The incremental role of obstructive sleep apnoea on markers of atherosclerosis in patients with metabolic syndrome

Objective: Metabolic syndrome (MS) is associated with subclinical atherosclerosis, but the relative role of obstructive sleep apnoea (OSA) is largely unknown. The main objective of this study is to determine the impact of OSA on markers of atherosclerosis in patients with MS.

Methods: Eighty-one consecutive patients with MS according to the Adult Treatment Panel III underwent a clinical evaluation, polysomnography, laboratory and vascular measurements of carotid intima media thickness (IMT), carotid-femoral pulse wave velocity (PWV) and carotid diameter (CD) in a blind fashion. OSA was defined as an apnoea-hypopnoea index (AHI) > or =15 events/hour. Multiple linear regression was performed to determine the variables that were independently associated with the vascular parameters.

Results: Fifty-one patients (63%) had OSA. No significant differences existed in age, sex, MS criteria, and cholesterol levels between patients with (MS+OSA) and without OSA (MS-OSA). Compared with MS-OSA patients, MS+OSA patients had higher levels of IMT (661+/-117 vs. 767+/-140 microm), PWV (9.6+/-1.0 vs. 10.6+/-1.6m/s), and CD (6705+/-744 vs. 7811+/-862 microm) (P<0.001 for each comparison). Among patients with MS+OSA, all vascular parameters were similar in patients with and without daytime sleepiness. The independent parameters associated with IMT, PWV, and CD were AHI, abdominal circumference, and systolic blood pressure (R(2)=0.42); AHI and systolic blood pressure (R(2)=0.38); and AHI, age, abdominal circumference and systolic blood pressure (R(2)=0.45), respectively. The R(2) of AHI for IMT, PWV and CD was 0.12, 0.10 and 0.20, respectively.

Conclusions: OSA is very common and has an incremental role in atherosclerotic burden in consecutive patients with MS.