Objectives: This study aims to evaluate electromechanical atrial and diastolic dysfunction (DD) in hypertensive patterns. Patients and methods: Between January 2022 and June 2025, a total of 176 patients who underwent both transthoracic echocardiography and 12-lead electrocardiography (ECG) were retrospectively analyzed. Based on 24-h ambulatory blood pressure monitoring, the patients with hypertension were classified into dipper (n=65) and non-dipper (n=76) groups, while a normotensive group was included as the control cohort (n=35). The dipping pattern was defined according to current hypertension guidelines, with a nocturnal systolic blood pressure (SPB) decline of ≥10% accepted as dipper status. The left atrial reservoir strain (LASr) was measured via speckle-tracking echocardiography, and P-wave dispersion (Pd) was manually calculated from standard ECGs. Results: Non-dipper patients exhibited significantly reduced LASr (19.27±5.1%) and increased Pd (50.57±8.1 ms) compared to dippers and controls (p<0.001). A strong inverse correlation between LASr and Pd was observed. The prevalence of DD reached the highest among non-dippers (92.0%). The receiver operating characteristic curve analysis identified a Pd cut-off of 40.5 ms with 83% sensitivity, 80% specificity, and area under the curve of 0.84 (95% confidence interval [CI]: 0.78-0.90) for detecting DD. Conclusion: Both LASr and Pd provide complementary insights into atrial mechanical and electrical remodeling in hypertensive patients. P-wave dispersion, as a simple and cost-effective ECG marker, may serve as a valuable tool for identifying DD, particularly when advanced imaging is unavailable. These findings support integrating Pd into routine hypertensive patient evaluation, although further studies are still warranted.