Effect of Repeated Sauna Treatment on Exercise Tolerance and Endothelial Function in Patients With Chronic Heart Failure
Does repeated sauna treatment (known as Waon therapy) improve cardiac exercise tolerance or neurohormonal responses in patients with chronic heart failure (HF)?
This was an unblinded, uncontrolled study of 41 patients with chronic HF. All patients underwent 5 days of Waon therapy for 3 weeks. Waon consisted of sitting in a dry sauna for 15 minutes, then being blanketed for 30 minutes, aiming to raise core temperature by 1-2 degrees Celsius. Endothelial progenitor cell (CD34+) count and flow-mediated dilation (FMD) of the brachial artery were measured before and after 3 weeks of therapy, and patients underwent 6-minute walk testing (6MWT) and cardiopulmonary stress testing (in n = 20) to assess for change in functional capacity.
The mean ± standard deviation patient age was 68.3 ± 13.5 years, 37%/54% were New York Heart Association (NYHA) class II/III, and 49% had a dilated cardiomyopathy with a mean left ventricular ejection fraction of 30 ± 13%. Following Waon therapy, improvements were noted in 6MWT distance (337-379 m, p < 0.001), peak oxygen consumption (804-871 ml/min, p < 0.001), B-type natriuretic peptide (550-416 pg/ml, p = 0.035), plasma norepinephrine (400-300 pg/ml), circulating CD34+ cells (1.1-1.3 per mm3, p = 0.025), and FMD (3.5-5.5%, p < 0.001).
The authors concluded that repeated sauna treatment improved exercise capacity and endothelial function in patients with systolic HF.
This interesting and novel study offered many clinically important positive results that warrant further investigation and validation. The authors state that Waon therapy improves exercise tolerance in HF by improving endothelial function, as evidenced by improvements in FMD and CD34+ count. Unfortunately, several study limitations exist. The HF population of study at baseline is poorly described (systolic vs. diastolic heart failure), and neither echo nor hemodynamic criteria were required to meet the HF definition. Further, lack of a control group and lack of blinding has the potential to bias several of the endpoint measures, including that of echocardiographic data, NYHA class assessment, and FMD. Lack of a control group also makes interpretation of functional capacity difficult, as patient ‘learning curve’ on repeat testing is well documented. Overall, this study as designed does not provide strong evidence supporting sauna therapy, but the pilot data are interesting and should be further investigated.
Keywords: Exercise Tolerance, Natriuretic Peptides, Heart Failure, Norepinephrine, Endothelial Cells
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