Elucidating the effects of obstructive sleep apnea (OSA) on cardiovascular outcomes is crucial in risk assessments and therapeutic recommendations for affected individuals. The Sleep and Stent Study is a multicenter observational study investigating the relationships between OSA and cardiovascular outcomes in patients treated with percutaneous coronary intervention (PCI). Eight centers in 5 countries (Singapore, China and Hong Kong, India, Myanmar, and Brazil) are participating in the study, and the recruitment target is 1600 patients. Adult patients age 18 to 80 years who have undergone successful PCI are eligible. Recruited patients will undergo an overnight sleep study using a level-3 portable diagnostic device before hospital discharge. The sleep tracings will be analyzed by a certified sleep technologist and audited by a sleep physician, both of whom will be blinded to other study data. The patients will be divided into 2 groups based on apnea-hypopnea index (AHI): OSA (AHI ≥15) and non-OSA (AHI <15) groups. The primary study endpoint of cardiovascular death, myocardial infarction, stroke, and unplanned revascularization will be compared between the OSA and non-OSA groups at a median follow-up of 2 years. Secondary endpoints include all-cause mortality, target-vessel revascularization, stent thrombosis, and hospitalization for heart failure. As of December 31, 2013, a total of 1358 patients have been recruited. Based on the complete preliminary results of the first 785 recruited patients, the prevalence of OSA was 48.3%. We expect the follow-up for primary endpoint to be completed in late 2015; study results will be presented in 2016.