**1. Introduction**

Heart failure (HF) is a clinical syndrome that is becoming a major public health problem worldwide because of its increasing incidence and prevalence as well as its related morbidity and mortality [1]. Despite its failure in about one-third of treated patients, cardiac resynchronization therapy (CRT) still remains the best treatment for symptomatic HF patients on full medical therapy [2,3].

Responders to CRT have shown clear evidence for improved cardiac performance, left ventricular (LV) function, and the reverse remodeling of the left atrium (LA) [4,5]. LA function can be assessed by various echocardiographic techniques, among which myocardial deformation has recently shown significant accuracy. Despite this, the relationship between CRT-related LA and ventricular function changes remains poorly established, irrespective of the fact that CRT is associated with both cavity reverse remodeling and reduced atrial arrhythmia [6–8].

The aim of this meta-analysis was to assess the relationship between clinical response to CRT, LA function improvement, and LV function improvement.
