Obstructive sleep apnea (OSA) is a major public health problem affecting at least 2-4% of middle-aged population. OSA resulted in hypoxia and sleep fragmentation, which resulted in neurocognitive dysfunction and cardiovascular sequelaes. The cardiovascular sequelaes in OSA included hypertension, coronary artery disease and heart failure. Our data showed among 599 moderate-sever OSA (AHI<15/hr)， 44.5% patients had cardiovascular disease, which included 41.4% having hypertension，7% having CAD and 2.4% having congestive heart failure。 Though OSA is well known to be highly correlated with fatal and non-fatal cardiac event, only limited studies investigated how OSA affected acute myocardial infarction (AMI). Most studies concluded that AMI would worsen OSA and vice versa. However, how AMI exactly interacts with OSA and what the prevalence of OSA in the first-time AMI is have never been answered. Within four weeks from Nov. 15th 2007, we screened ten patients of first-time AMI with single-vessel disease and Killip I. Five in 10 received PSG and three in five have moderate OSA.