Additional data from well-designed RCTs are needed to better define the role of this therapeutic strategy in patients with SIHD.942 4.4.4.2. Spinal Cord Stimulation Spinal cord stimulation at the T1 to T2 level has been advocated as a therapeutic option for patients with angina pectoris that is refractory to medical therapy and coronary revascularization. The stimulation lead is inserted into the epidural space and is connected to a pulse generator im- planted subcutaneously. A paresthetic stimulus is delivered in a continuous, cyclic, or intermittent manner. The mechanisms by which spinal cord stimulation leads to reduced angina are not well established. Although inhibition of pain transmission plays a role, some studies suggest that spinal cord stimulation also might reduce myocardial ischemia.943 945 The efficacy of spinal cord stimulation has been evaluated in several observational and cohort studies. The Prospective Italian Registry described outcomes in 104 patients with severe angina refractory to medical therapy over an average of 13 months after initiation of spinal cord stimulation.946 A .50% reduction in anginal symptoms was observed in 73% of patients. CCS class improved by $1 class in 80% and by $2 classes in 42% of patients. Similarly, in a cohort of 51 patients with refractory CCS Class III or IV angina, spinal cord stimulation was associated with a significant reduction in anginal episodes in 88% of subjects at 24 months of follow-up.947 There were no significant complications of therapy in either series. The published RCTs of spinal cord stimulation were small. 