The benefit of reperfusion therapies for ST-elevation acute myocardial infarction (STEMI) is limited by post-infarction left-ventricular (LV) dysfunction. Our aim was to investigate the effect of autologous bone marrow-derived stem cell (BMSC) transfer in the infarct-related artery on LV function and structure.

We did a randomised, double-blind, placebo-controlled study in 67 patients from whom we harvested bone marrow 1 day after successful percutaneous coronary intervention for STEMI. We assigned patients optimum medical treatment and infusion of placebo (n=34) or BMSC (n=33). Our primary endpoint was the increase in LV ejection fraction and our secondary endpoints were change in infarct size and regional LV function at 4 months' follow-up, all assessed by MRI. We assessed changes in myocardial perfusion and oxidative metabolism with serial 1-[¹¹C]acetate PET. Analyses were per protocol. This study is registered with clinicaltrials.gov, number NCT00264316.

Mean global LV ejection fraction 4 days after percutaneous coronary intervention was 46·9% (SD 8·2) in controls and 48·5% (7·2) in BMSC patients, and increased after 4 months to 49·1% (10·7) and 51·8% (8·8; OR for treatment effect 1·036, 95% CI 0·961–1·118, p=0·36). Compared with placebo infusion, BMSC transfer was associated with a significant reduction in myocardial infarct size (BMSC treatment effect 28%, p=0·036) and a better recovery of regional systolic function. Myocardial perfusion and metabolism increased similarly in both groups. We noted no complications associated with BMSC transfer and all but one patient in the BMSC group completed the 4 months' follow-up.

Intracoronary transfer of autologous bone marrow cells within 24 h of optimum reperfusion therapy does not augment recovery of global LV function after myocardial infarction, but could favourably affect infarct remodelling.