SLEEP-RELATED MYOCARDIAL-ISCHEMIA AND SLEEP STRUCTURE IN PATIENTS WITH OBSTRUCTIVE SLEEP-APNEA AND CORONARY HEART-DISEASE

Study objectives: Patients with coronary heart disease (CHD) and obstr uctive sleep apnea may have an increased cardiac risk due to nocturnal myocardial ischemia triggered by apnea-associated oxygen desaturation . Sleep structure in patients with obstructive sleep apnea is fragment ed by activation of the central nervous system (CNS) (arousal) due to obstructive apneas. Nocturnal myocardial ischemia may lead to activati on of the CNS as well. Patients: Fourteen patients with obstructive sl eep apnea and CHD disease and seven patients suffering from obstructiv e sleep apnea without CHD were studied. Overnight sleep studies and si multaneous six-lead ECG recordings were performed. In addition, sleep studies and ECG recordings were performed with administration of a sus tained-release nitrate in these patients in a double-blinded crossover design. Results: Analysis of three nights' recordings revealed 144 ep isodes of nocturnal myocardial ischemia in sir: subjects, Five patient s had underlying CHD and one patient exhibited diffuse wall defects of the coronary arteries; also, 85.4% of ischemic episodes were concomit ant with apneas and oxygen desaturation >3%, and 77.8% of ischemic epi sodes occurred during rapid eye movement (REM) sleep, although total a mount of REM sleep was only 18% of total sleep time. Mean oxygen satur ation was significantly lower (p <0.05) during apnea-associated ischem ic episodes than during nonapnea-associated ischemia (77.3% vs 93.1%), Nitrate administration did not reduce ischemic episodes. Sleep archit ecture (macrostructure) exhibited a reduction in sleep stages non-REM 3 and 4 and REM sleep. Comparing the microstructure of sleep (arousals ) within episodes with and without ischemia but similar criteria like sleep stage, apnea activity, and oxygen saturation, we found significa ntly more (p <0.01) and severe (p <0.001) arousals during periods with myocardial ischemia than during control episodes. In addition, micros tructure of sleep was disturbed by myocardial ischemia itself in absen ce of apneas. Conclusion: It is concluded that patients with CHD and o bstructive sleep apnea are endangered by apnea-associated ischemia and that these ischemic episodes lead to activation of the CNS and additi onal fragmentation of sleep. Patients with nocturnal ischemia should b e screened for underlying sleep apnea even if nitrate therapy fails.