The BOOST study (BOne marrOw transfer to enhance ST-elevation infarct regeneration) was the first randomized controlled clinical trial to investigate the effects of intracoronary bone marrow cell (BMC) transfer after ST-elevation myocardial infarction (STEMI). 60 patients with STEMI and successful percutaneous coronary intervention (PCI) with stent implantation were randomized 1:1 to a control (CON) or BMC group. Baseline mean left ventricular ejection fraction (LVEF) as assessed by cardiac magnetic resonance imaging (MRI) 4 days after PCI was 51.3% and 50.0% in the CON and BMC groups, respectively. As previously reported, BMC transfer led to a mean improvement of LVEF by 6.0 percentage points at 6 months (P=0.003) and 2.8 percentage points at 18 months (P=0.27) as compared to the CON group. Five years (61±11 months) after PCI, we have now assessed the clinical status and have repeated cardiac MRI in all surviving patients. 2 CON patients and 2 BMC patients had died after 5 years. The composite endpoint of death, recurrent MI, or hospitalization with heart failure occurred in 6 CON and 5 BMC patients. As compared to baseline, LVEF at 5 years had decreased by 3.3±9.5% in the CON group and by 2.5±11.9% in the BMC group (mean difference between BMC and CON, 0.8 percentage points; P=0.75). As compared to baseline, LV end-diastolic and end-systolic volume indices had increased and LV mass index had decreased at 5 years, with no significant differences between both groups. In patients with a higher baseline infarct transmurality (MRI late enhancement), BMC therapy prevented a deterioration of LVEF as compared to the CON group even at the 5-year time point (P<0.04). In conclusion, a single intracoronary application of bone marrow cells does not appear to promote a sustained improvement of LVEF in patients with STEMI and relatively preserved systolic function. It remains possible that BMCs are effective long-term in patients with more impaired systolic function and/or with preconditioning of the cells.
Intracoronary bone marrow cell transfer after myocardial infarction: 5-year follow-up from the randomized-controlled BOOST trial
