Atrial Fibrillation: A New Epidemic

Atrial fibrillation (AF) is one of the most common and chronic disorders in modern cardiology [Kirchhof P et al. Europace 2012], and its medical, social, and economic aspects are set to worsen in the coming decades [Camm AJ et al. Europace 2012]. Dawn Scantlebury, MBBS, DM, Mayo Clinic, Rochester, Minnesota, USA, discussed risk factors for AF in women in an urban setting.

The latest European Society of Cardiology (ESC) Guidelines for the Management of AF [Camm AJ et al. Europace 2012] report an estimated prevalence in the developed world of approximately 1.5% to 2.0%, with the average age of patients steadily rising to between 75 and 85 years. AF confers a 5-fold risk of stroke and a 3-fold incidence of congestive heart failure and higher mortality.

AF is less prevalent in women, but the absolute number with the condition is higher because incidence increases with age and women live longer than men [Gowd BM, Thompson PD. Cardiol Rev 2012]. AF risk rises with increased left atrial volume, which is associated with high body mass index (BMI) [Stritzke J et al. J Am Coll Cardiol 2009]. Dr. Scantlebury and colleagues postulated that obesity would be a risk factor for AF in women in the Kentucky Women's Health Registry (KWHR).

Online or paper questionnaires were administered to women who had indicated interest in being enrolled in research studies on the KWHR survey; content targeted gender-specific risk factors for AF. A total of 708 respondents—117 with AF and 591 controls—took part in the study.

Conventional risk factors significantly associated with AF included hypertension, coronary artery disease, rheumatic heart disease, valvular heart disease, and congestive heart failure (p<0.001). Obstructive sleep apnea, chronic obstructive pulmonary disease (p<0.001), and hyperthyroidism (p<0.05) were also significantly associated with the condition. Among those with AF, 60.3% were obese (BMI >30 kg/m²); 68.6% of those without AF were obese. The authors failed to show a significant relation between obesity and AF (p=0.08).

Conversely, in multivariable models adjusted for cardiovascular risk factors and interim myocardial infarction or heart failure, Wang et al. [JAMA 2004] observed a 4% increase in AF risk per 1-unit increment in BMI in men (p=0.02) and women (p=0.009). Adjusted HRs for AF associated with obesity were 1.52 (p=0.02) and 1.46 (p=0.03) for men and women, respectively, compared with normal-weight individuals (Figure 1).

Prospective data raise the possibility that interventions to promote normal weight may reduce the population burden of AF [Wang TJ et al. JAMA 2004]. Henry [West Indian Med J 2011] contends that preventing obesity is a critical factor in controlling noncommunicable diseases, the main public health problem in the Caribbean (Figure 2), and that effective obesity control will require strategic environmental changes. Findings from Im et al. [West J Nurs Res 2012] suggest that unique programs that promote physical activity should be developed that consider women's ethnic-specific attitudes.