Atrial fibrillation (AF) density showed a dose–response association with ischemic stroke risk independent of AF burden. This study, published in the European Heart Journal, evaluated the association between AF density and ischemic stroke risk and its incremental value over AF burden.
Data were analysed from two US cohorts of patients with cardiac implantable electronic devices remotely monitored between January 2010 and May 2025 through the Veterans Health

Administration and the University of North Carolina. AF burden, defined as percentage of time in AF, and AF density, ranging from 0 (dispersed episodes) to 1 (consolidated episodes), were assessed in 30-day intervals and categorized as low (>0–0.3), medium (>0.3–0.6), medium-high (>0.6–0.9), and high (>0.9–1.0). G-formula modelling was used to estimate 1-year stroke risk ratios (RRs), adjusting for baseline and time-varying covariates, with pooled estimates derived using random-effects meta-analysis.

Among 41,780 patients, 12,868 met inclusion criteria (mean age 72.0 years; median CHA2DS2-VASc score 4.0). Over a median follow-up of 4.0 years, 336 patients experienced ischaemic stroke (6.3 per 1000 person-years). AF density showed a dose response association with 1-year stroke risk (RR 1.75; 95% CI 1.25-2.44), consistent across device types, comorbidities, age, and anticoagulation status. At each level of AF burden, higher AF density was associated with greater stroke risk. 

AF density was associated with improved risk stratification compared with AF burden. Incorporation of density may refine stroke risk stratification in AF populations.