A warm footbath improves coronary flow reserve in patients with mild-to-moderate coronary artery disease

Backgrounds: Recent studies have shown that thermal therapy by means of warm waterbaths and sauna has beneficial effects in chronic heart failure. However, a comprehensive investigation of the hemodynamic effects of thermal vasodilation on coronary arteries has not been previously undertaken. In this study, we studied the effect of a warm footbath (WFB) on coronary arteries in patients with coronary artery disease (CAD), as well as any adverse effect. Methods: We studied 21 patients (33.3% men, mean age 60.8 ± 13.5 years) with CAD. Coronary flow Doppler examination of the left anterior descending coronary artery and coronary flow reserve (CFR) were performed and measured using adenosine before and after a WFB. Results: Systolic and diastolic blood pressure and heart rate did not change with the WFB. Mean velocity of diastolic coronary flow significantly increased (diastolic mean flow velocity: 18.3 ± 7.1 cm/sec initial, 21.5 ± 8.0 cm/sec follow-up, P = 0.002) and CFR significantly improved (1.6 ± 0.4 vs. 2.2 ± 0.5, P < 0.001) after WFB. The WFB was well accepted and no relevant adverse effects were observed. The change of CFR after WFB correlated well with diastolic function (E', r = 0.51, P = 0.031; E/E', r =-0.675, P = 0.002). Conclusions: A WFB significantly improved CFR without any adverse effects in patients with mild-to-moderate CAD and can be applied with little risk of a coronary artery event if appropriately performed.