Evidence that the degree of obstructive sleep apnea may not increase myocardial ischemia and arrhythmias in patients with stable coronary artery disease

ABSTRACT

There is controversy regarding whether obstructive sleep apnea is responsible for triggering myocardial ischemia, arrhythmias and heart rate variability in patients with coronary artery disease. OBJETIVE The objective of this study was to identify relationships between sleep apnea, myocardial ischemia and cardiac arrhythmia in patients with coronary artery disease. METHODS: Fifty-three patients with stable coronary disease underwent simultaneous polysomnography and electrocardiographic Holter recording. The apnea-hypopnea index (AHI) was defined as the number of apneas/hypopneas per hour of sleep. Patients were divided into a Control group (AHI15, n=23 pts) and an Apnea group (AHI>15, n=30 pts). A subgroup of 13 patients with an AHI>30 (Severe Apnea group) was also studied. We analyzed ischemic episodes (ST-segment depressions >1 mm, > 1 min), heart rate variability and the occurrence of arrhythmias during wakefulness and sleep. RESULTS: Baseline clinical characteristics among the groups were similar except for higher blood pressure in the Apnea groups (p<0.05). Myocardial ischemia was recorded in 39 (73.6 percent) patients. The number and duration of ischemic episodes significantly decreased during sleep in all groups; during wakefulness, patients with severe apnea exhibited fewer and shorter episodes in comparison with the controls. There were no significant differences in heart rate variability or in the occurrence of arrhythmias among the groups. Malignant ventricular arrhythmias, atrial fibrillation/flutter, bradycardia and high-degree atrioventricular blocks were not detected. CONCLUSION: Obstructive sleep apnea was not related to myocardial ischemia, heart rate variability or arrhythmias in patients with stable coronary artery disease and did not alter the circadian pattern of myocardial ischemia.