Efficacy and Safety of Targeted Intramyocardial Delivery of Auto CD34+ Stem Cells for Improving Exercise Capacity in Subjects With Refractory Angina

Main Inclusion Criteria: * Male or female participants who are 21 to 80 years of age at the time of signing the informed consent. * Participants with Canadian Cardiovascular Society (CCS) class III or IV chronic refractory angina. * Participants without control of their angina symptoms in spite of maximal tolerated doses of anti-angina drugs. Participants must be on optimal therapy for their angina and must have been on a stable anti-anginal medication regimen for at least 4 weeks before signing the informed consent form. * Participants with obstructive coronary disease unsuitable for conventional revascularization due to unsuitable anatomy or comorbidity as determined at the site and confirmed by an independent adjudication committee. * Participants must have evidence of inducible myocardial ischemia. * Participants must experience angina episodes. * Participants must be able to complete 2 exercise tolerance tests on the treadmill within 3 weeks of randomization. * If female of childbearing potential, subject must not be pregnant and agree to employ adequate birth control measures for the duration of the study. Main Exclusion Criteria: * Cardiovascular hospitalization within 60 days prior to potential study enrollment. Participant has had a successful or partially successful coronary artery bypass graft (CABG) within 6 months or PCTA within 60 days of potential study enrollment. * Participant has had a placement of a bi-ventricular pacemaker for cardiac resynchronization therapy (CRT) for heart failure within 180 days of potential study enrollment. * Participant has documented stroke or transient ischemic attacks (TIAs) within 60 days of potential study enrollment. * Participant has a history of moderate to severe aortic stenosis; or severe aortic insufficiency; or severe mitral stenosis; or severe mitral insufficiency. * Participant has a prosthetic aortic valve or a mechanical mitral valve replacement. * Participant has severe co-morbidity associated with a reduction in life expectancy to less than 3 years as a result of chronic medical illnesses. * Participants with cancer are excluded with the following exceptions: * Subjects with in-situ non-melanoma skin cancer or in-situ cervical cancer are not excluded. * Participants that have been cancer free for \>= 5 years as determined by their oncologist are not excluded. Subjects with a prior history of stem cell transplant for cancer are excluded no matter how long they have been cancer-free. * Participants with a history of leukemia or other bone marrow disease. * Participant has sickle cell disease or sickle cell trait. * Participants with proliferative retinopathy. * Participants with Hb A1c \> 9%. * Participant has platelet counts \>10% above the upper limit of normal (ULN) or platelet counts \< 70,000. * Participant has a hematocrit \< 30% prior to potential study enrollment. * Participant has a serum creatinine \> 2.5 mg/dL prior to potential study enrollment. * Participant tests positive for HIV, hepatitis B, or hepatitis C, or is on chronic immunosuppressive medications, or has had a previous stem cell transplant. * Participant has a known contraindication to Neupogen (filgrastim) or G-CSF. * Participant was previously enrolled in an active treatment group of cell therapy trials for cardiovascular disease including any phase of CD34+ stem cell trials. * Left ventricular (LV) thickness of \< 7 mm in the target areas of injection as measured by during a 2-D echocardiogram (ECHO). * Atrial fibrillation, atrial flutter, or other uncontrolled arrhythmias that would prohibit accurate electromechanical mapping and NOGA-guided intramyocardial injection. * Bleeding diathesis with an INR \> 1.8 when not receiving anti-thrombotic therapy. * Hepatic dysfunction as evidenced by elevated AST or ALT levels \> 2.5 x ULN. * Any previous transplant requiring immunosuppression. * Disease state requiring chronic immunosuppression.