Obstructive sleep apnea and electrocardiographic P-wave morphology.

Introduction: Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder with important cardiovascular implications. Left atrial abnormality can be identified by electrocardiographic P-wave morphology and is considered an important risk for atrial fibrillation (AF) and stroke, both of which have been associated with OSA. We hypothesized that severity of OSA would be associated with more abnormal electrocardiographic P-wave morphology as indicated by P-wave terminal force in V (PTFV ) and P-wave area in V (PWAV ).

Methods: Patients who underwent clinically indicated polysomnography and had 12-lead ECG were identified through medical record review. Logistic regression was used to determine the associations between the measures of OSA severity (apnea hypopnea index [AHI] and mean nocturnal oxygen [O ] saturation) and abnormal PTFV and PWAV (defined by >75% percentile value of the studied cohort) adjusting for age, sex, body mass index, and hypertension.

Results: A total of 261 patients (mean age: 57 years old, male: 52%) were included in the study. Multivariate analysis showed that AHI was associated with abnormal PTFV (>7,280 µV ms) and PWAV (>1,000 µV ms; OR: 1.5; 95% CI [1.1, 2.0], p = 0.008; OR: 1.5 [1.1, 2.1], p = 0.005 per 1 SD increase in AHI, respectively). Mean O saturation was associated with abnormal PWAV (OR: 0.72 [0.54, 0.98], p = 0.03). Results remained unchanged after excluding patients taking AV nodal blocking agents.

Conclusion: In a sleep clinic cohort, there was significant association between OSA severity and ECG-defined left atrial abnormality.