SaunaHeart & circulation
Sauna for chronic heart failure
Evidence review
Grade B· Moderate27 studiesLast reviewed November 8, 2026
Overview
Most trials in chronic heart failure tested Waon therapy, a hospital-based protocol developed in Japan: a far-infrared dry sauna at 140 F (60 C) for 15 minutes followed by 30 minutes of blanket rest, given once daily, usually 5 days a week, for 2 to 4 weeks alongside guideline medical therapy. Small randomized and controlled trials (n=30-188), mostly from one Japanese research network, report improvements in NYHA class, BNP, endothelial function, heart rate variability, ventricular ectopy and exercise capacity; a meta-analysis found lower BNP and a small LVEF gain (about 1.5 points). The largest multicenter RCT (WAON-CHF, n=149) did not meet its primary BNP endpoint, though walk distance, cardiothoracic ratio and NYHA class improved more than with medical therapy alone, and its neurohumoral subanalysis found no between-group differences. Outside this setting the evidence is limited to small studies: 140 F sauna in US and HFpEF pilots, single exposures to 176 F Finnish sauna and to warm-water immersion, leg-only heating added to cardiac rehabilitation, a German home hydrotherapy crossover trial, and a small Japanese controlled study in which 2 weeks of half-body hot-spring immersion at 104 F was followed by lower BNP and pulse wave velocity than daily showering.
Key findings
- WAON-CHF RCT (n=149, advanced HF, 10 sessions over 2 weeks): primary endpoint (change in BNP) not different between groups (P=0.4179); 6MWD +44.9 vs +12.7 m (P=0.0062), cardiothoracic ratio -1.58 vs -0.28% (P=0.0086) and NYHA class (P<0.05) favored Waon; LVEF unchanged. Adverse events 22% vs 15% (P=0.2962). A subanalysis found no between-group difference in BNP, CNP or aldosterone.
- Multicenter RCT (n=188, 2 weeks): LVEF 31.6% to 34.6% and BNP 542 to 394 pg/mL (both p<0.001) with Waon; no significant change in controls.
- Smaller RCTs vs control (n=30-54, 2-4 weeks): fewer premature ventricular beats (848 vs 3,097 per 24 h, Kihara 2004), lower BNP and oxidative-stress markers (Fujita 2011, within-group tests only), and better heart rate variability with Waon.
- Meta-analyses: in 7 controlled Waon studies (491 patients), sauna lowered BNP (-124.62 pg/mL, 95% CI -198.09 to -51.14) and cardiothoracic ratio (-1.82) and raised LVEF by 1.45 points (95% CI 0.55-2.35), with no effect on blood pressure (Källström 2018); thermal therapy studies pooled LVEF +4.4% across 16 studies and 506 patients (Ye 2020, includes uncontrolled studies).
- Non-randomized 5-year follow-up (n=129): HF hospitalization or cardiac death 31.3% with Waon vs 68.7% in controls (P<0.01).
- Elderly inpatients (n=34, retrospective, historical controls): 6MWD 362 m with Waon plus rehabilitation vs 286 m with rehabilitation alone (adjusted difference 147 m, 95% CI 41-253); baseline 6MWD not measured.
- HFpEF pilot (n=18, 10 weeks, 140 F): peak VO2 18.2 to 20.6 mL/kg/min (p<0.001); gains declined after stopping.
- Null or neutral results: leg-only far-infrared heating added to rehabilitation showed no between-group difference in peak VO2 or any secondary outcome (n=17), and a US crossover pilot found no significant change in quality of life or treadmill time (n=9).
- Half-body hot-spring immersion at 104 F, 10 min, 5 days/week for 2 weeks vs daily shower (n=26, not randomized): BNP 430.4 to 302.1 pg/mL and baPWV 17.0 to 16.5 m/s, with improved symptoms and LVEF in the bathing group; no change with showering (Kudo 2008).
Every study we reviewed
20 found benefit · 5 mixed results · 2 found no effect
Each study was checked on PubMed. The colored edge shows the direction of the result. The research library lists 46 studies on heart failure, across all heat and cold therapies, including case reports and older work not graded here.
[1]Meta-analysisn = 491Benefit
Effects of sauna bath on heart failure: A systematic review and meta-analysis.
