Inflammatory markers, their relation to maintenance of sinus rhythm after electrical cardioversion for atrial fibrillation (AF), and the effect of candesartan were investigated in a double-blind placebo-controlled study (CAPRAF). One hundred seventy-one patients with persistent AF were randomly assigned to receive candesartan 8 mg/day or placebo for 3 to 6 weeks before and candesartan 16 mg/day or placebo for 6 months after electrical cardioversion. Serum levels of high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha, interleukin-6, P-selectin, E-selectin, CD-40 ligand, and vascular cell adhesion molecule-1 were measured at baseline and end of study. Compared with patients with a relapse of AF, patients still in sinus rhythm at 6 months after cardioversion (n = 40) had lower baseline hs-CRP and E-selectin levels: median 2.36 mg/L (25th, 75th percentiles 1.28, 4.09) versus 3.44 mg/L (25th, 75th percentiles 1.66, 6.05, p = 0.031) and 32 ng/ml (25th, 75th percentiles 23, 42) versus 37 ng/ml (25th, 75th percentiles 28, 51, p = 0.042), respectively. Neither sustained sinus rhythm for 6 months nor treatment with candesartan had an impact on measured concentrations of markers of inflammation. In conclusion, low hs-CRP and E-selectin at baseline were associated with maintenance of sinus rhythm after electrical cardioversion.