Incidence, type of atrial fibrillation and risk factors for stroke: a population-based cohort study

Abstract

Purpose

The aims of this study were to estimate the incidence of atrial fibrillation and atrial flutter (AF), to assess the presence of provoking factors and risk factors for stroke and systemic embolism, and to determine the type of AF in patients with first-diagnosed AF.

Patients and methods

This cohort study was performed in northern Sweden between January 1, 2011 and December 31, 2012. Diagnosis registries were searched for the International Classification of Diseases-10 code for AF (I48) to identify cases of incident AF. All AF diagnoses were electrocardiogram-verified. Data pertaining to provoking factors, type of AF and presence of risk factors for stroke and systemic embolism according to the CHA₂DS₂-VASc score were obtained from medical records.

Results

The incidence of AF in the entire population was 4.0 per 1,000 person-years. The incidence was 27.5 per 1,000 person-years in patients aged ≥80 years. A total of 21% of all patients had a provoking factor in association with the first-diagnosed episode of AF. The CHA₂DS₂-VASc score was 2 or higher in 81% of the patients. Permanent AF was the most common type of AF (29%).

Conclusion

There was a considerable increase in the incidence of AF with age, and a provoking factor was found in one-fifth. The most common type of AF was permanent AF. Four in five patients had a CHA₂DS₂-VASc score of 2 or more.

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Keywords:

• atrial fibrillation
• atrial flutter
• incidence
• risk factors for stroke

Supplementary materials

Table S1 Detailed definitions of risk factors for stroke and systemic embolism and provoking factors for AF

Table S2 Incidence of first-diagnosed atrial fibrillation and atrial flutter presented as number of incident cases per two years and incidence per 1,000 person-years, by age and sex

Acknowledgments

Financial support was provided by a regional agreement between Umeå University and the Västerbotten County Council for the cooperation in the fields of Medicine, Odontology and Health, and by the Society for Medical Research in Skellefteå.

Disclosure

The authors report no conflicts of interest in this work.