Atrial (or atrial) fibrillation is the most common heart rhythm disorder. Often discovered by chance, the risks are nonetheless significant. This disorder is favored by aging (it concerns more than 10% of those over 80) and the presence of cardiac pathology (hypertension, heart valve disease, etc.), hyperthyroidism or obesity.

Atrial fibrillation, or rather atrial fibrillation, is an arrhythmia, that is, a heart rhythm disorder.

Normally, the atria and ventricles of the heart contract under the effect of an electrical impulse, at a regular rate of 60 to 100 beats per minute (at rest). Atrial fibrillation can cause more than 150 heartbeats per minute. This is called a tachyarrhythmia.

“Atrial fibrillation is defined by an anarchic and rapid electrical activity of the muscle of the two atria (which constitute the 2 upper chambers of the heart) and results in their disordered and inefficient contraction”, explains Professor Jacques Mansourati, cardiologist at the CHU de Brest .

In the event of atrial fibrillation, these too frequent electrical impulses then generate:

• Very fast and jerky contractions of the atria (up to 400 pulses per minute);
• In response, the lower chambers of the heart (ventricles) will also contract and beat fast and irregularly at the rate of 150 beats per minute. We will then speak of tachyarrhythmia.

Atrial fibrillation can:

• Occur in episodes / seizures, which sometimes last several days, between which the rhythm of the heart is regular. We speak of paroxysmal atrial fibrillation;
• Or stay present for the long term. The irregularity of the cardiac contractions is then constant). This is called permanent atrial fibrillation.

This arrhythmia affects 1% of the general population, but especially the elderly (more than 10% of those over 80). 20 to 30% of strokes (cerebrovascular accidents) are secondary to atrial fibrillation.

Atrial fibrillation rarely occurs in isolation. “The risk of developing this condition increases especially for patients with certain diseases,” continues the Professor. In particular cardiac pathologies such as arterial hypertension, disease of the coronary arteries, heart muscle or heart valves ”. Here are the main causes: 

• Diseases such as hyperthyroidism or chronic kidney disease, due to metabolic disturbances it causes, may be involved;
• Age (the risk increases with age) and the metabolic syndrome (obesity, diabetes, dyslipidemia), are, among others, well established risk factors;
• Obstructive sleep apnea syndrome appears to be a risk factor and poor response to treatment if not properly managed.

Atrial fibrillation is manifested by a rapid heartbeat, palpitations that last for several hours or more. Other symptoms may be a feeling of tightness or pressure in the chest, fatigue, or difficulty breathing. The disorders can go away when the acute attacks develop into permanent atrial fibrillation.

“But many patients do not feel any symptoms,” says the specialist. Atrial fibrillation is then discovered by chance during a routine exam and often too late. If left untreated, it can have serious consequences. The contractions of the atria become irregular and ineffective, blood clots tend to form in the heart. These clots or thrombi can be propelled into an artery and cause a stroke ”.

Based on the symptoms and a detailed medical examination, the doctor may suspect atrial fibrillation. The diagnosis is confirmed by a resting electrocardiogram (ECG) and, if necessary, a long-term ECG which will record the heart rate over 24 hours.

The treatment will tackle head-on the formation of clots in the atria and the regularization of the heartbeat.

• To prevent blood clots from forming in the heart, most patients need to take blood thinners such as vitamin K anticoagulants (VKA) or direct oral anticoagulants (DOAs);
• Medicines are also prescribed to lower the heart rate, that is, the pulse;
• Finally, if the disorder is severe or if heart failure develops, the doctor will try to bring the atrial fibrillation back to a normal sinus rhythm. “This rhythm control can be done in three ways: cardioversion by drugs (antiarrhythmics), electrical cardioversion and, increasingly by ablation by catheter aiming to isolate the pulmonary vein”, concludes our interlocutor.