An investigation into the ‘carry over’ effect of neurostimulation in the treatment of angina pectoris

Neurostimulation, by way of transcutaneous electrical nerve stimulation (TENS) and spinal cord stimulation, improves signs and symptoms of myocardial ischaemia, with evidence (from non-randomised studies) that this effect extends beyond the period of stimulation itself ('carry-over' effect). In this randomised controlled trial, 10 patients underwent baseline treadmill-exercise-testing (TET), followed by two further tests at fortnightly intervals. TENS was compared to placebo in a randomised fashion. TENS produced a significant increase in total exercise time (399.3 vs. 364.5 s, p < 0.05) and time to maximum ST depression (374 vs. 324 s, p = 0.01) without a significant difference in the maximum degree of ST depression (2.0 vs. 2.1 mm, p = NS). Rate-pressure product at peak exercise was not significantly different (197 vs. 193, p = NS). TENS produced a nonsignificant change in time to onset of angina (352 vs. 325 s, p = 0.07). Pre-treatment with TENS produces a significant improvement in exercise tolerance and measures of ischaemia but not significant improvement in symptoms.