New studies analyze risk factors, treatments for afib

One study found that early rhythm control was better than rate control for low-risk patients, another found that age at menarche and menopause was associated with afib risk, and another indicated that women's lower risk for afib is due to their smaller body size compared with men.

Early rhythm control therapy in atrial fibrillation was associated with a lower risk of cardiovascular events compared to rate control therapy in low-risk patients, a recent study found. Researchers studied 54,216 Korean patients with afib who received either rhythm or rate control therapy within a year of diagnosis to investigate whether the results of the EAST-AFNET 4 (Early Treatment of Atrial Fibrillation for Stroke Prevention Trial) could be generalized to patients whose stroke risk was too low to be included in the trial. Results were published Sept. 6 by Annals of Internal Medicine.

Among 37,557 eligible study participants (69.3%), early rhythm control was associated with lower risk for the primary composite outcome (cardiovascular death, ischemic stroke, hospitalization for heart failure, or myocardial infarction) than rate control (hazard ratio [HR], 0.86; 95% CI, 0.81 to 0.92). Among the 16,659 low-risk patients (30.7%) who did not meet the inclusion criteria (median age, 54 years; median CHA2DS2-VASc score, 1), early rhythm control was also consistently associated with lower risk for the primary outcome (HR, 0.81; 95% CI, 0.66 to 0.98). No significant differences in safety outcomes were found between the rhythm and rate control strategies regardless of trial eligibility. These results support considering early rhythm control in patients recently diagnosed with afib, the study authors concluded.

The second study was a population-based cohort analysis of women in the U.K. ages 40 to 69 years who did not have afib or a history of hysterectomy and/or bilateral oophorectomy at baseline. The median follow-up period for afib onset was 11.6 years. A total of 235,191 women were included, of whom 4,629 (2.0%) experienced new-onset afib. In multivariable-adjusted models, history of irregular menstrual cycle was associated with higher risk for afib (HR, 1.34; 95% CI, 1.01 to 1.79). Both early menarche (ages 7 to 11 years: HR, 1.10; 95% CI, 1.00 to 1.21) and late menarche (ages 13 to 18 years: HR, 1.08; 95% CI, 1.00 to 1.17) were associated with afib incidence. Early menopause (ages 35 to 44 years: HR, 1.24; 95% CI, 1.10 to 1.39) and delayed menopause (age ≥60 years: HR, 1.34; 95% CI, 1.10 to 1.78) were associated with higher risk of afib. Compared with women with one to two live births, those with no live births (HR, 1.13; 95% CI, 1.04 to 1.24) or seven or more live births (HR, 1.67; 95% CI, 1.03 to 2.70) had significantly higher afib risk. Results were published Sept. 1 by JAMA Network Open.

The study authors concluded that it's important to consider a woman's reproductive history when screening for prevention. An accompanying editorial agreed with the need to take a comprehensive reproductive history. “The study findings generally reinforce the notion of female reproductive health as a vital sign of cardiovascular health and aging. Identification of these factors may involve incorporating standard intake questions about these factors in new patient forms or in electronic medical record fields,” the editorial said.

The third study found that after researchers controlled for height and body size, women were at higher risk for afib than men, suggesting that sex differences in body size account for much of the protective association between female sex and afib. The prospective cohort analysis of 25,119 participants from the Vitamin D and Omega-3 Trial (VITAL) Rhythm Study found that over a median follow-up of 5.3 years, 900 confirmed cases of afib occurred among 12,362 men (495 events; 4.0%) and 12,757 women (405 events; 3.2%). After adjustment for age and treatment assignment, women were at lower risk for afib than men (HR, 0.68; 95% CI, 0.59 to 0.77; P<0.001). The inverse association between female sex and afib persisted after adjustment for race and ethnicity, smoking, alcohol use, hypertension, diabetes, thyroid disease, exercise, and body mass index (HR, 0.73; 95% CI, 0.63 to 0.85; P<0.001). However, female sex was positively associated with afib when height (HR, 1.39; 95% CI, 1.14 to 1.72; P=0.001), height and weight (HR, 1.49; 95% CI, 1.21 to 1.82; P<0.001), or body surface area (HR, 1.25; 95% CI, 1.06 to 1.49; P=0.009) was substituted for body mass index in the multivariate model. In stratified models, risk factor associations with incident afib were similar for women and men. The results were published Aug. 31 by JAMA Cardiology.