Auricular vagal nerve stimulation in peripheral arterial disease patients.

Background: Auricular nerve stimulation has been proven effective in different diseases. We investigated if a conservative therapeutic alternative for claudication in peripheral arterial occlusive disease (PAD) via electroacupuncture of the outer ear can be established.
Patients and Methods: In this prospective, double-blinded trial an ear acupuncture using an electroacupuncture device was carried out in 40 PAD patients in Fontaine stage IIb. Twenty patients were randomized to the verum group using a fully functional electroacupuncture device, the other 20 patients received a sham device (control group). Per patient, eight cycles (1 cycle = 1 week) of electroacupuncture were performed. The primary endpoint was defined as a significantly more frequent doubling of the absolute walking distance after eight cycles in the verum group compared to controls in a standardized treadmill testing. Secondary endpoints were a significant improvement of the total score of the Walking Impairment Questionnaire (WIQ) as well as improvements in health related quality of life using the Short Form 36 Health Survey (SF-36).
Results: There were no differences in baseline characteristics between the two groups. The initial walking distance significantly increased in both groups (verum group [means]: 182 [95 % CI 128-236] meters to 345 [95 % CI 227-463] meters [+ 90 %], p < 0.01; control group [means]: 159 [95 % CI 109-210] meters to 268 [95 % CI 182-366] meters [+ 69 %], p = 0.01). Twelve patients (60 %) in the verum group and five patients (25 %) in controls reached the primary endpoint of doubling walking distance (p = 0.05). The total score of WIQ significantly improved in the verum group (+ 22 %, p = 0.01) but not in controls (+ 8 %, p = 0.56). SF-36 showed significantly improvements in six out of eight categories in the verum group and only in one of eight in controls.
Conclusions: Electroacupuncture of the outer ear seems to be an easy-to-use therapeutic option in an age of increasingly invasive and mechanically complex treatments for PAD patients.