Written by Catherine Burger
Spoon Feed
This systematic review of 13 studies found slightly higher rates of adverse events after administration of diltiazem versus metoprolol, when treating atrial fibrillation (a-fib) with RVR.
Rate control with a side of hypotension
This systematic review and meta-analysis compared the rates of adverse events (hypotension with SBP<90 and/or bradycardia with HR <60) after administration of diltiazem vs metoprolol for patients presenting to the ED or ICU with atrial fibrillation with RVR. AJEM published a meta-analysis in 2021 that found diltiazem was more efficacious, worked faster, and had no increase in adverse events compared to metoprolol. Thirteen studies and 1660 patients were included; most studies were retrospective and performed in the US. 53% of patients received metoprolol, and 47% received diltiazem. Metoprolol doses ranged from 0.05 mg/kg to 0.15 mg/kg and diltiazem from 0.12 mg/kg to 0.25 mg/kg.
In the metoprolol group, 10% (92 of 888) had an adverse event reported, compared to 19% (143 of 772) in the diltiazem group. Patients who received metoprolol had a 26% lower risk of any adverse event, compared with diltiazem (RR 0.74, 95%CI 0.56–0.98, p= 0.034). When looking at individual adverse events, there was a higher rate of hypotension in the diltiazem vs metoprolol groups (15% v.s. 10%) that was not statistically significant. Patients with higher premedication heart rates were more likely to subsequently have an adverse event reported after medication administration, regardless of medication choice (correlation coefficient 0.11, 95 %CI0.03 to 0.19,p= 0.006). Across studies, both home- and hospital-administered medication dosing and documentation was inconsistent. The clinical significance of the adverse events analyzed also remains unclear (did the hypotension or bradycardia cause poor perfusion or escalation of care?).
How will this change my practice?
I will keep both metoprolol and diltiazem in my arsenal for treating a-fib with RVR. This study serves as a helpful reminder that I need to closely monitor for hypotension after treatment, especially in patients I have given diltiazem or patients with a very high premedication heart rate.
Source
Metoprolol vs diltiazem for atrial fibrillation with rapid ventricular rate: Systematic review and meta-analysis of adverse events. Am J Emerg Med. 2024 Dec 27;89:230-240. doi: 10.1016/j.ajem.2024.12.070. Epub ahead of print. PMID: 39764905
