Left atrial (LA) remodeling and dysfunction reflect chronic exposure to elevated left ventricular (LV) filling pressures. The aim of this longitudinal cohort study was to define the effect of reducing LV filling pressures on reverse remodeling of LA volume (LAV) and function.This retrospective cohort included 195 patients (52% men; mean age, 64 ± 14 years) in sinus rhythm with LA dilatation and sequential echocardiograms (median interval, 1 year; interquartile range, 0.5-2.0 years). One hundred seventy-four patients underwent medical therapy (82 with reduced E/e' ratios), and 21 underwent surgery for valvular heart disease. Biplane LAV (normal value, ≤ 68 mL for men, ≤ 62 mL for women), LA strain (ε) (normal value, >32%) and LV filling pressures (assessed as E/e' ratio; normal value, <13) were measured.Although LAV at baseline and follow-up were 88 ± 27 and 81 ± 24 mL, LA ε and E/e' ratio remained stable at 26 ± 11% and 14 ± 7, respectively. Changes in E/e' ratio were associated with changes in LAV (r = 0.37, P < .001) and LA ε (r = -0.51 P < .001). Although reduced E/e' ratio or improved LA ε at follow-up occurred in about 50% of the patients, only 26% (51 of 195) had normalized LAV. Compared with surgery, successful reduction of E/e' with medical therapy was less effective in reducing LAV (P < .001) but produced similar improvement in LA ε. Having normal or improved E/e' ratio at follow-up was not associated with normalization of LAV (relative risk, 1.29 [P = .326] and 1.22 [P = .421], respectively) but was associated with normalized LA ε (relative risk, 2.04 [P = .011] and 1.86 [P = .017], respectively) independently of LAV.Reduction in LV filling pressures reduces but rarely normalizes LAV. The strong association of reduced LV filling pressure with improved LA function indicated by LA longitudinal ε supports the increasing interest of LA ε measurement.