A study presented at the ESC annual meeting (25–29 August 2012) suggests that obesity increases the risk of atrial fibrillation in women of child-bearing age, indicating that lifestyles measures could be used to prevent the development of atrial fibrillation in this population.
Deniz Karasoy (Department of Cardiology, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark) and others explained that while obesity is an established risk factor for atrial fibrillation in older patients, its association with atrial fibrillation in younger patients has not been examined. Therefore, as the prevalence of obesity is “rising exponentially”, the authors “examined the incidence of atrial fibrillation in relation to body mass index (BMI) in fertile women.”
Karasoy et al reviewed data from nationwide registers of childbirth and hospitalisation to identity women (aged 20–50) who gave birth in Denmark for the first time between 2004 and 2009.
Karasoy et al categorised these women as being of “normal weight” (BMI, 18.5–25kg/m2), being “overweight” (BMI 25-30kg/m2), being “obese” (BMI 30–35kg/m2), or being “very obese” (BMI >35kg/m2) and followed them from the day of giving birth. The authors then correlated the incidence of atrial fibrillation in this population with BMI category.
Of the 271, 257 women identified (mean age 30.6 years), 110 new-onset cases of atrial fibrillation were reported after a mean follow-up period of 4.56 years. Karasoy et al noted: “For normal weight, obese, and very obese subjects, atrial fibrillation incidence rates (95% CI) were 7.4 (5.6–9.7), 8.5 (5.5-13.1), 15.8 (9.3–26.7), and 27.3 (15.5-48.1) per 100,000 person-years respectively.” They added that the risk of new-onset atrial fibrillation increased significantly with each unit increase in BMI-the risk of atrial fibrillation was two-fold higher in obese patients and more than three-fold higher in very obese patients.
Karasoy told Cardiac Rhythm News that the objective of the study was to raise awareness of the association between obesity and atrial fibrillation and to contribute further knowledge of the risk factors for atrial fibrillation among a “young and essentially healthy” population. He added: “Although, we have not investigated the effect of weight loss in our study, we believe that the key solution for management of atrial fibrillation in this population is comprehensive primary prevention. We cannot conclude any definitive management strategies regarding the secondary prevention from this study.”
Although Karasoy and his colleagues did not investigate the potential underlying mechanisms as to why obesity seems to increase the risk of atrial fibrillation, he said that a few studies have reviewed this link. He said: “These studies have found left atrial enlargement and impairment of diastolic function of the left ventricle in obese individuals. Both of these factors are well-established mediators of atrial fibrillation and, therefore, provide a possible pathophysiological explanation.”