CORRESPONDENCE

Stroke and atrial fibrillation

To the Editor: I write in response to two consecutive papers published in the SAMJ.^1,2 The striking feature in both was complete lack of reference to the presence or absence of atrial fibrillation.

More than 30% of strokes relate to atrial fibrillation, depending on the report referred to. Although not directly applicable to the article by Walker et al.,¹ it would have been reasonable for them to mention the presence or absence of atrial fibrillation in the same way as levels of blood pressure are reported.

In the paper by de Villiers et al.,² surely recurrent stroke is a major determinant of outcome following stroke? In the uncoagulated patient with atrial fibrillation the risk of recurrent stroke is extremely high. The implications of this are self-evident.

Traditionally, in sub-Saharan Africa a large emphasis has been placed on the danger of uncontrolled or poorly controlled hypertension. In the same light, the presence or absence of atrial fibrillation (particularly in the presence of valvular disease or heart failure) needs to be recognised, since the correct treatment for this is oral anticoagulant therapy with vitamin K antagonists. Documentation of the incidence of atrial fibrillation in paroxysmal or permanent atrial fibrillation is therefore essential in the setting of stroke and its long term outcome.^3-5

By 'spreading the word', there is little doubt that great improvement in terms of prevention of either first or second episodes of stroke in relation to atrial fibrillation can be achieved.

I W P Obel
Specialist Cardiologist
Milpark Hospital
Johannesburg
proobel@netactive.co.za

1. Walker RW, Jusabani A, Aris E, Gray WK, Mitra D, Swai M. A prospective study of stroke sub-type from within an incident population in Tanzania. S Afr Med J 2011;101(5):338-344.         [ Links ]

2. De Villiers L, Badri M, Ferreira M, Bryer A. Stroke outcomes in a socio-economically disadvantaged urban community. S Afr Med J 2011;101(5):345-348.         [ Links ]

3. Foster V, Ryden LE. ESC guidelines for management of patients with atrial fibrillation. J Am Coll Cardiol 2006;48:854-906.         [ Links ]

4. Lip GY, Edwards SJ. Stroke prevention with aspirin, warfarin and ximelagatran in patients with non-valvular atrial fibrillation. Thromb Res 2006;118:321-333.         [ Links ]

5. Lloyd-Jones D, Adams R, Carnethon N, et al. Heart disease and stroke statistics 2009 update. A report from AHA statistics subcommittee. Circulation 2009;119:e21-e181.         [ Links ]

Dr De Villiers replies: In our study atrial fibrillation as a cause of stroke was not specifically mentioned, as the aetiology of stroke was not the focus of the paper. Of the 196 patients 11.2% (N=22) had cardioembolic stroke, of whom 54.5% (N=12) were in atrial fibrillation. The outcomes for the patients with cardio-embolic stroke were worse than those for the whole cohort, with a 50% mortality at 6 months and 45.4% of survivors having severe disability (modified Rankin scores of 4 or 5) at 6 months in those with cardio-embolic stroke compared with a 6-month post-discharge mortality of 23% and 22% severe residual disability for the cohort as a whole. The point that patients with atrial fibrillation have a high risk of stroke recurrence is important, and what is particularly concerning in this study is that only 9% (N=2) of patients were on anticoagulation at follow-up.

Professor Walker replies: We thank Dr Obel for his response to our article. Atrial fibrillation is part of the scoring system for the Allen scoring system. We did not report the number of cases fulfilling each of the criteria laid out in the Siriraj or Allen scoring systems, because our intention was to focus on the key messages of the article. However, we have reported how many cases in the Hai (4 of 93 who had ECGs) and Dar-es-Salaam (3 of 39 who had ECGs) demographic surveillance sites had atrial fibrillation in an earlier publication from our study.¹

We acknowledge the importance of identifying and managing patients with atrial fibrillation in the prevention of stroke, though we also recognise that the lack, and expense, of monitoring facilities may mean that many people cannot receive oral anticoagulants in sub-Saharan Africa (SSA). We are currently engaged in a study of atrial fibrillation in a community in SSA and hope to be able to present our findings in the near future.

1. Walker R, Whiting D, Unwin N, et al. Stroke incidence in rural and urban Tanzania: a prospective, community-based study. Lancet Neurol 2010;9:786-792.         [ Links ]