II. Indications
- Chronic control
- Age over 65 years
- Coronary Artery Disease
- Contraindications to Antiarrhythmic medications
- Cardioversion unlikely to be effective (e.g. atrial enlargement)
- Acute episode
III. Precautions
- Beware agents (e.g. Amiodarone) which may cardiovert Atrial Fibrillation >48 hours
- Risk of embolic complications
IV. Exam: Target Heart Rate
- Heart Rate with Exercise: <110 bpm
-
Heart Rate at rest: <80 bpm
- Heart Rates up to 110 at rest may be acceptable for asymptomatic patients
- 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)
- Precautions
- Avoid these agents in WPW Syndrome or other accessory pathway (pre-excitation states)
- Exercise caution with rate control agents in Pulmonary Hypertension (dilated right heart)
- Risk of Cardiac Arrest
- Atrial Flutter is more difficult to rate control than Atrial Fibrillation
- However Atrial Flutter responds better to cardioversion
- Hypotension on presentation
- All rate control agents will decrease Blood Pressure
- Consider electrical cardioversion
- Consider Calcium Gluconate 2 g IV prior to Diltiazem infusion (without bolus)
- Consider Magnesium 2 g IV infusion
- Consider titratable, short-acting medications (e.g. Esmolol)
- Background
- Acute agent choice is often based on the agent patient is already taking
- Consider Diltiazem IV if on a Calcium Channel Blocker
- Consider Metoprolol IV if on a Beta Blocker
- Diltiazem IV is used most commonly for acute rate control in U.S. emergency departments
- Diltiazem IV may be preferred from study data
- More rapid acting, more effective and with less risk of Hypotension than Metoprolol
- Fromm (2015) J Emerg Med 49(2):175-82 +PMID:25913166 [PubMed]
- Metoprolol IV is preferred if ejection fraction <35%
- Acute agent choice is often based on the agent patient is already taking
-
Diltiazem
- Bolus: In 10-20 mg (or 0.35 mg/kg) increments up to 50 mg IV cummulative total bolus
- Next: 5-20 mg/hour IV infusion
- Avoid in WPW Syndrome or other accessory pathway or if ejection fraction <35%
- If Hypotension occurs, consider Calcium Gluconate 2 g IV (does not counter AV Block)
-
Metoprolol
- Bolus: 5 mg IV every 5 minutes up to 3 doses (15 mg)
- Next: 25-50 mg orally
- Avoid in WPW Syndrome or other accessory pathway
- Disposition
- Avoid Diltiazem with Metoprolol (risk of AV Block)
- If already on a rate control agent (e.g. Metoprolol or Diltiazem) when presented with RVR
- Increase the oral dose of that agent after IV rate control achieved
- If at maximum dose, consider adding Digoxin 0.125 mg or Amiodarone (consult cardiology)
- If not on a rate control agent, consider Metoprolol first
- Oral Metoprolol appears more effective for chronic rate control than oral Diltiazem
- 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)
-
Esmolol
- Bolus: 500 mcg/kg IV over 1 minute
- Next: 50 mcg/kg/min IV infusion
- Next: Titrate dose every 5 to 15 minutes (maximum dose 200 mcg/kg/min)
- Requires very close (1:1) monitoring
- Avoid in WPW Syndrome or other accessory pathway
-
Magnesium
- Bolus: 2.5 g IV over 20 minutes
- Next: 2.5 g IV over 2 hours
- Slow or stop infusion for Hypotension or respiratory depression
-
Procainamide
- Bolus: 20-30 mg/min IV until controlled rate
- Next: 2-6 mg/min IV up to 17 mg/kg
- Stop for Hypotension or QRS Widening >50%
-
Amiodarone
- Bolus: 150 to 300 mg IV
- Next: 1 mg/min IV infusion
- Prepare for Hypotension
-
Digoxin
- Bolus: 0.5 mg IV
- Next: 0.25 mg orally at 4 and 8 hours
- Avoid in WPW Syndrome or other accessory pathway
VII. Protocol: Rate Control if WPW Syndrome with preserved heart function
