Sleep‐Disordered Breathing and Long‐Term Outcome in ACS
Does obstructive sleep apnea (OSA) status predict major adverse cardiocerebrovascular events (MACCE) post–acute coronary syndrome (ACS)?
Consecutive ACS patients who underwent percutaneous coronary intervention between 2005 and 2008 were recruited from a single center. Bare-metal stents were implanted in all patients. Excluded were patients with prior OSA or cardiac surgery within 4 weeks and renal failure. All underwent home sleep study (Pulsleep LS100) within 7 days of discharge. OSA was defined as a frequency of apneas and hypopneas (AHI index) ≥5 events per hour. The major endpoint was incidence of MACCE: all-cause death, ACS, nonfatal stroke, and admission for congestive heart failure.
A total of 257 patients were evaluated and 241 were studied after exclusions for insufficient sleep data or prior OSA treatment. OSA was diagnosed in 126 (52.3%) patients: age: 63 ± 13 years; male: 78%; body mass index: 24.7 ± 3.8 kg/m2; left ventricular ejection fraction (EF) 56 ± 12. These baseline characteristics were no different compared to patients without OSA. Prevalence of baseline diabetes; hypertension; smoking; prior infarction; renal function; and dual antiplatelet, beta-blocker, angiotensin-converting enzyme, and statin use was similar between patients with or without OSA. Although there was no difference of ST-segment elevation myocardial infarction (STEMI) (79% vs. 72% with OSA vs. without OSA), the OSA group was more likely to have TIMI 0 flow at baseline compared to the group without OSA (76% vs. 58%, p = 0.017). During a median follow-up of 5.6 years, 27 patients (21.4%) in the OSA group and 9 (7.8%) in the no-OSA group had a MACCE (p = 0.006). Multivariable analysis revealed that the presence of sleep-disordered breathing was a significant predictor of MACCE (hazard ratio, 2.28; 95% confidence interval, 1.06–4.92; p = 0.035).
The authors concluded that among patients with ACS, the presence of OSA by unattended portable monitor is associated with higher MACCE.
OSA is underdiagnosed in populations with cardiovascular disease. OSA may worsen atherosclerosis by mechanisms thought to be triggered by intermittent hypoxia, leading to increased oxidative stress, sympathetic activation, and endothelial dysfunction. Since OSA has a highly effective therapy, finding a potentially treatable condition to reduce adverse events after ACS is of interest. A large number of MACCE in the OSA group included admissions for congestive heart failure. Although the average EF was ‘normal,’ the standard deviation suggests that a percentage may have had an EF, which predicts more events. In a recent study (SERVE-HF), adaptive servo ventilation resulted in increased mortality among symptomatic heart failure patients with OSA. The next phase of studies will include additional subclasses of patients with cardiovascular disease and OSA randomized to treatment approaches necessary to reduce MACCE.
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