Incidence and characteristics of phrenic nerve palsy following pulmonary vein isolation with the novel second-generation cryoballoon as compared to the first-generation balloon

Abstract

Purpose: To describe incidence and characteristics of Phrenic Nerve Palsy (PNP) following Pulmonary Vein Isolation (PVI) using the novel second-generation cryoballoon with enhanced surface cooling (CB2) as compared to the first-generation balloon (CB1). Methods: 191 consecutive patients with paroxysmal or persistent (< 6 months) atrial fibrillation underwent single-transseptal PVI with the CB2 (last 86 patients) or the CB1 (105 patients, control group) in conjunction with an endoluminal spiral mapping catheter. After successful PVI, one bonus CB application was applied for each PV. The right PN was continuously stimulated by a catheter from the superior caval vein during ablation of the septal PVs. In case of loss or weakening of diaphragm contraction, freezing was immediately stopped and no bonus application was applied. Transient PN palsy was defined as weakening/loss of diaphragm contraction with full recovery until discharge as demonstrated by chest fluoroscopy. Persistent PN palsy was defined as weakening/loss of diaphragm contraction present at discharge. Results: In total, PNP occurred in 9/86 (10,5%) patients in the CB2 group and 6/105 (5,7%) patients in the CB1 group (p = 0,23; chi-square test). Persistent PNP occurred in 3 (3,5%) and 2 (1,9%) patients in the CB2 and CB1 group, respectively (p = 0,66; Fisher's exact test). Transient PNP occurred in 6 (7%) and 4 (3,8%) patients in the CB2 and CB1 group, respectively (p = 0,25; Fisher's exact test). PNP occurred exclusively during freezing at the right superior PV in the CB1 group, while in 5 patients (5,8%) of the CB2 group, PNP occurred during freezing at the right inferior PV (RIPV). PNP was generally right-sided with the exception of 1 patient in the CB2 group (1,1%), in whom delayed left-sided PNP was demonstrated 1 day after the procedure with unimpaired intraprocedural diaphragm movement. In the CB2 group, 2/3 patients with persistent PNP demonstrated partial recovery of PN function during 3±2 months of follow-up, 2 patients felt mild exertional dyspnea. In the CB1 group, 1/2 patients with persistent PNP demonstrated complete recovery of PN function after 1 month. The other patient was asymptomatic and declined further chest fluoroscopy. Conclusions: We observed a numerical higher incidence of transient and persistent PNP following PVI with the novel CB2 vs. CB1, that did not, however, reach statistical significance. Particular awareness has to be given during ablation at the RIPV using CB2, since the majority of PNP cases occurred at this PV, which is in contrast to prior observations with the CB1.