P-wave duration and dispersion in patients with obstructive sleep apnea.

AIM: P-wave dispersion (Pd) has been reported to be associated with inhomogeneous and discontinuous propagation of sinus impulses. The purpose of this study was to investigate Pd in patients with obstructive sleep apnea (OSA) and to determine its relationship with severity of the disease.

METHODS: The study population included 67 patients referred to sleep laboratory. The Apnea-Hypopnea Index (AHI) was defined as the number of apneas and hypopneas per hour of sleep. Of the sixty-seven patients, 48 had AHI5 and were diagnosed as OSA. Nineteen of the patients had AHI<5 and were diagnosed as OSA (-) (Group 1), 32 of the patients had AHI between 5-30 (mild and moderate, group 2), 16 of the patients had AHI>30 (severe, group 3). The P-wave duration was calculated in all leads of the surface electrocardiogram. The difference between the maximum (Pmax) and minimum P (Pmin) wave duration was calculated and was defined as the P-wave dispersion (Pd). Echocardiographic examination was also performed.

RESULTS: Pmax was longer in group 3 compared to group 2 and group 1 (p=0.002, p<0.001 respectively). Pmax was longer in group 2 compared to group 1 (s<0.001). Pd was greater in group 3 compared to group 2 and group 1 (p<0.001 for both comparison). Pd was greater in group 2 compared to group 1 (p<0.001). Pmin did not differ between the groups. In patients with OSA, Pd was positively correlated with AHI (r=0.56, p<0.001), BMI (r=0.43, p=0.03), and mitral early diastolic to late diastolic velocity (E/A) ratio (r=0.37, p=0.01). Multiple linear regression analysis showed that only AHI was independently associated with Pd (beta=0.39, p=0.02).

CONCLUSION: Pd was found to be greater in patients with OSA than patients without OSA and to be associated with severity of the disease.