P wave duration and dispersion in Holter electrocardiography of patients with obstructive sleep apnea

The underlying mechanisms of the association between obstructive sleep apnea (OSA) and atrial fibrillation (AF) remained unclear. We investigated P wave parameters as indicators of atrial conduction status among OSA patients.

We studied 42 untreated OSA patients, categorized into mild (6), moderate (18), and severe (18) OSA based on the apnea/hypopnea index (AHI) and 18 healthy controls. Twenty-four-hour Holter electrocardiography was applied to measure P wave parameters including P wave duration and P wave dispersion; difference between the maximum (P-max) and minimum (P-min) measured P wave duration.

Mean P wave duration ranged from 110.2 ± 9.3 ms in mild OSA patients to 121.1 ± 15.4 ms in severe OSA patients and was 113.4 ± 10.0 ms in controls with no significant difference among the groups, P = 0.281. P wave dispersion and P-max were significantly longer in those with moderate OSA (68.0 ± 9.3 and 154.2 ± 9.3 ms) and those with severe OSA (71.6 ± 13.7 and 157.2 ± 13.3 ms) than controls (52.6 ± 15.3 and 142.1 ± 15.4 ms), P < 0.05. AHI was significantly correlated with P-max (r = 0.407, P = 0.012) and P wave dispersion (r = 0.431, P = 0.008). With linear regression analysis controlling for age, gender, and BMI, the AHI was independently associated with P wave dispersion (β = 0.482, P = 0.002).

Using Holter monitoring for measurement of P wave parameters, this study showed an association of OSA with prolonged P-max and P wave dispersion. These results indicate that patients with OSA have disturbances in atrial conduction associated with OSA severity. Repeating this study in a larger sample of patients is warranted.