Källström M et al. Clin Cardiol. 2018. PubMed 30239008 · DOI · Free full text
- Who
- 7 controlled studies of infrared (Waon) sauna in HF meta-analysed (6 randomized; 275 sauna, 216 control patients); 9 studies in the systematic review
- What
- Infrared sauna 140 F for 15 min + 30 min rest, 5 times/week for 2-4 weeks
- Protocol
- 140 °F · 15 min · 5/wk · 2-4
- Measured
- BNP, cardiothoracic ratio, LVEF, LV dimensions, BP
- Result
- Pooled mean differences, sauna vs control: BNP -124.62 pg/mL (95% CI -198.09 to -51.14); LVEF +1.45 percentage points (95% CI 0.55 to 2.35); cardiothoracic ratio -1.82 (95% CI -2.54 to -1.09). No significant effect on SBP (-2.58 mmHg, 95% CI -5.86 to 0.70), DBP (-1.42 mmHg, 95% CI -3.89 to 1.05), LVEDD or LA diameter. Strength of evidence moderate for BNP, LVEF and CTR; low or insufficient for the others. Only 2 studies reported adverse events (7 minor Waon-related events in Tei 2016; none in Basford 2009).
- Limitations
- All included studies were short (2-4 weeks), unblinded Waon trials, partly from the same research groups, with moderate risk of bias; one non-randomized study included; surrogate outcomes only; the LVEF gain is small; the review was not designed to assess safety.
[2]Meta-analysisBenefit
Can heat therapy help patients with heart failure?
Ye WN et al. Artif Organs. 2020. PubMed 32017138 · DOI
- Who
- Studies of thermal therapy (core temperature rise <=1.4 C) in heart failure; 506 patients in the largest pooled outcome
- What
- Thermal therapy (mostly Waon/far-infrared sauna; also warm-water bathing)
- Measured
- NYHA class, LVEF, FMD, BP, cardiothoracic ratio, BNP
- Result
- NYHA class improved (10 studies, 310 patients); LVEF +4.4% (16 studies, 506 patients); FMD +1.7% (4 studies, 130 patients); SBP -3.1% and DBP -5.31% (15 studies, 431 patients); cardiothoracic ratio -5.55% (8 studies, 347 patients); BNP decreased (9 studies, 303 patients).
- Limitations
- Pooled uncontrolled before-after studies with controlled trials; effects reported as percentages without confidence intervals in the abstract; mostly short Japanese studies.
[3]Systematic reviewBenefit
Passive heat therapy for cardiovascular disease: current evidence and future directions.
Rodrigues S et al. Appl Physiol Nutr Metab. 2025. PubMed 39819110 · DOI
- Who
- 18 studies of passive heat therapy in patients with cardiovascular disease (mean age 67), predominantly heart failure
- What
- Waon therapy, balneotherapy, water-perfused trousers, Finnish sauna, foot immersion; 20-90 min, 3-7 times/week, 2-8 weeks
- Protocol
- 20-90 min · 3-7/wk · 2-8
- Measured
- LVEF, FMD, BNP, NYHA class, 6MWD, resting HR and BP, thermoregulation
- Result
- Heat therapy consistently improved ejection fraction, flow-mediated dilation, BNP, NYHA class and 6-minute walk distance; improvements in resting heart rate and blood pressure were infrequent.
- Limitations
- No pooled estimates in abstract; heterogeneous modalities and cardiovascular diagnoses; includes uncontrolled studies.
[4]Systematic reviewBenefit
Far-infrared saunas for treatment of cardiovascular risk factors: summary of published evidence.
Beever R et al. Can Fam Physician. 2009. PubMed 19602651 · Free full text
- Who
- 9 human studies of far-infrared sauna (4 in congestive heart failure, 5 in people with coronary risk factors)
- What
- Far-infrared sauna
- Measured
- Clinical outcomes in CHF and cardiovascular risk factors
- Result
- Limited moderate evidence supporting far-infrared sauna in normalizing blood pressure and treating congestive heart failure; consistent fair evidence refuting a cholesterol-lowering effect.
- Limitations
- Small evidence base; qualitative synthesis without pooling; none of the reviewed studies had blinded placebo-control groups; follow-up 2-4 weeks.
[5]Randomized controlled trialn = 149Mixed
Waon Therapy for Managing Chronic Heart Failure - Results From a Multicenter Prospective Randomized WAON-CHF Study.
Tei C et al. Circ J. 2016. PubMed 27001189 · DOI · Free full text
- Who
- Hospitalized advanced HF, BNP >500 pg/mL on admission and >300 pg/mL after >1 week of medical therapy (19 Japanese centers)
- What
- Waon therapy once daily, 5 days/week for 2 weeks (10 sessions) (n=76) vs control (n=73), both on optimal medical therapy; cardiac rehabilitation not allowed during the study
- Protocol
- 140 °F · 15 min · 5/wk · 2 wk
- Measured
- Primary: change in log BNP at 2 weeks; secondary NYHA class, 6MWD, cardiothoracic ratio, echocardiography
- Result
- Primary endpoint not met: change in log BNP did not differ between groups (P=0.4179), although BNP fell within the Waon group (P=0.0135). Between-group differences favored Waon for 6MWD (+44.9 vs +12.7 m, P=0.0062), cardiothoracic ratio (-1.58 vs -0.28%, P=0.0086) and NYHA class (P<0.05); LVEF change did not differ (+0.87 vs +0.39%, P=0.5765). No deaths; adverse events 17 (22%) Waon vs 11 (15%) control (P=0.2962), including 7 Waon-related minor events (blood pressure decrease 2, hypovolemia 2, increased urine volume 1, weight loss 1, bleeding after tooth extraction 1) and 1 paroxysmal atrial fibrillation in the Waon group.
