*Review* **Improved Left Atrial Function in CRT Responders: A Systematic Review and Meta-Analysis**

**Ibadete Bytyçi 1,2, Gani Bajraktari 1,2, Per Lindqvist 1,3 and Michael Y. Henein 1,4,\***


Received: 19 December 2019; Accepted: 15 January 2020; Published: 21 January 2020

**Abstract:** Cardiac resynchronization therapy (CRT) is associated with reverse left atrial (LA) remodeling. The aim of this meta-analysis was to assess the relationship between clinical response to CRT and LA function changes. We conducted a systematic search of all electronic databases up to September 2019 which identified 488 patients from seven studies. At (mean) 6 months follow-up, LA systolic strain and emptying fraction (EF) were increased in CRT responders, with a −5.70% weighted mean difference (WMD) [95% confidence interval (CI) −8.37 to −3.04, *p* < 0.001 and a WMD of −8.98% [CI −15.1 to −2.84, *p* = 0.004], compared to non-responders. The increase in LA strain was associated with a fall in left ventricle (LV) end-systolic volume (LVESV) *r* = −0.56 (CI −0.68 to −0.40, *p* < 0.001) and an increase in the LV ejection fraction (LVEF) *r* = 0.58 (CI 0.42 to 0.69, *p* < 0.001). The increase in LA EF correlated with the fall in LVESV *r* = −0.51 (CI −0.63 to −0.36, *p* < 0.001) and the increase in the LVEF *r* = 0.48 (CI 0.33 to 0.61, *p* = 0.002). The increase in LA strain correlated with the increase in the LA EF, *r* = 0.57 (CI 0.43 to 0.70, *p* < 0.001). Thus, the improvement of LA function in CRT responders reflects LA reverse remodeling and is related to its ventricular counterpart.

**Keywords:** left atrial strain; cardiac resynchronization therapy; heart failure
