Atrial Fibrillation: What It Is, Causes, and How Dangerous It Is

Atrial fibrillation is not a "mood swing" of the heart but a specific electrophysiological mechanism. Below — what happens to the atria, where the chaotic rhythm comes from, what the numbers mean, and in which cases delay is dangerous.

What is atrial fibrillation (fibrillation of the atria)

Atrial fibrillation, AF, colloquially "afib" — a supraventricular tachyarrhythmia with chaotic electrical activity of the atria: impulses are generated at a rate of 350–700 per minute, and there is no coordinated contraction of the atria. The chambers of the heart work in an uncoordinated way, the ventricles do not fill completely and do not pump enough blood to the lungs and body.

Why atrial fibrillation occurs: causes and risk factors

The basis is changes in the heart tissue or its electrical signaling. Among the causes: arterial hypertension, heart failure, valvular disease, coronary artery disease (in 20% of patients with AF), cardiomyopathies, myocarditis and pericarditis, hyperthyroidism, diabetes, obesity, chronic kidney disease, COPD, sleep apnea.

Risk increases with age (especially after 65 years) and is higher in men. Smoking, alcohol (even about 10 g per day is associated with an approximately 5% increase in risk), and certain medications — levothyroxine, lithium, salbutamol, endurance training — contribute. Heredity matters: among more than 2200 patients with AF, 30% had parents who also had AF. In 30–45% of cases of paroxysmal and 20–25% of persistent AF, the arrhythmia occurs in young people without heart pathology.

Signs of atrial fibrillation

The main one is an irregular pulse: beats occur at different intervals. Next — a sensation that the heart is pounding, fluttering, or skipping beats; a rate above 100 per minute; marked fatigue, the most common symptom; exercise is harder to tolerate; pain or pressure in the chest; shortness of breath, dizziness, presyncope. Some people feel nothing — the arrhythmia is found on examination or during testing for another reason.

The course can be paroxysmal (episodes start and stop on their own), persistent (the rhythm is restored after treatment), and permanent. By ventricular rate, tachycardic (more than 90 per minute), normocardic, and bradycardic (less than 60) forms are distinguished.

How atrial fibrillation manifests on a blood pressure monitor and pulse

The clue is not the number but the rhythm: in AF the pulse is irregular, and the definitive diagnosis is made by ECG. Low blood pressure may be among the symptoms.

How atrial fibrillation is diagnosed

The decisive sign is ECG: there are no P waves; instead, multiple f waves appear. The doctor clarifies symptoms, lifestyle, other diseases, and family history, performs an examination, and orders tests:

• electrocardiogram — records the absence of P waves and f waves;
• echocardiography — structure of the heart and valves;
• chest X-ray;
• blood tests, including to look for other causes of symptoms;
• a wearable monitor that records the heart's electrical activity.

Is it dangerous: risks and complications, when a doctor is needed

Yes, monitoring is necessary. AF causes about 25% of ischemic strokes, and its presence increases the frequency of cardioembolic stroke and systemic thromboembolism 5-fold; thrombi form predominantly in the left atrial appendage due to slowed blood flow. Other complications include heart failure, thrombi, sudden cardiac arrest, cognitive impairment, and dementia. A chronic course increases the risk of death by approximately 1.5–2 times. Prevalence is 1–2% of the population, about 8% among people over 80 years; the risk for a person over 40 years is 26% in men and 23% in women.

There is no cure, but treatment controls symptoms and reduces the risk of complications. Referral to a cardiologist is made when AF is suspected, with recurring or worsening palpitations, and also if the diagnosis already exists but treatment is not helping.

Atrial fibrillation by itself is not a reason to call an ambulance. Call 103 or 112 if, against a background of rapid or irregular heartbeat, there is chest pain, shortness of breath, sweating, nausea or vomiting, fainting, severe dizziness or a fall, sudden severe headache, weakness or numbness on one side of the face or body, blurred vision or loss of vision, confusion, or difficulty speaking.

This material is for reference: it explains the mechanism and key points but does not replace consultation with a doctor, who will assess your specific situation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer