Background: (LVDD) either remains latent or manifests as heart failure with preserved ejection fraction (HFpEF). Little is known about echocardiographic parameters associated with symptomatic phenotype. Objective: To investigate echocardiographic parameters associated with symptomatic state in LVDD. Methods: Three hundred and thirty patients with definite diagnosis of LVDD (according to ASE/EACVI recommendations 2016) were included and divided into asymptomatic LVDD and HFpEF groups according to presence of dyspnea and brain natriuretic peptide levels. We excluded patients with left ventricular ejection fraction <50%, significant valvular heart disease, chronic lung disease, or renal dysfunction. Results: Mean age was 61.2 ± 8.3 years; 71% were females. Both groups were matched regarding age, gender, comorbidities, and drug history. HFpEF group showed significantly larger BMI (P = .04), significantly higher IVS thickness (P < .001), LA diameter (P < .001), LA volume index (P = .004), E velocity (P = .001), TR jet velocity (P = .03), and average E/e' ratio (P < .001).On the contrary, lateral e' velocity was significantly lower in HFpEF group (P < .001). By regression analysis, lateral e' velocity was the best independent predictor of symptomatic state. Area under ROC curve of lateral e' velocity was 0.789 (0.667-0.911, P < .001) to predict symptomatic state in LVDD with the best cutoff value of ≤8.2 cm/s (76% sensitivity and 79% specificity). Moreover, lateral e' velocity was significantly negatively correlated with NYHA class in HFpEF group. Conclusion: Reduced lateral e' velocity was associated with symptomatic state in LVDD. Moreover, it was significantly negatively correlated with NYHA class in HFpEF.