Contemporary analysis of phrenic nerve injuries following cryoballoon-based pulmonary vein isolation: A single-centre experience with the systematic use of compound motor action potential monitoring

PLoS One. 2020 Jun 25;15(6):e0235132. doi: 10.1371/journal.pone.0235132. eCollection 2020.


Background: Phrenic nerve injury (PNI) remains one of the most frequent complications during cryoballoon-based pulmonary vein isolation (CB-PVI). Since its introduction in 2013, the use of compound motor action potential (CMAP) for the prevention of PNI during CB-PVI is increasing; however, systematic outcome data are sparse.

Methods: The CMAP technique was applied in conjunction with abdominal palpation during pacing manoeuvres (10 mV, 2 ms) from the superior vena cava for 388 consecutive patients undergoing CB-PVI between January 2015 and May 2017 at our tertiary arrhythmia centre. Cryoablation was immediately terminated when CMAP amplitude was reduced by 30%.

Results: Reductions in CMAP amplitude were observed in 16 (4%) of 388 patients during isolation of the right veins. Of these, 11 (69%) patients did not manifest a reduction in diaphragmatic excursions. The drop in CMAP amplitude was observed in 10 (63%) patients during ablation of the right superior pulmonary veins (PVs) and in 7 (44%) patients during ablation of the right inferior PVs. Postprocedural persistent PNI was observed in three of four patients for a duration of 6 months, with one of these patients remaining symptomatic at the 24-month follow-up. One of the four patients was lost to long-term follow-up.

Conclusions: All PNIs occurred during right-sided CB-PVI and were preceded by a reduction in CMAP amplitude. Thus, the standardized use of CMAP surveillance during CB-PVI is easily applicable, reliable and compared with other studies, results in a lower number of PNIs.

Publication types

  • Clinical Trial
  • Observational Study

MeSH terms

  • Action Potentials*
  • Aged
  • Atrial Fibrillation* / physiopathology
  • Atrial Fibrillation* / surgery
  • Cryosurgery / adverse effects*
  • Female
  • Follow-Up Studies
  • Humans
  • Intraoperative Neurophysiological Monitoring*
  • Male
  • Middle Aged
  • Phrenic Nerve* / injuries
  • Phrenic Nerve* / physiopathology
  • Pulmonary Veins* / physiopathology
  • Pulmonary Veins* / surgery

Grants and funding

The author(s) received no specific funding for this work.