248 Presence of endothelial colony-forming cells is associated with reduction of microvascular obstruction limiting infarct size and left ventricular remodelling: MRI study in acute myocardial infarction

Background Endothelial colony-forming cells (ECFCs) have proliferative and vasculogenic capacities and can be detected in patients (pts) with myocardial infarction (MI). High ECFC levels reportedly lead to positive left ventricular (LV) remodelling after acute MI, but the mechanism of this improvement has never been assessed. We evaluated the relationship between ECFC levels and microvascular obstruction (MVO), and the impact of this relation on infarct size and LV remodelling at 6 months as assessed by magnetic resonance imaging (MRI). Methods 109 pts Results ECFC colonies were detected in 51/109 pts (47.2%) at admission (ECFC pos pts). At 5 days, MVO was more frequently observed (63% vs 33%; p = 0.003) and of greater magnitude (7 ± 6% vs 3 ± 5%, p = 0.0004) in ECFC neg patients versus ECFC pos pts respectively. At 6 months, there was a significantly greater reduction in infarct size in ECFC pos pts (−33.7 ± 33.2% vs −15.1 ± 24.6%, ECFC pos vs ECFC neg respectively; p = 0.003). This reduction in infarct size was associated with a significant improvement in LV ejection fraction and a significant reduction in LV end diastolic and systolic volumes in ECFC pos pts. A significant positive correlation was observed among ECFC pos pts between MVO at day 5 and infarct size at 6 months (r 2 =0.58, p 2 =0.33, p Conclusion The presence of ECFC colonies is associated with a reduced degree of microvascular obstruction early after myocardial infarction, leading to reduced infarct size and positive LV remodelling at 6 months and can be considered as a marker of microvascular integrity in acute MI pts.