What is paroxysmal atrial fibrillation?

Paroxysmal Atrial Fibrillation

Paroxysmal atrial fibrillation is a recurrent form of atrial fibrillation characterized by self-terminating episodes that last less than 7 days (typically less than 24 hours) and resolve spontaneously without intervention. 1

Definition and Characteristics

Paroxysmal atrial fibrillation (PAF) is distinguished from other forms of AF by its temporal pattern:

• Episodes terminate spontaneously within 7 days of onset
• Most episodes resolve within 24 hours
• No intervention (such as cardioversion) is required for termination
• Episodes must last longer than 30 seconds to meet diagnostic criteria
• The arrhythmia is considered recurrent after 2 or more episodes

During episodes, the electrocardiogram (ECG) shows:

• Absence of consistent P waves
• Rapid oscillations or fibrillatory waves that vary in amplitude and shape
• Irregular ventricular response that is typically rapid when AV conduction is intact 1

Classification Within the AF Spectrum

Atrial fibrillation exists on a continuum with several distinct patterns:

1. First-detected AF: Initial presentation, regardless of duration or symptoms
2. Paroxysmal AF: Self-terminating episodes lasting ≤7 days
3. Persistent AF: Episodes lasting >7 days or requiring intervention to terminate
4. Long-standing persistent AF: Continuous AF lasting ≥12 months where rhythm control is still considered
5. Permanent AF: AF where no further attempts at rhythm control are planned 1, 2

It's important to note that patients may experience different patterns over time, and the classification is based on the most frequent presentation. A patient with predominantly paroxysmal AF may occasionally experience persistent episodes, or vice versa. 1

Clinical Significance and Prognosis

Paroxysmal AF has important clinical implications:

• Represents approximately 40% of all AF cases 3
• Can progress to persistent or permanent forms over time
• Carries similar stroke risk as persistent AF when risk factors are present
• Stroke prevention decisions should be based on CHA₂DS₂-VASc score, not the AF pattern 2
• Has better outcomes with electrical cardioversion and catheter ablation compared to persistent AF 4

Management Considerations

Management of paroxysmal AF focuses on:

1. Stroke prevention: Anticoagulation based on stroke risk assessment, not the AF pattern
2. Rate control: To manage symptoms during episodes
3. Rhythm control: To reduce episode frequency and duration
4. Treatment of underlying conditions: To reduce triggers and progression

Patients with paroxysmal AF should be carefully monitored as they may develop regular tachycardias, especially when taking certain antiarrhythmic medications like class IC agents (flecainide, propafenone) 5. These medications can potentially cause proarrhythmic effects, particularly in patients with structural heart disease 6.

Pitfalls and Caveats

Important considerations when managing paroxysmal AF:

• Do not assume paroxysmal AF has lower thromboembolic risk than persistent forms
• Patients may not recognize all episodes, as some can be asymptomatic
• Class IC antiarrhythmic drugs (like flecainide) can cause proarrhythmic effects including ventricular tachycardia in 0.4% of PAF patients 6
• Regular tachycardias may develop in patients with PAF, especially those on class IC drugs 5
• PAF can progress to persistent or permanent forms, particularly without appropriate treatment

Paroxysmal AF requires the same careful approach to risk stratification and management as other forms of atrial fibrillation, with particular attention to stroke prevention regardless of the intermittent nature of the arrhythmia.