Relationship between metabolic syndrome and sleep-disordered breathing in patients with cardiovascular disease - Metabolic syndrome as a strong factor of nocturnal desaturation

Objective Metabolic syndrome (MetS) is one of the coronary risk factors for cardiovascular disease and is closely related with sleep-disordered breathing (SDB). Our aim in this study was to estimate the relationship between sleep-related breathing events and coronary risk factors, including MetS. Methods We determined the prevalence of MetS in 195 patients with cardiovascular disease. Based on Japanese MetS criteria, 56 patients had MetS (Group A), whereas 139 patients did not (Group B). We assessed SDB and sleep-related breathing events, including nocturnal desaturation, in both groups using a type 3 apparatus (Morpheus (R); Teijin Pharma Limited, Tokyo, Japan). Results Seventy-seven percent of the patients with MetS (43/56) met the criteria for SDB based on apnea hypopnea index (AHI). The AHI value was significantly greater in Group A than in Group B (30.1 +/- 19.0/hr vs. 17.7 +/- 14.7/hr; p < 0.001). Nocturnal oximetry showed that Group A spent a greater percentage of time at pulse-oximetric oxygen saturation below 90% (CT 90) than did Group B (10.6 +/- 13.2% vs. 5.0 +/- 12.5%; p < 0.01). On multivariate logistic regression analysis for CT 90, MetS showed that the odds ratio was 2.629 (95% confidence interval: 1.259. 5.592; p=0.011). Conclusion These results suggest that SDB is common in cardiovascular patients with MetS. Patients with MetS frequently experience asleep-related breathing event. Compared with the incidence of apnea hypopnea, MetS is an equivalently strong factor of nocturnal desaturation in patients with cardiovascular disease.