How strong is the evidence for Heat Therapy?

A systematic review and meta-analysis found heat therapy produces modest improvements in blood pressure and peripheral vascular function, and a separate meta-analysis found heat therapy may help patients with heart failure, though the evidence for the latter is not yet strong enough for firm clinical recommendations. That evidence is currently rated emerging (37/100), built on 6 published studies, including 3 meta-analyses -- still too little to draw firm conclusions from.