Nine (16.4%) patients were concomitantly treated with a P-glycoprotein (P-gp) and/or CYP P450 3A4 (CYP3A4) inhibitor: six (10.9%) with amiodarone and three (5.5%) with diltiazem, all of whom had AF. The gene discussed is ABCB1; the disease is atrial fibrillation.