Hot Water Immersion After Myocardial Infarction

Study Overview
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Brief Summary
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Myocardial infarction (MI) is a leading cause of death in developed countries, including Sweden. Standard treatment for patients after MI includes exercise-based cardiac rehabilitation which contributes to improved cardiovascular function and reduces the risk of hospital readmissions, new cardiovascular events and mortality. Thermotherapy may also have beneficial effects on cardiovascular disease by a reduction in inflammatory status and improved metabolism and vascular function. Given the well-documented effects of exercise training on cardiac rehabilitation and recent evidence that thermotherapy may improve cardiovascular function, we wish to investigate the effect of exercise combined with hot water immersion (HWI) in cardiac rehabilitation post-MI. This is a single-centre, randomized controlled clinical trial in patients with recent MI. Our aim is to investigate whether exercise training combined with HWI improves inflammatory and metabolic status, cardiovascular function as well as psychological well-being, compared with exercise training alone. Patients will be randomized 1:1 to an 8 week intervention with exercise training 2 times per week followed by 15 minutes of hot water immersion, or to a control group with exercise training alone. The primary endpoint is changes in the inflammatory marker interleukin (IL-) 6 between groups at 8 weeks. Secondary endpoints include other biomarkers of inflammation, metabolism, effects on cardiovascular function and psychological benefits. Secondary prevention after MI has improved during the last decades but readmissions and death following acute MI remain large health challenges. If HWI in addition to standard cardiac rehabilitation can lower inflammation more than standard therapy alone, and improve metabolic, cardiovascular and psychological status, it could be a cost-effective and safe complementary strategy for secondary prevention after MI, particularly for those with limited exercise capability.

Official Title
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Hot Water Immersion in Rehabilitation After Myocardial Infarction (HOT-MI) - a Randomized Controlled Study

Conditions
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Cardiac Disease, Cardiac Rehabilitation

Intervention / Treatment
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* Other: Thermotherapy


Participation Criteria
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Eligibility Criteria
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Inclusion criteria Patients with a diagnosis of ST-elevation myocardial infarction (STEMI) or non-STEMI Concomitant participation in standard care exercise-based cardiac rehabilitation Male or female patients ≥ 18 years Written informed consent Exclusion criteria Regularly performing hot water immersion, sauna or other types of thermotherapy Not willing to perform hot water immersion regularly Febrile illness or acute, ongoing infection <18 years of age Inability to provide informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Hot water immersion<br>Patients allocated to hot water immersion will enter a bath and submerge down to the neck in warm water (40 degrees celsius) for 15 min. | Other: Thermotherapy<br>* Hot baths directly after an exercise session<br>|
| No Intervention: Control<br>Patients allocated to control group will sit down for a 15 min rest. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Concentrations of interleukin 6 (IL-6) in blood | Change in IL-6 between groups after 8 weeks of intervention | 8 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Concentrations of other biomarkers of inflammation in blood | Change in IL -1b, IL-10, tumor necrosis factor (TNF)-a, High sensitivity C-reactive protein, heat shock protein-72 after 8 weeks of intervention | 8 weeks | 
| Concentrations of biomarkers of metabolism in blood | Heat shock factor (HSF)-1, High density lipoprotein, Low density lipoprotein, triglycerides, cholesterol, leptin and adiponectin, glucose, insulin | 8 weeks | 
| Change in percent in endothelial flow-mediated dilatation (FMD) | Change after 8 weeks of intervention | 8 weeks | 
| Change in sympathetic/parasympathetic activity | Change in heart rate variability after 8 weeks of intervention | 8 weeks | 
| Change in score of participants´ subjectively reported psychological well-being | Measured with the Questionnaire Clinical Outcomes in Routine Evaluation (Core-GP), change after 8 weeks of intervention | 8 weeks | 
| Change in diastolic and systolic blood pressure (mm(Hg) | Change after 8 weeks of intervention | 8 weeks |