Selection criteria
To qualify for analysis, studies must include randomized controlled
trials, cross-sectional studies, case-control studies, or cohort studies
evaluating the outcomes of LBBAP implantation in HFrEF patients. Case
reports and case series were excluded from the study. The qualified
studies must have statistical outcomes in the form of mean ± standard
deviation (SD) or median (interquartile range Q1–Q3) with p-values to
determine the level of significance in the statistical hypothesis test.
The inclusion of studies was not limited by sample size or ethnicity of
the population. Any disagreements concerning study choices were settled
through a collaborative discussion between the two investigators. The
Newcastle-Ottawa quality assessment scale and the modified
Newcastle-Ottawa scale were used to assess the quality of study for
case-control studies and the result of interest for cohort and
cross-sectional studies (Tables 1–2) [22] . The evaluation
was conducted in three domains: four items of study group selection (S),
two items of group comparability (C), and three items of exposure and
outcome (O). The bias assessment results were displayed as a number,
with the S, C, and O domains receiving a maximum of 4, 2, and 3,
respectively.