Literature review and search strategy
A systematic literature search was conducted, including studies up until May 2021 in the databases MEDLINE (via PubMed), EMBASE (via Scopus), and the Cochrane Database of Systematic Reviews. We aimed to identify studies that analyzed how individuals with HFrEF, particularly pacing-induced cardiomyopathy (PICM), responded to LBBAP implantation. Two investigators (N.S. and R.C.) separately compiled the systematic literature review using a search strategy that included the terms “left bundle branch pacing” and (“heart failure” or “pacing-induced cardiomyopathy”) (Supplementary 1 ). There were no language restrictions. Reference lists of recognized studies were manually searched for relevant research as well. This systematic review and meta-analysis followed the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) standards and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.