IV Metoprolol vs Diltiazem for A fib with RVR and Concomitant Heart Failure
/Background
Atrial fibrillation is a prevalent disease entity that affects over 500,000 new people annually. A subset of these patients develop an accelerated rate either primarily or due to other factors known as rapid ventricular response. If untreated, atrial fibrillation can increase clot formation and lead to an increased risk for heart attack and stroke as well as development of congestive heart failure. Concomitant atrial fibrillation and heart failure makes treatment more difficult and increases the odds of mortality up to 57% compared to isolated heart failure. For treatment, the American Heart Association’s 2019 guidelines recommend limiting use of non-dihydropyridiine CCB due to potential for negative inotropic effects. However, it is still used in certain cases. Currently, there is limited data investigating outcome differences between beta blockers and calcium channel blockers for atrial fibrillation with rapid ventricular response in a patient diagnosed with heart failure.
Study design
This was a retrospective-IRB approved study evaluating adult patients >18 years of age who had documented heart failure with reduced ejection fraction (HFrEF) or heart failure with preserved ejection fractures (HFpEF). Inclusion criteria included echocardiogram performed within previous 12 moths or within 24 hours of admission in patients who presented in atrial fibrillation with rapid ventricular response to a heart rate (HR) >120. Exclusion criteria included those presenting in an exacerbation of their heart failure or those treated with other agents within first 30 minutes of receiving the study drug.
Their primary effectiveness outcome was successful HR control <110bpm within 30 minutes and secondary included successful control at 60 minutes and HR control at ED transfer/discharge. Additional secondary outcomes of interest included evaluation of HR in beats per minute, reduction in HR both numerically and those >20%, time to adequate HR control, total dose of meds give, additional agents used for HR control, use of fluids and crossover to other medications.
Safety outcomes were monitored and included bradycardia, hypotension +/- vasopressor use, dyspnea and hypoxia, change in EF on subsequent echocardiogram and acute kidney injury +/- use of renal replacement therapy.
Results
They screened 2,580 patients and 193 were included (59 for metoprolol, 134 diltiazem). Groups were decently matched overall with average age 78, predominantly white and female. Overall, mostly HFpEF with average EF 48%. They found successful rate control at 30 mins not significantly different with 55% for diltiazem and 41% for metoprolol (p=0.063). Overall, diltiazem was faster, had a grossly higher reduction in HR at 30 minutes and 60 minutes and a greater frequency of reduction >20% at 30 and 60 minutes as well as time of discharge/transfer. There were similar lengths of say overall and no significant difference in safety outcomes.
Subgroup analysis
The larger subgroup was HFpEF (n=123) and overall they found more frequent rate control with diltiazem at 30 mins 56% vs metoprolol 36% (p=0.037). Additionally, a higher HR reduction at 30 and 60 minutes, as well as ED discharge/transfer. However, notably, these patients had a higher frequency of hypotension 28% vs 7% (p=0.005).
For the HFrEF group, there were similar rates of HR control at 30 minutes. The diltiazem group had greater reduction in HR at 30 and 60 minutes. However, no difference noted in success of HR control at 60 min and transfer/discharge. There was no difference in safety outcomes. They did note on echocardiogram evaluation that there was a trend towards improvement in EF with metoprolol group (10% vs 2.1% p=0.05).
Discussion
The researchers concluded that there was no difference in rate control at 30 minutes when utilizing diltiazem vs metoprolol based on this study. Other interesting notes included that those who received metoprolol were more likely to crossover to diltiazem after 30 minutes and additionally received more doses of medication overall. The study is unfortunately limited due to retrospective nature, probable selection bias due to small sample size and has limited generalizability due to exclusion of concurrent heart failure exacerbation on presentation. Additionally, average EF very high overall with predominantly HFpEF patients. Regarding diltiazem, it is worth noting that it has potential to be unsafe, as more hypotension developed overall, but very few patients required pressors. Additionally, many of the patients in the study ended up on diltiazem drips whether it be for ease of use, titratability or other factors. A wonderful next step would be to see a randomized control trial investigating this same clinical question…
Authorship
Written by Bronwyn Finney, MD, PGY-3 University of Cincinnati Department of Emergency Medicine
Peer Review, Editing, Podcast Editing by Jeffery Hill, MD MEd, Associate Professor, University of Cincinnati Department of Emergency Medicine
Cite As
Finney, B. Hill, J. (April 22, 2023) IV Metoprolol vs Diltiazem for A fib with RVR and Concomitant Heart Failure. TamingtheSRU. https://www.tamingthesru.com/blog/2023/4/22/iv-metoprolol-vs-diltiazem-for-a-fib-with-rvr-and-concomitant-heart-failure
