Key takeaways:

• An eGFR decline of 30% or greater occurred more frequently among adults with new-onset vs. no atrial fibrillation.
• Women and adults with diabetes with new-onset atrial fibrillation had faster eGFR decline rates.

Working-age adults in Japan with new-onset atrial fibrillation had faster rates of eGFR decline vs. those without, according to study data published in JAMA Network Open.

Incident atrial fibrillation (AF) is often observed as a risk for heart failure, but its association with kidney function is less understood, according to Shingo Fukuma, MD, PhD, professor at Hiroshima University Graduate School of Biomedical and Health Sciences, and colleagues. With growing recognition about the importance of identifying cardiovascular-kidney-metabolic (CKM) syndrome earlier, the researchers explored whether new-onset AF was associated with kidney function decline among working-age adults.

Data derived from Mori Y, et al. JAMA Netw Open. 2026;doi:10.1001/jamanetworkopen.2026.12823.

“These insights are essential for informing optimal treatment strategies for new-onset AF and mitigating the growing global burden of CKM syndrome,” Fukuma and colleagues wrote.

In a retrospective cohort study, the researchers reviewed serial ECG and eGFR records and insurance claims data from 141,060 working-age adults in Japan (mean age, 49.8 years; 81.8% men) from April 2015 to April 2023. Adults with new-onset AF (n = 23,510) were matched 1:5 with adults with normal sinus rhythm (n = 117,550).

The primary outcome was the annual rate of eGFR decline, and the secondary outcome was an eGFR decline of 30% or greater compared with baseline.

After a median 4.73 years of follow-up, results showed the annual rate of eGFR decline was significantly greater among adults with new-onset AF vs. those without AF (difference = –0.29 mL/min/1.73 m²; 95% CI, –0.32 to –0.26).

In addition, the incidence of a 30% or greater decline in eGFR was significantly greater among adults with new-onset AF vs. those without AF (HR = 2.91; 95% CI, 2.72-3.11). The estimated 7-year incidence of eGFR decline of at least 30% was greater for adults with new-onset AF vs. those without AF (11% vs. 4.9%).

In subgroup analyses, the researchers observed a faster eGFR decline among women with new-onset AF vs. women without AF (difference = 0.39 mL/min/1.73 m²; 95% CI, 0.32-0.47) and adults with diabetes and new-onset AF vs. those with diabetes without AF (difference = 0.55 mL/min/1.73 m²; 95% CI, 0.44-0.65).

Overall, the findings suggest new-onset AF may be independently associated with kidney function decline among working-age adults, according to the researchers.

More research is needed to better understand mechanisms that may link AF with CKD and treatment options for this patient population, the researchers wrote.

“Further investigation is needed on the cumulative impact of AF on CKD progression and on the effectiveness of AF treatments for improving kidney outcomes,” Fukuma and colleagues wrote.