What is the difference between right-sided and left-sided atrial fibrillation (AFib) in terms of management and treatment?

Right-Sided vs Left-Sided Atrial Fibrillation: Understanding the Differences

There is no clinical distinction between "right-sided" and "left-sided" atrial fibrillation in medical practice, as atrial fibrillation is a whole-atrial arrhythmia that affects both atria, though the left atrium plays a more critical role in thromboembolic risk. 1

Pathophysiology and Clinical Significance

Left Atrium in Atrial Fibrillation

• The left atrium and particularly the left atrial appendage are the primary sites of thrombus formation in AF
• Over 90% of thrombi in non-valvular AF form in the left atrial appendage
• Left atrial structural changes (dilation, fibrosis) are major contributors to AF development and maintenance
• Left atrial dysfunction is directly linked to stroke risk in AF patients

Right Atrium in Atrial Fibrillation

• Right atrial involvement in AF is less clinically significant for thromboembolic risk
• Right atrial thrombi are much less common and typically associated with specific conditions:
  • Right-sided heart failure
  • Pulmonary hypertension
  • Presence of central venous catheters
  • Right atrial structural abnormalities

Management Implications

Anticoagulation

• Anticoagulation decisions are based on stroke risk assessment tools like CHA₂DS₂-VASc, not on which atrium appears more affected 1
• Direct oral anticoagulants (DOACs) are recommended over vitamin K antagonists for eligible patients 1
• A reduced dose of DOAC therapy is not recommended unless patients meet specific criteria, to prevent underdosing and avoidable thromboembolic events 1

Left Atrial Appendage Management

• Surgical closure of the left atrial appendage should be considered as an adjunct to oral anticoagulation in patients with AF undergoing endoscopic or hybrid AF ablation 1
• Stand-alone endoscopic surgical closure of the left atrial appendage may be considered in patients with AF and contraindications for long-term anticoagulant treatment 1

Ablation Strategies

• Catheter ablation targeting the left atrium (particularly pulmonary vein isolation) is the cornerstone of AF ablation
• Right atrial ablation is typically only performed in specific cases where right atrial triggers or drivers are identified
• Success rates for catheter ablation of typical atrial flutter (a right atrial macro-reentrant circuit) exceed 97% 2

Clinical Assessment and Follow-up

• Echocardiography is essential to evaluate both atria, valvular function, and ventricular function 2
• Regular follow-up should include assessment of:
  • Rate control adequacy
  • Symptoms
  • Medication side effects
  • ECG at each visit
  • Echocardiogram at baseline and every 1-2 years 2

Common Pitfalls to Avoid

• Failing to assess both stroke and bleeding risks when determining anticoagulation strategy 2
• Inadequate rate control monitoring
• Not considering left atrial appendage closure in patients with contraindications to anticoagulation
• Overlooking the need for follow-up echocardiography to detect tachycardia-induced cardiomyopathy 2

The management of atrial fibrillation follows the AF-CARE framework (Atrial Fibrillation—[C] Comorbidity and risk factor management, [A] Avoid stroke and thromboembolism, [R] Reduce symptoms by rate and rhythm control, [E] Evaluation and dynamic reassessment) regardless of which atrium appears more affected on imaging or electrophysiological studies 1.