoring

This approach involves slowing the heart rate to an acceptable rate by administering medicines that slow down the heartbeat. But the pace remains irregular. In most cases, the body quickly gets used to an irregular heartbeat with a normal frequency.

• This strategy is applied when attempts to control the heart rate have failed.
• Heart rate control may also be indicated in people who have few symptoms of AF or in seniors who have other illnesses. In this case, the prognosis and quality of life are no different between this strategy and heart rate control (see above).
• The drugs often used for this treatment are beta-blockers. But other drugs can also be administered. When a single drug does not produce the desired effect, a combination of drugs can also be tried.
• This strategy is applied when it comes to permanent AF, i.e. that we accept that the rhythm will never be regular again.

Ablation

When the heart continues to beat too quickly despite medication, the cardiologist may attempt ablation.

• He does this by inserting a catheter in the groin and sliding it to the heart. Once there, it cauterizes (it ‘burns’) small pieces of tissue from the heart. This forms a scar, preventing the electrical stimulus from passing through. In total, the treatment lasts between 2 and 4 hours.
• There are 2 different forms of ablation. Some methods allow the heart to regain a regular rhythm, others not. Sometimes a pacemaker is implanted during the same operation.

Prevention of thrombosis

AF can cause blood clots to form, which then travel to the brain and trigger a stroke. To avoid it, you can take anti coagulants.

• The doctor will assess the appropriateness of this preventive treatment in your particular situation. This depends in particular on your risk of thrombosis.
• Here are some examples of factors that increase the risk of blood clots:
  • a high age;
  • the female sex;
  • hypertension;
  • diabetes ;
  • a history of thrombosis.
• The vast majority of people over 65 who have AF need to take anticoagulants (medicines that thin the blood).

Treatment with anti coagulants increases the risk of bleeding but, when patients are well selected, the advantages outweigh the disadvantages. Most often, treatment uses vitamin K antagonists, such as Marcoumar or Marevan, or newer generation drugs known as AOD, such as Eliquis, Pradaxa Lixiana, and Xarelto.

Relapse prevention

Without treatment, 80 to 90% of people who have had an episode of AF experience a recurrence within a year. A treatment medicated is therefore put in place as a preventive measure.

• These drugs can only completely prevent new episodes of AF in rare cases. The goal of treatment is therefore to reduce the frequency of relapses and symptoms.
• The drugs used to do this are tablets that slow the heart rate (beta blockers) or keep the heart rate under control (antiarrhythmics).

In addition, it is important to address the underlying risk factors to prevent AF, as well as adopting a healthy lifestyle :

• engage in physical activity;
• control your weight;
• stop smoking.

For people who have rare, brief episodes of AF without other symptoms, the “pill in the pocket” strategy is sometimes indicated. This strategy involves always having medication on hand and only taking it if you have an episode of AF.

Want to know more?

• www.mongeneraliste.be/maladies/fibrillation-auriculaire-quand-le-coeur-s-emballe

Sources

• Foreign clinical practice guide ‘Therapeutic approach to atrial fibrillation: rate control or rhythm control?’ (2008), updated on 03/16/2017 and adapted to the Belgian context on 06/13/2019 – ebpracticenet

• https://bestpractice.bmj.com/info/

¹ KCE – Federal Center of Expertise for Healthcare