- Limitations
- Primary endpoint not met; open-label (statisticians blinded); 2-week treatment with no longer follow-up; groups differed in BMI and diabetes frequency; some outcomes analysed in fewer patients than randomized.
[6]Randomized controlled trialn = 188Benefit
Beneficial effects of Waon therapy on patients with chronic heart failure: results of a prospective multicenter study.
Miyata M et al. J Cardiol. 2008. PubMed 18922381 · DOI · Free full text
- Who
- Patients with chronic HF after >=1 week standard therapy (Japan, multicenter)
- What
- Waon therapy daily for 2 weeks (n=112) vs control (n=76)
- Protocol
- 140 °F · 15 min · daily/wk · 2 wk
- Measured
- LVEF, LV dimensions, BNP, cardiothoracic ratio, NYHA
- Result
- Waon: LVEF 31.6% to 34.6% (p<0.0001), LVDd 60.6 to 59.1 mm (p<0.0001), BNP 542 to 394 pg/mL (p<0.001); control: LVEF 36.6% to 37.3%, BNP 440 to 358 pg/mL (not significant). NYHA class and CTR improved in both groups.
- Limitations
- Described as both case-control and randomized in the abstract; unequal group sizes; within-group comparisons reported rather than between-group tests; 2 weeks only.
[7]Randomized controlled trialn = 30Benefit
Effects of repeated sauna treatment on ventricular arrhythmias in patients with chronic heart failure.
Kihara T et al. Circ J. 2004. PubMed 15564698 · DOI · Free full text
- Who
- NYHA II-III chronic HF with >=200 PVCs/24 h
- What
- Waon therapy 5 days/week for 2 weeks (n=20) vs bed rest at 75 F (n=10)
- Protocol
- 140 °F · 15 min · 5/wk · 2 wk
- Measured
- 24-h Holter PVC count, heart rate variability, BNP
- Result
- PVCs/24 h fell from 3,161 to 848 with sauna vs 3,048 to 3,097 in controls (between-group p<0.0001 in the full-text table); SDNN 113 to 142 vs 111 to 112 ms; BNP 425 to 229 vs 415 to 419 pg/mL (sauna vs non-treated). All patients completed the study; no dyspnea, angina or palpitations with sauna.
- Limitations
- Small; single center; 2 weeks; randomization method not described; no blinding; HRV analysed in 24 of 30 (atrial fibrillation excluded).
[8]Randomized controlled trialn = 40Benefit
Effect of Waon therapy on oxidative stress in chronic heart failure.
Fujita S et al. Circ J. 2011. PubMed 21173495 · DOI · Free full text
- Who
- Chronic HF on standard optimal medication (Japan)
- What
- Waon therapy once daily, 5 days/week for 4 weeks (n=20) vs standard therapy alone (n=20)
- Protocol
- 140 °F · 15 min · 5/wk · 4 wk
- Measured
- Oxidative stress (hydroperoxides), BNP, nitric oxide metabolites
- Result
- Waon: hydroperoxides 422 to 327 U.CARR (P<0.001), BNP 402 to 225 pg/mL (P<0.001), NO metabolites 71.2 to 92.0 umol/L (P<0.05), LVEF 31.8% to 35.8% (P<0.01); controls: hydroperoxides 422 to 431 (P=0.59), BNP 374 to 362 (P=0.85), LVEF 34.3% to 36.5% (P=0.25). Only within-group tests reported; no between-group test of change.
- Limitations
- Small; randomized (method not described) but not blinded; within-group comparisons only; 4 weeks; surrogate endpoints; adverse events not reported.
[9]Randomized controlled trialn = 54Benefit
Improvement of autonomic nervous activity by Waon therapy in patients with chronic heart failure.
Kuwahata S et al. J Cardiol. 2011. PubMed 20884178 · DOI · Free full text
- Who
- Chronic HF on conventional therapy (Japan)
- What
- Waon therapy plus medication (n=27) vs conventional therapy alone (n=27), 4 weeks
- Protocol
- 4 wk
- Measured
- Cardiac output, LVEF, heart rate variability
- Result
- Cardiac output and LVEF increased with Waon but not in controls (values not in abstract). After 4 weeks, HF power and HF norm were higher and LF/HF ratio and LF norm lower in the Waon group than in controls (significant between-group differences).
