Atrial fibrillation is the most common clinically evident arrhythmia in HD patients and has been found to occur in up to 40% of patients in studies using implantable loop recorders.6,30,31 In the non-HD population, the evidence supporting the use of mineralocorticoid receptor antagonists to prevent atrial fibrillation is somewhat conflicting. The gene discussed is NR3C2; the disease is atrial fibrillation.