II. Indications

  1. Chronic control
    1. Age over 65 years
    2. Coronary Artery Disease
    3. Contraindications to Antiarrhythmic medications
    4. Cardioversion unlikely to be effective (e.g. atrial enlargement)
  2. Acute episode
    1. Atrial Fibrillation with Rapid Ventricular Rate

III. Precautions

  1. Beware agents (e.g. Amiodarone) which may cardiovert Atrial Fibrillation >48 hours
    1. Risk of embolic complications

IV. Exam: Target Heart Rate

  1. Heart Rate with Exercise: <110 bpm
  2. Heart Rate at rest: <80 bpm
    1. Heart Rates up to 110 at rest may be acceptable for asymptomatic patients
    2. Van Gelder (2010) N Engl J Med 362(15):1363-73 +PMID: 20231232 [PubMed]

V. Preparations: First-Line Agents for acute rate control (rapid ventricular rate)

  1. Precautions
    1. Avoid these agents in WPW Syndrome or other accessory pathway (pre-excitation states)
    2. Exercise caution with rate control agents in Pulmonary Hypertension (dilated right heart)
      1. Risk of Cardiac Arrest
    3. Atrial Flutter is more difficult to rate control than Atrial Fibrillation
      1. However Atrial Flutter responds better to cardioversion
    4. Hypotension on presentation
      1. All rate control agents will decrease Blood Pressure
      2. Consider electrical cardioversion
      3. Consider Calcium Gluconate 2 g IV prior to Diltiazem infusion (without bolus)
      4. Consider Magnesium 2 g IV infusion
      5. Consider titratable, short-acting medications (e.g. Esmolol)
  2. Background
    1. Acute agent choice is often based on the agent patient is already taking
      1. Consider Diltiazem IV if on a Calcium Channel Blocker
      2. Consider Metoprolol IV if on a Beta Blocker
    2. Diltiazem IV is used most commonly for acute rate control in U.S. emergency departments
    3. Diltiazem IV may be preferred from study data
      1. More rapid acting, more effective and with less risk of Hypotension than Metoprolol
      2. Fromm (2015) J Emerg Med 49(2):175-82 +PMID:25913166 [PubMed]
    4. Metoprolol IV is preferred if ejection fraction <35%
  3. Diltiazem
    1. Bolus: In 10-20 mg (or 0.35 mg/kg) increments up to 50 mg IV cummulative total bolus
    2. Next: 5-20 mg/hour IV infusion
    3. Avoid in WPW Syndrome or other accessory pathway or if ejection fraction <35%
    4. If Hypotension occurs, consider Calcium Gluconate 2 g IV (does not counter AV Block)
  4. Metoprolol
    1. Bolus: 5 mg IV every 5 minutes up to 3 doses (15 mg)
    2. Next: 25-50 mg orally
    3. Avoid in WPW Syndrome or other accessory pathway
  5. Disposition
    1. Avoid Diltiazem with Metoprolol (risk of AV Block)
    2. If already on a rate control agent (e.g. Metoprolol or Diltiazem) when presented with RVR
      1. Increase the oral dose of that agent after IV rate control achieved
      2. If at maximum dose, consider adding Digoxin 0.125 mg or Amiodarone (consult cardiology)
    3. If not on a rate control agent, consider Metoprolol first
      1. Oral Metoprolol appears more effective for chronic rate control than oral Diltiazem
      2. Contrast with IV forms, in which Diltiazem appears more effective in acute rate control

VI. Preparations: Second-Line Agents for acute rate control (rapid ventricular rate)

  1. Esmolol
    1. Bolus: 500 mcg/kg IV over 1 minute
    2. Next: 50 mcg/kg/min IV infusion
    3. Next: Titrate dose every 5 to 15 minutes (maximum dose 200 mcg/kg/min)
    4. Requires very close (1:1) monitoring
    5. Avoid in WPW Syndrome or other accessory pathway
  2. Magnesium
    1. Bolus: 2.5 g IV over 20 minutes
    2. Next: 2.5 g IV over 2 hours
    3. Slow or stop infusion for Hypotension or respiratory depression
  3. Procainamide
    1. Bolus: 20-30 mg/min IV until controlled rate
    2. Next: 2-6 mg/min IV up to 17 mg/kg
    3. Stop for Hypotension or QRS Widening >50%
  4. Amiodarone
    1. Bolus: 150 to 300 mg IV
    2. Next: 1 mg/min IV infusion
    3. Prepare for Hypotension
  5. Digoxin
    1. Bolus: 0.5 mg IV
    2. Next: 0.25 mg orally at 4 and 8 hours
    3. Avoid in WPW Syndrome or other accessory pathway

