What is paroxysmal atrial fibrillation (PAFib)?

Paroxysmal Atrial Fibrillation (PAF)

Paroxysmal atrial fibrillation (PAF) is a type of atrial fibrillation that is self-terminating, usually within 48 hours, although episodes may continue for up to 7 days. 1

Definition and Classification

• PAF is characterized by episodes of irregular, uncoordinated atrial activation with consequent deterioration of mechanical function that terminate spontaneously, typically within 48 hours 1
• PAF is distinguished from persistent AF (lasting >7 days or requiring cardioversion), long-standing persistent AF (≥1 year), and permanent AF (when rhythm control is no longer pursued) 1
• PAF comprises between 25% and 62% of all AF cases, with similar underlying causes to sustained AF 2
• The 48-hour time point is clinically significant as the likelihood of spontaneous conversion decreases after this period, and anticoagulation must be considered 1

Diagnosis

• Diagnosis requires ECG documentation showing:
  • Absence of consistent P waves
  • Irregular fibrillatory waves that vary in amplitude, shape, and timing
  • Irregular ventricular response that is typically rapid when AV conduction is intact 1
• Clinical symptoms that should trigger ECG monitoring include palpitations, dyspnea, or fatigue 1
• More intense and prolonged monitoring is justified in highly symptomatic patients, those with recurrent syncope, or patients with potential indication for anticoagulation 1
• Transtelephonic monitoring has shown a highly significant correlation between perceived symptoms and documented PAF episodes 3

Clinical Significance and Complications

• PAF is associated with the same risk of thromboembolic complications as permanent AF 4
• PAF can trigger life-threatening ventricular arrhythmias in susceptible patients 1
• PAF is independently associated with:
  • Heart failure-related death
  • Fatal and nonfatal stroke
  • Long-term disease progression with heart failure symptoms 1
• Acute clinical deterioration during PAF episodes may cause syncope or heart failure due to reduced diastolic filling and cardiac output 1

Management Approaches

Rhythm Control

• The main objective of PAF management is prevention of paroxysms and long-term maintenance of sinus rhythm 2
• Class 1c drugs are highly effective for PAF, with beta-blockers as useful alternatives 2
• For patients with severe coronary artery disease or poor ventricular function, amiodarone is likely the drug of choice 2
• Flecainide has been shown in controlled trials to significantly reduce PAF recurrence rates compared to placebo 3

Rate Control

• During PAF episodes, beta-blockers, verapamil, and digoxin can be effective in controlling heart rate 1
• In some cases, AV node ablation and permanent ventricular pacing may be necessary for selected patients with difficult-to-control ventricular rates 1

Anticoagulation

• Anticoagulation therapy should follow the same approach as for sustained AF 2, 4
• Warfarin (INR 2.0-3.0) is recommended for most PAF patients, especially those with risk factors for thromboembolism 4
• Even one or two episodes of PAF have been associated with increased risk for systemic thromboembolism 1
• The threshold for initiation of anticoagulant therapy should be low and can include patients after the initial PAF episode 1
• Risk factors warranting anticoagulation include: previous stroke, hypertension, age >65, diabetes, previous myocardial infarction, reduced left ventricular function, heart failure, or enlarged left atrium 4

Non-Pharmacological Options

• Emerging non-pharmacological therapeutic options include:
  • Pacemakers
  • Catheter-based ablation techniques
  • Implantable atrial defibrillators 2, 5
• Catheter-based ablation has proven more successful compared to drug therapy in achieving rhythm control, with highest efficiency in paroxysmal AF 5

Natural Course and Progression

• AF typically progresses from short, rare episodes to longer and more frequent attacks 1
• Over time (years), many patients will develop sustained forms of AF 1
• Only a small proportion of patients without AF-promoting conditions (2-3%) will remain in paroxysmal AF over several decades 1
• Asymptomatic PAF episodes are common even in symptomatic patients, making monitoring important for proper management 1

Special Considerations

• PAF may be the first manifestation of underlying cardiac conditions like hypertrophic cardiomyopathy 1
• Certain drugs can induce PAF, requiring review of pharmacological history in patients with new-onset AF 1
• Silent (asymptomatic) PAF is a likely cause of some cryptogenic strokes and neurocognitive impairment 1