What is atrial fibrillation (Afib) with rapid ventricular response (RVR)?

Atrial Fibrillation with Rapid Ventricular Response (RVR)

Atrial fibrillation with rapid ventricular response (AFib with RVR) is a cardiac arrhythmia characterized by irregular, chaotic atrial activity with an abnormally fast ventricular rate, typically exceeding 100 beats per minute, which can lead to hemodynamic compromise and requires prompt medical intervention. 1

Definition and Pathophysiology

• AFib is the most common cardiac arrhythmia, characterized by disorganized electrical activity in the atria
• RVR occurs when excessive electrical impulses from the atria pass through the AV node, causing the ventricles to contract rapidly
• Typically defined as ventricular rates >100 beats per minute, often >120-150 beats per minute
• The irregular and rapid ventricular response can decrease cardiac output by:
  • Reducing ventricular filling time
  • Causing loss of atrial kick (contribution to ventricular filling)
  • Creating beat-to-beat variability in stroke volume

Clinical Significance

• AFib with RVR can lead to significant morbidity and mortality 2
• Can cause or worsen heart failure, particularly in patients with pre-existing cardiac dysfunction
• May precipitate tachycardia-induced cardiomyopathy with prolonged rapid rates 3
• Can lead to hemodynamic instability, hypoperfusion, and cardiac ischemia in acute presentations 2
• Represents a medical emergency when associated with hemodynamic compromise

Clinical Presentation

• Symptoms may include:
  • Palpitations
  • Shortness of breath
  • Chest discomfort
  • Dizziness or lightheadedness
  • Fatigue
  • Syncope (in severe cases)
• Physical examination typically reveals:
  • Irregular pulse
  • Tachycardia
  • Variable intensity of first heart sound
  • Signs of heart failure may be present (if complicated)

Management Approach

Immediate Assessment

1. Evaluate hemodynamic stability (blood pressure, perfusion, mental status)
2. Obtain 12-lead ECG to confirm diagnosis
3. Determine if this is a primary AFib event or secondary to another condition

Hemodynamically Unstable Patients

• Immediate electrical cardioversion is indicated for patients with hemodynamic instability 1, 2
• Synchronized cardioversion at 120-200 joules (biphasic) or 200 joules (monophasic)
• Consider sedation if time permits

Hemodynamically Stable Patients

Rate Control Strategy

• First-line medications:

  • Beta blockers (e.g., metoprolol 2.5-5 mg IV bolus over 2 minutes, up to 3 doses) 1
  • Non-dihydropyridine calcium channel blockers (e.g., diltiazem 0.25 mg/kg IV over 2 minutes, then 5-15 mg/h) 1

• Beta blockers may be preferred in patients with:

  • Coronary artery disease
  • Heart failure with reduced ejection fraction (use cautiously)
  • Hypertension

• Calcium channel blockers may be preferred in patients with:

  • COPD/asthma (where beta blockers may be contraindicated)
  • Heart failure with preserved ejection fraction 1

• Amiodarone (150 mg IV over 10 minutes, then 0.5-1 mg/min) can be considered when beta blockers and calcium channel blockers are contraindicated 1

• Digoxin may be added for additional rate control but is generally not effective as monotherapy in acute settings 4

Rhythm Control Strategy

• Consider in symptomatic patients or those with first episode of AFib
• Options include:
  • Electrical cardioversion
  • Pharmacological cardioversion with amiodarone, flecainide (if no structural heart disease), propafenone (if no structural heart disease), or ibutilide 1

Special Considerations

• Wolff-Parkinson-White (WPW) Syndrome: Avoid AV nodal blocking agents (beta blockers, calcium channel blockers, digoxin) as they can increase conduction through the accessory pathway and precipitate ventricular fibrillation 3

  • Use procainamide or ibutilide instead 3
  • Consider immediate cardioversion if unstable

• Thyrotoxicosis: Beta blockers are first-line therapy for rate control 3

  • If beta blockers are contraindicated, non-dihydropyridine calcium channel blockers can be used 3

• Heart Failure: Use beta blockers cautiously; amiodarone may be preferred for acute rate control 3

Complications and Long-term Management

• Tachycardia-induced cardiomyopathy can develop with persistent AFib with RVR 3

  • Usually reversible within 6 months of adequate rate or rhythm control 1

• Anticoagulation should be considered based on CHA₂DS₂-VASc score to prevent thromboembolic events 1

• For refractory cases, AV node ablation with pacemaker implantation may be considered, but only after thorough trials of pharmacological management 1

Pitfalls and Caveats

• Do not administer AV nodal blocking agents in patients with suspected WPW syndrome (wide complex tachycardia with irregular rhythm)
• Avoid combination of beta blockers with calcium channel blockers without specialist supervision due to risk of severe bradycardia or heart block 1
• Monitor for hypotension after administration of rate-controlling medications
• Remember that controlling the rate does not eliminate the need for anticoagulation assessment
• Uncontrolled AFib with RVR can lead to deterioration of ventricular function and increased mortality 1