Am J Emerg Med. 2025 Nov 15;100:54-58. doi: 10.1016/j.ajem.2025.11.017. Online ahead of print.

INTRODUCTION: Intravenous (IV) diltiazem is frequently used for rate control in atrial fibrillation with rapid ventricular response (AF with RVR). While current guidelines recommend weight-based dosing using actual body weight, there is limited evidence supporting this approach in patients with obesity. This study aimed to compare diltiazem dosing practices and clinical outcomes between obese and non-obese patients.

METHODS: This single-center retrospective cohort study included adult patients who received IV diltiazem for AF with RVR in the emergency department between January 1 and December 31, 2022. Patients were stratified by BMI into <30 and ≥ 30 groups. The primary outcome was a comparison of the initial weight-based diltiazem bolus dose. Secondary outcomes included total bolus dose, rate control at 30 min, 3 h, and 6 h, and adverse events. Propensity score-adjusted logistic regression was used to evaluate associations between dosing and outcomes.

RESULTS: A total of 296 patients were included. Patients with BMI ≥30 received lower initial and total bolus doses based on actual body weight (initial 0.16 mg/kg vs 0.21 mg/kg, p < 0.0001; total 0.19 mg/kg vs 0.25 mg/kg, p < 0.0001). When calculated using ideal body weight, obese patients received slightly higher mg/kg doses (initial 0.27 mg/kg vs 0.23 mg/kg, p = 0.0028). Rate control was achieved in 65-69 % of patients at 30 min, 86-87 % at 3 h, and over 93 % at 6 h, with no significant differences in adverse events between BMI groups. Propensity score-adjusted analysis showed that higher initial bolus doses were associated with increased odds of achieving rate control at all time points, without any difference in adverse events.

CONCLUSION: Diltiazem was effective and well tolerated in patients with obesity, even at lower actual-body-weight-based doses. Higher initial doses increased the likelihood of early rate control without increasing adverse events, suggesting modestly higher, individualized dosing may be safe and effective. Ideal-body-weight-based dosing better aligned with guideline targets, supporting its use in obese patients. Prospective studies are needed to determine optimal dosing strategies to maximize the efficacy and safety of diltiazem.

PubMed:41274181 | DOI:10.1016/j.ajem.2025.11.017