Temporary cessation of spinal cord stimulation in angina pectoris -: effects on symptoms and evaluation of long-term effect determinants

Background Spinal cord stimulation (SCS) has been used since 1985 for patients with refractory angina pectoris. Spinal cord stimulation has anti-ischaemic effects and reduces angina effectively. After long-term treatment, temporary cessation of stimulation may occur due to SCS battery depletion or electrode fracture. The aim of the present study was to assess anginal symptoms and functional status during SCS dysfunction and after its restitution. Design A prospective follow-up study of angina patients treated with SCS, where temporary SCS dysfunction had occurred. Methods Thirty-two patients treated with SCS for angina pectoris over 65 months, on average (range 14-181 months), were included. Complete stimulator dysfunction had occurred due to battery depletion (n=25) or electrode fracture (n=7). The number of anginal attacks and the amount of short-acting nitrates consumed were assessed during dysfunction and after restitution of SCS function. The Seattle Angina Questionnaire (SAQ) was used to assess functional status. Results The anginal frequency increased during dysfunction (18.9 per week) and decreased after restitution of SCS function (7.6 episodes per week; p<0.001). The consumption of short-acting nitrates decreased as well (21.7 versus 7.1 tablets per week; p<0.01). The functional status according to the SAQ also improved with regard to anginal stability, anginal frequency, and disease perception. No evidence of tolerance development to SCS was found. Conclusion This study indicates that SCS relieves angina effectively also after long-term treatment, without development of tolerance. The findings suggest that mechanisms other than placebo and spontaneous variation of symptoms are responsible for the improvement in angina during SCS.