Abstract 3686: Myocardial Contrast Echocardiographic Documentation of Neovascularization in Infarct Zone in Patients with Acute Myocardial Infarction (MI): Its Relation to Bone-Marrow Derived Endothelial Progenitor Cells (EPCs)
Background It was reported that EPCs in peripheral blood play important role in the neovascularization to maintain myocardial viability after acute MI. However, there is limited clinical evidence of neovascularization in infarct zone. The aims of this study were to document neovascularization in the infarct zone with myocardial contrast echocardiography (MCE) in patients with MI in relation to amount of EPCs in peripheral blood.
Methods and Results Study population consisted of 17 patients with acute MI undergoing primary PCI. We performed triggered end-systolic MCE image at every 6 cardiac cycles with continuous infusion of Levovist at days-2 and 14. We measured video intensity (VI) of whole, center and margin of infarct zone and of normal myocardium in order to evaluate the microvascular integrity. We expressed VI of infarct zone as a ratio to VI of normal myocardium (VI ratio). White blood cells (WBCs) and CD34 positive (CD34+) cells were counted at days-1, 7 and 14. Results At day-2, 5 patients (29%) showed no-reflow phenomenon, but all patients showed contrast enhancement at day-14. VI ratio increased significantly from day-2 to day-14 in whole and center of infarct zone (0.88±0.13 vs. 1.06±0.20, p<0.005, 0.79±0.17 vs. 1.09±0.31, p<0.01). Ratio of CD34+ cells to total WBCs significantly (p<0.05) increased from day-1 to day-7 and kept high level at day-14 (10.5±6.8×10-5 vs. 32.3±19.8×10-5 vs. 26.4±14.3×10-5). Percent increase in CD34+ cells from day-1 to day-7 was correlated with improvement in VI ratio of whole, center and margin of infarct zone (r2=0.66, p<0.0001, r2=0.615, p<0.0005, r2=0.68, p<0.0001, respectively)
Conclusion Improvement in microvascular integrity, that reflects coronary neovascularization, occurs in infarct zone in patients with reperfused acute MI. And the improvement of microvascular integrity was associated with the increase of EPCs at day-7 after the onset of acute MI.