**5. Conclusions**

Clinical response to CRT is associated with an improvement of LA function, reflecting cavity reverse remodeling. These changes are related to their ventricular counterparts, thus supporting the importance of assessing LA function in patients treated by CRT for heart failure. Future studies should focus on concordant changes in LA and LV function that contribute to clinical improvement of patients receiving CRT for heart failure.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2077-0383/9/2/298/s1, Figure S1: Flow chart of study section, Figure S2: Comparison of baseline LVEDV, LVESV, LVEDd and EF in group of patients with CRT responders vs. CRT non responders, Figure S3: Comparison of baseline QRS duration and LA dimension in group of patients with CRT responders vs. CRT non responders, Figure S4: Weighted summary correlation between LA strain and LA EF, Figure S5: Relationship between LA strain change and (a) male gender; (b) age, Figure S6: Summary of QUADAS-2 Assessment of Selected Studies, Table S1: Summary of quality assessment analysis (Quality Assessment of Diagnostic Accuracy Studies-QUADAS 2), Table S2: Echocardiographic characteristics of LA functional measurements, Echocardiographic characteristics of LA functional measurements, Table S3: Summary of QUADAS-2 Assessment of Selected Studies.

**Author Contributions:** I.B. and M.Y.H., designed and drafted the article; I.B. and G.B. performed the literature search, study selection and data extraction. I.B. and M.Y.H., analyzed and interpreted the data; M.Y.H., G.B. and P.L. critically revised the article. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
