Abstract 3419: Positive Effect of Bone Marrow Progenitor Cell Transfer on Regional Post Infarction Ventricular Remodeling by Magnetic Resonance Imaging. Insights from the REPAIR AMI Trial.

Objective : The acute loss of myocytes during infarction increases loading conditions, which in turn triggers adverse remodeling of infarcted, adjacent and remote regions. Late Gadolinium Enhancement (LGE) cardiac MRI (CMR) can distinguish these regions and thus determine the effect of bone marrow progenitor cell (BMC) therapy on regional remodeling and function. Methods : 47 patients from the REPAIR AMI trial who underwent CMR at baseline and 12 month were evaluated in a segment by segment fashion according to the AHAs 17 segment model, defining LGE positive segments as infarcted and LGE negative segments as adjacent or remote. We measured enddiastolic wall diameters (WD) and wall thickening (WT) at 0 and 12 month by serial MRI. Results : WD decreased in all patients and all segments with a tendency to smaller diameters in BMC treated patients. In the prespecified subgroup of patients with larger infarcts (EF below the median of 48.9%) we observed a positive effect on adverse remodeling in BMC patients not only in infarcted but also in the remote areas. Infarcted segments showed a decrease in WD of 21.9% ± 4.0 SE in the BMC group vs. 8.5% ± 3.4 in the Placebo Group p=0.02. In BMC patients WD decreased in remote segments by 8.1% ± 4.4 SE compared to 4.9% ± 3.3 SE in the Placebo group, p=0.03. This effect on remodeling translates into a functional benefit. In remote segments WT decreases in both gropus but significantly so only in Placebo patients (BMC-7.8% ± 5.4 p= 0.2 vs. Placebo −13.9% ± 4.4 p=0.002, p for interaction 0.4). The largest effect was observed in the infarcted segments where BMC therapy led to an increase in WT of 26.6% ± 5.1 SE compared to Placebo 0.7% ± 4.6 SE p= 0.0001. The positive effect is mediated by wall diameters, regression analysis shows a significant inverse relationship between WD and WT, p = 0.0001 Conclusion : BMC therapy effectively prevents adverse remodeling not only in the infarct zone but also in remote segments for patients with large infarcts resulting in increased contractility. This seems to be mediated by a positive effect on enddiastolic wall geometry yielding smaller wall diameters.