*2.2. Study Selection*

The criteria for inclusion in the meta-analysis were: (i) studies investigating patients undergoing cardiac resynchronization therapy; (ii) reporting left atrial predictors of CRT responders and non-responders; (iii) over three months of completed follow-up; and (iv) an enrolled population of adults aged ≥18 years.

Exclusion criteria were: (i) insufficient statistical data to compare two groups; (ii) less than three months follow-up period; (iii) non-human subjects; and (iv) articles not published in English.
