Lattice-shaped catheter ablation for incessant inducible AVNRT in patient undergoing atrial fibrillation ablation: a case report

This report describes the first use of the Affera Sphere-9 dual-energy catheter for slow pathway modification in atrioventricular nodal re-entrant tachycardia (AVNRT) during atrial fibrillation (AF) ablation in a patient with a dual-chamber pacemaker, illustrating a streamlined single-catheter approach.

A 74-year-old man with prior cryoablation for AF, mitral valve repair, and a recently implanted dual-chamber pacemaker was referred for repeat AF ablation due to symptomatic, recurrent AF (30% burden). Left atrial mapping with the Sphere-9 catheter revealed reconnection at the right superior pulmonary vein, right carina, and across prior roof and floor lines. Using pulsed field (4-s lesions, 8 mm spacing) and supplemental radiofrequency (RF) energy, the left atrial posterior wall was re-isolated. Cavo-tricuspid isthmus ablation was performed with RF and pulsed field applications, achieving bidirectional block. During subsequent testing, typical AVNRT was induced. To maximize efficiency, slow pathway modification was performed with the same Sphere-9 catheter, using shortened RF applications (3 s), a lower target temperature (60°C), and an 80% current limit, at an inferior-posterior site 1.3–2.5 cm from the His signal. Junctional acceleration was observed without atrioventricular block, indicating successful slow pathway modification. The procedure was completed without fluoroscopy or complications, and follow-up device interrogation showed no recurrence of AF or AVNRT.

This case demonstrates the feasibility and acute safety of using a single dual-energy lattice-tip catheter for combined AF and AVNRT ablation, potentially reducing procedure time, catheter exchanges, and cost; larger studies are needed to assess long-term outcomes.