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AF more common than guidelines suggest

Atrial fibrillation (AF) is more common than present guidelines suggest, according to a study1 published recently in Stroke, which also finds that the associated risk of ischaemic stroke increases with age, close to that of hypertension in individuals aged ≥80 years.

Authors extracted data from the hospital, specialised outpatient, and primary healthcare and drug registries in a Swedish region with 1.56 million residents. They identified all individuals who had received an AF diagnosis during the previous five years; all stroke events during 2010; and patients with AF aged ≥50 years who had received warfarin during 2009.

AF had been diagnosed in 38,446 subjects who were alive at the beginning of 2010 (prevalence of 3.2% in the adult [≥20 years] population); ≈46% received warfarin therapy. In 2010, there were 4,565 ischaemic stroke events and 861 intracranial haemorrhages. AF had been diagnosed in 38% of ischaemic events (≥50% among those aged ≥80 years) and in 23% of intracranial haemorrhages.

An AF diagnosis was often lacking in hospital discharge records after stroke events. Warfarin therapy was associated with an odds ratio of 0.50 (confidence interval, 0.43–0.57) for ischaemic stroke and, despite an increased risk of intracranial haemorrhage, an odds ratio of 0.57 (confidence interval, 0.50–0.64) for the overall risk for stroke.

Professor Lennart Bergfeldt (Sahlgrenska University Hospital, Gothenburg, Sweden)

Professor Lennart Bergfeldt (Sahlgrenska University Hospital, Gothenburg, Sweden)

Because a majority of patients with AF with increased risk for stroke had not received anticoagulation therapy, there is a large potential for improvement, the authors concluded.

Speaking to BJC Arrhythmia Watch, co-author Professor Lennart Bergfeldt (Sahlgrenska University Hospital, Gothenburg, Sweden) said: “The applicability of our results to other European countries is very much dependent on the age (demographic) structure in the countries in question. Judging from hospital data alone the prevalence of AF in Sweden varied between 2.5 and 3.5% in two regions that differed 3.4 years in mean age. The age and sex stratified prevalence is probably similar in the European countries.”

“American guidelines state a prevalence of 0.4–1.0% while the European counterpart estimates the prevalence in the general population to be 1.5–2.0%. This gives a range for our result of 1.6 to 8 times the figures in the guidelines or 160-800%,” he added.

“The presently available new oral anticoagulants certainly offer new possibilities that we have been waiting for a very long time. For different reasons discussed at length and in detail in the literature since their arrival, these substances are far from ideal. If the problems related to them can be satisfactorily resolved there is no doubt in my mind that they to large extent will replace warfarin. However, they have e.g. so far not proven sufficient effect in patients with mechanical valve prostheses, and some patients might actually prefer to get regular feedback on their warfarin therapy and feel confident that in case of a bleeding complication there is a widely available antidote,” he continued.

“We certainly know that warfarin is not (has not been) used to the extent that it is indicated for primary and secondary thromboembolic prophylaxis. Unfortunately, we know very little about the reasons (doctors’ and patients’ factors) behind this under-treatment,” Professor Bergfeldt concluded.

References

1. Björck S, Palaszewski B, Friberg L, Bergfeldt L. Atrial fibrillation, stroke risk, and warfarin therapy revisited a population-based study. Stroke 2013. http://dx.doi.org/10.1161/​STROKEAHA.113.002329

Published on: September 18, 2013

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ENDORSED BY

  • ArrhythmiaAlliance
  • Stars
  • Anticoagulation Europe
  • Atrial Fibrillation Association
 

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