Key Takeaway
Infrared sauna bathing was associated with short-term improvements in cardiac function in heart failure patients, including reduced BNP levels and improved left ventricular ejection fraction.
Summary
This systematic review and meta-analysis by Kallstrom et al. (2019) investigated whether sauna bathing could benefit patients with heart failure. The authors searched PubMed, Cochrane Library, and CINAHL databases, screening 1,444 studies and identifying 9 controlled studies that met inclusion criteria, of which 7 were included in the meta-analysis.
All qualifying studies used infrared sauna (specifically far-infrared at approximately 60 degrees C for 15 minutes, followed by 30 minutes of rest with blanket wrapping, performed five times weekly for 2-4 weeks). This protocol is consistent with the Japanese Waon therapy approach. The meta-analysis found significant improvements in B-type natriuretic peptide (a biomarker for heart failure severity), left ventricular ejection fraction, and cardiothoracic ratio.
However, no significant effects were found for blood pressure or certain heart chamber measurements. The authors noted that evidence strength varied from moderate to insufficient and emphasized the need for more research on long-term effects and the potential benefits of Finnish-style sauna for cardiovascular health.
Methods
- Systematic review and meta-analysis of controlled studies
- Databases searched: PubMed, Cochrane Library, CINAHL
- 1,444 studies screened, 9 met inclusion criteria, 7 included in meta-analysis
- Inclusion: controlled studies comparing sauna exposure to no sauna in heart failure patients
- All qualifying studies used infrared sauna (Waon therapy protocol)
- Typical protocol: 60 degrees C for 15 minutes + 30 minutes rest, 5x/week, 2-4 weeks
Key Results
- Significant reduction in B-type natriuretic peptide (BNP) levels
- Improved left ventricular ejection fraction (LVEF)
- Reduced cardiothoracic ratio
- No significant effects on blood pressure
- No significant effects on certain heart chamber measurements
- All positive effects observed with infrared sauna (Waon therapy)
- Benefits were short-term over 2-4 week intervention periods
Figures
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Limitations
- Small number of included studies (7 in meta-analysis)
- Evidence strength varied from moderate to insufficient
- Only infrared sauna studies qualified (no Finnish sauna data in heart failure)
- Short intervention periods (2-4 weeks) with no long-term follow-up
- Most studies from Japanese research groups using same Waon therapy protocol
- Limited generalizability to other sauna types or protocols