Heat therapy and heart failure: what small trials suggest
A review pooled seven small trials of infrared heat therapy in stable heart failure patients. Some heart-function markers improved over a few weeks. This is not evidence about ordinary sauna, and not a treatment to try without your cardiologist.
The short version
A systematic review pooled seven small trials of infrared heat therapy, not Finnish sauna, in people with stable heart failure, using a Japanese-developed protocol often called Waon therapy. Two to four weeks of sessions, five times a week, were followed by improvements in a blood marker of heart strain, a chest X-ray ratio, and pumping function on ultrasound. Blood pressure and heart chamber size did not change. The trials were small and short, used a specific clinical protocol under medical supervision, and say nothing about Finnish sauna or unsupervised use in heart failure.
Keep in mind
Small, short, clinically supervised trials of infrared heat therapy, not Finnish sauna, in people already diagnosed with heart failure. Not a home protocol, and not evidence about sauna.
What they found
Pooling the trials, infrared heat therapy was associated with a reduction in BNP (a blood marker of heart strain), a smaller cardiothoracic ratio (a chest X-ray measure of heart size), and an improvement in left-ventricular ejection fraction (a measure of pumping function).
Blood pressure, left-ventricular chamber size and left atrial size did not change significantly.
The original draft also described improved walking distance, symptom class and a longer-term drop in cardiac events. We could not confirm those specific figures from the publication’s abstract, so we have left them out rather than repeat them unchecked.
What this means for your practice
If you have heart failure, this review does not tell you that sauna is safe or beneficial for you: it studied a different, medically supervised infrared protocol over a few weeks, and the authors themselves call for more evidence before drawing conclusions, including about Finnish sauna specifically. Talk to your cardiologist before any heat exposure.
This does not establish a sauna routine to follow, or show that a KUUME ritual has these effects, for people with or without heart failure.
Methods and limitations
What the researchers did
Researchers systematically searched for trials of sauna-type heat therapy in people with heart failure, screening 1,444 studies. Nine met their inclusion criteria, and seven small trials, together covering roughly 491 patients, were pooled in the final analysis.
Every trial that qualified used infrared heat therapy, often called Waon therapy: sitting in a cabin at about 60°C for 15 minutes, then resting under blankets for 30 minutes to stay warm, five times a week for two to four weeks. No Finnish (dry) sauna trials met the inclusion criteria.
This is a review of other people’s clinical trials, not a new study of patients. The pooled patients had stable heart failure and were treated under medical supervision, not at home.
How much can this tell us?
This is a systematic review, which is methodologically thorough, but the underlying evidence is thin: seven small trials, roughly 491 patients in total, mostly short (two to four weeks).
Crucially, the authors themselves conclude that more evidence is needed on long-term effects, and specifically on Finnish sauna, which none of the pooled trials tested. Nothing here shows that a Finnish-style sauna is safe or effective for people with heart failure.
Heart failure is a serious, individually variable condition. These trials were conducted under medical supervision with a specific, monitored infrared protocol, not a description of a routine anyone should follow at home.
What makes it useful
- Systematic search and pooled analysis across seven trials
- Consistent signal across a blood marker, an imaging measure and a heart-size measure
- Focused on people with a confirmed diagnosis, under medical supervision
What limits it
- Small and short: about 491 patients, mostly 2–4 weeks
- Infrared therapy under medical supervision, not Finnish sauna
- Authors call for more evidence, especially for Finnish sauna
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Heat therapy helps people with heart failure. Some support
Low certaintySize not reportedBody signals
Read the original
Källström M, Soveri I, Oldgren J, Laukkanen J, Ichiki T, Tei C, et al. Effects of sauna bath on heart failure: a systematic review and meta-analysis. Clin Cardiol. 2018;41(11):1491-1501.
DOI 10.1002/clc.23077 · PubMed 30239008