What are the next steps for a patient with paroxysmal atrial fibrillation (PAF) who underwent a 2-day ambulatory monitor showing normal sinus rhythm, rare premature atrial contractions (PACs), and episodes of supraventricular tachycardia (SVT)?

Management of Paroxysmal Atrial Fibrillation with Normal Sinus Rhythm on Monitoring

For a patient with paroxysmal atrial fibrillation who shows normal sinus rhythm on a 2-day ambulatory monitor with episodes of SVT and PVCs, exercise treadmill testing should be performed to assess chronotropic competence, followed by continued monitoring for arrhythmia burden.

Interpretation of Current Monitoring Results

The 2-day ambulatory monitor shows:

• Predominant rhythm: Normal sinus rhythm (average HR 61 bpm, range 39-149 bpm)
• No atrial fibrillation or flutter detected
• Rare premature atrial contractions (PACs)
• 6 episodes of supraventricular tachycardia (SVT), longest 8 beats, fastest 149 bpm
• 2% premature ventricular contractions (PVCs)
• Nocturnal bradycardia to 39 bpm
• No symptoms reported
• Patient failed to achieve 85% of maximum predicted heart rate for age

Next Steps in Management

1. Exercise Treadmill Testing

• Perform exercise treadmill testing to formally assess chronotropic competence 1
• This will help evaluate:
  • Heart rate response to exercise
  • Potential exercise-induced arrhythmias
  • Correlation between exertion and arrhythmia burden
  • Possible underlying coronary artery disease, especially in patients ≥30 years 1

2. Extended Monitoring

• Consider longer-term monitoring (7-14 days) since:
  • Paroxysmal AF can be asymptomatic and may not be captured in a 2-day period 2
  • Asymptomatic AF episodes occur approximately 12 times more frequently than symptomatic episodes in patients with PAF 2
• Modern leadless ambulatory recorders allow for longer monitoring during daily activities and exercise 1

3. Evaluation for Underlying Conditions

• Assess for contributing conditions:
  • Hypertension
  • Coronary artery disease (especially in patients ≥30 years)
  • Structural heart disease via echocardiogram 1
  • Thyroid function
  • Sleep apnea
  • Alcohol or stimulant use

Management Considerations

Rate vs. Rhythm Control Strategy

• Since the patient has paroxysmal AF with episodes of SVT but is currently asymptomatic:
  • For younger individuals with paroxysmal AF, rhythm control may be a better initial approach 1
  • For older patients with hypertension or heart disease, rate control may be reasonable initial therapy 1

SVT Management

• The presence of SVT episodes requires attention as:
  • SVT can trigger AF episodes 3, 4
  • 18% of patients with AVNRT can develop atrial fibrillation 3
  • The cumulative proportion of patients with PSVT who develop AF reaches 29% at 2 years 4

PVC Management

• 2% PVC burden is generally low risk
• No specific treatment needed for asymptomatic PVCs at this burden level 1
• Monitor for any increase in frequency or complexity

Follow-up Plan

1. Complete exercise treadmill testing to assess chronotropic competence
2. Perform echocardiogram to evaluate for structural heart disease
3. Consider extended monitoring (7-14 days) to better capture potential AF episodes
4. Regular follow-up with assessment of:
   • Rhythm status with ECG
   • Symptoms related to arrhythmias
   • Need for anticoagulation based on CHA₂DS₂-VASc score 1

Common Pitfalls to Avoid

• Assuming absence of AF on a 2-day monitor excludes significant PAF
• Overlooking the relationship between SVT and AF development
• Failing to assess for underlying structural heart disease
• Neglecting to evaluate for chronotropic incompetence when suggested by monitoring
• Underestimating asymptomatic arrhythmia burden and associated stroke risk

The management approach should follow the AF-CARE pathway recommended in current guidelines: Comorbidity and risk factor management, Avoid stroke and thromboembolism, Reduce symptoms by rate and rhythm control, and Evaluation with dynamic reassessment 1.