Association Between Stroke Lesion Size and Atrial Fibrillation Detected After Stroke: An Observational Cohort Study.

Background: Atrial fibrillation detected after stroke (AFDAS) is considered to be a distinct entity influenced by cardiogenic and neurogenic factors. We hypothesized that patients with AFDAS have larger stroke lesions than patients without atrial fibrillation (AF) and with known AF (KAF).

Results: Consecutive patients with magnetic resonance imaging-confirmed acute ischemic stroke admitted to a university hospital between October 2020 and January 2023 were prospectively registered. We categorized patients as AFDAS, no AF or KAF upon hospital discharge. We manually segmented diffusion-weighted imaging lesions to determine lesion volume. We analyzed 1420 patients (median age, 78; 47.2% women, median National Institutes of Health Stroke Scale score, 3; median hospital stay, 5 days). Of these, 81 had AFDAS (5.7%), 329 had KAF (23.2%) and 1010 had no AF (71.1%). Lesion volume was larger in patients with AFDAS (median, 5.4 mL [interquartile range, 1.0-21.6]) compared with patients with no AF and KAF (median, 0.7 [interquartile range,0.2-4.4] and 2.0 [interquartile range,0.3-11.1] mL, respectively; both P<0.001). Lesion volume was independently associated with AFDAS compared with no AF (adjusted odds ratio, 1.37 [95% CI, 1.20-1.58] per log mL) and KAF (adjusted odds ratio, 1.22 [95% CI, 1.07-1.41] per log mL). Patients in the highest lesion volume quartile (>6.5 mL) were more likely to be diagnosed with AFDAS compared with the lowest quartile (<0.22 mL, 13.6% versus 2.1%; adjusted odds ratio, 5.88 [95% CI, 2.30-17.40]). These associations were more pronounced when excluding 151 patients with nonembolic lesion pattern and similar when excluding 199 patients with KAF on oral anticoagulation.

Conclusions: Larger stroke lesions were independently associated with AFDAS diagnosis during index stroke hospitalization highlighting a potential neurogenic contribution to AFDAS pathogenesis.