Atrial Fibrillation: Causes, Risks and Treatment

Atrial Fibrillation: Causes, Risks and Treatment

Atrial fibrillation (AF or AFib) is the most common sustained cardiac arrhythmia — an abnormal heart rhythm in which the upper chambers of the heart (the atria) beat chaotically and very rapidly instead of with the coordinated, regular contractions of a normal heartbeat. AF becomes more common with increasing age.

AF can increase the risk of stroke and heart failure. A fast or irregular heartbeat with chest pain, severe breathlessness, fainting or stroke-like symptoms needs emergency assessment; do not wait for a travel consultation.

How the Normal Heart Rhythm Works

In a healthy heart, each beat is initiated by an electrical impulse from the sinoatrial (SA) node — the heart's natural pacemaker — located in the right atrium. This impulse spreads across both atria, causing them to contract and push blood into the ventricles. It then passes through the atrioventricular (AV) node to trigger coordinated ventricular contraction.

This sequence produces the regular pulse felt at the wrist: 60–100 beats per minute at rest, with each beat efficient and rhythmic.

What Happens in Atrial Fibrillation

In AF, instead of a single ordered electrical impulse from the SA node, multiple chaotic electrical signals fire simultaneously from many sites within and around the atria. The atria quiver (fibrillate) rather than contract properly.

Because the AV node cannot conduct every disorganised signal to the ventricles, only some signals get through — unpredictably. This produces the hallmark of AF: an irregularly irregular pulse, often rapid (140–160 beats per minute in untreated AF).

Atrial Flutter

Closely related to AF, atrial flutter involves a single, fast but organised circuit of electrical activity cycling around the right atrium, causing very rapid atrial contractions (250–350 per minute). The ventricles typically respond to every second or third atrial beat, producing a rapid but often regular pulse of around 150 beats per minute. Many people with atrial flutter also experience AF at other times.

Causes and Risk Factors

AF can occur in people with structurally normal hearts, but it is more commonly associated with underlying conditions:

• Hypertension (high blood pressure) — the single most common risk factor; causes left atrial enlargement
• Coronary artery disease — reduces blood supply to the atrial tissue
• Heart failure — raised atrial pressure promotes AF; AF worsens heart failure, creating a vicious cycle
• Heart valve disease — particularly mitral valve stenosis or regurgitation (enlarges the left atrium)
• Cardiomyopathy — disease of the heart muscle
• Congenital heart defects
• Obstructive sleep apnoea — intermittent oxygen desaturation triggers electrical changes in atrial tissue
• Hyperthyroidism (overactive thyroid) — excess thyroid hormone overstimulates the heart
• Excess alcohol — "holiday heart" syndrome; acute or chronic alcohol use is a well-established trigger
• Obesity — an independent risk factor independent of associated hypertension and diabetes
• Age — increasing age raises the likelihood of AF

Types of AF by Duration

Type	Definition
Paroxysmal	Episodes that start and stop spontaneously, lasting less than 7 days
Persistent	AF continuing beyond 7 days; management depends on the individual case
Long-standing persistent	AF lasting more than 12 months
Permanent	AF is accepted as the ongoing rhythm; rhythm restoration is no longer pursued

Symptoms

Symptoms vary widely — some people are unaware they have AF; others are significantly disabled by it.

Common symptoms include:

• Palpitations — an awareness of the heartbeat, often described as fluttering, racing or irregular
• Breathlessness — on exertion or at rest, particularly when the ventricular rate is rapid
• Fatigue and reduced exercise tolerance
• Dizziness or light-headedness
• Chest tightness or discomfort
• Weakness

Symptoms can vary with heart rate and other conditions. Improvement in symptoms does not remove the need to assess stroke risk.

In some people, a stroke is the first sign of AF. Appropriate anticoagulation can reduce stroke risk but does not eliminate it.

Why Atrial Fibrillation Increases Stroke Risk

When the atria fibrillate rather than contract, blood stagnates within them — particularly in the left atrial appendage (LAA), a small pouch in the left atrium. Stagnant blood tends to clot. These clots can break off, travel through the circulation, and block a cerebral artery, causing a stroke.

The cardiologist assesses stroke risk using an appropriate validated tool alongside the clinical history. Age, previous stroke, heart failure and other conditions matter. A score is not a standalone prescription: the choice also depends on bleeding risk, valve disease, medicines and patient preferences. This article does not supply a universal score threshold or a zero-risk category.

