We found significantly higher serum hs‐CRP and sCD‐40L levels in the overall AF (Chronic AF + SCAF) group (hs‐CRP: 4.5 ± 3.4 vs 2.3 ± 2.9 mg/L, P < .01; sCD‐40L: 6.4 ± 4.8 vs 3.1 ± 3.4 ng/mL, P < .01) and chronic AF subgroup (hs‐CRP: 4.9 ± 3.4 vs 2.3 ± 2.9 mg/L, P < .01; sCD‐40L: 6.9 ± 5.1 vs 3.1 ± 3.4 ng/mL, P < .01) compared to patients with sinus rhythm. Here, CD40LG is linked to atrial fibrillation.