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. One study tested the efficacy of spinal cord stimulation in 13 patients with chronic, intractable angina compared with 12 controls over 6 weeks.912 Patients with spinal cord stimulation demonstrated greater exercise duration and time to angina during treadmill testing and fewer bouts of angina and fewer episodes of ST depression on ambulatory echocardiographic monitoring. A subsequent trial com- pared spinal cord stimulation to CABG.911 Subjects included 104 patients with severe angina who would not be expected to derive survival benefit from revascularization, were at increased risk of surgical complications, and were unsuitable for PCI. Patients in both groups had significant symptom relief. Those assigned to bypass surgery had greater increases in exercise capacity and less ST depression on treadmill testing than did those treated with spinal cord stimulation. Mortality and cardiovascular morbidity rates were lower in the spinal cord stimulation group. In summary, studies of spinal cord stimulation suggest that this technique might have some use as a method to relieve angina in patients with symptoms that are refractory to standard medical therapy and revascularization. There is a paucity of data on the mechanisms and long-term risks and benefits of this therapeutic approach, however. Acupuncture is used by some practitioners for the relief of acute and chronic pain. The efficacy of acupuncture in the treatment of angina pectoris has not been studied rigorously, however. In part this is due to the difficulty of blinding both patients and healthcare providers. 