CD34 and angina pectoris: Class III–IV chronic refractory angina, according to the Canadian Cardiovascular Society, despite optimal medical management, and be ruled ineligible for further revascularization via PCI involving stenting or bypass surgery with at least seven angina attacks per week and restricted exercise tolerance. Three dosages of CD34+ cells—1 x 104, 1 x 105, or 5 x 105 cells per kilogram—were given to patients at random, along with a placebo. For this study, a total of 37 patients who received autologous CD34+ cells were involved. 13.5% of patients were female, with a mean age of 57.9 ±7.5 years.