The goal of this study is to develop a novel study design to safely and ethically conduct a long-term randomized controlled trial among patients at high risk for both sleep apnea and cardiovascular events that will examine whether effective positive airway pressure(PAP) therapy reduces cardiovascular risk. Patients with transient ischemic attack(TIA) or stroke have a high prevalence of sleep apnea(60-80%), and they are at high risk of cardiovascular events(myocardial infarction, congestive heart failure, recurrent stroke, and cardiovascular death)in the first year post event, despite current prevent strategies. Therefore, the treatment of sleep apnea may represent a novel therapeutic target to reduce cardiovascular outcomes in this high risk population.
The proposed study is a randomized controlled trial among patients with transient ischemic attack (TIA) and minor stroke, comparing strategies for the diagnosis and treatment of sleep apnea with usual care over 6-12 months at 2 sites (Yale University School of Medicine and Indiana University School of Medicine). Patients with TIA and minor stroke will be randomly assigned to either usual care or a diagnosis and treatment approach that includes ambulatory polysomnography and initiation of autotitrating CPAP for sleep apnea in a 1:2 (control:intervention) randomization scheme. Intervention patients with sleep apnea will receive either a standard CPAP treatment intervention or an enhanced protocol designed to increase long-term CPAP adherence. The primary outcomes will include: (a) the impact of CPAP on pathophysiologic markers in the following domains of cardiovascular risk: inflammation (CRP, Il-6), heightened sympathetic activity/parasympathetic withdrawal (plasma catecholamines and heart rate variability (HRV)), insulin resistance (HOMA-IR, HbA1C), endothelial injury (flow mediated vasodilation), and atherosclerosis (carotid intima-media thickness); and (b) long-term (6-12 month) CPAP adherence.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
255
Yale University
New Haven, Connecticut, United States
University of Indiana
Indianapolis, Indiana, United States
HOMA IR Change From Baseline
The homeostasis model assessment-estimated insulin resistance (HOMA-IR). HOMA IR change is one of the measures used to assess cardiovascular risk. HOMA-IR Index (measured by calculating - fasting insulin (microU/L) x fasting glucose (nmol/L)/22.5.). The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline and up to 12 months
CRP Change From Baseline
C-reactive protein (CRP) is a blood test marker for inflammation in the body. CRP is produced in the liver and its level is measured by testing the blood. CRP is classified as an acute phase reactant, which means that its levels will rise in response to inflammation. CRP is one of the measures used to assess cardiovascular risk. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline and up to 12 months
IL-6 Change From Baseline
IL-6 is a type of protein known as a cytokine, produced by cells of the immune system in response to an infection. IL-6 test results measure the amount of IL-6 circulating in the blood and are used as one sign of systemic inflammation. Il-6 is one of the measures used to assess cardiovascular risk. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline and up to 12 months
Catecholamine Change From Baseline
Catecholamine testing measures the amounts of catecholamines which are a group of similar substances/hormones released into the blood in response to physical or emotional stress. The primary catecholamines are dopamine, epinephrine (adrenaline), and norepinephrine. Catecholamine is one of the measures used to assess cardiovascular risk. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline and up to 12 months
Heart Rate Variability Change From Baseline
Heart rate variability (HRV) is the constant variation in milliseconds between heartbeats. HRV is one of the measures used to assess cardiovascular risk. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline and up to 12 months
24-H Systolic Blood Pressure Mean Change From Baseline
24-H Systolic Blood Pressure is one of the measures used to assess cardiovascular risk- this was assessed multiple times and averaged across a in 24 hour time period. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline and up to 12 months
Flow-mediated Vasodilation Mean Change From Baseline
Flow-mediated vasodilation is performed when the brachial artery diameter is measured (in mm) during three conditions; baseline (after at least 10 min supine rest), during reactive hyperaemia (induced by inflation to 250 mmHg and then deflation of a sphygmomanometer cuff around the forearm) and finally after the administration of sublingual nitroglycerin. A linear array, high resolution ultrasound transducer is used to provide B-mode images of the target vessel, proximal to the forearm cuff. Flow-mediated vasodilation is one of the measures used to assess cardiovascular risk and the mean of the change in the multiple measurements was used at each time point. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
Carotid Intima-Medial Thickness Mean Change From Baseline
Carotid Intima-Medial Thickness are measurements of the mean values of Intima-media thickness (IMT) of carotid arteries. Caroid Intima-Medial Thickness mean change is one of the measures used to assess cardiovascular risk. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
CPAP Adherence Rates Change From Baseline
CPAP adherence rates were calculated as hours of CPAP use per night. The change from baseline up until the final measurement (up to 12 months) was assessed. The Respironics M-series (now System One, Phillips Respironics, North Ryde, Australia) produced a record of the patient adherence (hours of use per night) throughout the duration of the follow up period.