- Limitations
- Small; open-label; numeric effect sizes not in abstract; surrogate endpoints.
[10]Randomized controlled trialn = 149No effect
Neurohumoral Modulation During Waon Therapy in Chronic Heart Failure - Subanalysis of Waon-CHF Study.
Ichiki T et al. Circ J. 2017. PubMed 28202884 · DOI · Free full text
- Who
- Advanced HF in the multicenter WAON-CHF trial (Japan)
- What
- Waon therapy (n=76 in the tables; the abstract states 77) vs control (n=73); plasma neurohormones before and after 2 weeks of treatment
- Protocol
- 140 °F · 15 min · 5/wk · 2 wk
- Measured
- BNP, C-type natriuretic peptide, aldosterone
- Result
- BNP, aldosterone and CNP did not differ significantly between Waon and control groups. In subgroups, BNP improved with Waon in patients on ACE inhibitor/ARB or spironolactone, aldosterone in those with diabetes, hypertension or inotrope use, and CNP in those with eGFR <60.
- Limitations
- Secondary analysis of open-label WAON-CHF (PMID 27001189); subgroup findings exploratory and not adjusted for multiplicity; adverse events not reported in this paper.
[11]Crossover trialn = 9Mixed
Safety, acceptance, and physiologic effects of sauna bathing in people with chronic heart failure: a pilot report.
Basford JR et al. Arch Phys Med Rehabil. 2009. PubMed 19154844 · DOI
- Who
- NYHA III-IV chronic HF, age 62-87 (US)
- What
- Sauna 3 times/week for 4 weeks vs usual care, crossover
- Protocol
- 140 °F · 15 (up to 20) min · 3/wk · 4 wk
- Measured
- Safety, acceptance, MLWHFQ, treadmill duration, neurohormones
- Result
- Well tolerated, no adverse effects; MLWHFQ and treadmill changes not significant between phases; noradrenaline fell 24% (P=.049).
- Limitations
- Very small pilot; underpowered for efficacy.
[12]Crossover trialn = 15Benefit
Thermal hydrotherapy improves quality of life and hemodynamic function in patients with chronic heart failure.
Michalsen A et al. Am Heart J. 2003. PubMed 14564334 · DOI
- Who
- Mild chronic HF, NYHA II-III, LVEF 30-40%, mean age 64, 10 women (Germany)
- What
- 6 weeks of home-based Kneipp hydrotherapy (structured daily warm- and cold-water applications) vs 6 weeks without, randomized crossover
- Protocol
- daily/wk · 6 wk
- Measured
- Quality of life (PLC questionnaire), HF symptoms, exercise heart rate and BP
- Result
- Hydrotherapy improved 3 of 6 quality-of-life dimensions (mood, physical capacity, enjoyment; P<=.05) and HF-related symptoms, and lowered heart rate at rest and at 50 W; BP decreased non-significantly; no relevant adverse effects.
- Limitations
- Small; unblinded; combined warm and cold applications, so heat cannot be isolated.
[13]Controlled trial (not randomized)n = 30Benefit
Repeated sauna treatment improves vascular endothelial and cardiac function in patients with chronic heart failure.
Kihara T et al. J Am Coll Cardiol. 2002. PubMed 11869837 · DOI · Free full text
- Who
- NYHA II-III chronic HF, mean age 62 (Japan)
- What
- Dry sauna daily for 2 weeks (n=20) vs 45 min bed rest in a 75 F room (n=10, matched for age, sex and NYHA class)
- Protocol
- 140 °F · 15 min · daily/wk · 2 wk
- Measured
- Brachial flow-mediated dilation, nitroglycerin-induced dilation, BNP, symptoms
- Result
- Symptoms improved in 17 of 20 sauna patients; FMD increased and BNP decreased significantly, while nitroglycerin-induced dilation did not change; FMD change correlated with BNP improvement. No variable changed in controls.
- Limitations
- Not randomized (matched controls); small; 2 weeks; numeric values not in abstract.
[14]Controlled trial (not randomized)n = 54Benefit
Combined effects of repeated sauna therapy and exercise training on cardiac function and physical activity in patients with chronic heart failure.
Haseba S et al. Disabil Rehabil. 2016. PubMed 25941983 · DOI
- Who
- Hospitalized chronic HF (Kagoshima, Japan)
- What
- Repeated sauna therapy plus exercise training (n=26) vs repeated sauna therapy alone (n=28), each once a day, 5 days/week, admission to discharge
- Protocol
- 5/wk · admission to discharge
- Measured
- NYHA class, BNP, LVEF, cardiothoracic ratio, Barthel Index, ambulation
- Result
- Both groups improved NYHA class, cardiothoracic ratio, BNP, LVEF, Barthel Index and ambulation capacity; the only significant between-group difference was a larger Barthel Index gain with combined therapy.
