title: Phrenic nerve injury during ablation with the second-generation cryoballoon: analysis of the temperature drop behaviour in a large cohort of patients.
abstract: OBJECTIVE
  The present study sought to analyse the relationship between the temperature drop during the cryoenergy application and the occurrence of phrenic nerve injury (PNI) in a large cohort of patients having undergone second-generation cryoballoon ablation (CB-A).
  
  
  RESULTS
  The first 550 consecutive patients having undergone CB-A for atrial fibrillation were enrolled. Attained temperatures at 20, 30, 40, and 60 s during cryoablation in the right-sided pulmonary veins (PVs) were collected. Diagnosis of PNI was made if reduced motility or paralysis of the hemidiaphragm was detected. The incidence of PNI in the study population was 7.3% (40/550); among them, only four (0.7%) did not resolve until discharge and one (0.2%) still persisted at 23 months. Patients with PNI exhibited significantly lower temperatures at 20, 30, and 40 s after the beginning of the cryoapplication in the right superior PV (RSPV) (P = 0.006, P = 0.003, and P = 0.003, respectively). The temperature drop expressed as Δ temperature/Δ time was also significantly higher in patients with PNI. Low temperature during the early phases of the freezing cycle (less than -38°C at 40 s) predicted PNI with a sensitivity of 80.5%, a specificity of 77%, and a negative predictive value of 97.9%. Among patients with a fast temperature drop during RSPV ablation, an RSPV diameter >23.55 × 17.95 mm significantly predicted PNI occurrence.
  
  
  CONCLUSIONS
  The analysis of the temperature course within the first 40 s after the initiation of the freezing cycle showed that the temperature dropped significantly faster in patients with PNI during ablation in the RSPV.
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium mugnai.giacomo@gmail.com.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Mugnai
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Carlo
authors.initials: C
authors.lastname: de Asmundis
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Vedran
authors.initials: V
authors.lastname: Velagic
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Burak
authors.initials: B
authors.lastname: Hünük
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Erwin
authors.initials: E
authors.lastname: Ströker
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Kristel
authors.initials: K
authors.lastname: Wauters
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Ghazala
authors.initials: G
authors.lastname: Irfan
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Overeinder
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Ebru
authors.initials: E
authors.lastname: Hacioglu
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Jaime
authors.initials: J
authors.lastname: Hernandez-Ojeda
authors.affiliation: Department of Anaesthesiology, UZ Brussel-VUB, Brussels, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Poelaert
authors.affiliation: Department of Anaesthesiology, UZ Brussel-VUB, Brussels, Belgium.
authors.forename: Christian
authors.initials: C
authors.lastname: Verborgh
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Paparella
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Pedro
authors.initials: P
authors.lastname: Brugada
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Laarbeeklaan 101, Brussels 1090, Belgium.
authors.forename: Gian-Battista
authors.initials: GB
authors.lastname: Chierchia
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000601:surgery*; D001530:Belgium; D003452:Cryosurgery / Q000009:adverse effects* / Q000379:methods; D003964:Diaphragm / Q000294:innervation* / Q000503:physiopathology; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010243:Paralysis / Q000209:etiology; D010791:Phrenic Nerve / Q000293:injuries*; D011667:Pulmonary Veins / Q000601:surgery; D012372:ROC Curve; D013696:Temperature; D016896:Treatment Outcome
keywords: Atrial fibrillation; Cryoballoon; Phrenic nerve injury; Pulmonary vein isolation