Effects of pacing-induced myocardial stress and spinal cord stimulation on whole body and cardiac norepinephrine spillover

Aims Spinal cord stimulation has been used in the treatment of intractable angina pectoris since the beginning of the 1980s. This study was designed to investigate whether the documented anti-ischaemic effects of spinal cord stimulation are mediated through a decrease in sympathetic activity. Methods and Results Ten patients with a spinal cord stimulator implanted as anti-anginal treatment were included in the study. Atrial pacing until the patient experienced moderate angina was performed and after 50 min rest the procedure was repeated during spinal cord stimulation. Total body and cardiac norepinephrine spillover was calculated and the former was found to have increased during pacing (47%, P =0·02). When spinal cord stimulation was applied, total body norepinephrine spillover decreased at a comparable pacing rate (18%, P =0·02). Cardiac norepinephrine spillover was not affected during the procedure. Conclusion The results of this study indicate that the anti-ischaemic effect of spinal cord stimulation is not due to reduced cardiac sympathetic activity. However, spinal cord stimulation decreases overall sympathetic activity which may benefit the heart, possibly by reducing oxygen demand.