Atrial fibrillation (AF) is a major public health burden worldwide, and its prevalence is set to increase owing to widespread population ageing, especially in rapidly developing countries such as Brazil, China, India, and Indonesia. Despite the availability of epidemiological data on the prevalence of AF in North America and Western Europe, corresponding data are limited in Africa, Asia, and South America. Moreover, other observations suggest that the prevalence of AF might be underestimated-not only in low-income and middle-income countries, but also in their high-income counterparts. Future studies are required to provide precise estimations of the global AF burden, identify important risk factors in various regions worldwide, and take into consideration regional and ethnic variations in AF. Furthermore, in response to the increasing prevalence of AF, additional resources will need to be allocated globally for prevention and treatment of AF and its associated complications. In this Review, we discuss the available data on the global prevalence, risk factors, management, financial costs, and clinical burden of AF, and highlight the current worldwide inadequacy of its treatment.

Atrial fibrillation (AF) is the most common sustained arrhythmia in women and men worldwide. During the past century, a range of risk factors have been associated with AF, severe complications from the arrhythmia have been identified, and the prevalence has been increasing steadily. Whereas evidence has accumulated regarding sex differences in coronary heart disease and stroke, the differences between women and men with AF has received less attention. We review the current literature on sex-specific differences in the epidemiology of AF, including incidence, prevalence, risk factors, and genetics, and in the pathophysiology and the clinical presentation and prognosis of patients with this arrhythmia. We highlight current knowledge gaps and areas that warrant future research, which may potentially advance understanding of variation in the risk factors and complications of AF, and ultimately aid more-tailored management of the arrhythmia.

Objective Power spectral analysis of heart rate variability is used clinically to assess cardiac autonomic function. High frequency power is related to respiratory sinus arrhythmia and therefore to parasympathetic cardiovagal tone. The relationship of low frequency (LF) power to cardiac sympathetic tone is less clear. We reported previously that LF power may reflect baroreflex function; however, in the previous study LF power was not adjusted for possible influences of respiration. In this study we assessed relationships of LF power, including respiration-adjusted LF power (LFa) using the ANSAR ANX 3.0 device, with cardiac sympathetic innervation and baroreflex function in chronic autonomic failure patients who either had or did not have neuroimaging evidence of cardiac sympathetic denervation. Methods Values for LF power with patients seated at baseline and during the Valsalva maneuver were compared between groups with low or normal myocardial concentrations of 6-[18F]fluorodopamine-derived radioactivity. Baroreflex-cardiovagal gain (BRS) was calculated from the slope of cardiac interbeat interval vs. systolic pressure during the Valsalva maneuver with subjects supine. Results Individual values for LF and LFa were unrelated to myocardial 6-[18F]fluorodopamine-derived radioactivity. During both sitting rest and the Valsalva maneuver the logs of LF and LFa correlated positively with the log of BRS (r=0.61, p=0.0005; r=0.47, p=0.009; r=0.69, p<0.0001; r=0.60, p=0.0006). Patients with low BRS (≤3 msec/mm Hg) had low LF and LFa regardless of the status of cardiac innervation. Conclusion LF and LFa reflect baroreflex function independently of cardiac sympathetic innervation.