- Limitations
- No sauna-free control, so the effect of sauna itself cannot be isolated; allocation not described as randomized; length of stay not given.
[15]Controlled trial (not randomized)n = 17No effect
A controlled clinical trial of leg thermal therapy in conjunction with standard cardiac rehabilitation in patients with decompensated heart failure.
Ogino T et al. J Phys Ther Sci. 2025. PubMed 40511315 · DOI · Free full text
- Who
- Decompensated hospitalized HF, median age 75 (Japan)
- What
- Leg thermal therapy (far-infrared dry heating of the legs only) added to cardiac rehabilitation (n=11) vs cardiac rehabilitation alone (n=6), 5 times/week, 1 month
- Protocol
- 113 °F · 20 min · 5/wk · about 4
- Measured
- Peak VO2, anaerobic threshold VO2, noradrenaline, complications
- Result
- No between-group difference in peak VO2 (primary outcome) or in any secondary outcome. Anaerobic-threshold VO2 rose and noradrenaline fell within the leg-heating group only. One leg-heating patient was excluded for active infection; no intervention-related complications.
- Limitations
- Very small and unbalanced groups; pseudorandomized by even/odd medical record number; open-label with unblinded assessors; partial-body (leg) heating rather than whole-body sauna; evaluations done early in patients discharged before one month.
[16]Retrospective cohortn = 34Benefit
Effect of Inpatient Cardiac Rehabilitation Combined with Waon Therapy on Exercise Capacity in Elderly Patients with Heart Failure: A Pilot Study.
Yamamoto K et al. Phys Ther Res. 2025. PubMed 40980348 · DOI · Free full text
- Who
- Decompensated hospitalized HF patients unable to walk 200 m independently, mean age 79.5 (Japan)
- What
- Inpatient cardiac rehabilitation plus Waon therapy (n=16, 2021-2024) vs cardiac rehabilitation alone (n=18, 2020-2021), 5-session program
- Protocol
- 140 °F · 15 min · 5 sessions
- Measured
- 6-minute walk distance at program completion; adverse events
- Result
- 6MWD 362.2 vs 286.3 m (p=0.038); adjusted difference 147.0 m (95% CI 41.3-252.8, p=0.012). No adverse events.
- Limitations
- Retrospective single-center observational study with sequential (historical) control periods; highly selected (16 of 540 Waon-rehabilitation and 18 of 194 rehabilitation patients); 6MWD not measured at baseline, so only end-of-program values were compared; no follow-up after discharge.
[17]Prospective cohortn = 129Benefit
Waon therapy improves the prognosis of patients with chronic heart failure.
Kihara T et al. J Cardiol. 2009. PubMed 19304125 · DOI · Free full text
- Who
- NYHA III-IV chronic HF admitted 1999-2001
- What
- Waon daily for 5 days in hospital then >=2/week after discharge (n=64) vs matched controls (n=65)
- Protocol
- 140 °F · 15 min · >=2 after discharge/wk · up to 5 years
- Measured
- Cardiac events due to heart failure or cardiac death over 60 months
- Result
- Cardiac events 31.3% Waon vs 68.7% control (P<0.01); deaths 8 vs 12.
- Limitations
- Not randomized (matched controls); single center; adherence after discharge not reported in abstract.
[18]Pilot / uncontrolled studyn = 41Benefit
Effect of repeated sauna treatment on exercise tolerance and endothelial function in patients with chronic heart failure.
Ohori T et al. Am J Cardiol. 2012. PubMed 21944673 · DOI
- Who
- Chronic HF (mean age 68)
- What
- Waon therapy 5 times/week for 3 weeks (no control group)
- Protocol
- 140 °F · 15 min · 5/wk · 3 wk
- Measured
- 6MWD, LVEF, BNP, norepinephrine, FMD, peak VO2
- Result
- 6MWD 337 to 379 m (p<0.001); LVEF 30.4% to 32.5% (p=0.023); BNP 550 to 416 pg/mL (p=0.035); FMD 3.5% to 5.5% (p<0.001); peak VO2 increased.
- Limitations
- Uncontrolled before-after design.
[19]Pilot / uncontrolled studyn = 18Benefit
Effects of Sauna bathing on Exercise Capacity and Muscle Function in HFpEF.
