Does impaired left ventricular relaxation affect P wave dispersion in patients with hypertension?

Objective: P wave dispersion (PD) is considered to reflect the heterogeneous conduction in atria. We investigated whether there was a correlation between the left ventricular (LV) relaxation and PD. Method and Results: Fifty-three hypertensive patients less than or equal to60 years old were divided into two groups: Group A, 27 patients, aged 54 +/- 5 years with the impaired LV relaxation and Group B, 26 patients, aged 51 +/- 8 years with normal LV relaxation. The P wave durations were measured in all 12 leads of ECG and PD was defined as the difference between maximum and minimum P wave duration (Pmax-Pmin). Mitral inflow velocities (E and A), E deceleration time (DT), isovolumic relaxation time (IVRT), left atrial and ventricular diameters, and wall thickness of LV were obtained by echocardiography. Clinical characteristics of both groups were comparable. The wall thickness of LV, Pmax, and left atrial dimension were not different in both groups. A velocity was higher (P < 0.001), but E velocity (P = 0.03) and E/A ratio (P < 0.001) were lower in group A than in group B. IVRT and DT were also significantly longer in group A. PD was significantly higher in group A compared to group B (51 +/- 9 vs 41 +/- 11 ms, P = 0.01). This difference resulted from the Pmin (61 +/- 10 vs 67 +/- 9 ms, P = 0.03, respectively). Multivariate analysis revealed a significant correlation between PD and A velocity (r = 0.46, P = 0.01), E/A ratio (r = -0.53, P = 0.001), DT (r = 0.65, P < 0.001), and IVRT (r = 0.73, P < 0.001). Conclusion: This study suggests that impaired LV relaxation contributes to the heterogeneous atrial conduction in hypertensive patients.