High-density mapping of upper loop macroreentry surrounding the superior vena cava: Substrate-evolved ablation...

Area of Science:

• Electrophysiology
• Cardiac Arrhythmias
• Interventional Cardiology

Background:

• Scar-related macroreentry atrial flutter (AFL) around the superior vena cava (SVC) is known but poorly understood.
• The link between arrhythmogenic substrates and optimal ablation strategies for SVC-AFL requires further investigation.

Purpose of the Study:

• To identify the electrophysiologic substrate of SVC-AFL.
• To determine optimized ablation strategies for SVC-AFL using high-resolution mapping.

Main Methods:

• Retrospective analysis of 16 patients with SVC-AFL from 7 institutions (June 2017-May 2023).
• High-resolution activation mapping to identify electrophysiologic substrates.
• Substrate-based linear ablation and cavotricuspid isthmus ablation.

Main Results:

• SVC-AFL was identified in 1.2% of patients with macroreentrant atrial tachycardias, often post-cardiac surgery or ablation.
• A longitudinal surgical scar from SVC to the right atrium was the substrate for macroreentry in all patients.
• Shorter SVC-AFL circuits (<180 mm) showed more slow conduction areas (P=.023).
• All tachycardias were terminated by ablating the scar-to-barrier channel; cavotricuspid isthmus block was achieved in all patients.

Conclusions:

• Surgical incisions/scars extending from the SVC to the right atrium promote SVC-AFL development.
• Substrate-based linear lesions combined with prophylactic cavotricuspid isthmus ablation yield favorable clinical outcomes for SVC-AFL.