The Effects of Obstructive Sleep Apnea and Its Intervention on Coronary Heart Disease

Obstructive sleep apnea(OSA) is an important identifiable cause of hypertension. Previous study has suggested that OSA significantly increases cardiovascular morbidity and mortality, especially in patients with pre-existing cardiovascular disease.The standardized treatment of moderate/severe OSA is continuous positive airway pressure (CPAP). Most of short-term trials indicated that CPAP treatment reduced BP in patients with OSA. But relevant studies have a relative short duration with only but few more than one year. In our opinion, they are not sufficient to detect the real effect of CPAP on reduction in BP. Besides, the impact of OSA on metabolic disorder is still unclear.We hypothesized that long-term CPAP treatment could reduce blood pressure and improve metabolic disorder in patients with coronary heart disease (CHD)and OSA.

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive partial (hypopnea) or complete (apnea) occlusion of the upper airway during sleep caused by collapse of the pharyngeal airway, resulting in sleep fragmentation and oxyhemoglobin desaturation. Kiely and colleague's study showed that over 20% of hypertensive patients exhibit OSA, whereas prevalence of hypertension in the setting of OSA exceeds 50%. One study confirmed that OSA is an important identifiable cause of hypertension. OSA is considered as one of the most common risk factors of resistant hypertension. Previous study has suggested that OSA significantly increases cardiovascular morbidity and mortality, especially in patients with pre-existing cardiovascular disease. Several studies confirmed that CPAP reduced systolic blood pressure (SBP) and diastolic blood pressure (DBP) in patients with OSA. Additionally, some papers reported that there was a protective effect of CPAP therapy against death from cardiovascular disease in patients with severe OSA. Other researches regarding the antihypertensive effect of CPAP therapy, however, showed that CPAP had no antihypertensive effect. But relevant studies have a relative short duration with only but few more than one year. In our opinion, they are not sufficient to detect the real effect of CPAP on reduction in BP. According to our knowledge, there is no report about long-term effect of CPAP on BP in hypertensive patients with coronary revascularization (CRV) and OSA under conventional antihypertensive medications. Therefore, we conducted a long-term, prospective controlled study to investigate the effects of CPAP on BP, metabolic disorder, clinical symptoms, cardiovascular and cerebrovascular events in patients with CHD and OSA on conventional treatment.

Eligibility Criteria:
Inclusion Criteria:

* men and women, aged 45 to 75 years old
* verified diagnosis of hypertension by medical history or receiving antihypertensive drugs
* established diagnosis of CHD
* at least 3-month optimal treatment for hypertension
* moderate or severe OSA

Exclusion Criteria:

* if they had secondary hypertension
* central sleep apneas
* history of significant chronic renal, or hepatic failure or severe pulmonary disease
* diagnosed with malignant cancer with a life expectancy of less than 2years
* regular use of medications that can affect BP(including corticosteroids or sedative drugs)
* severe psychiatric disease
* sustained excessive alcohol use
* current use of CPAP treatment for OSA or pharyngeal surgery for OSA
* New York Heart Association Class III-IV degree
* declined to participate or were unable to give informed consent