Introduction

  • Atrial Fibrillation is the most common sustained arrhythmia seen in the emergency department and requires emergent treatment to prevent myocardial ischemia and acute heart failure.
  • Beta-blockers and calcium channel blockers are used for acute rate control in the treatment of atrial fibrillation with rapid ventricular response.

Clinical Detail

ParameterMetoprololDiltiazem
MOACompetitive beta1- adrenergic receptor inhibitor (cardio-selective); decreased contractility, heart rate, and cardiac conduction time, increased relaxationNon-dihydropyridine CCB selective to L-type calcium channel in cardiac cells; decreased heart rate and conduction time, increased vasodilation
Dose2.5-5mg IV
Repeat every 5 minutes as needed
Max total dose of 15mg		Bolus: 0.25mg/kg IV
Repeat 0.35mg/kg after 15 minutes if needed
After bolus: continuous infusion 5-10mg/hr IV, max 15mg/hr or PO IR 30-90 mg
AdministrationIV bolus over 2 minutesIV bolus over 2 minutes
PK/PDOnset: 1-2 minutes
Peak: 20 minutes
Metabolism: hepatic CYP2D6
Half-life: 3-4 hours		Onset: 3 minutes with IV bolus
Duration: 1-3 hours with IV bolus, 0.5-10 hours after cessation of continuous infusion
Metabolism: hepatic CYP3A4 and conjugation
Half-life: ~3.5 hours with bolus, 4-5 hours with continuous infusion
Adverse EffectsBradycardia
Hypotension
AV block
Bronchospasms at doses >100mg
CNS effects- fatigue, depression, sleep disturbance		Bradycardia
Peripheral edema
Hypotension
AV block
Drug Interactions and warningsAvoid in decompensated heart failure
Masks symptoms of hypoglycemia and hyperthyroidism		Symptomatic hypotension
Mild AST/ALT elevations
Avoid in heart failure
CompatibilityCompatible with NS or D5WCompatible with NS, D5W, or D5-1/2NS
CommentsAbrupt cessation can result in angina and MIContinuous infusions should not be continued beyond 24 hours due to accumulation

Evidence

Author, yearDesign/sample sizeIntervention & ComparisonOutcome
Hargrove, 2021Retrospective (n=51)Diltiazem
Metoprolol		No difference regarding sustained rate control for 3 hours (diltiazem 87.5% vs metoprolol 78.9%)
Shorter time to rate control with diltiazem (15min vs 30min)
No differences in bradycardia or hypotension
Hirschy, 2019Retrospective cohort (n=48)Diltiazem IV push
Metoprolol IV push		No difference in successful rate control within 30 minutes in patients with HFrEF (diltiazem 50% vs metoprolol 62%)
No differences in hypotension, bradycardia, conversion, or signs of worsening heart failure
Hines, 2016Retrospective cohort (n=100)Diltiazem
Metoprolol		Predictors for initial selection of metoprolol over diltiazem included past history of atrial fibrillation, diabetes, and prescription for BB prior to ED visit
Prescription of CCB prior to ED visit was a negative predictor for metoprolol use in the ED
No differences in efficacy or safety
Kuang, 2016Retrospective cohort (n=398)BB naïve patients
Patients on chronic BB therapy		BB naïve patients achieved successful rate control at higher rates than those on chronic BB therapy (56.1% vs 42.4%) and had shorter LOS (1.79 days vs 2.64 days)
Martindale, 2015Systematic review (n=92)Diltiazem
Metoprolol		In the ED, diltiazem is more effective at rapidly controlling ventricular rates than metoprolol
Administration of calcium prior to diltiazem does not prevent hypotension
Fromm, 2015Prospective, randomized, double blind (n=52)Diltiazem 0.25mg/kg (max 30mg)
Metoprolol 0.15mg/kg (max 10mg)		Diltiazem decreased heart rate more rapidly and substantially within first 30min
No differences in hypotension and bradycardia
Scheuermeyer, 2013Retrospective cohort (n=259)CCB: diltiazem or verapamil
BB: metoprolol or atenolol		No difference in admission rates, length of stay, adverse events, and 7 or 30-day ED revisits between CCB and BB
Demircan, 2005Prospective, randomized (n=40)Diltiazem 0.25mg/kg (max 25mg)
Metoprolol 0.15mg/kg (max 10mg)		Successful rate control (HR <100bpm, decrease by 20%, or return to sinus rhythm) was higher with diltiazem at 2 minutes
Successful rate control was similar at 20 minutes (diltiazem 90% vs metoprolol 80%)
No incidences of hypotension

Conclusions

  • Diltiazem has a quicker onset of action and therefore a faster onset to rate control but is not correlated with a significant difference in long-term outcomes.
  • Both medications are appropriate options for treatment of acute rate control, and treatment choice should be based on patient specific factors such as comorbidities, drug interactions, and prior therapy.

References

  • Micromedex [Electronic version]. Greenwood Village, CO: Truven Health Analytics. Retrieved February 17,
  • 2021, from http://www.micromedexsolutions.com/
  • Lexicomp [Electronic version]. Macedonia, OH: Truven Wolters Kluwer Health. Retrieved February 19, 2021.
  • https://online.lexi.com/lco/action/login.
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  • ventricular rate: Metoprolol vs. Diltiazem. Am J Emerg Med. 2021; 40:15-19.
  • Hirschy R, Ackerbauer KA, Peksa GD, O'Donnell EP, DeMott JM. Metoprolol vs. diltiazem in the acute
  • management of atrial fibrillation in patients with heart failure with reduced ejection fraction. Am J Emerg
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    • PMID: 26830391.

  • Martindale JL, deSouza IS, Silverberg M, Freedman J, Sinert R. β-Blockers versus calcium channel blockers for
  • acute rate control of atrial fibrillation with rapid ventricular response: a systematic review. Eur J Emerg Med.
  • 2015 Jun;22(3):150-4. PMID: 25564459.
  • Fromm C, Suau SJ, Cohen V, et al. Diltiazem vs. metoprolol in the management of atrial fibrillation or flutter
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  • Demircan C, Cikriklar HI, Engindeniz Z, 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; 22:411-414.
  • Scheuermeyer FX, Grafstein E, Stenstrom R, et al. Safety and efficacy of calcium channel blockers versus beta- blockers for rate control in patients with atrial fibrillation and no acute underlying medical illness. Acad Emerg
  • Med. 2013; 20(3):222-230.
Tags:atrial fibrillation beta blockers calcium channel blockers rate control