Figure 3 shows the distribution of log serum aldosterone by CYP11B2 genotype and AF status. Log aldosterone concentration was significantly higher in those with versus without AF (p = 0.036). There was no significant association between log aldosterone concentration examined as a continuous variable and CYP11B2 −344T>C genotype (p = 0.13). However, 50% of patients with the CYP11B2 −344CC genotype versus 8% with the TC or TT genotype had log aldosterone levels in the upper 90th percentile for the study sample (OR 11, 95% CI 2.0 to 62, p = 0.015). This evidence concerns the gene CYP11B2 and atrial fibrillation.