Safety of Diltiazem for Acute Management of Atrial Fibrillation (AF) in Patients with Heart Failure and Reduced Ejection Fraction in the Emergency Department.

Background: Diltiazem is an effective rate control agent for atrial fibrillation with rapid ventricular rate (AF RVR). However, its negative inotropic effects may increase the risk for worsening heart failure in patients with a reduced ejection fraction (EF).

Objectives: This observational study aims to describe the incidence of worsening heart failure in patients who receive intravenous diltiazem for acute atrial fibrillation management.

Methods: Adult patients that received diltiazem in the emergency department (ED) for AF RVR (heart rate ≥ 100 beats/min) from 2021 to 2022 and had a prior documented EF were included. The primary outcome is worsening heart failure within 24 h of diltiazem administration. Secondary outcomes include return ED visits and death within 7 days. EF percentage was compared across outcomes using Wilcoxon rank-sum tests. Outcomes were compared by reduced EF (< 50%) and preserved EF (≥ 50%). Continuous data were summarized with medians and interquartile ranges, and categorical features were summarized with frequency counts and percentages. Wilcoxon rank-sum tests were used for numeric outcomes and chi-squared tests or Fisher's exact tests for categorical outcomes, with a p-value < 0.05 considered statistically significant.

Results: There were 674 patients with AF RVR that received diltiazem, and 386 patients met the inclusion criteria for analysis. Baseline demographics included a median age of 72 (64-81) years, with 14.5% of patients having a prior diagnosis of congestive heart failure. EF < 50% was identified in 13.7% of patients (n = 53), of which approximately 30% of these patients safely discharged home after receiving i.v. diltiazem. The primary outcome of worsening heart failure occurred in 7/41 (17%) and 10/207 (4.8%) patients with reduced and preserved ejection fractions, respectively, who were admitted to the hospital (p = 0.005).

Conclusion: The development of worsening heart failure is multifactorial and may include the use of diltiazem in critically ill patients requiring hospital admission.