LAUSR

Cryoballoon (CB) has been widely utilized in the treatment of drug-refractory atrial fibrillation (AF), but the balance point between efficacy and safety has been unclear. The protocol based on the time-to-isolation (TTI) was expected to provide patients with individualized ablation strategies. All studies up to June 2020 comparing the CB of TTI-based protocol (TTIP) and conventional protocol (ConP) in PubMed, Embase, and Cochrane Library databases were searched. The pooled OR or SMD with 95% CIs for each outcome were calculated with inverse-variance random effect model. The Egger method was used to evaluate the publication bias and the subgroup analysis was conducted according to the type of atrial fibrillation. Six studies enrolling a total of 1770 patients with drug-refractory AF were included. The pool real-time recording of pulmonary veins potential was 71% (95% CI: 61 ~ 81%, I2 = 97.9%) and a similar incidence of freedom from ATs after 1 year (OR: 1.12; 95% CI: 0.86 ~ 1.46, I2 = 0.0%, P = 0.481) was observed between two protocols. No difference was observed in complications (OR: 0.67; 95% CI: 0.43 ~ 1.04, I2 = 0.0%, P = 0.717) and phrenic nerve palsy (OR: 0.70; 95% CI: 0.37 ~ 1.35, I2 = 0.0%, P = 0.807). TTIP could significantly decrease the CB freezes per patient (SMD: − 2.44; 95% CI: − 4.46 to approximately − 0.41; I2 = 99.5%, P = 0.00) and shorten the cryotherapy application time (SMD: − 3.04; 95% CI: − 4.18 to approximately − 1.89; I2 = 97.4%, P = 0.00), procedure time (SMD: − 1.51; 95% CI: − 2.08 to approximately − 0.94; I2 = 95.4%, P = 0.00), and fluorescence time (SMD: − 0.70; 95% CI: − 1.25 to approximately − 0.15; I2 = 95.7%, P = 0.00). TTIP is safe and effective and it opens a new chapter in the field of individualized protocol of CB for patients with AF.