Background: Non-invasive detection of vascular dysfunction in the early stage is clinically important in patients with sleep apnea syndrome (SAS). Flow-mediated dilatation (FMD) is a novel clinical marker of endothelial function. However, it is not clear whether this is useful in the SAS patient.
Methods: Echocardiographic parameters and FMD were measured in 129 patients with SAS. Apnea-hypopnea index (AHI) was defined by polygraphy, and patients were divided into the two Groups: Group A (moderate-severe SAS: AHI≥ 15 times/hr, n=93) and Group B (mild SAS: AHI 5-15 times/hr, n=36).
Results: There were no significant differences in echocardiographic parameters between the two groups. However, FMD was significantly lower in Group A than in Group B (3.5±1.6 vs. 7.8±3.1, P< 0.01).
Conclusions: Although cardiac function was not different, vascular dysfunction was evident in patients with moderate-severe SAS. FMD is a useful tool to identify impaired endothelial function non-invasively in patients with SAS.