Men develop atrial fibrillation 10 years earlier than women, finds studyBMJ 2017; 359 doi: https://doi.org/10.1136/bmj.j4802 (Published 16 October 2017) Cite this as: BMJ 2017;359:j4802
Men develop atrial fibrillation (AF) an average of 10 years earlier than women, and weight is a major risk factor, a pooled analysis of four large European community based studies has found.1
AF is the most common heart rhythm disorder, and its prevalence is increasing. Previous studies have shown that it is twice as common in men as in women, but the risk of adverse outcomes such as stroke is higher in women.
Researchers followed up 79 793 middle aged people (median age 49.6 years) in four community based European cohorts from Denmark, Finland, Italy, and Sweden. No participants had AF at baseline, but they were followed up over a median of 12.6 years for its incidence, and data were collected on mortality and risk factors including body mass index (BMI), blood pressure, and total cholesterol.
“It’s crucial to better understand modifiable risk factors of atrial fibrillation,” said the lead author, Christina Magnussen, of the University Heart Center in Hamburg, Germany. “If prevention strategies succeed in targeting these risk factors, we expect a noticeable decline in new onset atrial fibrillation.”
The results, reported in Circulation, showed fewer cases of AF in women (n=1796; 4.4%) than in men (n=2465; 6.4%). Men developed AF a decade earlier, on average: cumulative incidence curves showed that AF incidence increased steeply in men after age 50, whereas in women this increase occurred after age 60 (P<0.001).
Incident AF in both sexes was associated with all cardiovascular risk factors (apart from diabetes mellitus), a history of stroke or myocardial infarction, and blood levels of B type natriuretic peptide. But BMI was more strongly related to new onset AF in men (hazard ratio per standard deviation increase 1.31 (95% confidence interval 1.25 to 1.38)) than in women (1.18 (1.12 to 1.23)).
BMI, at about 20%, accounted for nearly half of the population attributable risk for AF from all risk factors combined (41.9% in women and 46.0% in men).
“We advise weight reduction for both men and women,” said Magnussen. “As elevated body mass index seems to be more detrimental for men, weight control seems to be essential, particularly in overweight and obese men.”
Total cholesterol was inversely associated with incident AF, and a stronger risk reduction was seen in women (0.86 (0.81 to 0.90)) than in men (0.92 (0.87 to 0.99)). This association persisted even after accounting for cholesterol lowering drugs. The researchers said that this “counterintuitive” inverse association may be explained by the membrane stabilising characteristics of cholesterol, although the mechanism is not clear.
Further analysis showed that AF was associated with a more than 3.5-fold increased risk of death, with no evidence of a sex difference.
“AF poses a significant risk for premature mortality,” concluded the authors of the study, which was funded by the European Union Seventh Framework Programme and other non-profit organisations.