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At the heart of general practice since 1960

How hot are you on atrial fibrillation?


Test your knowledge for the nMRCGP with this little GEM from GPnotebook


Test your knowledge for the nMRCGP with this little GEM from GPnotebook

Atrial fibrillation (AF) is an atrial rhythm that is ineffective, chaotic, irregular and rapid. Atrial electrical activity is very rapid (400 to 700 beats per minute). However each electrical impulse results in the depolarisation of only a small islet of atrial myocardium and an irregular ventricular rate.

Q How common is AF?

A The prevalence is:

• 0.4 per cent of the population

• 2.4-4.0 per cent of over-60-year-olds

• 10 per cent of over-80-year-olds

Prevalence is greater in men than women (1.1 per cent versus 0.8 per cent).

Q In an ECG for a patient with AF there may be both irregular and normal QRS complexes observed. What are the ECG changes seen?

A A typical ECG in AF shows a rapid irregular tachycardia in which P waves are absent. QRS complexes are generally normal, and the ventricular rate in patients with untreated AF ranges between 150 and 220 beats per minute. Flutter-like waves may be seen transiently in V1.

AF is sometimes confused with atrial flutter; where the atrial rate is greater than 250 and there is an atrio-ventricular block because the ventricles cannot match the atrial rate. In atrial flutter there may be a 'saw-tooth' baseline. The QRS complexes are normal in atrial flutter.

Q When is echocardiography indicated?

A Transthoracic echocardiography (TTE) should be performed in patients with AF:

• for whom a baseline echocardiogram is important for long-term management, such as younger patients

• for whom cardioversion (electrical or pharmacological) is being considered

• in whom there is a high risk or a suspicion of structural or functional heart disease (such as heart failure or heart murmur) that influences management (for example, choice of antiarrhythmic drug)

• in whom refinement of clinical risk stratification for antithrombotics is needed TTE should not be performed solely for further stroke risk stratification in AF patients for whom the need to initiate anticoagulation therapy has already been agreed.

Q When is rate control a better treatment target than rhythm control in a patient with chronic AF?

A NICE says rate control is the preferred initial option in the following AF patients:

• over 65

• with coronary artery disease

• with contraindications to antiarrhythmic drugs

• unsuitable for cardioversion

• without congestive heart failure

Rhythm control is the preferred initial treatment option in the following AF patients:

• those who are symptomatic

• younger patients

• those presenting for the first time with lone AF

• those with AF secondary to a treated/corrected precipitant

• those with congestive heart failure

Patients unsuitable for cardioversion include those with:

• contraindications to anticoagulation

• structural heart disease (such as a large left atrium >5.5 cm, mitral stenosis) that precludes long-term maintenance of sinus rhythm

• a long duration of AF (usually >12 months)

• a history of multiple failed attempts at cardioversion and/or relapses, even with antiarrhythmic drugs or non-pharmacological approaches

• an ongoing but reversible cause of AF (such as thyrotoxicosis).

This fortnightly series is based on GPnotebook Educational Modules (GEMs) – the full version is available via GPnotebook Plus, a service free to UK medics at www.gpnotebook.co.uk

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