Journal Update – Beta Blocker vs. Calcium Channel Blocker for Rate Control in Atrial Fibrillation

09 Jul
July 9, 2015

Atrial FibrillationBackground: Atrial fibrillation (AF) is a commonly encountered dysrhythmia in the Emergency Department (ED). Atrial flutter is less common but its management is very similar to that of AF. In patients with chronic AF or unknown time of onset and a rapid ventricular response (RVR), rate control and consideration and initiation of anticoagulation therapy are the standard ED approach. Both beta-blockers and calcium channel blockers are commonly used for rate control in the ED but it is unclear whether one of these agents is superior to the other as there is scant high-quality data on the topic (Demircan 2005).

Clinical Question: Is diltiazem or metroprolol the more effective agent for rate control in AF with RVR in the ED?

Article: Fromm C et al. Diltiazem vs. metoprolol in the management of atrial fibrillation or flutter with rapid ventricular rate in the emergency department. J Emerg Med 2015. PMID: 25913166

Population: Adult patients > 18 years presenting with atrial fibrillation or atrial flutter.

Intervention: Diltiazem 0.25 mg/kg (max dose of 30 mg) or metoprolol 0.15 mg/kg (max dose of 10 mg) IV

Control: None

Outcome

  • Primary: Heart Rate < 100 beats per minute (bpm) within 30 minutes of drug administration
  • Secondary: SBP, DBP and Heart Rate at 0, 5, 10, 15, 20, 25 and 30 minutes

Design: Prospective, randomized, non-inferiority, double-blind study


Excluded:

  • Atrial rate < 120 bpm or > 220 bpm
  • SBP < 90 mm Hg
  • 2nd or 3rd degree AV block
  • Exclusion CriteriaTemperature > 38oC
  • Acute STEMI
  • Known NYHA Class IV heart failure
  • Chronic COPD
  • Prehospital administration of any AV nodal blocking agent
  • History of allergic reaction to diltiazem or metoprolol
  • History of sick sinus or pre-excitation syndrome
  • History of anemia
  • Pregnancy or breastfeeding
  • Cocaine/methamphetamine use within 24 hours

Clinical Bottom Line

Primary Results

  • 54 patients met inclusion criteria (diltiazem n = 25, metoprolol n = 29)
  • 52 patients included in analysis (1 excluded post-randomization from each intervention group)

Critical Findings

  • Primary Outcome (HR < 100 bpm at 30 min)
    • Diltiazem group 95.8% vs. Metoprolol group 46.4% (p < 0.0001)
    • Diltiazem had more rapid rate control than metoprolol at every time interval measured
    • No difference in bradycardia events or hypotension events between groups

Strengths:

  • Although small, this is the largest RDCT comparing diltiazem versus metoprolol head to head
  • Randomization and blinding were well done

Limitations:

  • Convenience sample of patients
  • Group initially calculated an n = 200 patients to achieve 80% power to detect noninferiority. However, they only collected 52 patients due to early stoppage based on the degree of benefit. It is possible that the results would have regressed to the mean if full enrollment was pursued.

Other Issues:

  • About 20% of patients in both groups received adenosine at some point

Authors Conclusions: “Diltiazem was more effective in achieving rate control in ED patients with AFF and did so with no increased incidence of adverse effects.”

Our Conclusions: Diltiazem is non-inferior to metoprolol for rapid rate control in patients with AF and RVR. Larger, multicenter RDCTs are needed.

Potential to Impact Current Practice: This study helps to defend what is the most common practice in the ED for patients with AF and RVR who require rate control.

Bottom Line: The best available evidence demonstrates that diltiazem achieves rate control faster than metoprolol in patients with AF and RVR. Diltiazem should be considered the first line agent.

Read More

References

  1. Demircan C et al. Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation. Emerg Med J 2005;22:411–4. PMID: 15911947

Post Peer Reviewed By: Salim Rezaie (Twitter: @srrezaie)

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Anand Swaminathan

Clinical Assistant Professor of Emergency Medicine at Bellvue/NYU
REBEL EM Associate Editor and Author

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7 replies
  1. António Gonçalves says:

    Very interesting! In my ED we rarely if ever give diltiazem.
    It would be good to know the effect beyond 30 min because we don’t just throw them out after HR is controlled.

    Reply
    • Salim Rezaie says:

      I typically load my patients with an oral dose after I have got them rate controlled with IV diltiazem. I use a formula I borrowed from the EM PharmD blog: http://empharmd.blogspot.com/2012/10/diltiazem-iv-to-po-conversion.html

      There is a formula that can be used to estimate the total daily oral dose from an IV diltiazem drip.
      Oral dose = {IV drip rate (in mg/hr) x 3 + 3}x10

      In general the standard rates for diltiazem convert as follows:
      5 mg/hr –> 180 mg/day
      7.5 mg/hr –> 260 mg/day
      10 mg/hr –> 330 mg/day
      15 mg/hr –> 480 mg/day

      This should get you past the initial 30 minutes.

      Salim

      Reply
  2. Dylan Morrs says:

    I thought a big limitation was the dosing regimen. My experience has always been Metop 5mg IV q5m x3 or 0.25mg/kg Dilt (usually 20mg) so their dosing doesn’t seem to reflect (my) real world dosing, and would set the trial up to favor Dilt.

    Reply
    • Salim Rezaie says:

      Hello Dylan,
      You bring up a great point. The initial doses used in this trial were:

      “Upon enrollment, patients were randomly assigned, in a 1:1 ratio, to receive diltiazem administered parenterally at a dose of 0.25 mg/kg (to a maximum dose of 30 mg) or metoprolol administered at a dose of 0.15 mg/kg (to a maximum dose of 10 mg).”

      So in a 70kg patient

      Diltiazem = 17.5mg IV
      Metoprolol = 10.5mg IV

      I typically use 20mg diltiazem IV and metoprolol 5mg q5min x3 as my initial doses. This would mean that the diltiazem dose is actually under dosed in a 70kg person by 2.5mg. I have never given a 10mg dose of metoprolol IV all at once, due to the hypotension that it could potentially cause, and wonder if that is why it was dosed as it was, as a single dose. I agree a more real life dosing for metoprolol would be 5mg IV q5min and not a bolus of 10mg IV.

      If you look at the ACC/AHA recs for doses they suggest:

      Metoprolol: 2.5 to 5 mg IV bolus over 2 min; up to 3 doses (Class I, LOE C)
      Diltiazem: 0.25 mg/kg IV over 2 min (Class I, LOE B)

      So although dosing is a bit funny, I am not sure that metoprolol was that under dosed.

      Salim

      Reply
  3. Stephen says:

    Do you know why they excluded patients with an atrial rate <220? The title of the article includes atrial flutter and this would seem to exclude atrial flutter patients who typically have an atrial rate close to 300bpm. Thanks

    Reply
    • Salim Rezaie says:

      Hello Stephen,
      Great question. It is not really stated in the paper why these patients were excluded. So its not exactly clear. I wonder if these patients were deemed too unstable for chemical cardioversion and maybe got electrical cardioversion instead? That is my best guess, but if I can figure out something more definitive, will be sure to reply to you on here again.

      Salim

      Reply
  4. Craig Rosebrock says:

    I tend to see a conversion more often to sinus with beta blockers … but that is my ICU exp. I tend to not use dilt so much.. just my experiance

    thanks for posting this

    Reply

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