Evaluation of the Effects of Sauna Therapy on Congestion and Loop Diuretic Use in Patients With Heart Failure With Reduced or Moderately Reduced Ejection Fraction (SAUNA-HF RCT)

Impact of Sauna Therapy on Congestion and Loop Diuretic Adjustment in Patients With Heart Failure

This study aims to evaluate the effect of sauna therapy on congestion levels during cardiac rehabilitation in patients with heart failure who have an impaired or moderately impaired ejection fraction, compared to standard cardiac rehabilitation care. To investigate this, patients with reduced cardiac function who are hospitalized as part of a cardiac rehabilitation program will be included. These patients will be randomly assigned to two groups: standard cardiac rehabilitation program (control group) and sauna group (intervention group). The study will also assess whether this approach could allow for a reduction in the dose of diuretics, which are commonly used to remove excess fluid, thereby helping to avoid certain side effects. The expected benefits include a reduction in symptoms such as shortness of breath and swelling, improvements in quality of life and physical fitness, and enhanced blood vessel function.

Study Overview

• Status: Not yet recruiting
• Conditions: Heart Failure
• Intervention / Treatment: Device: Sauna

• Study Type: Interventional
• Enrollment (Estimated): 46
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Guillaume Baudry; Phone Number: +33 03 83 15 73 22; Email: g.baudry@chru-nancy.fr

Study Locations

• France
  • Nancy, France
    • Centre Hospitalier Régional Universitaire de Nancy
    • Contact: Guillaume Baudry; Phone Number: +33 03 83 15 73 22; Email: g.baudry@chru-nancy.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age ≥ 18 years.
• Heart failure with ejection fraction <50% confirmed by an echocardiogram within the past year.
• NYHA class II-III.
• Loop diuretic dose ≥ 40 mg/day of furosemide (or equivalent) for at least 30 days.
• NT-proBNP > 400 pg/ml or BNP > 100 pg/ml.
• Systolic blood pressure ≥ 100 mmHg.
• Estimated glomerular filtration rate (eGFR) ≥ 20 ml/min/1.73 m².
• Patient scheduled for a hospital-based cardiac rehabilitation program for a minimum of 3 weeks.
• Person who has undergone a preliminary clinical examination suitable for clinical research.
• Person affiliated with a social security system or a beneficiary of such a system.
• Person who has received complete information about the organization of the clinical research and has signed informed consent.

Exclusion Criteria:

• Person presenting a contraindication to sauna therapy (for example, intolerance to heat).
• Serum sodium < 130 mmol/L.
• Serum potassium > 5.5 mmol/L.
• Active infection, liver disease, or peripheral vascular disease.
• Acute coronary syndrome or recent stroke (<90 days).
• Participation in another interventional clinical trial.
• Person subject to Articles L. 1121-5, L. 1121-7, and L. 1121-8 of the Public Health Code (applicable in France) :- pregnant, giving birth, or breastfeeding woman , minor (non-emancipated), person adult subject to a legal protection measure (guardianship, curatorship, judicial protection) , adult unable to express consent, persons deprived of liberty by judicial or administrative decision, persons receiving psychiatric care under Articles L. 3212-1 and L. 3213-1…

