Straight and crosier‑shaped catheter techniques for phrenic nerve stimulation during cryoballoon pulmonary vein isolation for the treatment of atrial fibrillation

Abstract

Background: Cryoablation is an effective and safe method of pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). However, monitoring of phrenic nerve function during cryoballoon PVI remains an important issue.

Aims: We aimed to compare 2 techniques of phrenic nerve stimulation (PNS) with the use of either a straight or a crosier‑shaped decapolar deflectable catheter.

Methods: The study included 218 patients (mean [SD] age, 61.8 [10.9] years; 87 women) referred for cryoballoon PVI for AF. Patients were randomly assigned to PNS with either a straight or a crosier‑shaped catheter.

Results: The groups did not differ in demographic characteristics or PVI effectiveness. The current threshold during PNS was lower in the group in which the crosier‑shaped catheter was applied (mean [SD], 6.7 [4.9] mA vs 4.8 [3.7] mA; P < 0.01). In this group, the procedure time was shorter (mean [SD], 72.6 [22.8] min vs 64.4 [14.8] min; P < 0.01), fewer repositioning maneuvers were required (31.8% vs 19.4%; P < 0.05), and atrial capture during PNS was observed more frequently (11.5% vs 29.6%; P < 0.01).

Conclusions: Straight and crosier‑shaped catheter techniques are equally effective in monitoring for phrenic nerve palsy. The crosier‑shaped catheter maintains its position better, thus leading to fewer dislocations and requiring fewer correction maneuvers, which might correlate with shorter procedure time. Moreover, this technique provides lower pacing thresholds. Both techniques may be safely used in patients with AF, and if stable phrenic nerve capture cannot be achieved, switching to another technique seems reasonable.