Samer Mansour1; Nicolas Noiseux1; Roy Denis-Claude2; Gobeil Francois3; Alain Rivard3; Guy Leclerc3
1 CRCHUM， Montreal， Canada2 HMR， Montreal， Canada3 CRCHUM， Montreal， Canada 
    BACKGROUND: Bone Marrow Stem cell therapy has emerged as a promising approach to improve healing of the infarcted myocardium， to treat cardiac failure and to restore lost cardiac function. Despite initial excitement， recent clinical trials using non-homogenous human stem cells preparations showed variable and mixed results， raising concerns about the best cell type to transplant. Selected CD133+ hematopoeitic stem cells are candidate cells with high potential.
OBJECTIVE: The purpose of this study is to report the security of the intra-coronary injection of CD133+ stem cells for cardiac repair in patients with dysfunctional myocardium following acute myocardial infarction (MI). 
    METHODS AND RESULTS: We report on the first 20 patients that were enrolled in the COMPARE-AMI， the first double randomized controlled trial comparing the safety， efficacy and functional effect of intra-coronary injection of selected CD 133+ cells following acute myocardial infarction. The mean age was 51.2±8.6 years with a predominance of males (90%); culprit lesion was located on the left anterior descending artery in 90%， maximum troponin and CKMB were 8.7±7.5 Ug/L and 340.6±261.4 U/L respectively. To date， there is no protocol-related complication to report such as death， MI， stroke， or sustained ventricular arrhythmia. Re-PCI was necessary at 4 months of follow-up in 2 patients to treat in-bare metal stent restenosis. Fractional flow reserve (FFR) was significantly lower in the stented-culprit artery compared to the non-culprit artery at baseline: 0.88±0.05 vs 0.96±0.04， P=0.000002. However， at 4 months follow-up (n=14) no significant difference was found in the delta FFR compared to baseline in the culprit vs non-culprit artery (–3.8%±7.36 vs –1.1%±4.4 respectively， P=0.24) suggesting no acceleration of the atherosclerosis by the treatment. Finally， at 4 month of follow-up， MRI assessment of the LVEF (n=14 patients) showed a significant improvement compared to baseline (52.1%±7.1 vs 41.4%±5.1， P=0.000015). 
    CONCLUSION: Following acute MI， intra-coronary injection of CD133+ stem cells is secure and feasible， with possible beneficial effects on LVEF. COMPARE-AMI will help identify the optimal cell type that will improve cardiac recovery of the infracted myocardium.