Randomized comparison of two targets in typical atrial flutter ablation

Area of Science:

• Cardiology
• Electrophysiology
• Medical Device Technology

Background:

• Atrial flutter ablation is anatomically guided to two sites in the inferior right atrium: anterior (A) and posterior (P) isthmus.
• The efficacy and safety of targeting these specific sites require prospective comparison.

Purpose of the Study:

• To prospectively compare the effectiveness and safety of ablating the anterior (A) versus posterior (P) isthmus for typical atrial flutter.

Main Methods:

• 72 consecutive patients with typical atrial flutter were randomized to initiate ablation at either the anterior (A) or posterior (P) isthmus.
• If initial ablation failed after 15 radiofrequency (RF) pulses, the alternate site was targeted.
• Key metrics included success rate, radiofrequency pulses, procedure time, fluoroscopy time, and atrioventricular (AV) nodal conduction impairment.

Main Results:

• Complete bidirectional isthmus block was achieved in 30/36 group A patients versus 25/36 group P patients before 15 RF pulses.
• Among successful ablations, group A showed significantly lower RF pulses, procedure time, and fluoroscopy time compared to group P.
• Atrioventricular (AV) nodal conduction impairment occurred in 5 patients during P ablation, with one permanent block; no AV block occurred with A ablation.

Conclusions:

• While both anterior (A) and posterior (P) isthmus sites are effective for atrial flutter ablation, initiating ablation at the anterior site (A) appears easier.
• Targeting the anterior isthmus (A) first is associated with reduced procedure time, energy use, and fluoroscopy.
• Posterior isthmus (P) ablation carries a significant risk of transient or permanent atrioventricular (AV) block.