Both MPO and SELP concentrations were significantly lower in non-AF individuals compared to AF patients before catheter ablation (26 ng/ml, 22–40 vs. 48 ng/ml, 32–72, p = 0.010 and 19 ng/ml, 18–24 vs. 42 ng/ml, 38–47, p = 0.001) and after catheter ablation during FU (26 ng/ml, 22–40 vs. 45 ng/ml, 27–82, p = 0.037 and 19 ng/ml, 18–24 vs. 37 ng/ml, 32–42, p = 0.001). This evidence concerns the gene SELP and atrial fibrillation.