Low-dose diltiazem in atrial fibrillation with rapid ventricular response

Diltiazem is one of the most commonly used medications to control the rapid ventricular response in atrial fibrillation (AF). The recommended starting dose is an intravenous bolus of 0.25 mg/kg over 2 minutes. To avoid hypotension, we have empirically used a lower dose of diltiazem. We compared the efficacy and safety of different doses of diltiazem in rapid AF.

A retrospective chart review was undertaken in patients who presented to the emergency department with rapid AF. Patients were divided into 3 groups according to diltiazem dosage: low dose (≤ 0.2 mg/kg), standard dose (> 0.2 and ≤ 0.3 mg/kg), and high dose (> 0.3 mg/kg). We compared the rates of therapeutic response (adequate rate control) and complications (such as hypotension). Multivariate regression analysis was used to determine the effect of diltiazem dose on the occurrence of complications.

A total of 180 patients were included in the analysis. There were no significant differences in the rates of therapeutic response for the low-, standard-, and high-dose groups (70.5%, 77.1%, and 77.8%; P = .605). The rates of hypotension in the low-, standard-, and high-dose groups were 18%, 34.9%, and 41.7%, respectively. After adjusting confounding variables, the rate of hypotension was significantly lower in the low-dose group in comparison with the standard-dose group (adjusted odds ratio, 0.39; 95% confidence interval, 0.16-0.94).

Low-dose diltiazem might be as effective as the standard dose in controlling rapid AF and reduce the risk of hypotension.