Bekfani T et al. Eur J Heart Fail. 2026. PubMed 41831305 · DOI · Free full text
- Who
- Stable outpatients with HFpEF
- What
- Supervised sauna twice weekly for 10 weeks, session length increased from 8 to 15 min
- Protocol
- 140 °F · 8-15 min · 2/wk · 10 wk
- Measured
- Peak VO2, 6MWT, muscle function, QoL, safety
- Result
- Peak VO2 18.2 to 20.6 mL/kg/min (p<0.001); 6MWT 494 to 527 m (p=0.006); E/e' and quadriceps strength improved; 97% adherence, no adverse events. Peak VO2 declined 3 months after stopping (p<0.01).
- Limitations
- Uncontrolled single-arm pilot; 18 of a planned 20 patients enrolled, 16 at 3-month follow-up; full text read from the publisher HTML.
[20]Pilot / uncontrolled studyn = 49Benefit
Waon therapy improves quality of life as well as cardiac function and exercise capacity in patients with chronic heart failure.
Sobajima M et al. Int Heart J. 2015. PubMed 25740582 · DOI · Free full text
- Who
- Chronic HF, mean age 69 (Toyama, Japan)
- What
- Waon therapy once daily for 3 weeks (no control group)
- Protocol
- 140 °F · 15 min · daily/wk · 3 wk
- Measured
- LVEF, BNP, 6MWD, FMD, SF-36 quality of life
- Result
- 6MWD 323 to 366 m, LVEF 33% to 37% and BNP 455 to 354 (all P<0.01); FMD 3.6% to 5.1% (P<0.01); both physical and mental component scores of SF-36 improved; physical improvement correlated with BNP change (r=-0.327). No patient had worsening symptoms or complications.
- Limitations
- Uncontrolled before-after design; 3 weeks with no long-term follow-up; same center as Ohori 2012, so patient overlap is possible.
[21]Case series / reportn = 21Mixed
Cardio-Ankle Vascular Index Reflects the Efficacy of Waon Therapy in Heart Failure Patients.
Nakagami T et al. Int Heart J. 2022. PubMed 36450548 · DOI · Free full text
- Who
- Refractory chronic HF, NYHA II-IV, treated with Waon therapy at one Japanese center 2011-2022 (27 treated, 21 analysed)
- What
- Waon therapy, 10 sessions over 2 weeks; patients classified by BNP response
- Protocol
- 140 °F · 15 min · 5/wk · 2 wk
- Measured
- Cardio-ankle vascular index (CAVI), BNP response, HF rehospitalization or cardiac death at 12 months
- Result
- BNP improved in 11 of 21 analysed patients (responders). CAVI fell from 10.3 to 9.6 in responders (P=0.021) but not in nonresponders (9.6 to 9.5, P=0.919). Of 27 treated, 3 could not tolerate the heat and stopped early; all 3 died of HF within one month of stopping. HF rehospitalization or cardiac death at 12 months was higher in the 'noneffective or intolerable' group (10 nonresponders plus the 3 dropouts, n=13) than in the 'effective' group (11 responders plus 3 patients without CAVI data, n=14) (log-rank P=0.001).
- Limitations
- Retrospective, uncontrolled, single center; small; responder grouping is post hoc and the outcome comparison mixes responders, dropouts and excluded patients; heat intolerance in 3 of 27 refractory patients.
[22]Pilot / uncontrolled studyn = 15Benefit
Safety and efficacy of repeated sauna bathing in patients with chronic systolic heart failure: a preliminary report.
Miyamoto H et al. J Card Fail. 2005. PubMed 16105634 · DOI
- Who
- Hospitalized stable chronic systolic HF, mean NYHA class 2.8 (Japan)
- What
- 60 C sauna bathing once daily for 4 weeks (no control group)
- Protocol
- 140 °F · daily/wk · 4 wk
- Measured
- Safety, symptoms, LVEF, 6MWD, peak VO2, catecholamines, HF admissions
- Result
- Completed by all without adverse effects; symptoms improved in 13 of 15; LVEF 30% to 34%; 6MWD 388 to 448 m; peak VO2 13.3 to 16.3 mL/kg/min; norepinephrine 633 to 443 pg/mL; HF admissions 2.5 to 0.6 per year (all reported as significant).
- Limitations
- Uncontrolled preliminary study; small; before-after comparison of admission rates is prone to regression to the mean.
[23]Pilot / uncontrolled studyn = 10Benefit
Thermal therapy improves left ventricular diastolic function in patients with congestive heart failure: a tissue doppler echocardiographic study.
Kisanuki A et al. J Cardiol. 2007. PubMed 17460879
- Who
- Congestive HF (Japan)
- What
- Single 60 C dry sauna session
- Protocol
- 140 °F · single session/wk
- Measured
- LV diastolic function by pulsed and tissue Doppler echocardiography
- Result
- After sauna, early mitral inflow velocity (E) and mitral annular velocity (E') increased, E-wave deceleration time decreased, and E/E' fell 30 min after sauna (all significant; values not in abstract); LV and LA dimensions unchanged.
