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

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.