The Clinical Outcomes in Patients with Critical Limb Ischemia One Year after Spinal Cord Stimulation

Background: The aim of this study was to evaluate the long-term outcomes of spinal cord stimulation in patients with critical limb ischemia and to test the hypothesis that the dynamics of clinical changes one year after therapy depend both on the clinical determinants associated with the underlying disease and on factors related to systemic atherosclerosis. Methods: This prospective cohort study included 56 patients with critical limb ischemia. All patients before and after spinal cord stimulation were examined in terms of the dynamics of their clinical changes using the Rutherford scale and transcutaneous oxygen tension (TcPO₂, mm Hg) in the affected foot. The active orthostatic test was used to assess the functional state of peripheral perfusion. Results: One year after spinal cord stimulation, 74% of patients showed positive clinical outcomes. No changes were observed in 9.3% of patients, whereas adverse clinical outcomes were revealed in 16.7% of cases. The TcPO₂ values were significantly reduced before spinal cord stimulation: 10.5 (6.4–16.0) mm Hg. The functional status of the peripheral microvasculature was also disturbed. One year after therapy, TcPO₂ significantly increased and the adaptive mechanisms of the microvasculature were improved in more than 70% of patients. Logistic regression analysis showed that the initially low TcPO₂ values (<10 mm Hg) with a lack of gain in TcPO₂ during the orthostatic test are associated with the negative clinical outcomes after spinal cord stimulation. The gain in TcPO₂ during the orthostatic test to >10 mm Hg is associated with the positive clinical outcomes after spinal cord stimulation. The age-adjusted Charlson Comorbidity Index >5 and duration of critical ischemic symptoms also had a negative effect on the clinical outcomes after spinal cord stimulation. Conclusions: The positive clinical outcomes were revealed in most patients with critical limb ischemia one year after spinal cord stimulation. The low values of peripheral tissue metabolism with the disturbed functional status of the microvasculature are associated with the negative clinical outcome. The patients with baseline TcPO₂ <10 mm Hg can recover if they still have a sufficient microcirculatory reserve capacity. Duration of critical ischemic symptoms and high comorbidity burden with allowance for age are negative factors affecting the clinical outcome.