VII. Protocol: Rate Control if WPW Syndrome with preserved heart function

  1. General
    1. Risk of embolus if rhythm cardioverts
    2. Consider Atrial Fibrillation Anticoagulation
  2. Avoid Harmful agents
    1. Adenosine
    2. Beta Blocker
    3. Calcium Channel Blocker
    4. Digoxin
  3. Recommended agents (Use only 1 agent)
    1. Electrical Synchronized Cardioversion if unstable
    2. Class IA Agents
      1. Procainamide
    3. Class IC Agents
      1. Propafenone (Rythmol)
      2. Flecainide (Tambocor)
    4. Class III Agents
      1. Sotalol (Betapace)
  4. Mixed Evidence
    1. Amiodarone (Cordarone) may induce ventricular Arrhythmias in WPW (per 2010 ACLS guidelines)

VIII. Protocol: Rate control if WPW with Ejection Fraction <40%

  1. General
    1. Risk of embolus if rhythm cardioverts
    2. Consider Atrial Fibrillation Anticoagulation
  2. Recommended agents
    1. Electrical Synchronized Cardioversion
    2. Amiodarone (Cordarone)

IX. Protocol: Rate control if Heart function preserved (No WPW)

  1. General
    1. Risk of embolus if rhythm cardioverts
    2. Consider Atrial Fibrillation Anticoagulation
  2. Recommended agents
    1. Beta Blockers (preferred)
      1. Metoprolol (Lopressor) - preferred
      2. Propranolol (Inderal)
      3. Esmolol (Brevibloc)
    2. Calcium Channel Blocker
      1. Verapamil (Calan)
      2. Diltiazem (Cardizem) - preferred
        1. See Diltiazem for dosing protocol
  3. Second line agents
    1. Digoxin
      1. Effect on Heart Rate is delayed 3 hours (contrast with 5 minutes for Diltiazem)
    2. Amiodarone
      1. Not as effective as Diltiazem or Magnesium for rate control in most cases
      2. Used in critically ill patients with Atrial Fibrillation
      3. Clemo (1998) Am J Cardiol 81(5): 594-8 [PubMed]
    3. Magnesium Sulfate
      1. Effective adjunctive management of ventricular response rate control
      2. Slows AV nodal conduction and decreases Heart Rate
      3. Davey (2005) Ann Emerg Med 45(4): 347-53 [PubMed]

X. Protocol: Rate control if Ejection Fraction <40% (No WPW)

  1. General
    1. Risk of embolus if rhythm cardioverts
    2. Consider Atrial Fibrillation Anticoagulation
  2. Recommended agents
    1. Diltiazem (Cardizem) - preferred
    2. Amiodarone
    3. Digoxin (Lanoxin)
      1. Avoid Digoxin for Atrial Fibrillation Rate Control outside of comorbid CHF
      2. Increased mortaility when used for Atrial Fibrillation Rate Control
      3. Whitbeck (2012) Eur Heart J 10.1093/eurheartj/ehs348
        1. http://eurheartj.oxfordjournals.org/content/early/2012/11/14/eurheartj.ehs348.full

XI. Management: Choosing Longterm Rate Versus Rhythm Control

  1. Older studies compared rate control to medication-based rhythm control as treatment arm
    1. Rate control has less drug-related adverse effects
    2. Rate control has equivalent efficacy to rhythm control
      1. Same survival benefit
      2. Same Cerebrovascular Accident risk
    3. Rhythm control may offer benefit in age <65 years
    4. Wyse (2002) N Engl J Med 347:1825-33 [PubMed]
  2. Newer studies compared rate control to catheter ablation
    1. Catheter ablation appears superior to rate control in comorbid Heart Failure
    2. Marrouche (2018) N Engl J Med 378:417-27 [PubMed]
  3. Rhythm control may be preferred in high risk cardiovascular patients in Atrial Fibrillation <1 year
    1. NNT 91 to prevent one cardiovascular death, hospitalization or Cerebrovascular Accident in 5 years
    2. But rhythm control is associated with serious complications in 2% of patients
    3. Camm (2022) J Am Coll Cardiol 79(19): 1932-48 [PubMed]
    4. Kirchhof (2020) N Engl J Med 383(14): 1305-16 [PubMed]

XII. Management: Rate Control Agent Selection

  1. Beta Blockers (e.g. Metoprolol) are typically most effective oral agents for rate control
    1. Contrast with Diltiazem IV, which is typically more effective than IV Beta Blockers
    2. Avoid non-selective Beta Blockers in acute CHF, COPD, Asthma

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