Atrial fibrillation

Question 1

How common is it?

Answer 1

Roughly 1.6% prevalence, so incredibly common, 835,000 people in England.

Question 2

Who does it affect?

Answer 2

Men slightly more than women

Question 3

What causes it?

Answer 3

ischaemic heart disease
hypertension
valvular heart disease
hyperthyroidism.

Rheumatic heart disease
sick sinus syndrome
pre-excitation syndromes (such as Wolff-Parkinson-White syndrome),
heart failure
electrolyte depletion
lung cancer
pulmonary embolism
thyrotoxicosis
diabetes mellitus.

Question 4

How does it present?

Answer 4

People with an irregular pulse and any of the following: shortness of breath, palpitations, chest discomfort, syncope or dizziness, reduced exercise tolerance, malaise or polyuria.

Question 5

Signs on examination?

Answer 5

An irregular pulse.

Absence of this makes a diagnosis of AF unlikely, but its presence does not reliably indicate AF. Suspect paroxysmal AF if symptoms are episodic and last less than 48 hours.

Question 6

Investigations

Answer 6

ECG. In AF, the ECG will show no P-waves, a chaotic baseline, and an irregular ventricular rate. The ventricular rate is often 180-180 bpm but can be lower, especially in asymptomatic people. The ventricular complexes look normal unless there is ventricular conduction defect.

Question 7

Treatment

Answer 7

Rate control: aims to reduce the heart rate at rest and during exercise but the patient will remain in AF. β-blockers or calcium antagonists (verapamil, diltiazem) are the preferred treatment except in predominantly sedentary people where digoxin is used.

Rhythm control is generally appropriate in younger patients (i.e. <65 years of age), patients who are highly symptomatic, patients who also have congestive heart failure, and individuals with recent onset AF (<48h). Conversion to sinus rhythm is achieved by electrical DC cardioversion and then administration of β-blockers to suppress the arrhythmia. Other agents used depend on the presence (use amiodarone) or absence (use sotalol, flecainide, propafenone) of underlying heart disease.

Catheter ablation techniques such as pulmonary vein isolation are used in patients who do not respond to antiarrhythmic drugs.

Question 8

Conditions that would present similarly

Answer 8

Atrial flutter – characterised by a saw-tooth pattern of regular atrial activation on the electrocardiogram.

Atrial extra systoles – common cause of an irregular pulse.

Ventricular ectopic beats.

Sinus tachycardia – sinus rhythm with more than 100 beats per minute.

Supraventricular tachycardia, including atrial tachycardia, atrioventricular nodal re-entry tachycardia and Wolff-Parkinson-White syndrome.

Multifocal atrial tachycardia.