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Completed

NCT Number: NCT05632614

Blood Flow Reserve: Effects After Training With Heavy Inspiratory Exercises

The goal of this single-site, parallel-group, double-blind, sham-controlled randomized control trial is to examine the effect of high-intensity inspiratory muscle strength training (IMST) on coronary blood flow assessed using positron emission tomography coronary perfusion imaging in patients with coronary artery disease (CAD).

The main question it aims to answer are:

• if high-intensity IMST will improve coronary blood flow in patients with CAD, which could be assessed using positron emission tomography coronary perfusion imaging.

Participants will be asked to complete the 8-week high-intensity or low-intensity IMST. Researchers will compare high and low-intensity IMST groups to see if coronary blood flow increases after IMST.

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Key information

Conditions

Coronary Artery Disease Arterial Occlusive Diseases Arteriosclerosis Cardiovascular Diseases Coronary Disease Heart Diseases Myocardial Ischemia Vascular Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Ottawa Heart Institute

Ottawa, Ontario, K1Y 1J7, Canada

About this study

Coronary artery disease (CAD) is a leading cause of morbidity and mortality. With the aging population, increasing number of patients with CAD has frailty and immobility. The health benefits of traditional aerobic exercise have been well-established; however, alternative exercise programs, such as inspiratory muscle training (IMST), may provide greater merits. IMST is a form of exercise that engages the diaphragm and accessory respiratory muscles to repeatedly inhale against resistance, which can be achieved in less time and widely applicable even for immobile or frail patients compared to conventional aerobic exercise. Since barriers to conventional exercise training include immobility, lack of time, and access to facilities, IMST may be a beneficial exercise form that can overcome those factors. A previous study has shown that high-intensity IMT can lower blood pressure and improved vascular endothelial function. Improvements in endothelial function of coronary arteries could improve coronary blood flow, leading to the improvement of anginal symptoms as well as quality of life. IMST might offer a widely applicable, feasible, time-efficient form of training for CAD patients. Our study will examine the preliminary efficacy of IMST on coronary blood flow in patients with CAD.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • ≥18 years of age;
  • Patients referred to PET at the University of Ottawa Heart Institute;
  • able to perform a respiratory exercise testing; and,
  • Patients with clinical stability, including no change in medications for the past one month.

Exclusion criteria

  • unstable angina or established diagnosis of severe valvular heart disease, hypertrophic obstructive cardiomyopathy, chronic obstructive pulmonary disease;
  • unable to follow training/breathing instructions;
  • unable to return for follow-up visit;
  • presence of any major non-cardiac problem that would adversely affect survival during the study in the opinion of the investigator; or,
  • unable to provide informed consent.

Treatment and study plan

High-intensity IMST

Device

Participants will use the POWERbreathe KHP2 inspiratory muscle training device. All participants will be assigned to perform 30 inspiratory maneuvers (5 sets of 6, 1-minute rest between sets), 6 days per week, for 6 weeks. Participants will be trained at 55% PIMAX during week 1, 65% PIMAX during week 2, and 75% PIMAX during weeks 3 to 6.

Low-intensity IMST

Device

Participants will use the POWERbreathe KHP2 inspiratory muscle training device. All participants will be assigned to perform 30 inspiratory maneuvers (5 sets of 6, 1-minute rest between sets), 6 days per week, for 6 weeks.Participants will be trained at 15% PIMAX during week 1, 17% PIMAX during week 2, and 19% PIMAX during weeks 3 to 6.

Primary outcomes

  1. Global myocardial flow reserve

    Time frame: Through study completion, an average of 8 weeks

    Change in global myocardial flow reserve on positron emission tomography coronary perfusion imaging before and after IMST

  2. Global stress myocardial blood flow

    Time frame: Through study completion, an average of 8 weeks

    Change in global stress myocardial blood flow on positron emission tomography coronary perfusion imaging before and after IMST

Secondary outcomes

  1. Global rest myocardial blood flow

    Time frame: Through study completion, an average of 8 weeks

    Change in global rest myocardial blood flow on positron emission tomography coronary perfusion imaging before and after IMST

  2. Maximum myocardial flow reserve

    Time frame: Through study completion, an average of 8 weeks

    Change in maximum myocardial flow reserve on positron emission tomography coronary perfusion imaging before and after IMST

  3. Maximum myocardial blood flow at rest and stress

    Time frame: Through study completion, an average of 8 weeks

    Change in maximum myocardial blood flow at rest and stress on positron emission tomography coronary perfusion imaging before and after IMST

  4. Global coronary vascular resistance at stress and rest

    Time frame: Through study completion, an average of 8 weeks

    Change in global coronary vascular resistance at stress and rest on positron emission tomography coronary perfusion imaging before and after IMST

  5. Maximum coronary vascular resistance at stress and rest

    Time frame: Through study completion, an average of 8 weeks

    Change in maximum coronary vascular resistance at stress and rest on positron emission tomography coronary perfusion imaging before and after IMST

  6. Mean segmental (17-segment model) myocardial flow reserve

    Time frame: Through study completion, an average of 8 weeks

    Change in mean segmental (17-segment model) myocardial flow reserve on positron emission tomography coronary perfusion imaging before and after IMST

  7. Mean segmental (17-segment model) myocardial blood flow at stress and rest

    Time frame: Through study completion, an average of 8 weeks

    Change in mean segmental (17-segment model) myocardial blood flow at stress and rest on positron emission tomography coronary perfusion imaging before and after IMST

  8. Maximal segmental (17-segment model) myocardial blood flow at stress and rest

    Time frame: Through study completion, an average of 8 weeks

    Change in maximal segmental (17-segment model) myocardial blood flow at stress and rest on positron emission tomography coronary perfusion imaging before and after IMST

  9. Summed stress score, summed rest score, and summed difference score

    Time frame: Through study completion, an average of 8 weeks

    Change in summed stress score, summed rest score, and summed difference score on positron emission tomography coronary perfusion imaging before and after IMST

  10. % left ventricular ischemia

    Time frame: Through study completion, an average of 8 weeks

    Change in % left ventricular ischemia on positron emission tomography coronary perfusion imaging before and after IMST

  11. General quality of life

    Time frame: Through study completion, an average of 8 weeks

    Change in general Quality of life assessed using the EQ5D-5L

  12. Angina symptom

    Time frame: Through study completion, an average of 8 weeks

    Change in angina symptom assessed using the Seattle angina Questionnaire

  13. Adherence of IMST program

    Time frame: Through study completion, an average of 8 weeks

    The proportion of participants adhering to prescribed IMST sessions

  14. Respiratory Muscle Strength

    Time frame: Through study completion, an average of 8 weeks

    Respiratory Muscle Strength assessed by % change in maximal inspiratory pressure

  15. Resting blood pressure

    Time frame: Through study completion, an average of 8 weeks

    Resting blood pressure measured in a seated position after a 5-minute rest period using an automated blood pressure monitor.

Sponsors and collaborators

Lead sponsor

Ottawa Heart Institute Research Corporation

Other

Registry information

Official study title

The Efficacy of Inspiratory Muscle Strength Training on Coronary Blood Flow in Patients With Coronary Artery Disease

Acronym: BREATHE

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
Nov 30, 2022
Registry last updated
May 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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