Abstract 5731: An Increase of Intrinsic Endothelial Progenitor Cells after Acute Myocardial Infarction was Associated with Spontaneous Neovascularization but not with Improvement of Left Ventricula Remodeling
Endothelial progenitor cells (EPC) increase after acute myocardial infarction and may contribute to neovascularization in the infarct zone. The aim of this study was to elucidate the relation of EPC release to recovery of microvascualr and myocardial function. Eighteen patients with acute myocardial infarction (AMI) undergoing primary PCI within 12 hours after onset were enrolled. CD34+ cells were counted at days-1, 7 and 14 as an index of EPC. We performed triggered end-systolic myocardial contrast echocardiography (MCE) at every 6 cardiac cycles with continuous infusion of Levovist at days-2 and 14. We performed left ventriculography 6 months later to calculate left ventricular ejection fraction (LVEF) and end-diastolic volume index (LVEDVI). The number of EPC at day-7 was significantly higher than that at day-1 (1.29+/−0.75 vs. 2.10+/−1.25/micL, p<0.001). It was correlated with myocardial blood volume (MBV), that implies microvascular integrity, at day-14 measured from MCE image (r2=0.652, p<0.005) and with an increase in MBV from day-1 to day-7 (r2=0.533, p<0.005). To evaluate the correlation between EPC and LV function, we divided patients into two groups according to the number of EPC at day-7. LVEF and LVEDVI were comparable between the higher number of EPC and the lower number of EPC groups (49.3+/−12.2 vs. 52.4+/−8.1%, 65.2+/−13.1 vs. 69.1+/−16.6ml/m2). EPC spontaneously released after AMI and number of released EPC is correlated to the amount of neovascularization in the infarct zone. The number of EPC was not necessarily related to the functional improvement or attenuation of LV remodeling.