Obstructive Sleep Apnea (OSA) is a condition in which a person stops breathing for several seconds at a time due to relaxation of the throat muscles. This can occur many times during sleep. It is known to cause sleepiness and poor concentration during the day. Research indicates that OSA may be a modifiable risk factor for cardiovascular disease due to its association with hypertension, stroke, heart attack and sudden death. The standard therapy for symptomatic OSA is continuous positive airway pressure (CPAP). CPAP has been shown to effectively reduce snoring, obstructive episodes and daytime sleepiness and to modestly reduce blood pressure and other risk factors for cardiovascular disease. The overall aim of SAVE is to determine if CPAP can reduce the risk of heart attack, stroke or heart failure for people with OSA.
There is increasing evidence to indicate that OSA is an important modifiable risk factor for CV disease including stroke, MI, and heart failure. Increased nocturnal arterial blood pressure (BP), hypercoagulability, oxidative stress, inflammation, insulin resistance and cardiac arrhythmias are all associated with OSA. These effects are presumed to accelerate the progression of atheromatous disease, particularly within the coronary or cerebral vasculature. Moreover, OSA also appears to increase the risk of sudden death during sleep, which is different from the circadian pattern of sudden death in those without OSA, suggesting that episodes of apnea may have a direct triggering effect for cardiac arrhythmias or MI.
CPAP is now standard therapy for symptomatic OSA, with adherence to treatment comparable to that of other therapies for common chronic diseases. CPAP can eliminate apneas and improve daytime sleepiness, mood and quality of life. Furthermore, short term (1-3 months) randomised controlled trials of CPAP have shown modest reductions in blood pressure (BP) and other markers of CV disease, including C-reactive protein (CRP) and coagulation. However, the epidemiological data is complicated by potential residual confounding factors and the randomised evidence is limited. Thus, a direct causal link between OSA and CV disease remains inconclusive. The management of OSA, therefore, remains principally directed towards symptom control rather than CV risk modification.
The present trial aims to test whether long-term use of CPAP can reduce the incidence of CV events. If the trial shows that CPAP treatment of OSA reduces the incidence of CV events it will influence clinical practice toward the early detection and management of OSA, and add CPAP to the range of strategies available for the prevention of CV disease.
- Continuous Positive airway pressure (CPAP) Device
Intervention Desc: CPAP worn nightly ARM 1: Kind: Experimental Label: 1 Description: CPAP plus standard care of cardiovascular risk factors
- Standard Care Behavioral
Intervention Desc: Standard care of cardiovascular risk factors ARM 1: Kind: Experimental Label: 2 Description: Standard care alone
- Allocation: Randomized
- Masking: Open Label
- Purpose: Prevention
- Endpoint: Efficacy Study
- Intervention: Parallel Assignment
Anesthetic for surgery - local versus general. Randomization will be by telephone to the trial office. Data will be collected at baseline (prior to randomization) and this will include demographic details, known risk factors, diagnostic procedures and findings, and indications for surgery. The follow-up data will be collected when the patient is discharged from acute care, and operative details and any early complications will be recorded. At 1 month post-surgery, a stroke physician, blind to the type of anesthesia, will review the patient. Also the patient will be asked to complete a health related quality of life questionnaire including the widely used EuroQol and Short Form 36, plus a carotid endarterectomy (CEA) specific questionnaire designed to capture patient satisfaction levels with the method of anaesthesia. Length of time spent in the recovery room, intensive care unit (ICU) and high dependency unit (HDU), and length of overall acute hospital stay will be recorded. Annual follow up will be by post to the family doctor and to the patient, seeking details of any strokes.
|Type||Measure||Time Frame||Safety Issue|
|Primary||A composite of the CV endpoints of CV death, non-fatal acute myocardial infarction, non-fatal stroke, hospital admission for heart failure, and new hospitalisation for unstable angina or transient ischaemic attack|
|Secondary||Composite of CV death, MI & ischaemic stroke; components of primary composite endpoint; re-vascularisation procedures; all-cause death; new onset atrial fibrillation; new onset diabetes; OSA symptom scores; mood; health-related quality of life; in a sub-sample of 600 subjects pathophysiological mechanisms of CPAP-induced CV event reduction will be explored by assessing various intermediate markers of CV risk|
|Primary||A composite of the CV endpoints of CV death, non-fatal acute myocardial infarction, non-fatal stroke, hospital admission for heart failure, and new hospitalisation for unstable angina or transient ischaemic attack.||Reviewed 6-monthly; average patient follow up, 4 years||No|
|Secondary||Composite of CV death, MI & ischaemic stroke; components of primary composite endpoint; re-vascularisation procedures; all-cause death; new onset atrial fibrillation; new onset diabetes; OSA symptom scores; mood; health-related quality of life.||Reviewed 6-monthly; average patient follow up, 4 years.||No|
|Secondary||In a sub-sample of 600 subjects pathophysiological mechanisms of CPAP-induced CV event reduction will be explored by assessing various intermediate markers of CV risk||baseline and at 6-months, 2 and 4 years following randomisation||No|
|Secondary||Cardiac MRI to assess effects of CPAP on cardiac structure and function.||Randomisation and at 6 months follow-up||No|