Does local passive heat therapy reduce systolic blood pressure in patients with autonomic failure and supine hypertension?
Local passive heat therapy significantly lowers supine and overnight systolic blood pressure in patients with autonomic failure, offering a novel non-pharmacological treatment approach.
Background Supine hypertension affects a majority of patients with autonomic failure; it is associated with end-organ damage and can worsen daytime orthostatic hypotension by inducing pressure diuresis and volume loss during the night. Because sympathetic activation prevents blood pressure (BP) from falling in healthy subjects exposed to heat, we hypothesized that passive heat had a BP-lowering effect in patients with autonomic failure and could be used to treat their supine hypertension. Methods and Results In Protocol 1 (n=22), the acute effects of local heat (40-42°C applied with a heating pad placed over the abdomen for 2 hours) versus sham control were assessed in a randomized crossover fashion. Heat acutely decreased systolic BP by -19±4 mm Hg (versus 3±4 with sham, PP=0.013 ) and cardiac output (-15±5% versus -2±4%, P=0.013). In Protocol 2 (proof-of-concept overnight study; n=12), we compared the effects of local heat (38°C applied with a water-perfused heating pad placed under the torso from 10 pm to 6 am) versus placebo pill. Heat decreased nighttime systolic BP (maximal change -28±6 versus -2±6 mm Hg, Pr=0.57, P=0.072) and an improvement in the morning upright systolic BP (r=-0.76, P=0.007). Conclusions Local heat therapy effectively lowered overnight BP in patients with autonomic failure and supine hypertension and offers a novel approach to treat this condition. Future studies are needed to assess the long-term safety and efficacy in improving nighttime fluid loss and daytime orthostatic hypotension. Registration URL: https://www.clinicaltrials.gov; Unique identifiers: NCT02417415 and NCT03042988.
Okamoto et al. (Fri,) studied this question.