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

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…