Objectives: Sleep apnea syndrome and acute coronary syndrome (ACS) are related, but any further association with congestive heart failure (CHF) remains unclear.
Methods: Sixty-five patients with ACS (ACS group) and 48 patients with CHF (CHF group)underwent Holter electrocardiography and respiratory monitoring to identify sleep apnea.
Results: There were significant differences in age, sex, frequency of smoking, and ejection fraction between the two groups. The apnea hypopnea index showed similar high values in both ACS group (21.7 +/- 17.0/hr) and CHF group (19.4 +/- 17.9/hr). In the ACS group, 24 patients (37%) had central sleep apnea syndrome and 29 patients (45%) had obstructive sleep apnea syndrome. There were no significant differences in the incidences of central and obstructive sleep apnea syndromes between the two groups. Sympathetic nerve activity was significantly higher in ACS group than in CHF group (low/high frequency power ratio in overall study, 2.64 +/- 2.43 vs 1.24 +/- 1.05, p = 0.0003; in asleep study, 2.64 +/- 2.35 vs 1.23 +/- 1.04, p = 0.0002; in awake study, 2.73 +/- 2.36 vs 1.50 +/- 1.46, p = 0.002).
Conclusions: Sleep apnea was observed at the same frequency in the ACS group and the CHF group including higher sympathetic nerve activity, and there was no significant difference in frequency of desaturation. This study suggested that sleep disorder breathing is frequently and similarly associated with both CHF and ACS.