The following is the summary of “Intravenous metoprolol versus diltiazem for atrial fibrillation with concomitant heart failure” published in the December 2022 issue of Emergency medicine by Compagner, et al.

Rapid ventricular response (RVR) atrial fibrillation (Afib) is treated quickly with intravenous push (IVP) metoprolol (MET) or diltiazem (DIL). Diltiazem’s adverse inotropic effects make it inappropriate for use in HF patients. Therefore, it is common for HF patients to be left out of treatment comparison studies for atrial fibrillation. Hirschy et al. compared the efficacy and safety of intravenous (IVP) metoprolol and diltiazem in treating patients with HF who also had atrial fibrillation (Afib) with right ventricular repolarization (RVR). Results for both groups in terms of safety and efficacy were similar.

Between January 1, 2018, and July 31, 2021, patients with Afib with RVR and HF who presented to the emergency center (EC) were assessed in this retrospective, IRB-approved study. Patients were required to be 18 years or older, have a documented baseline ejection fraction, and be treated with either intravenous (IV) metoprolol or diltiazem in the EC (EF). Whether or whether the patient’s heart rate (HR) was successfully controlled 30 minutes after receiving IVP metoprolol or diltiazem was the primary efficacy outcome, with HR control defined as HR <100 beats per minute (bpm). Reductions in HR of >20% 30 minutes after IVP, 60 minutes after IVP, and at the time of release or transfer from the EC were considered secondary efficacy outcomes. Time to adequate HR control, total IVP metoprolol or diltiazem dose, additional rate-controlling medications, and crossover between metoprolol and diltiazem were additional secondary outcomes. Bradycardia, hypotension, hypoxemia, dyspnea, increased oxygen demand, altered ejection fraction (EF), acute kidney damage, and renal replacement therapy were all considered adverse events.

Aged 73.3 ± 12.2 years, 63% were female, and of the 2,580 patients assessed, 193 were included (134 DIL vs. 59 MET). Heart failure with reduced ejection fraction (HFrEF) was present in 30% of patients, whereas heart failure with preserved ejection fraction (HFpEF) was present in 64%. The mean EF was 48.2 ± 14.2%. (HFpEF). Within 30 minutes of receiving the IVP, there was no significant difference in effective heart rate control between the two groups (55% DIL vs. 41% MET, P=0.063). Heart rate (HR) was more successfully regulated by DIL than by MET (13 [9, 125] DIL vs. 27 [5, 50] MET, min, P=0.009). At both 30 and 60 minutes, DIL led to higher reductions in HR than MET did (33.2 ± 25.4 DIL vs. 19.7 ± 19.7 MET, bpm, P<0.001) and at 60 min (31 ± 23.5 DIL vs. 19.6 ± 19.1 MET, bpm, p = 0.002).  30 minutes after IVP (63% DIL vs. 27% MET, P<0.001), 60 minutes after IVP (59% DIL vs. 41% MET, P=0.019), and at the time of patient release or transfer from the EC (70% DIL vs. 49% MET, P=0.005) were all times when HR reductions of 20% or higher occurred more frequently with DIL.

There was no discernible variation in risk-free outcomes. It is difficult to provide immediate care for people with Afib who also have RVR and HF. IVP diltiazem lowered HR rapidly and by 20% or more frequently than IVP metoprolol, and there were no significant variations in safety outcomes between the two, despite successful rate control after 30 min was not significantly different between diltiazem and metoprolol. Diltiazem’s safety in Afib and HF patients needs more research.