Efficacy and safety of diltiazem versus metoprolol in the management of atrial fibrillation with rapid ventricular response

Background: Atrial fibrillation (A-fib) with rapid ventricular response (RVR) is the most common cardiac arrhythmia treated in the emergency department. Intravenous (IV) diltiazem or IV metoprolol is often recommended when managing hemodynamically stable patients experiencing A-fib with RVR, particularly with a heart rate (HR) exceeding 150 beats per minute (bpm). This study evaluates whether IV diltiazem or IV metoprolol is more efficacious by examining outcomes of patient mortality, HR over 120 bpm, and intensive care unit (ICU) admissions. Methods: This retrospective study analyzed data from 59 U.S. academic medical centers/healthcare organizations (HCOs) within the TriNetX database. Among patients with Afib and HR over 150 bpm between September 22, 2003, and September 22, 2023, 8,762 were administered diltiazem and 10,604 received metoprolol. Propensity score matching was conducted for demographics and pre-existing diagnoses linked to mortality. Outcomes were evaluated 1–7 days post-treatment. Results: After propensity score matching, 14,598 patients with A-fib and RVR were analyzed, evenly divided into two groups. Those treated with IV diltiazem had a significantly lower 7-day mortality rate [3.3% vs. 5.1%; relative risk (RR) =0.643; 95% confidence interval (CI): 0.547–0.755; P<0.001], lower myocardial infarction (MI) rates (2.4% vs. 3.4%; RR =0.703; 95% CI: 0.581–0.850; P<0.001), were less likely to maintain a HR above 120 bpm (35.7% vs. 40.1%; RR =0.891; 95% CI: 0.855–0.929; P<0.001), and had fewer ICU admissions (13.4% vs. 19.9%; RR =0.672; 95% CI: 0.624–0.724; P<0.001) compared to the IV metoprolol group. The results showed similar trends in the unmatched population of patients. Conclusions: IV diltiazem showed superiority in reducing mortality, HR control, and decreased ICU admissions over IV metoprolol for managing A-fib with RVR. This data, drawn from a substantially larger population than previous studies, coupled with the findings of prior randomized trials, may support the preferential use of IV diltiazem for A-fib with RVR.