Study Suggests Women More Likely to Develop AFib than Men When Accounting for Height and Weight

Christine Albert, MD, MPH

New data from the VITAL Rhythm Study is highlighting the need for greater emphasis on identification and prevention of atrial fibrillation (AF) among female patients.

A prospective cohort analysis of data from the Vitamin D and Omega-3 Trial (VITAL) Rhythm Study by clinicians at the Smidt Heart Institute at Cedars-Sinai Medical Center, the study produced results suggesting women had a lower risk of developing incident AF than their male counterparts, but further analysis controlling for both height and weight suggested females had a 49% greater risk of developing AF than their male counterparts.

“This is the first study to show an actual flip in the risk of atrial fibrillation,” said senior investigator Christine Albert, MD, MPH, chair of the Department of Cardiology in the Smidt Heart Institute, in a statement. “In this population of 25,000 individuals without prior heart disease, after adjusting for differences in height, women were at higher risk for developing AF than their male counterparts—upward of 50%.”

Albert, who also led the VITAL Rhythm trial, together with colleagues from the Smidt Heart Institute conducted the current study with the intent of further exploring whether the potential sex differences in incidence of AF observed in previous studies were independent of sex differences in prevalent cardiovascular disease body size, and other risk factors. With this in mind, investigators designed the current study as a prospective cohort analysis of data from the VITAL Rhythm study related to men aged 50 years or older and women aged 55 years or older without a history of AF, cardiovascular disease, or cancer at baseline.

From the study, investigators identified a cohort of 25,119 individuals for inclusion in their analyses. This cohort had a mean age of 67 (SD, 7.1) years, 51% were women, and the median follow-up was 5.3 (IQR, 5.1-5.7) years. During the follow-up period, a total of 900 confirmed incident AF events occurred among the 12,362 men included in the trial and 12,757 women included in the trial, which correlates to event rates of 4.0% and 3.2%, respectively. For the purpose of analysis, sex, height, BMI, body surface area (BSA), and other AF risk factors at study enrollment were used as exposures in the investigator’s multivariable Cox proportional hazards models used to determine associations between sex and AF.

Initial analyses, which adjusted for age and treatment assignment, suggested women were at a lower risk for incident AF than their male counterparts (HR, 0.68 [95% CI, 0.59-0.77]; P <.001). Investigators noted this inverse association persisted even after adjustment for race and ethnicity, smoking, alcohol intake, diabetes status, thyroid disease, exercise, and BMI (HR, 0.73 [95% CI, 0.63-0.85]; P <.001). Conversely, an increased risk of incident AF was observed for women when height (HR, 1.39 [95% CI, 1.14-1.72]; P=.001), height and weight (HR 1.49 [95% CI, 1.21-1.82]; P <.001), or BSA (HR, 1.25 [95% CI, 1.06-1.49]; P=.009) were substituted for BMI in the multivariate model. Investigators pointed out risk factor associations with incident AF were similar for women and men in stratified models.

“Atrial fibrillation is a disease we want to prevent, regardless of sex or gender,” said Albert. “This informative study is an important step for the medical community to take note of, and begin discussing AFib risk with all patients, whether male or female.”

This study, “Sex Differences in Atrial Fibrillation Risk,” was published in JAMA Cardiology.