Bleeding in Patients With Atrial Fibrillation

To the Editor A recent study reported a higher incidence of serious bleeding in patients using diltiazem, compared with metoprolol, in conjunction with apixaban or rivaroxaban for the treatment of atrial fibrillation. The authors also reported a higher proportion of women in the diltiazem group (59.3% vs 50.4%). We read this study with particular interest given postmarketing data on uterine bleeding in women taking various direct oral anticoagulants, with rates of abnormal uterine bleeding as high as 67%. While we acknowledge that rates of uterine bleeding would be lower in this postmenopausal population, the higher proportion of female patients in the group with a higher rate of bleeding (diltiazem users) does raise questions about the role of sex as a biological variable in these findings.