MRCP exam update: AF and anticoagulation

Current situation

The prevalence of AF doubles with each advancing decade from the age of 50 years.  

AF is an independent risk factor for developing a stroke; its presence increases the risk five-fold.

The most important decision to be made for a patient with AF is whether or not they should be given anticoagulation therapy. 

Anticoagulation is underused in clinical practice, partly because it is not known whether trial efficacy translates into clinical practice.

What is the evidence?

Many patients with non-rheumatic AF are reluctant to take warfarin or aspirin because of the increased risk of bleeding.

With a stroke risk rate of 51 per 1,000 person-years, warfarin was calculated to have prevented 28 ischaemic strokes but to have lead to 11 major or fatal bleeding episodes.

Aspirin prevented 16 ischaemic strokes and caused six major or fatal bleeding episodes.

If presented with these figures, many more patients may well refuse stroke prevention treatments (Arch Intern Med 2006; 166: 1,269). 

A study from Scotland shows that the risk of bleeding while taking warfarin in primary care seems to be similar to that found in trials from secondary care.

The risk of bleeding was double in those taking warfarin compared to those either aspirin or no treatment — 9 per cent compared to 4.7 per cent (Br J Gen Pract 2006; 56: 697). 

Analysis from the SPORTIF III and V trials has shown that treatment with ximelagatran is associated with a lower risk of bleeding than warfarin in patients with nonvalvular atrial fibrillation (Arch Intern Med 2006; 166: 853)

Implications for practice

Anticoagulation is indicated in patients with valvular heart disease. Those AF patients without valvular heart disease are at significantly increased embolic risk if they are over the age of 65 years or have had previous embolic events, for example, diabetes and hypertension. 

If any of the above risk factors are present then the benefits of warfarin outweigh the risks and it should be given to AF patients unless there are specific contraindications.

Many people dislike taking tablets every day and would choose lifestyle change rather than medication, if possible.

It is very important that doctors take patients’ preferences into account when considering anticoagulation.

Available guidelines

‘Atrial Fibrillation: National Clinical Guideline for Management in Primary and Secondary Care’ recommends that treatment with antithrombotics be started as soon as possible in patients with newly diagnosed AF, unless contraindicated.

Useful websites — Royal College of Physicians — NICE

Dr Louise Newson is a GP in the West Midlands and author of ‘Hot Topics for MRCGP and general Practitioners’. PasTest 2006

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