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


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%).


CONCLUSIONS
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.
Department of Public Health and Clinical Medicine, Skellefteå Research Unit, Umeå University, Umeå, Västerbotten, Sweden.
Cecilia
C
Johansson
Department of Public Health and Clinical Medicine, Skellefteå Research Unit, Umeå University, Umeå, Västerbotten, Sweden.
Erik
E
Dahlqvist
Department of Public Health and Clinical Medicine, Skellefteå Research Unit, Umeå University, Umeå, Västerbotten, Sweden.
Jonas
J
Andersson
Department of Public Health and Clinical Medicine, Skellefteå Research Unit, Umeå University, Umeå, Västerbotten, Sweden.
Jan-Håkan
JH
Jansson
Department of Public Health and Clinical Medicine, Skellefteå Research Unit, Umeå University, Umeå, Västerbotten, Sweden.
Lars
L
Johansson
atrial fibrillation; atrial flutter; incidence; risk factors for stroke