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NCT Number: NCT06388226

Leg Heat Therapy in Heart Failure With Preserved Ejection Fraction

The objective of this pilot study is to establish evidence to support the validity of HT in improving skeletal muscle function and physical capacity of patients with HFpEF. Our central hypothesis is that HT treatment will lead to improvements in skeletal muscle and microvascular function compared to a control intervention. As a result, we anticipate that patients treated with HT will demonstrate improved skeletal muscle microvascular blood flow and oxygenation resulting in enhanced exercise tolerance. To explore this hypothesis, we propose the following specific aim: Explore the effects of home-based HT on exercise tolerance in patients with HFpEF.

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Key information

Conditions

Heart Failure With Preserved Ejection Fraction

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

IU Health Methodist, Indianapolis, Indiana, United States

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Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Men and women older than 18 years
  • Established diagnosis of heart failure with preserved ejection fraction (HFpEF) including left ventricular ejection fraction (LVEF) ≥50% as evidenced by Doppler echocardiography and/or ratio of the early mitral inflow velocity (E) to septal tissue Doppler velocity (e') >8 and at least 1 other sign of chronically elevated filling pressures, including an enlarged left atrium (left atrial volume index >34 mL/m2), an elevated N-terminal pro-brain natriuretic peptide (NT-pro-BNP) level within the past year, long-term loop diuretic use for control of symptoms, or elevated filling pressures (mean pulmonary capillary wedge pressure >12 mmHg) on prior cardiac catheterization
  • Stable medical treatment

Exclusion criteria

  • Recent hospitalization (within the previous 1 month)
  • Unstable angina and/or uncontrolled cardiac arrhythmia causing symptoms or hemodynamic compromise (including severe bradycardia or tachycardia, sick sinus syndrome, or multifocal premature ventricular contractions)
  • Presence of any clinical condition that makes the patient unsuitable to participate in the trial, e.g., significant ischemic or valvular heart disease, cor pulmonale, unstable coronary artery disease, primary renal (e.g., estimated glomerular filtration rate (eGFR) <25 mL/min/1.73 m2) or hepatic disease (e.g., aspartate aminotransferase and alanine aminotransferase levels >3.0 times the upper limit of the normal range), pulmonary, neuromuscular, orthopedic disorders, among others
  • Inability to exercise on the treadmill
  • Inability to provide informed consent
  • Concern for inability of the patient to comply with study procedures and/or follow up (e.g., alcohol or drug abuse)
  • Any contraindication to heat therapy and/or inability to fit into water-circulating trousers
  • Impaired thermal sensation in the leg

Treatment and study plan

Leg heat therapy

Device

A sous vide heating immersion circulator heats up the water inside the water tank to 42ºC. A water pump circulates temperature-regulated water through the trousers.

Leg sham therapy

Device

A sous vide heating immersion circulator heats up the water inside the water tank to 33ºC. A water pump circulates temperature-regulated water through the trousers.

Primary outcomes

  1. Change in time to exhaustion during treadmill exercise

    Time frame: Baseline to 2-month follow-up

    The investigators will determine whether daily leg heat therapy for 90 min using water-circulating trousers perfused with water heated to 42ºC improves the time to exhaustion during treadmill exercise testing at 2-month follow-up compared to a sham treatment.

Secondary outcomes

  1. Change in maximal pulmonary oxygen uptake during treadmill exercise

    Time frame: Baseline to 2-month follow-up

    Maximal pulmonary oxygen uptake (VO2max) will be evaluated during treadmill exercise testing. The investigators will determine whether leg heat therapy improves VO2max at 2-month follow-up compared to the sham treatment.

  2. Change in triceps surae microvascular oxygenation during treadmill exercise

    Time frame: Baseline to 2-month follow-up

    Microvascular oxygenation will be assessed using near-infrared spectroscopy (NIRS) during treadmill exercise testing. The investigators will determine whether leg heat therapy improves muscle microvascular oxygenation at 2-month follow-up compared to the sham treatment.

  3. Change in systolic blood pressure

    Time frame: Baseline to 2-month follow-up

    The systolic blood pressure will be measured in triplicate using a blood pressure monitor. The investigators will determine whether leg heat therapy improves systolic blood pressure at 2-month follow-up compared to the sham treatment.

  4. Change in diastolic blood pressure

    Time frame: Baseline to 2-month follow-up

    The diastolic blood pressure will be measured in triplicate using a blood pressure monitor. The investigators will determine whether leg heat therapy improves blood pressure at 2-month follow-up compared to the sham treatment.

  5. Change in Minnesota Living with Heart Failure Questionnaire (MLHFQ) score

    Time frame: Baseline to 2-month follow-up

    Health-related quality of life will then be assessed via the MLHFQ, which is a validated, self-administered, 21-item disease-specific instrument for patients with heart failure. Items are scored in a 6-point Likert scale (0 to 5) and reflect physical, emotional and socioeconomic status during the past 4 weeks. The questionnaire is scored by summation of all 21 responses (with higher scores indicating poorer quality of life).

  6. Change in triceps surae microvascular oxygenation during reactive hyperemia

    Time frame: Baseline to 2-month follow-up

    Microvascular oxygenation will be assessed using near-infrared spectroscopy (NIRS) during reactive hyperemia. The investigators will determine whether leg heat therapy improves muscle microvascular oxygenation at 2-month follow-up compared to the sham treatment.

  7. Change in triceps surae volume

    Time frame: Baseline to 2-month follow-up

    The volume of calf muscles will be determined using magnetic resonance (MR) images. The investigators will determine whether leg heat therapy improves calf muscle volume at 2-month follow-up compared to the sham treatment.

  8. Change in triceps surae intramuscular fat content

    Time frame: Baseline to 2-month follow-up

    The intramuscular fat content of calf muscles will be determined using magnetic resonance (MR) images. The investigators will determine whether leg heat therapy reduces intramuscular fat content at 2-month follow-up compared to the sham treatment.

  9. Change in the time constant for phosphocreatine recovery after dynamic exercise

    Time frame: Baseline to 2-month follow-up

    Magnetic resonance spectroscopy tuned to phosphorous (31PMRS) will be used to measure the time constant for PCr recovery (τ) after dynamic planar flexion exercise. The investigators will determine whether leg heat therapy reduces the time constant for PCr recovery at 2-month follow-up compared to the sham treatment.

  10. Change in maximal plantar flexor strength

    Time frame: Baseline to 2-month follow-up

    The maximal voluntary contraction (MVC) strength of the plantar flexor muscles will be assessed using an MR-compatible ergometer. Participants will be asked to perform three plantar-flexor MVCs separated by a one-minute rest period. The MVC torque will be considered the highest peak torque value measured over the three trials. The investigators will determine whether leg heat therapy improves maximal plantar flexor strength at 2-month follow-up compared to the sham treatment.

Study contacts

Contact information is provided by the study sponsor or research team.

Daniel Hirai, PhD

CONTACT

[email protected]

765-494-7113

Doris Muriathiri, MPH, CCRP

CONTACT

[email protected]

317-274-0903

Sponsors and collaborators

Lead sponsor

Indiana University

Other

Collaborators

  • Purdue University

Registry information

Official study title

Leg Heat Therapy to Improve Functional Performance in Heart Failure With Preserved Ejection Fraction (HFpEF)

Important dates

Study start
2024
Primary completion
2026
Study completion
2026
First posted
Apr 29, 2024
Registry last updated
Nov 17, 2025

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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