The Impact of Obstructive Sleep Apnea on the Outcomes in Patients of First-Time Acute Myocardial Infarction

Objectives: Obstructive sleep apnea (OSA) affects 4% middle-aged men and 2% women. Symptoms of OSA include snore, unrefresh sleep, witnessed apnea, excessive daytime sleepiness and hypertension. Untreated OSA patients are associated with three fold risk of fetal and non-fetal cardiovascular events than control subjects. However, the prevalence rate and impact of OSA in patients with acute myocardial infarction (AMI) was not clear so far. The conflicts of studies come from variable period of AMI, heart function at enrollment, techniques used to diagnose OSA, time to revascularization, and target endpoint. Therefore, this project aimed to achieve the four goals: (1) To determine the prevalence rate of OSA in patients with first-time AMI (2) To identify the clinical characteristics and risk factors in AMI patients associated with OSA (3) To study the impact of OSA on the prognosis of AMI patients after revascularization (4) To identify the clinical and molecular factors attributing to AMI in OSA patients Study design: Longitudinal, observational study Participants: AMI patients who were first-time, Killip I-II, post primary percutaneous coronary intervention (PCI) were eligible for this study. Exclusion criteria included: refuse to participate, require mechanical ventilation, active neurologic event, chronic pulmonary disease, active infection, need sedatives or narcotics within 3 days of sleep study, and participate in other study at the same time.

Protocol: Eligible patients were screened with polysomnography (PSG) within 5th to 7th days after onset of AMI. Patients who had AHI more than 15/hr were considered as suffering from OSA. Patients were followed up for five years. The primary endpoint was mortality rate and cardiac events. The secondary endpoint was left ventricular function and variables related to cardiovascular disease (CVD) and metabolic syndrome. The acute phase of AMI was defined as within 14 days of the onset of AMI and the chronic phase was defined as > 14 days of onset.

Statistic: The baseline demographics of patients with or without OSA were compared to determine the factors associated with OSA in AMI patients. The impact of OSA on AMI in acute and chronic phase was determined by comparing the mortality rate, incidences of cardiac events, left ventricular function, CVD risk factors, and metabolic profiles between AMI patients with and without OSA. Factors attributing to AMI in OSA patients were determined by comparing the clinical data and mRNA expression of angiogenesis and other related genes in OSA patients with the acute phase of AMI and patients without major CVD.

Clinical implication: Because the prevalence rate of OSA in patients of first-time AMI but no significant heart failure was extremely high, early PSG screening and identifying factors associated with OSA will allow for early diagnosis and intervention. Understanding interaction between OSA and AMI will help prevent the morbidity and mortality in AMI patients. Also, it allows for prediction of cardiovascular outcomes and early management in OSA patients.