Is Paroxysmal Atrial Tachycardia (PAT) the same as Atrial Fibrillation (FIB)?

Paroxysmal Atrial Tachycardia (PAT) vs. Atrial Fibrillation (AF): Key Differences

No, Paroxysmal Atrial Tachycardia (PAT) and Atrial Fibrillation (AF) are distinctly different cardiac arrhythmias with different electrocardiographic patterns, mechanisms, and clinical implications. 1

Electrocardiographic Differences

Atrial Fibrillation

• Characterized by uncoordinated atrial activation with rapid oscillations or fibrillatory waves that vary in amplitude, shape, and timing
• P waves are replaced by irregular fibrillatory waves
• Completely irregular ventricular response when AV conduction is intact
• No isoelectric baseline between atrial deflections 1

Atrial Tachycardia (including PAT)

• Shows regular, organized atrial activity with discrete P waves
• Typically has an isoelectric segment between P waves
• Originates from a focal point in the atrium
• Mechanism can be automaticity or a microreentry circuit 1

Mechanistic Differences

• AF: Results from multiple reentrant wavelets or rapid focal firing with chaotic conduction through the atria
• PAT: Typically originates from a single focal source or small reentrant circuit 1

Classification Distinctions

It's important to note that "paroxysmal" refers to the pattern of occurrence (sudden onset and termination) rather than the specific arrhythmia mechanism:

• Paroxysmal AF: Episodes of AF that terminate spontaneously or with intervention within 7 days
• PAT: A form of supraventricular tachycardia with abrupt onset and termination, with regular atrial activity 1

Clinical Presentation Differences

• AF: Often presents with irregular palpitations, may be asymptomatic in some cases
• PAT: Typically presents with regular palpitations with abrupt onset and termination 1

Diagnostic Approach

The definitive distinction between these arrhythmias is made through ECG recording during an episode:

• AF: Shows absence of consistent P waves, irregular fibrillatory waves, and irregular R-R intervals
• PAT: Shows regular P waves with consistent morphology and an isoelectric baseline between them 1

Treatment Implications

The distinction between these arrhythmias is crucial as their management strategies differ:

• AF: Management focuses on stroke prevention, rate control, and possibly rhythm control
• PAT: Management typically involves vagal maneuvers, adenosine for acute termination, and catheter ablation for definitive treatment 2

Common Pitfalls

1. Confusing terminology: The term "paroxysmal" describes the pattern of occurrence (sudden onset/offset), not the specific arrhythmia mechanism
2. Misdiagnosis: Atrial flutter may sometimes be misdiagnosed as AF when fibrillatory activity is prominent in multiple ECG leads 1
3. Coexistence: Some patients may experience both arrhythmias at different times, complicating diagnosis 3

Understanding these differences is essential for proper diagnosis and management, as the treatment approaches and prognostic implications differ significantly between these two arrhythmias.