- Limitations
- Acute single session; uncontrolled; very small.
[24]Pilot / uncontrolled studyn = 34Benefit
Acute hemodynamic improvement by thermal vasodilation in congestive heart failure.
Tei C et al. Circulation. 1995. PubMed 7743620 · DOI
- Who
- Chronic CHF, NYHA II-IV, mean LVEF 25%, mean age 58 (Japan)
- What
- Single warm-water bath (10 min at 105.8 F) or sauna (15 min at 140 F) with right-heart catheter monitoring
- Protocol
- 105.8 (water bath); 140 (sauna) °F · 10 (bath); 15 (sauna) min · single session/wk
- Measured
- Invasive hemodynamics, echocardiography, oxygen consumption
- Result
- Cardiac and stroke index increased and systemic vascular resistance decreased during and after both baths (P<.01). Pulmonary artery, wedge and right atrial pressures rose during the warm-water bath (P<.05) but fell during sauna (P<.05), and fell below baseline after each (P<.01). Heart rate rose 20-25 bpm; LVEF increased and mitral regurgitation decreased after both.
- Limitations
- Acute single exposure; uncontrolled; filling pressures rose transiently during water immersion.
[25]Pilot / uncontrolled studyn = 10Mixed
Preliminary clinical experience with waon therapy in Korea: safety and effect.
Sohn IS et al. J Cardiovasc Ultrasound. 2010. PubMed 20706566 · DOI · Free full text
- Who
- Chronic HF (Korea)
- What
- Waon therapy once daily, 5 days/week; 5 patients treated for more than 2 weeks
- Protocol
- 140 °F · 15 min · 5/wk · >2 (5 patients)
- Measured
- Safety, symptoms, echocardiography
- Result
- No worsening of HF symptoms; 4 of 5 patients treated >2 weeks reported symptom improvement and smaller LV volume; LVEF and diastolic indices trended better without statistical significance. Per session, systolic BP fell from 119 to 111 mmHg (p=0.005) and oral temperature rose by 1.0 C.
- Limitations
- Very small; uncontrolled; only 5 of 10 continued beyond 2 weeks (2 lost to follow-up, 2 could not keep up daily visits, 1 stopped for no change in symptoms); efficacy changes not significant.
[26]Pilot / uncontrolled studyn = 37Mixed
Acute effects of Finnish sauna and cold-water immersion on haemodynamic variables and autonomic nervous system activity in patients with heart failure.
Radtke T et al. Eur J Prev Cardiol. 2016. PubMed 26152773 · DOI
- Who
- Men with chronic heart failure (n=12, mean age 62), coronary artery disease (n=13) and controls (n=12) (Switzerland)
- What
- Two consecutive Finnish sauna exposures at 176 F followed by head-out cold-water immersion at 54 F (single session)
- Protocol
- 176 (sauna); 54 (cold immersion) °F · single session/wk
- Measured
- Cardiac output, blood pressure, heart rate variability, arrhythmias
- Result
- Well tolerated by all. Cardiac output and heart rate rose after sauna and after cold immersion (p<0.05); systolic BP fell during sauna (nadir at 6 min) and rose with cold immersion in all groups (p<0.05). No change in LF/HF ratio and no excessive adrenergic activation or complex arrhythmias in heart failure patients.
- Limitations
- Single session; small; stable selected men; acute tolerability only, not efficacy.
[27]Controlled trial (not randomized)n = 26Benefit
Immersion in Hot Spring Improves Cardiovascular Functions in Patients with Chronic Heart Failure
Kudo Y et al. The Journal of the Japanese Society of Balneology, Climatology and Physical Medicine. 2008. Not in PubMed: sourceJapanese publication; title and summary translated by SaunaLMN. Original title: 温泉入浴による慢性心不全患者の心血管機能改善効果について
- Who
- Chronic systolic heart failure, NYHA II-III, dilated or ischemic cardiomyopathy (Beppu, Japan)
- What
- Hot-spring immersion to the sternum or below (half-body bathing) at 104 F (40 C) for about 10 min, then 1 h rest, 5 days/week for 2 weeks (n=13) vs daily shower only (n=13)
- Protocol
- 104 °F · 10 min · 5/wk · 2 wk
- Measured
- NYHA class/symptoms, LVEF, cardiothoracic ratio, mean BP, BNP, ADMA, brachial-ankle pulse wave velocity
- Result
- After 2 weeks of hot-spring bathing, symptoms and LVEF improved and mean BP, BNP (430.4 to 302.1 pg/mL), ADMA (0.61 to 0.59) and baPWV (17.0 to 16.5 m/s) fell significantly; heart rate and cardiothoracic ratio did not change. The shower group showed no significant changes.
