Spatial dissociation between atrial exit and the putative slow pathway substrate in atypical AVNRT

Area of Science:

• Electrophysiology
• Cardiac Arrhythmias
• Catheter Ablation

Background:

• Atypical atrioventricular nodal reentrant tachycardia (AVNRT) involves complex reentrant circuits.
• Identifying precise ablation targets for atypical AVNRT is challenging due to variable atrial exit locations of slow pathways.

Purpose of the Study:

• To investigate the spatial relationship between high-peak frequency (PF) regions during sinus rhythm and retrograde slow pathway atrial exits in atypical AVNRT.
• To assess the feasibility of a substrate-oriented ablation strategy using PF mapping.

Main Methods:

• Eleven patients with atypical AVNRT underwent catheter ablation guided by PF mapping during sinus rhythm.
• High-PF sites and earliest atrial activation sites during retrograde slow pathway conduction were identified.
• Ablation was primarily targeted at high-PF regions, with additional atrial exit ablation if needed.

Main Results:

• High-PF sites were consistently identified, typically near the 5 o'clock tricuspid annulus.
• A significant spatial dissociation (mean 10.9 mm) was observed between high-PF sites and earliest atrial activation sites.
• Ablation at high-PF regions alone successfully eliminated retrograde slow pathway conduction in 82% of patients, with 100% acute success and no recurrences at 6 months.

Conclusions:

• Atrial exits in atypical AVNRT are often spatially separated from the slow pathway substrate identified by sinus rhythm PF mapping.
• Sinus rhythm high-PF mapping presents a potentially feasible substrate-oriented approach for atypical AVNRT ablation, requiring further validation.