AIMS: We aimed to examine temporal changes in left ventricular (LV) structures and their prognostic impacts in patients with heart failure (HF) and preserved ejection fraction (HFpEF). METHODS AND RESULTS: In the Chronic Heart Failure Analysis and Registry in the Tohoku District-2 (CHART-2) study (n = 10 219), we divided 2698 consecutive HFpEF patients (68.9 ± 12.2 years, 32.1% female) into three groups by LV hypertrophy (LVH) and enlargement (LVE) at baseline: (-)LVH/(-)LVE (n = 989), (+)LVH/(-)LVE (n = 1448), and (+)LVH/(+)LVE (n = 261). We examined temporal changes in LV structures and their prognostic impacts during a median 8.7-year follow-up. From (-)LVH/(-)LVE, (+)LVH/(-)LVE to (+)LVH/(+)LVE at baseline, the incidence of the primary outcome, a composite of cardiovascular death or HF admission, significantly increased. Among 1808 patients who underwent echocardiography at both baseline and 1 year, we noted substantial group transitions from baseline to 1 year; the transition rates from (-)LVH/(-)LVE to (+)LVH/(-)LVE, from (+)LVH/(-)LVE to (-)LVH/(-)LVE, from (+)LVH/(-)LVE to (+)LVH/(+)LVE, and from (+)LVH/(+)LVE to (+)LVH/(-)LVE were 27% (182/671), 22% (213/967), 6% (59/967), and 26% (44/170), respectively. In the univariable Cox proportional hazard model, patients who transitioned from (+)LVH/(-)LVE to (+)LVH/(+)LVE or remained in (+)LVH/(+)LVE had the worst subsequent prognosis [hazard ratio (HR) 4.65, 95% confidence interval (CI) 3.09-6.99, P < 0.001; HR 4.01, 95% CI 2.85-5.65, P < 0.001, respectively], as compared with those who remained in (-)LVH/(-)LVE. These results were unchanged after adjustment for the covariates including baseline LV ejection fraction (LVEF) and 1-year LVEF change. CONCLUSION: In HFpEF patients, LV structures dynamically change over time with significant prognostic impacts, where patients who develop LVE with LVH have the worst prognosis.