Nocturnal Hypoxemia Due to Obstructive Sleep Apnea Is an Independent Predictor of Poor Prognosis After Myocardial Infarction

Abstract

BackgroundObstructive sleep apnea (OSA) is an important risk factor for the development of cardiovascular diseases including myocardial infarction (MI). The aim of this study was to investigate the effects of OSA on prognosis after MI, and to determine which specific measures of OSA severity best predicted outcomes.Methods and ResultsWe performed a prospective study, in which 112 patients without a prior diagnosis of sleep apnea underwent comprehensive polysomnography within a median of 7 days after MI. Patients were followed up at 6‐monthly intervals (±2 weeks) for a total of 48 months. Patients classified with central apnea (n=6) or those using continuous positive airway pressure (n=8) after polysomnography were excluded from analyses. The primary end point was major adverse cardiac events, including death from any cause, recurrent MI, unstable angina, heart failure, stroke, and significant arrhythmic events. Forty of 98 patients (41%) had OSA (apnea‐hypopnea index ≥15 events/h). OSA patients had higher major adverse cardiac event rates when compared to those without OSA (47.5% versus 24.1%; χ2=5.41, P=0.020). In a multivariate model that adjusted for clinically relevant variables including age, left ventricular ejection fraction, diabetes mellitus, oxygen desaturation index, and arousal index, significant hypoxemia, as defined by nocturnal nadir oxygen saturation ≤85%, was an independent risk factor for major adverse cardiac events (hazard ratio=6.05, P=0.004) in follow‐up 15 months after baseline.ConclusionsNocturnal hypoxemia in OSA is an important predictor of poor prognosis for patients after MI. These findings suggest that routine use of low‐cost nocturnal oximetry may be an economical and practical approach to stratify risk in post‐MI patients.

Excessive Daytime Sleepiness Independently Predicts Increased Cardiovascular Risk After Myocardial Infarction

“…Cox proportional hazards analysis was used to compute hazard ratios (HRs) for EDS in the prediction of MACE and reinfarction during follow‐up. Diabetes mellitus, left ventricular ejection fraction, and nocturnal nadir oxygen saturation (minSaO 2 ), which have been reported to be strong prognostic factors in this patient group,2 were incorporated, together with age, AHI, and depression for adjustment in the statistical models of MACE. Only age and minSaO 2 (ie, strongest prognostic factor2) were adjusted for in several multivariate models given the relatively small number of outcome events (if ≤20 events) to avoid overfitting of the Cox model.…”

“…Diabetes mellitus, left ventricular ejection fraction, and nocturnal nadir oxygen saturation (minSaO 2 ), which have been reported to be strong prognostic factors in this patient group,2 were incorporated, together with age, AHI, and depression for adjustment in the statistical models of MACE. Only age and minSaO 2 (ie, strongest prognostic factor2) were adjusted for in several multivariate models given the relatively small number of outcome events (if ≤20 events) to avoid overfitting of the Cox model. The appropriateness of the proportional hazards assumption was examined using graphical methods and tested with the Schoenfeld residuals test using Stata 12 (StataCorp).…”

“…E pidemiological studies have shown that sleep-disordered breathing (SDB) is associated with increased risk for cardiovascular disease (CVD) and poor prognosis. 1,2 Excessive daytime sleepiness (EDS) is a common symptom in patients with SDB and has been associated with an increased risk of motor vehicle accidents, occupational injuries, and the development of cerebrovascular diseases and CVD. 3,4 Moreover, longitudinal studies have shown that EDS is an independent risk factor for adverse outcomes in patients with coronary artery disease 5 and predicts cardiovascular mortality.…”

The association between different features of sleep‐disordered breathing and blood pressure: A cross‐sectional study

“…Minimal oxygen saturation during sleep, the number of desaturations <90% per hour and T90, were significantly associated with adverse events in heart failure patients with reduced ejection fraction, whereas the AHI was not . Nocturnal hypoxemia in OSA has been shown to be an important predictor of poor prognosis for patients after myocardial infarction . In comparison to the AHI, T90 and HL describe the hypoxemic burden during night and may be particularly important to predict progression of cardiac remodeling and cardiovascular events triggered by hypoxia.…”

“…20,21 Nocturnal hypoxemia in OSA has been shown to be an important predictor of poor prognosis for patients after myocardial infarction. 22 In comparison to the AHI, T90 and HL describe the hypoxemic burden during night and may be particularly important to predict progression of cardiac remodeling and cardiovascular events triggered by hypoxia.…”