Sleep apnea in acute coronary syndrome: high prevalence but low impact on 6-month outcome

BACKGROUND AND PURPOSE: We postulate that the prevalence of sleep-disordered breathing (SDB) in subjects admitted with acute coronary syndrome (ACS) is high, self-report of SDB symptoms is helpful in identifying patients with ACS at risk for SDB, and prospective risk for adverse ACS outcomes is associated with SDB.

PATIENTS AND METHODS: Consecutive patients admitted to the VA hospital with ACS over approximately 1 year were invited to participate. The Cleveland sleep habits questionnaire was administered, and a portable sleep study (Eden-trace, Level 3 monitoring) was performed within 72h of admission.

RESULTS: Of 104 patients with complete and adequate sleep studies, 66.4% had an apnea-hypopnea index (AHI) >10/h, and 26.0%, an AHI>30 with the prevalent apnea pattern being obstructive (72.1%). Neither pre-test probability for sleep apnea per questionnaire (P=0.67) nor degree of subjective sleepiness (P=0.83) predicted SDB. Although symptoms of dyspnea and paroxysmal nocturnal dyspnea were significantly higher in SDB (AHI> or =10) compared to non-SDB (AHI<10) 6 months after admission for ACS, odds of readmission were not significantly different, and this lack of association persisted after covariate adjustment. The factors predicating readmission, but only at 1 month, were age and diabetes.

CONCLUSIONS: In the setting of ACS, the prevalence of SDB was very high in this population and was not detected by self-reports of sleepiness or composite risk for SDB. The odds of adverse outcome for ACS up to 6 months were no different in patients with SDB compared to those without SDB, as compared to effects of an older age or presence of diabetes.