RESUMEN
Spinal cord stimulation (SCS) is believed to be effective in treating refractory angina. The need for SCS-related chest paresthesia, however, has hitherto made impossible placebo-controlled trials. Subliminal (non paresthesic) SCS, however, might be also effective on anginal pain. In this trial we compared subliminal SCS with paresthesic SCS and with sham SCS. Twenty-five refractory angina patients, who had never received SCS before, underwent SCS device implantation and were randomized to three groups: paresthesic SCS (group PS; n=10), subliminal SCS (group SS; n=7) or "sham" SCS (group NS; n=8). After 1month group NS patients were randomized to either group PS or SS. After 1month, changes in angina episodes (p=0.016), nitroglycerin use (p=0.015), angina class (p=0.02), quality of life score (p=0.05), and items 2 (p=0.008) and 3 (p=0.009) of Seattle angina questionnaire differed significantly among groups. Group PS showed significant improvement in outcomes compared to group NS, whereas there were no significant differences between groups SS and NS; furthermore, only nitroglycerin use differed significantly between groups PS and SS. At 3months, a significant difference between groups PS and SS was observed in angina attacks (p=0.002), but not in other variables. Thus, in this study, paresthesic, but not subliminal SCS was superior to sham SCS in improving clinical status in refractory angina patients. The lack of significant differences between PS and SS groups in this small study suggests that a possible role for subliminal SCS in individual patients deserves to be assessed in larger trials with appropriate statistical power.