Eligible studies
For the most precise study selection, each database was scanned through
combination of two key words: (1) cryoballoon ablation ANDphrenic nerve injury and cryoballoon ablation ANDcompound motor potential action OR (2) CMAP . Initially,
301 potentially relevant articles were identified according to the
adopted search strategy. As illustrated in the flow diagram (Fig. 1),
the first review excluded 216 papers based on screening the titles and
abstracts, and an additional 21 articles were excluded after a detailed
evaluation in addition to 64 articles thoroughly enrolled with timeline
and centers origin with intermeshing of records. Finally, 48 eligible
observational controlled and noncontrolled trials that fulfilled all
inclusion criteria for PNI registry [2,5–17,20–60] Figure 1. For
metanalysis of PN protection, location of PNI, and time to resolution of
PNI, different criteria ware used; thus, a significantly less papers met
the final criteria, and each part of the analysis was estimated
separately. Nevertheless, the method and equipment of CBA is unified so
that they can be analyzed together and in dependent subgroups.
The studies included in this meta-analysis were published between
September 2008 [21] and May 2019 [60]. Two randomized controlled
trials met the inclusion criteria [54,57]. The reasons for final
exclusion were lack of essential clinical outcome data, repeated records
in databases, review articles, duplicated studies, and non-controlled
trials. As to the quality of those included studies forty-eight
full-text studies were allocated a NOS score of ≥ 7 [19].