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Sauna; A 15-minute sauna session at 60 degrees Celsius during hospitalization for cardiac rehabilitation.	Device: Sauna; A 15-minute sauna session at 60 degrees Celsius, five times a week for three weeks during hospitalization for cardiac rehabilitation. The sauna sessions will be followed by 30 minutes of recovery in a seated position. In addition to the sauna, patients will benefit from cardiac rehabilitation care for 3 weeks.
No Intervention: Control; Usual care as part of a day hospital stay for cardiac rehabilitation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Median change in NT-proBNP levels.	Between randomization and the end of the third week.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Daily dose of loop diuretics.		Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Weight in kilograms.		Day 1, end of weeks 1,2 and 3, and 3-month follow-up.
Congestion score: ADVoR congestion score.	ADVoR congestion score is a grading scale taking account oedema, pleural effusion and ascites. The score can range from 0 to 10 with "0" being the best result meaning " no congestion " and "10" the worst meaning " maximum congestion ".	Day 1, end of week 3, and 3-month follow-up.
Congestion score: Ambrosy congestion score.	Ambrosy congestion score is a grading scale taking account dyspnoea, orthopnoea, jugular venous distension, rales and oedema. The score can range from 0 to 18, "0" being the best outcome (no congestion) and "18" the worst outcome (maximum congestion).	Day 1, end of week 3, and 3-month follow-up.
Estimated plasma volume (EPV): Duarte formula.		Day 1, end of week 3, and 3-month follow-up.
Dyspnea visual analog scale: Cumulative dyspnea assessment (AUC).	The minimum value is "0" (best outcome) and means "no dyspnea". The maximum value is "10" (worst outcome) and means "maximum dyspnea".	Day 1, beginning of weeks 2 and 3.
Concentration of natriuretic peptides (NT-proBNP).		Day 1, end of week 1, beginning and end of week 2, beginning and end of week 3, and 3-month follow-up.
Evaluation of renal function through rate of serum creatinine allowing to estimate glomerular filtration rate.	Estimate glomerular filtration rate is calculated by the following formula : Clearance (mL/min) = weight (kg) x (140-age) x K / serum creatinine (μmol/L) ; K=1.23 for man and 1.04 for woman.	End of weeks 1, 2, and 3 and 3-month follow-up.
Evaluation of renal function through renal function assessment.		Day 1 and end of week 3.
Dose of diuretics.		Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Concentration of serum electrolytes (Cl-, Na+, K+).		Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Blood osmolality in mmol/L.	Blood osmolality in mmol/L is calculated using natremia, glycemia and uremia. The formula is : Natremia in mmmol/L*2 + glycemia in mmol/L *5.56 + uremia in mmol/L*16.6.	Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Concentration of urinary electrolytes (Cl-, Na+, K+).		Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Urinary osmolality in mmol/L.	Urinary osmolality in mmol/L is calculated using natremia, glycemia and uremia. The formula is : (natremia in mmol/L + kaliemia in mmol/L+ chloride in mmol/L) + (glycemia in mmol/L*5.56) + (uremia in mmol/L*16.6).	Day 1, beginning and end of weeks 1, 2, and 3, and 3-month follow-up.
Hemoconcentration biomarkers : Hct.	Hemoconcentration was assessed using hematocrit (%).	Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Hemoconcentration biomarkers : Hb.	Hemoconcentration was assessed using hemoglobin (g/dL).	Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Hemoconcentration biomarkers : total protein.	Hemoconcentration was assessed using total protein (g/L).	Time Frame: Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Hemoconcentration biomarkers : copeptin.	Hemoconcentration was assessed using copeptin concentrations (pmol/L).	Time Frame: Day 1, end of weeks 1, 2, and 3, and 3-month follow-up.
Inferior vena cava diameter (millimeters, mm) measured by transthoracic echocardiography during inspiration.	The inferior vena cava (IVC) diameter will be measured in millimeters using transthoracic echocardiography.	Day 1, end of week 1, beginning and end of week 2, beginning and end of week 3, and 3-month follow-up.
Inferior vena cava diameter (millimeters, mm) in expiration measured by transthoracic echocardiography during expiration.	IVC diameter will be measured in millimeters using transthoracic echocardiography.	Day 1, end of week 1, beginning and end of week 2, beginning and end of week 3, and 3-month follow-up.
Inferior vena cava respiratory variation / collapsibility index (percentage, %) assessed by transthoracic echocardiography.	VCI respiratory variation will be assessed using transthoracic echocardiography and expressed as the collapsibility index. Collapsibility index will be measured as the ratio between IVC diameter in inspiration (outcome 17) and IVC diameter in expiration (outcome 18) expressed in %.	Day 1, end of week 1, beginning and end of week 2, beginning and end of week 3, and 3-month follow-up.
Lung ultrasound score (8 points).	Evaluation of lung comet presence measured by an 8-points lung echography and rated on a scale ranging from 0 (minimum - best outcome : no congestion) to 10 (maximum - worst outcome : maximum congestion) per point.	Day 1, end of week 3, and 3-month follow-up.
Quantification of changes in systolic and diastolic function.		Day 1 and 3-month follow-up.
Heart rate in Beats Per Minute (BPM).		Multiple daily measurements : 4 times a day, 5 days a week for 3 weeks.
Heart rate variability in millisecond (ms).		Multiple daily measurements : 4 times a day, 5 days a week for 3 weeks.
Blood pressure in mmHg.	Blood pressure will be measured daily for 3 weeks and at 3-month follow-up.	Up to 3 weeks and at 3-month follow-up.
Monitoring of changes in pulmonary blood pressure.	Changes in pulmonary blood pressure will be measured with echocardiography.	Day 1 and at 3-month follow-up.
Composite clinical endpoint of hospitalization or emergency visits for heart failure or all-cause death.		At 3-month follow-up.
Body composition parameters assessed by bioelectrical impedance analysis.	Evaluation of the patient's body composition parameters. This measure includes the assessment of fluid distribution-Total Body Water (TBW), Intracellular Water (ICW), and Extracellular Water (ECW)-as well as tissue compartments: body protein mass, body mineral mass, and fat mass. The device records multiple parameters, the analysis will focus specifically on these pre-specified indicators of body composition.	Day 1, end of Week 1, beginning and end of Week 2, beginning and end of Week 3, and at 3-month follow-up.
Specific to the sauna group : weight in kilograms.	Weight will be measured before and after each sauna session.	Up to 3 weeks.
Specific to the sauna group : blood pressure in mmHg.	Blood pressure will be measured before and after each sauna session.	Up to 3 weeks.
Specific to the sauna group : temperature in °C.	Temperature will be measured before and after each sauna session.	Up to 3 weeks.
Specific to the sauna group : heart rate in Beats Per Minute (BPM).	Heart rate will be measured continuously during each sauna session.	Up to 3 weeks.
Specific to the sauna group : sodium chloride concentration in sweat.	The concentration of sodium chloride in sweat will be measured during one sauna session per week (three measurements in total).	Up to 3 weeks.

Collaborators and Investigators

• Sponsor: BAUDRY Guillaume

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: February 12, 2026
• First Submitted That Met QC Criteria: March 11, 2026
• First Posted (Actual): March 12, 2026

Study Record Updates

• Last Update Posted (Actual): March 12, 2026
• Last Update Submitted That Met QC Criteria: March 11, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: heart failure; sauna; congestion
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Heart Diseases; Heart Failure; Therapeutics; Hyperthermia, Induced; Balneology; Steam Bath
• Other Study ID Numbers: 2025-A02089-40

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No