CD34 and atrial fibrillation: Three consecutive, randomized, double-blinded, placebo-controlled trials in the United States, in patients with obstructive coronary artery disease (CAD) and Canadian Cardiovascular Society (CCS) class 3–4 refractory angina, established the feasibility of the intra-myocardial delivery of auto-CD34+ cells, showing significant improvements in short- and long-term anginal frequency (AF) and total exercise time (TET) [15,16,18].