Cardiac rhythm disturbances and ST-segment depression episodes in patients with obstructive sleep apnea-hypopnea syndrome and its mechanisms.

STUDY OBJECTIVES To compare the frequency of daytime and nocturnal cardiac arrhythmias and ST-segment depression episodes among patients with obstructive sleep apnea-hypopnea syndrome (OSAHS), snoring subjects, and healthy subjects, and to analyze the relationship between the cardiac disturbances, sleep characteristics, and sympathetic tone in patients with OSAHS. PATIENTS AND INTERVENTIONS Twenty-one consecutive patients with OSAHS, 12 snorers without hypersomnolence, and 15 healthy subjects were selected. Polysomnography, 24-h Holter ECG recording, and urinary catecholamine determination were simultaneously performed on all subjects. RESULTS Patients with OSAHS had more daytime and nocturnal episodes of sinus and supraventricular arrhythmias and couplets than the snoring and control groups. Moreover, nocturnal ST-segment depression episodes were more frequent in the OSAHS group than in control subjects (0.565 +/- 0.826/h vs 0 +/- 0/h [mean +/- SD]). In patients with OSAHS, arousal index and daytime epinephrine levels were related to daytime and nocturnal ST-segment depression episodes, whereas minimum arterial oxygen saturation was related to nocturnal sinus bradycardia and supraventricular tachycardia. Epinephrine and norepinephrine urinary concentrations correlated with sinus and supraventricular arrhythmias. CONCLUSIONS Patients with OSAHS have a higher frequency of cardiac rhythm disturbances and ST-segment depression episodes than snoring and control subjects. Moreover, ST-segment changes are related to sympathetic tone and sleep fragmentation, whereas most of the rhythm disturbances in patients with OSAHS are associated with sleep fragmentation, nocturnal hypoxemia, and sympathetic tone.