Interatrial conduction block in an obstructive sleep apnea patient: An electrical premonitor of atrial fibrillation

Obstructive sleep apnea (OSA) is an important sleep disorder and is associated with increased cardiovascular morbidity and mortality. Several recent studies have demonstrated an association OSA and atrial fibrillation (AF). Therefore, it is of great importance understanding the pathophysiological substrate and the interaction between OSA and AF. Moreover, it is well accepted that interatrial block (IAB), evaluated not only by the P-wave duration but also by the P-wave morphology, has the potential to give information about the anatomical substrate predisposing to AF. OSA and AF share many risk factors and comorbidities, including older age, male gender, obesity, hypertension, heart failure, and coronary artery diseases. IAB is defined when the P-wave is ≥120 ms which signifies excessive time for sinus impulses to conduct from the right atrium to the left atrium and may predict future AF events. Accordingly, recent studies have suggested that OSA is associated with atrial functional and structural remodeling which indeed are associated with increased risk of AF. We speculate that IAB, a known factor to predict future AF episodes, may associate with OSA and contribute to the development of arrhythmic events. In the present case, the report presents a woman with OSA and IAB on the surface electrocardiogram (ECG)automatic P-wave analysis and some short episodes of AF in the external event recorder monitoring.