Abstract / Summary
Cardiovascular diseases, particularly chronic heart failure (CHF) and coronary artery disease (CAD), impose a significant global burden with persistent symptoms despite standard therapies. Sauna therapy, including Waon and Finnish sauna, induces physiological responses such as vasodilation and autonomic modulation, showing promise in improving cardiac function and symptoms. This systematic review aimed to evaluate the effects of sauna therapy on cardiac function, vascular outcomes, biomarkers, exercise capacity, quality of life, and safety in adults with CHF or stable CAD. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed, Cochrane Library, Scopus, Google Scholar, Web of Science, and ScienceDirect were searched through August 2025 for clinical trials comparing sauna interventions with standard care or control conditions. Thirteen studies were included after screening 347 records: Seven randomized controlled trials, two quasi- experimental studies, three pre–post studies, and one cohort study. Risk of bias was assessed using Joanna Briggs Institute tools, and the data were synthesized systematically. Sauna therapy improved left ventricular ejection fraction (LVEF) (LVEF; +2–4%, p < 0.05 in 5/8 studies), cardiothoracic ratio, B-type natriuretic peptide (–20– 50%, p < 0.01), endothelial function (flow-mediated dilation +1–2%, p < 0.05 in 3/4 studies), 6-min walk distance (+45 m, p < 0.01), NewYork Heart Association (NYHA) (NYHA class, and heart rate variability. Long-term Waon therapy reduced cardiac events by 38% over 5 years ( p < 0.01). No serious adverse events occurred. Sauna therapy, especially Waon, offers safe adjunctive benefits for CHF, with mixed results in CAD. However, larger randomized controlled trials are needed for confirmation.