What is the investigation and treatment for a patient with atrial fibrillation (AF) with rapid ventricular response (RVR), tachycardia, normal blood pressure, and no symptoms?

Management of Atrial Fibrillation with RVR in a Hemodynamically Stable Patient

For a patient with atrial fibrillation with rapid ventricular response (heart rate 140), normal blood pressure, and no symptoms, initial management should focus on rate control with a beta-blocker or non-dihydropyridine calcium channel blocker, followed by comprehensive evaluation for underlying causes and assessment for anticoagulation. 1, 2

Initial Assessment and Stabilization

• Confirm diagnosis of AF with RVR on ECG
• Assess hemodynamic stability (already confirmed stable with normal BP)
• Obtain baseline 12-lead ECG to:
  • Verify AF rhythm
  • Look for pre-excitation (WPW syndrome)
  • Evaluate for ischemic changes
  • Check for bundle branch blocks or prior MI

Immediate Rate Control Therapy

First-line medications (choose one):

1. Beta-blockers:

   • Metoprolol 2.5-5 mg IV bolus over 2 minutes (may repeat up to 3 doses) 2
   • Esmolol 500 mcg/kg IV over 1 min, then 60-200 mcg/kg/min IV infusion

2. Non-dihydropyridine calcium channel blockers (if no heart failure):

   • Diltiazem 0.25 mg/kg IV over 2 minutes, then 5-15 mg/h IV infusion 2
   • Verapamil 0.075-0.15 mg/kg IV over 2 minutes

Second-line medication:

• Amiodarone 150 mg IV over 10 minutes, then 0.5-1 mg/min IV infusion (if beta-blockers and calcium channel blockers are contraindicated or ineffective) 2, 3

Important cautions:

• Avoid calcium channel blockers if suspected heart failure or reduced ejection fraction
• Avoid digoxin as sole agent for rate control in paroxysmal AF 1
• Avoid all AV nodal blocking agents if WPW syndrome is suspected 1

Comprehensive Evaluation

Minimum workup required 1:

1. Laboratory tests:

   • Complete blood count
   • Electrolytes, BUN, creatinine
   • Thyroid function tests (TSH, free T4)
   • Liver function tests
   • Cardiac biomarkers (troponin)

2. Imaging:

   • Transthoracic echocardiogram to assess:
     • Left ventricular size and function
     • Left atrial size
     • Valvular disease
     • Evidence of structural heart disease

Additional testing to consider:

• 6-minute walk test (if adequacy of rate control is questioned)
• Holter or event monitoring (to evaluate rate control)
• Exercise testing (if exercise-induced AF is suspected)
• Transesophageal echocardiogram (if cardioversion is planned)

Anticoagulation Assessment

1. Calculate CHA₂DS₂-VASc score to assess stroke risk 2

2. Initiate anticoagulation if:

   • Score ≥2 in men or ≥3 in women (definite recommendation)
   • Consider if score is 1 in men or 2 in women

3. Preferred anticoagulants:

   • Direct oral anticoagulants (DOACs) are preferred over vitamin K antagonists 2

Long-term Management Considerations

Rate vs. Rhythm Control Strategy

Consider rhythm control if:

• First episode of AF
• Young patient
• Symptomatic despite adequate rate control
• Difficulty achieving adequate rate control

Consider rate control if:

• Elderly asymptomatic patient
• Long-standing persistent AF
• Multiple failed cardioversion attempts

Target Heart Rate

• Target heart rate <110 bpm at rest 2
• No evidence that strict rate control (<80 bpm) is beneficial compared to lenient control (<110 bpm) 1

Follow-up Recommendations

• Continuous cardiac monitoring until heart rate stabilizes
• Regular assessment of symptoms, heart rate, and blood pressure
• Outpatient follow-up within 1-2 weeks
• Consideration for long-term oral rate control medications

Common Pitfalls to Avoid

1. Failing to identify and treat underlying causes of AF (thyroid disease, electrolyte abnormalities, etc.)
2. Using calcium channel blockers in patients with heart failure or reduced ejection fraction
3. Delaying anticoagulation assessment and initiation when indicated
4. Administering AV nodal blocking agents in patients with WPW syndrome
5. Using digoxin as monotherapy for acute rate control

The evidence strongly supports using beta-blockers or calcium channel blockers as first-line agents for rate control in AF with RVR, with recent studies suggesting diltiazem may achieve rate control faster than metoprolol, though both are effective and safe 4, 5. For patients with heart failure, beta-blockers remain the preferred first-line agent, though recent evidence suggests diltiazem may be safer than previously thought in selected heart failure patients 6.