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This study is being done to better understand the influence of cardiovascular disease on brain blood flow regulation and cognitive function, determine whether exercise-based cardiac rehabilitation can lead to better regulation of brain blood flow that may help to improve or maintain cognitive function, and determine whether exercise intensity influences changes in brain blood flow regulation and cognitive function.
This study will investigate the influence of exercise training and intensity (as part of cardiac rehabilitation) on improving cerebral blood flow regulation and cognitive function following a cardiac event. This will be a randomized control trial, recruiting adults in mid-life (years 40-65) with coronary artery disease, enrolling in cardiac rehabilitation following a cardiac-related hospital admission. Patients that enroll in the Mayo Clinic cardiac rehabilitation will be randomized 1:1 to high intensity interval training (HIIT) or moderate intensity continuous training (MICT), with stratification for sex and coronary artery bypass graft surgery. Patients that decline enrollment in cardiac rehabilitation will be recruited as an observational control group, which will be matched to the intervention groups by age decade, sex, BMI category, and surgical status. Patients that enroll in cardiac rehabilitation but decline randomization will be recruited as an observational cardiac rehabilitation group. A healthy control group without cardiovascular disease will also be recruited for baseline comparison of outcome measures.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Cardiac rehabilitation - High intensity interval training (HIIT) | Experimental | Patients attending cardiac rehabilitation randomized to HIIT. |
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| Cardiac rehabilitation - Moderate intensity continuous training (MICT) | Active Comparator | Patients attending cardiac rehabilitation randomized to MICT. |
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| Cardiac rehabilitation - control | Placebo Comparator | The control group (12 week period) will include participants who have declined cardiac rehabilitation. |
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| Healthy control group | No Intervention | Healthy age-matched adults without cardiovascular disease, who will complete baseline assessments only. No intervention period. | |
| Cardiac rehabilitation - observational | Other | This observational group will include patients who are completing an exercise-based cardiac rehabilitation program in line with standard care but are not part of the randomized exercise protocol groups (HIIT or MICT). Participants in this group will be combined with HIIT and MICT (as exercise-based cardiac rehabilitation group) for Aims 1b and 2b. |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Cardiac rehabilitation - high intensity interval training (HIIT) | Behavioral | During cardiac rehabilitation (12-weeks, 3 sessions/week), exercise training will comprise of 4x4-min high intensity aerobic intervals at a rating of perceived exertion 15-17 (hard to very hard), interspersed by a 3-min active recovery at a rating of perceived exertion 11-13 (fairly light to somewhat hard). Warm-up (4-min) and cool-down (3-min) at a light intensity. |
| Measure | Description | Time Frame |
|---|---|---|
| Cerebral blood flow regulation (as cerebrovascular reactivity) | Measured as the change in cerebral blood flow during a stepped protocol of increases in inhaled carbon dioxide concentrations. Reactivity will be measured as the regression slope of cerebral blood flow velocity (cm per second) per mmHg increase in end-tidal carbon dioxide. | Baseline and follow-up at 3-months |
| Measure | Description | Time Frame |
|---|---|---|
| Cognitive function | The main domains of cognitive function assessed using a neuropsychometric testing battery will be executive function, processing speed, and memory. Scores from these domains will be combined as the NIH Toolbox Fluid composite score, and assessed for change from baseline to follow-up. Analyses will also be completed for each separate cognitive domain. | Baseline and follow-up at 3-months |
| Measure | Description | Time Frame |
|---|---|---|
| Cerebral blood flow regulation (as neurovascular coupling) | Measured as the change in cerebral blood flow during a visual stimulus | Baseline and follow-up at 3-months |
| Cerebral blood flow regulation (as autoregulation) |
Inclusion Criteria for Patients with Cardiovascular Disease:
Inclusion Criteria for Healthy controls:
Exclusion Criteria for participants in randomized cardiac rehabilitation groups (HIIT & MICT) :
Exclusion Criteria for participants in the observational control group and observational cardiac rehabilitation group:
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| Name | Affiliation | Role |
|---|---|---|
| Bruce D Johnson, PhD | Mayo Clinic | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Mayo Clinic in Rochester | Rochester | Minnesota | 55905 | United States |
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| ID | Term |
|---|---|
| D002318 | Cardiovascular Diseases |
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Randomized control trial comparing two cardiac rehabilitation exercise groups: 1) high intensity interval training; and 2) moderate intensity continuous training. There will also be an observational control group who decline participation in cardiac rehabilitation, and an observational cardiac rehabilitation group who participate in cardiac rehabilitation but decline randomization. There is also a healthy control group without cardiovascular disease for baseline comparison only (no intervention).
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| Cardiac rehabilitation - moderate intensity continuous training (MICT) | Behavioral | During cardiac rehabilitation (12-weeks, 3 sessions/week), exercise training will comprise of 34-min of continuous aerobic exercise at a rating of perceived exertion 11-13 (fairly light to somewhat hard). Warm-up (3-min) and cool-down (3-min) at a light intensity. |
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| Cardiac rehabilitation - control | Behavioral | Participants will receive exercise advice in line with usual hospital discharge procedures. This involves exercise physiologists providing verbal and written information on achieving the national physical activity guidelines (150min/week of moderate intensity exercise) 60 and range of movement exercises for surgical patients with sternotomy. However, no structured or supervised exercise training program or other contact with participants will be provided after hospital discharge, to reflect the usual care process for patients that decline cardiac rehabilitation. |
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| Cardiac rehabilitation - observational | Behavioral | During cardiac rehabilitation (12-weeks), program frequency and exercise training protocol will align with clinical care decisions and/or patient choice rather than random assignment. |
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Measured as the change in cerebral blood flow from seated position to standing position.
| Baseline and follow-up at 3-months |
| Cerebral blood flow regulation to exercise | Measured as the regression slope of cerebral blood flow per increase in cardiac output (L) during a staged submaximal exercise test to 75% of maximal heart rate. | Baseline and follow-up at 3-months |
| Cerebral ventricular and white matter hyperintensity volumes | Measured using MRPAGE and FLAIR MRI. Expressed as percentage of total intracranial volume | Baseline and follow-up at 3-months |
| Resting cerebral blood flow with MRI | Measured using arterial spin labelling MRI. Global cerebral blood flow will be expressed as the average of gray matter perfusion across all atlas regions. | Baseline and follow-up at 3-months |