Nocturnal oxygen desaturation in coronary artery disease.

Nocturnal oxygen desaturation and sleep apnea may provoke myocardial ischemia and arrhythmias in patients with coronary artery disease (CAD). Additionally, these factors may accelerate coronary atherosclerosis in the long term and they may play a role in the progression of the disease process. On the other hand, studies related to this subject are limited. This study was conducted to investigate the nocturnal oxygen desaturation and apneas during sleep in patients with CAD and to assess the possible association of these factors with CAD. We studied 22 male patients with CAD confirmed by coronary angiography who did not have symptomatic pulmonary disease and fourteen male healthy controls without known heart disease. Patients were randomly selected from men undergoing coronary angiography. Controls were age and sex matched and selected from the population registry. The normal controls were of similar body mass index to the patients. None of them were obese. The patients and controls underwent standard polysomnography. Men with CAD and controls had a similar apnea-hypopnea index (2.3 +/- 3.8 vs. 1.2 +/- 1.7). Mean oxygen desaturation index was higher among patients than controls (2.1 vs. 0.5, p < 0.05). Patients with CAD spent 3.1% (9.7 +/- 13.6) of total sleep time desaturated, while the same proportion in controls were 0.5% (1.9 +/- 4.1)(p < 0.05). Although both groups of patients were of similar heart rates at initial, the development of bradycardia during sleep was significantly higher in patients compared with controls (43.3% vs. 25.3%, p < 0.05). The results demonstrate that sleep disordered breathing, in particular nocturnal oxygen desaturation, occurs more common in patients with CAD compared to controls. Additionally, patients are at higher risk of developing bradycardia during sleep. This findings suggest that oxygen desaturation during sleep might contribute to the progression of CAD.