Safety of Bone Marrow Stem Cell Mobilization Induced by Granulocyte-Colony Stimulating Factor: 30 Days’ Blinded Clinical Results from the Stem Cells in Myocardial Infarction (STEMMI) Trial

Background: Mobilization of circulating stem cells from the bone marrow with granulocyte-colony stimulating factor (G-CSF) might promote the repair of myocardial damage after ST-elevation myocardial infarction. However, concern has been raised about the safety of G-CSF. Objective: To determine the short-term (30 days) safety of G-CSF therapy after an ST-elevation myocardial infarction treated with acute percutaneous coronary intervention (PCI). Methods: Patients with an ST-elevation myocardial infarction (treated with PCI <12 h after symptom onset) were enrolled in the STEMMI trial and randomized to G-CSF (10 µg/kg/day) or placebo for 6 days in a double-blind design. Clinical follow-up for this report was done after 1 month. The treatment allocation remains blinded and long-term follow-up is ongoing. Results: Seventy-eight patients (age 56 ± 8.4 years, 80% males, maximal creatine kinase MB 307 ± 193 µg/l) were included. G-CSF treatment was initiated 1 day (range 0–2) after PCI. Three (4%) patients suffered major adverse cardiac events in the first 30 days (1 died in progressive shock, 1 had a subacute stent thrombosis, and 1 developed significant mitral valve regurgitation). No patients had symptoms of early aggressive restenosis, and there were no cases of unstable angina or re-infarction. Eleven patients had minor musculoskeletal pain during the G-CSF treatment period. Conclusion: In this relatively small population of patients there were few major adverse cardiac events and G-CSF treatment after ST-elevation myocardial infarction seemed safe in the short (30 days) term. Further studies of long-term safety will clarify the future role of G-CSF treatment in this setting.