Diagnosis

Electrocardiogram (ECG)

AF is confirmed by ECG, which shows:

• Absence of distinct P waves (replaced by irregular, low-amplitude fibrillatory activity)
• Irregularly irregular R-R intervals — no pattern to when ventricles contract
• Variable ventricular rate — it may be rapid, normal or slow; a rapid rate is not required for diagnosis

A single 12-lead ECG captures the rhythm if AF is ongoing. A 24-hour or 7-day Holter monitor is used to detect paroxysmal AF that comes and goes.

Additional Investigations

• Echocardiogram — assesses heart structure and valve function; the team decides whether additional imaging is needed to evaluate a suspected clot
• Thyroid function tests — to exclude hyperthyroidism as a reversible cause
• Full blood count, kidney function, liver function — baseline before starting anticoagulation
• Sleep study — if obstructive sleep apnoea is suspected

Treatment

Treatment of AF has three main goals:

1. Rate control — prevent the ventricles from beating too fast
2. Rhythm control — restore and maintain normal sinus rhythm where appropriate
3. Anticoagulation — reduce stroke risk when indicated

Rate Control

Rate-control treatment and the target heart rate are individual decisions. Rate control does not replace assessment of stroke prevention. Medication options include:

• Beta-blockers (e.g. metoprolol, bisoprolol) — selected according to the clinical circumstances
• Calcium channel blockers (e.g. diltiazem, verapamil) — alternative
• Digoxin — useful when other agents are not tolerated, particularly in heart failure

Rhythm Control

The cardiologist discusses whether rhythm control is appropriate, taking symptoms, heart function, disease duration and preferences into account. Options include:

• Cardioversion — electrical treatment to restore rhythm; the team must assess procedure risks and the need for anticoagulation or clot evaluation
• Antiarrhythmic drugs — flecainide (in structurally normal hearts), amiodarone (broadly effective but with side effects requiring monitoring), sotalol, dronedarone
• Catheter ablation — an option for selected patients, with benefits and risks to discuss

Catheter Ablation for Atrial Fibrillation

Catheter ablation is a minimally invasive procedure performed under sedation or light general anaesthesia. Thin catheters are passed through the femoral vein to the heart, where radiofrequency energy (or cryotherapy) creates scar lines that electrically isolate the pulmonary veins — the most common triggers of AF — from the left atrium.

Results depend on AF type, other health conditions, the procedure and follow-up. AF can recur and repeat treatment may be needed. Ask the treating centre for outcomes relevant to your situation rather than assuming a published percentage is a personal forecast.

Anticoagulation

Anticoagulants reduce the likelihood of stroke but can cause bleeding. A clinician must assess the balance and choose the medicine and dose. Do not start, stop or change treatment based on this guide.

Direct oral anticoagulants include rivaroxaban, apixaban, dabigatran and edoxaban. Their use is not interchangeable with warfarin in every patient: mechanical heart valves and moderate-to-severe mitral stenosis are important exceptions to the general preference for DOACs in AF guidance. Kidney function, other medicines and monitoring requirements also need review.

Left atrial appendage occlusion may be considered for selected patients after specialist assessment. It is not a simple substitute for anticoagulation whenever someone dislikes or has difficulty taking a medicine; procedure risks and subsequent medication requirements must be discussed.

AF Management in China

Ask the receiving cardiology service which assessments are needed, how rhythm monitoring will be arranged and whether an electrophysiology consultation is appropriate. ECG, echocardiography and ambulatory monitoring answer different questions and may require separate appointments.

If considering ablation or left atrial appendage occlusion, confirm the indication, specific procedure, risks, admission arrangements and continuing medication and follow-up. Obtain an itemised hospital quotation and confirm language support and any PriumCare coordination separately. This guide does not guarantee same-day completion, a particular device, outcomes comparable to another country or lower cost.

Contact a PriumCare care navigator to arrange an AF assessment or ablation consultation.

Sources and editorial correction

• NHS: atrial fibrillation.
• ACC/AHA/ACCP/HRS guideline (2023).

Editorial source correction: 25 October 2026. This check addressed stroke-prevention absolutes, risk-score and rate-target simplifications, anticoagulant exceptions, procedural claims, undated prevalence and unsupported service comparisons. It is not a clinical review of the whole article and does not certify an individual treatment plan. No named medical reviewer is claimed. Original publication date is retained.

Additional editorial source clarification

Editorial clarification: 25 October 2026. This targeted update addresses the specific diagnostic, treatment-selection or service claims identified in the sources below. It is not a clinical review of the whole article; the original publication date is retained.

• Source 1