Study objectives: It has been suggested that sleep-disordered breathing (SDB) is a risk factor for ischemic heart disease, and may be associated with increased morbidity and mortality due to cardiovascular disease. The aim of this study was to examine the relation between nocturnal oxygen desaturation (NOD) due to SDB and the Gensini score, which is given to define the severity of coronary atherosclerosis, based on coronary angiograms findings, in patients with coronary artery disease.
Design: We examined the NOD index (ODI) (desaturation of > 3%/events per hour) using pulse oximetry in 59 consecutive patients with coronary artery disease (ejection fraction, > 40%) that was diagnosed by coronary angiography, 30 patients with angina pectoris and 29 patients with old myocardial infarction. The Gensini score was calculated for each patient from the coronary arteriogram. The patients were classified into the following three groups according to the severity of oxygen desaturation: ODI of < 5 events per hour (group N; 16 patients); ODI of ≧ 5 but < 15 events per hour (group A; 27 patients); and ODI of ≧ 15 events per hour (group B; 16 patients). The groups then were examined for the relation between the ODI and the Gensini score.
Results: Of the total number of patients, 72.9% had a nocturnal ODI of more than five events per hour. The Gensini score was significantly higher in groups A and B than in group N, and showed a significant positive correlation with the ODI (R = 0.45; p = 0.01) in all patients. Multiple regression analysis showed that the ODI was the most significant, independent determinant of the Gensini score among the coronary risk factors tested, and that it explained 13.4% of the variance.
Conclusion: These findings suggest that NOD due to SDB may be an important contributor to coronary atherosclerosis in the patients with cardiovascular disease.