Time frame: Baseline to up to 12 months
HOMA IR Change From Baseline With CPAP Use
The homeostasis model assessment-estimated insulin resistance (HOMA-IR). HOMA IR change is one of the measures used to assess cardiovascular risk. HOMA-IR Index (measured by calculating - fasting insulin (microU/L) x fasting glucose (nmol/L)/22.5.) To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
CRP Change From Baseline With CPAP Use
C-reactive protein (CRP) is a blood test marker for inflammation in the body. CRP is produced in the liver and its level is measured by testing the blood. CRP is classified as an acute phase reactant, which means that its levels will rise in response to inflammation. CRP is one of the measures used to assess cardiovascular risk. To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
IL-6 Change From Baseline With CPAP Use
IL-6 is a type of protein known as a cytokine, produced by cells of the immune system in response to an infection. IL-6 test results measure the amount of IL-6 circulating in the blood and are used as one sign of systemic inflammation. IL-6 is one of the measures used to assess cardiovascular risk. To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
Catecholamine Change From Baseline With CPAP Use
Catecholamine testing measures the amounts of catecholamines which are a group of similar substances/hormones released into the blood in response to physical or emotional stress. The primary catecholamines are dopamine, epinephrine (adrenaline), and norepinephrine. Catecholamines change is one of the measures used to assess cardiovascular risk. To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
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Time frame: Baseline to up to 12 months
Heart Rate Variability Change From Baseline With CPAP Use
Heart rate variability (HRV) is the constant variation in milliseconds between heartbeats. HRV is one of the measures used to assess cardiovascular risk. To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
24-H Mean Systolic Blood Pressure Change From Baseline With CPAP Use
24-H Mean Systolic Blood Pressure change is one of the measures used to assess cardiovascular risk- this was assessed multiple times and averaged across a in 24 hour time period. To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
Flow-mediated Vasodilation Mean Change From Baseline With CPAP Use
Flow-mediated vasodilation is performed when the brachial artery diameter is measured (in mm) during three conditions; baseline (after at least 10 min supine rest), during reactive hyperaemia (induced by inflation to 250 mmHg and then deflation of a sphygmomanometer cuff around the forearm) and finally after the administration of sublingual nitroglycerin. A linear array, high resolution ultrasound transducer is used to provide B-mode images of the target vessel, proximal to the forearm cuff. Flow-mediated vasodilation is one of the measures used to assess cardiovascular risk and the mean of the change in the multiple measurements was used at each time point. To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months
Carotid Intima-Medial Thickness Change From Baseline With CPAP Use Change
Carotid Intima-Medial Thickness are measurements of the mean values of Intima-media thickness (IMT) of carotid arteries. Caroid Intima-Medial Thickness change is one of the measures used to assess cardiovascular risk. To determine if CPAP use had an impact on cardiovascular risk, these measures were compared among CPAP usage groups. The change from baseline up until the final measurement (up to 12 months) was assessed. The carotid intimal thickness measurement was obtained by averaging the distance between the lumen-intima interface and the media-adventitia interface obtained from 5 contiguous sites 1 mm apart.
Time frame: Baseline to up to 12 months
Medication-adjusted 24-H SBP Change From Baseline
Change in medication-adjusted 24-hour SBP, which is calculated as \[mean 24-hour SBP in mmHg\] + \[patient's DDD × (8.0 mmHg), was assessed between CPAP adherence groups. The change from baseline up until the final measurement (up to 12 months) was assessed.
Time frame: Baseline to up to 12 months