-
General
- Risk of embolus if rhythm cardioverts
- Consider Atrial Fibrillation Anticoagulation
- Avoid Harmful agents
- Recommended agents (Use only 1 agent)
- Electrical Synchronized Cardioversion if unstable
- Class IA Agents
- Class IC Agents
- Class III Agents
- Mixed Evidence
- Amiodarone (Cordarone) may induce ventricular Arrhythmias in WPW (per 2010 ACLS guidelines)
VIII. Protocol: Rate control if WPW with Ejection Fraction <40%
-
General
- Risk of embolus if rhythm cardioverts
- Consider Atrial Fibrillation Anticoagulation
- Recommended agents
- Electrical Synchronized Cardioversion
- Amiodarone (Cordarone)
IX. Protocol: Rate control if Heart function preserved (No WPW)
-
General
- Risk of embolus if rhythm cardioverts
- Consider Atrial Fibrillation Anticoagulation
- Recommended agents
- Beta Blockers (preferred)
- Metoprolol (Lopressor) - preferred
- Propranolol (Inderal)
- Esmolol (Brevibloc)
- Calcium Channel Blocker
- Beta Blockers (preferred)
- Second line agents
- Digoxin
- Effect on Heart Rate is delayed 3 hours (contrast with 5 minutes for Diltiazem)
- Amiodarone
- Not as effective as Diltiazem or Magnesium for rate control in most cases
- Used in critically ill patients with Atrial Fibrillation
- Clemo (1998) Am J Cardiol 81(5): 594-8 [PubMed]
- Magnesium Sulfate
- Effective adjunctive management of ventricular response rate control
- Slows AV nodal conduction and decreases Heart Rate
- Davey (2005) Ann Emerg Med 45(4): 347-53 [PubMed]
- Digoxin
X. Protocol: Rate control if Ejection Fraction <40% (No WPW)
-
General
- Risk of embolus if rhythm cardioverts
- Consider Atrial Fibrillation Anticoagulation
- Recommended agents
XI. Management: Choosing Longterm Rate Versus Rhythm Control
- Older studies compared rate control to medication-based rhythm control as treatment arm
- Rate control has less drug-related adverse effects
- Rate control has equivalent efficacy to rhythm control
- Same survival benefit
- Same Cerebrovascular Accident risk
- Rhythm control may offer benefit in age <65 years
- Wyse (2002) N Engl J Med 347:1825-33 [PubMed]
- Newer studies compared rate control to catheter ablation
- Catheter ablation appears superior to rate control in comorbid Heart Failure
- Marrouche (2018) N Engl J Med 378:417-27 [PubMed]
- Rhythm control may be preferred in high risk cardiovascular patients in Atrial Fibrillation <1 year
- NNT 91 to prevent one cardiovascular death, hospitalization or Cerebrovascular Accident in 5 years
- But rhythm control is associated with serious complications in 2% of patients
- Camm (2022) J Am Coll Cardiol 79(19): 1932-48 [PubMed]
- Kirchhof (2020) N Engl J Med 383(14): 1305-16 [PubMed]
XII. Management: Chronic Rate Control Agent Selection
-
Beta Blockers (e.g. Metoprolol) are typically most effective ORAL agents for rate control
- Contrast with Diltiazem IV, which is typically more effective than IV Beta Blockers
- Avoid non-selective Beta Blockers in acute CHF, COPD, Asthma
- Diltiazem
XIII. References
- (2000) Circulation, 102(Suppl I):86-9
- Casaletto (2014) Crit Dec Emerg Med 28(4): 10-19
- Orman, Mattu and Herbert in Herbert (2016) EM:Rap 16(9):6-7
- Stiell (2011) Canadian J Cardiol 27(1): 38-46 [PubMed]
- Wann (2011) Circulation 123(1): 104-23 [PubMed]
- King (2002) Am Fam Physician 66(2):249-56 [PubMed]
- Gutierrez (2011) Am Fam Physician 83(1): 61-8 [PubMed]
- Falk (2001) N Engl J Med 344:1067-78 [PubMed]
- Li (1998) Emerg Med Clin North Am 16:389-403 [PubMed]
- Dell'Orfano (1998) Am Fam Physician, 58(2):471-80 [PubMed]
- Hebbar (2002) Am Fam Physician 65(12):2479-86 [PubMed]