2.2 Study selection and data abstraction
The abstracts retrieved from the search were reviewed by two investigators. Articles were included :(1) Study type:observational study and randomized controlled study; (2)study object: patients who need permanent pacemaker implantation; (3)clearly define the conditions for LBBAP success; (4)The ECG characteristics and pacing parameters of baseline and follow-up including QRS duration, capture threshold, R-wave amplitude (perception), impedance, etc. (5)have a clear follow-up time. Articles were excluded: (1) report the acute response only and follow-up time of LBBAP less than 1 month; (2)repeated data from the same research center, unable to obtain full text or original data after contacting the author; (3)case reports, animal studies etc.; (4)documents in languages other than Chinese and English. The extracted data included gender, age, indication of device implantation, number of enrolled patients, success rate of implantation, follow-up time, QRS duration at baseline and follow-up, capture threshold at baseline and follow-up, R-wave amplitude at baseline and follow-up, impedance at baseline and follow-up. For continuous variables, means, standard deviations, and sample sizes were extracted to estimate the overall average values.