- Limitations
- Patients were 'divided into two groups' without stated randomization; within-group statistics; 13 per group; 2 weeks; article in Japanese with English abstract.
Protocols used in the studies
Waon trials: far-infrared dry sauna at 140 F (60 C) for 15 min, then 30 min supine rest under blankets, once daily, usually 5 days a week, for 2 to 4 weeks (WAON-CHF: 10 sessions over 2 weeks), usually started in hospital; one non-randomized cohort continued at least twice weekly after discharge for up to 5 years. Other protocols: 140 F sauna 3 times/week for 4 weeks (US crossover pilot) or 8-15 min twice weekly for 10 weeks (HFpEF pilot); leg-only far-infrared heating at 113 F (45 C) for 20 min, 5 times/week, with cardiac rehabilitation; daily home Kneipp warm- and cold-water applications for 6 weeks; half-body hot-spring immersion at 104 F (40 C) for about 10 min, 5 days/week for 2 weeks; single exposures to a 105.8 F (41 C) warm-water bath for 10 min, a 140 F sauna for 15 min, or two 176 F (80 C) Finnish sauna sessions followed by 54 F (12 C) cold immersion. No controlled trial has tested repeated 176-194 F Finnish sauna in heart failure.
What is still unknown
Effect on mortality and HF hospitalization in an adequately powered randomized trial; independent replication outside the Japanese Waon research network; sham- or attention-controlled trials with blinded outcome assessment; durability after stopping; the minimum effective home protocol; effects in HFpEF; safety and efficacy of repeated higher-temperature Finnish sauna and of hot-water immersion; interaction with diuretic dosing.
Safety
Cautions for sauna in this condition
- In WAON-CHF there were no deaths, but adverse events occurred in 17 (22%) Waon vs 11 (15%) control patients (P=0.2962), including 7 Waon-related minor events (fall in blood pressure, hypovolemia, increased urine output, weight loss, bleeding after tooth extraction) and one paroxysmal atrial fibrillation (PMID 27001189). No adverse events were reported in the elderly inpatient Waon study (PMID 40980348), a 4-week 140 F sauna pilot (PMID 16105634) or the HFpEF pilot (PMID 41831305); a US crossover pilot found 140 F sauna well tolerated in NYHA III-IV patients (PMID 19154844).
- In a single-center series of refractory NYHA II-IV heart failure, 3 of 27 patients could not tolerate the heat of Waon therapy and stopped early; all 3 died of heart failure within one month of stopping (PMID 36450548). Heat intolerance may mark very advanced disease.
- Trial protocols used 140 F (60 C), mostly in supervised hospital settings with blanket rest afterwards and fluid replacement, in patients who were stable or stabilized after admission; safety data do not extend to unsupervised home use, acute decompensation, or repeated use of hotter traditional sauna (176 F was studied only as a single exposure, PMID 26152773).
- Warm-water immersion raised pulmonary artery, wedge and right atrial pressures during the bath, whereas 140 F sauna lowered them (PMID 7743620); upright neck-deep immersion transiently raised pulmonary pressures in patients after extensive myocardial infarction (review, PMID 18377766). Immersion is hemodynamically different from dry sauna.
- Cold-water immersion after sauna raised systolic BP (PMID 26152773), and immersion in 72 F water increased premature ventricular beats in stable heart failure (PMID 19696059).
- Sauna was studied as an adjunct to stable guideline medical therapy; WAON-CHF recorded hypovolemia and falls in blood pressure, and its authors advised water replacement and diuretic or antihypertensive dose adjustment (PMID 27001189).
For clinicians
Suggested rationale
In small randomized and controlled trials, mostly from Japanese hospital programs, repeated 140 F far-infrared (Waon) sauna therapy improved symptoms, BNP and exercise capacity over 2-4 weeks (Miyata 2008; Kihara 2004), and in the largest multicenter RCT it improved 6-minute walk distance, cardiothoracic ratio and NYHA class versus medical therapy alone but did not meet its primary BNP endpoint (Tei 2016, WAON-CHF); pooled LVEF gain was about 1.5 points (Källström 2018). This supports low-temperature, supervised thermal therapy only as a possible adjunct to guideline-directed medical therapy in stable patients; it has not been shown to reduce mortality or hospitalization in a randomized trial.
Suggested wording only. The treating clinician decides whether it reflects their clinical judgment for this patient.
Typical ICD-10 codes: I50.9, I50.22, I50.32, I50.42. Examples only; the clinician assigns the code.
What a letter of medical necessity should containWho can write it: physicians, NPs, PAs and others