Methods:

Background: Although investigations from nonsurgical populations have shown an association between untreated OSA and greater rates of adverse CV events, the relationship between unrecognized OSA and adverse postoperative CV events among surgical patients remains unproven.

In this prospective, international, multicenter trial, patients ≥45 years of age, scheduled to undergo major noncardiac surgery, with ≥1 Revised Cardiac Risk Index (RCRI) factor (i.e., history of heart failure, coronary artery disease, diabetes requiring treatment, stroke/transient ischemic attack, or renal insufficiency with creatinine ≥1.98 mg/dl) and no previous diagnosis of OSA, were enrolled and followed for 30 postoperative days. Before surgery, all underwent an overnight preoperative sleep study using a portable sleep-monitoring device and high-resolution pulse-oximeter wrist watch to determine OSA diagnosis (defined as respiratory event index [REI] ≥5) and OSA severity (mild [REI 5-15], moderate [REI 15-30], or severe [REI >30]). The primary composite outcome was 30-day CV mortality, myocardial injury (defined changes in high-sensitivity troponin T), heart failure, thromboembolism, atrial fibrillation, or stroke. Serial electrocardiogram (ECG) and troponin assays were collected at 6 hours, 12 hours, and days 1-3 after surgery, and continuous pulse oximetry was performed on the first three postoperative nights.