Sleep-disordered breathing and myocardial ischemia in patients with coronary artery disease.

STUDY OBJECTIVES To examine the occurrence of nocturnal myocardial ischemia and its relationship to sleep-disordered breathing (apneas and oxygen desaturations) in randomly selected men and women undergoing coronary angiography because of angina pectoris. DESIGN An observational study using an overnight sleep study and Holter recording to examine disordered breathing (oxyhemoglobin desaturations > or = 4% and apnea-hypopneas), heart rates, and ST-segment depressions (> or = 1 mm, > or = 1 min). SETTING University Hospital, Umeå, a teaching hospital in northern Sweden. PATIENTS One hundred thirty-two men and 94 women referred for consideration of coronary intervention were randomly included, by lot. RESULTS ST-segment depressions occurred in 59% (134 of 226) of the patients, and nocturnal ST-segment depressions occurred in 31% (69 of 226). A ST-segment depression occurred within 2 min after an apnea-hypopnea or desaturation in 12% (27 of 226) of patients. This temporal association was seen in 19% of nocturnal ST-segment depressions (71 of 366), more frequently in men (p < 0.01) and in more severely disordered breathing (p < 0.001). Most of these ST-segment depressions were preceded by a series of breathing events: three or more apnea-hypopneas or desaturations or both in 70% (50 of 71). CONCLUSION Episodes of nocturnal myocardial ischemia are common in patients with angina pectoris. However, a temporal relationship between sleep-disordered breathing and myocardial ischemia is present only in a minority of the patients, but occurs more frequently in men and in more severely disordered breathing.