Effect of Obstructive Sleep Apnea in Acute Coronary Syndrome

The effect of obstructive sleep apnea (OSA) on clinical outcomes after acute coronary syndrome (ACS) is incompletely defined. We sought to determine the prevalence of OSA in patients with ACS and evaluate prognostic impact of OSA and continuous positive airway pressure (CPAP) therapy in these patients. This was a prospective longitudinal cohort study of 73 patients admitted on cardiac intensive care unit for ACS. Cardiorespiratory sleep study and/or polysomnography were performed in all patients. CPAP was recommended if Apnea-Hypopnea Index ≥5. The main study outcome was a composite of death for any cause, myocardial infarction, and myocardial revascularization. OSA was diagnosed in 46 patients (63%). Age and cardiovascular risk factors were not significantly different between groups. OSA was classified as mild (m-OSA) in 14 patients (30%) and as moderate-to-severe (s-OSA) in 32 patients (70%). After a median follow-up of 75 months (interquartile range 71 to 79), patients with s-OSA had lower event-free survival rate. After adjustment for gender, patients with s-OSA showed a significantly higher incidence of the composite end point (hazard ratio 3.58, 95% CI 1.09 to 17.73, p = 0.035). Adherence to CPAP occurred in 19 patients (41%), but compliance to CPAP therapy did not reduce the risk of composite end point (hazard ratio 0.87, 95% CI 0.31 to 2.46, p = 0.798). In conclusion, OSA is an underdiagnosed disease with high prevalence in patients with ACS. It is urgent to establish screening protocols because those have high diagnostic yield and allow identifying a group of patients with manifestly unfavorable prognosis.