2.2 Study selection and data extraction
Titles and abstracts were retrieved from articles searched using the
keywords “left bundle branch pacing” or “left bundle branch area
pacing.” Studies were included if the article was in English and met
the following criteria: patients aged >18 years; included
patients with an LVEF from 35–50%; LVEF or QRS duration follow-up was
performed after the procedure; and for LBBAP CRT, both patients with
pacing indications (de novo or upgrade), and with HF without pacing
indications (de novo CRT), were included. Among studies satisfying the
above criteria, a pooled analysis of patients with a baseline LVEF of
35–50% was used. Editorials, review articles, case reports/letters,
and abstracts were excluded. The quality of the literature was evaluated
by the above two researchers using the Newcastle-Ottawa scale
criteria.21