Principal Findings:

Bone marrow cell harvest volume averaged 130 ml, with 304 million total nucleated cells and 172 mononuclear cells. The infarct artery was in the left coronary in 62% of patients and in the right coronary in 37%. Post-PCI TIMI flow grade 3 was present in 91% of patients. All but one patient received aspirin, and glycoprotein IIb/IIIa inhibitors were used in 78% of the bone marrow group and 64% of the placebo group.

Global left ventricular (LV) ejection fraction increased by 2.1% in the bone marrow group, and 3.9% in the placebo group. LV mass index at four months was lower in the bone marrow group compared with the placebo group (p=0.018), as was infarct size (p=0.036). Similar results were observed in infarct size in the subgroup of patients who underwent PCI within six hours and in patients with infarct size >20% of LV mass index.

There was no difference in change in systolic wall motion from baseline to four months in the infarct region (1.1 mm for placebo vs. 0.6 mm for bone marrow, p=0.49) or in the border zone (1.1 mm vs. 0.6 mm, p=0.94). However, end diastolic wall thickness reduction was larger in the bone marrow group compared with placebo in both the infarct region (-1.7 mm vs. -1.2 mm, p=0.04) and the remote area (-0.9 mm vs. -0.4 mm, p=0.05). There were no differences in PET perfusion indices or metabolic indices in the infarct region or in the border zone.

There were no differences in adverse events during admission or at four-month follow-up, with atrial tachycardia on Holter in 19% of the bone marrow group and 15% of the placebo group.