WEDNESDAY, March 4, 2026 (HealthDay News) -- For patients with atrial fibrillation (AF) receiving apixaban or rivaroxaban, use of diltiazem versus metoprolol is associated with an increased risk for serious bleeding complications, according to a study published online Feb. 24 in the Annals of Internal Medicine.Ghadeer K. Dawwas, Ph.D., from the Vanderbilt University School of Medicine in Nashville, Tennessee, and colleagues compared the risk for bleeding among AF patients using apixaban or rivaroxaban in combination with diltiazem versus metoprolol. A total of 23,000 users of diltiazem and 23,000 users of metoprolol were included in the matched cohort of AF patients.The researchers found that diltiazem versus metoprolol was associated with a higher risk for bleeding events after propensity score matching (rate difference, 5.4 per 1,000 person-years). With high- versus low-dose diltiazem, the risk for bleeding increased (risk difference, 9.2 versus 2.6 for high- and low-dose, respectively). The estimated risk differences between diltiazem and metoprolol were 0.48 and 0.31 percentage points, respectively, at 12 and six months."Our examination of diltiazem dosages indicated a dose-dependent relationship, with higher doses associated with more bleeding," the authors write.Abstract/Full Text (subscription or payment may be required).Sign up for our weekly HealthDay newsletter