There is good evidence that people with an irregular heart beat should have it checked by a doctor. The link between atrial fibrillation -- the most common disturbance of heart rhythm -- and risk of stroke is now beyond dispute, with studies indicating that diagnosed atrial fibrillation (AF) increases the risk of stroke five times. Similarly, one in five patients diagnosed with stroke are also found to have AF.
Atrial fibrillation, whose prevalence continues to rise, was described last year as the "new epidemic" in cardiovascular disease, even though AF can be successfully controlled by the detection and management of risk factors, by rhythm control treatments, and by the use of antithrombotic therapies.(1) These therapies have been improved in the past few years by the introduction of new anticoagulant drugs, such that AF -- like high blood pressure or smoking -- may now be considered a "modifiable" risk factor for stroke, whose treatment can reduce the degree of risk.
Professor Freek Verheugt, from the Onze Lieve Vrouwe Gasthuis in Amsterdam and speaking on behalf of the European Society of Cardiology (ESC), says: "All individuals with irregular heart beat should see a doctor, who can diagnose whether this heart rhythm disorder is likely to lead to stroke. If so, blood thinning medication can reduce the risk of stroke by up to 70%."
The latest ESC Clinical Practice Guidelines on Cardiovascular Disease Prevention, which were revised this year, describe stroke as the "second major cardiovascular disease" (after coronary heart disease) and, like CHD, with enormous scope for prevention.(2) Indeed, more than 50% of the reductions seen in heart disease mortality over recent decades relate to changes in risk factors. In addition, the treatments prescribed to lower blood pressure, for example, also reduce the risk of stroke, such that stroke prevention is still the most evident effect of antihypertensive treatment.
The Interstroke study, which was reported in 2010 following an analysis of stroke data from 22 countries, indicates that just ten risk factors are associated with 90% of total stroke risk.(3) The highest attributable effect of individual risk factors was 35% from hypertension, 26.5% for waist-to-hip ratio, and 19% for current smoking.(3)
The ESC emphasises that most of these risks for stroke are also the same major risks for coronary heart disease -- high blood pressure, smoking, obesity, lack of exercise and excessive alcohol consumption. In addition, AF, this common disorder of heart rhythm, is also clearly associated with an increased risk of stroke. Indeed, the very latest ESC guidelines on AF, published in August, state: "Diagnosing AF before the first complications occur is a recognized priority for the prevention of strokes," and that "even short episodes of 'silent' AF convey an increased risk for stroke." (4)
While the guidelines advise that the evidence in favour of aspirin in stroke prevention is "weak," they add that a new range of anticoagulant drugs are "broadly preferable" for stroke prevention in AF, but, because experience remains limited, they are recommended within the context of "strict adherence to approved indications." The guidelines state that these novel anticoagulants "offer efficacy, safety, and convenience" compared with previous therapies.
Professor Verheugt emphasises that stroke is not an inevitable consequence of aging and that, by identifying and modifying risk factors, there are substantial opportunities to reduce stroke risk -- through lifestyle interventions and the control of high blood pressure and AF.
1. Atrial fibrillation is now prevalent in almost 2% of the general population, with the average age of patients steadily rising -- presently between 75 and 85 years. AF is associated with a five-fold risk of stroke and three-fold risk of heart failure.
2. European Clinical Practice Guidelines on cardiovascular disease prevention in clinical practice (version 2012), Eur Heart J 2012; 33: 1635-1701.
3. O'Donnell MJ, Xavier D, Liu L, et al. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the INTERSTROKE study): a case-control study. Lancet 2010; 376: 112-123.
4. The Task Force for the management of atrial fibrillation of the European Society of Cardiology (ESC). 2012 focused update of the ESC Guidelines for the Management of Atrial Fibrillation. Eur Heart J 2012; doi:10.1093/eurheartj/.
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