Granulocyte colony-stimulating factor for stem cell mobilisation in acute myocardial infarction: a randomised controlled trial

Background To determine whether granulocyte colony-stimulating factor (G-CSF) improves clinical outcomes after large ST-elevation myocardial infarction (STEMI) when administered early in patients with left ventricular (LV) dysfunction after successful percutaneous coronary intervention (PCI). Methods STEM-AMI OUTCOME was designed as a prospective, multicentre, nationwide, randomised, open-label, phase III trial (ClinicalTrials.gov ID: NCT01969890) to demonstrate the efficacy and safety of early G-CSF administration in reducing 2-year cardiac mortality and morbidity in patients with STEMI with LV ejection fraction ≤45% after PCI. The primary outcome was a composite of all-cause death, recurrence of myocardial infarction and hospitalisation for heart failure. Due to low recruitment and event rates, the study was discontinued and did not achieve adequate statistical power to verify the hypothesis. Results Patients were randomly allocated to G-CSF (n=260) or standard of care (SOC; n=261). No difference was found in the composite primary outcome between study groups (HR 1.20; 95% CI 0.63 to 2.28). The 2-year mortality was 2.31% in the G-CSF and 2.68% in the control group (HR 0.88; 95% CI 0.29 to 2.60). Adverse events did not differ between the G-CSF (n=65) and SOC groups (n=58; OR 1.17; 95% CI 0.78 to 1.75). In post hoc analyses on the intervention group, we observed a trend towards fewer composite primary outcomes in patients with low bone marrow (BM) cell mobilisation (n=108) versus those with high mobilisation (n=152, with peak leucocyte count >50×109/L; HR 2.86; 95% CI 0.96 to 8.56). Primary outcomes were lower in patients with severe LV systolic dysfunction at discharge treated with G-CSF than in controls (interaction β±SE, −0.08±0.04; p=0.034). Conclusions Although inconclusive, this is the largest trial in the field of cell-based cardiac repair after STEMI providing evidence of the tolerability and long-term safety of G-CSF treatment. The results prompt further studies to understand which patient can benefit most from BM cell mobilisation.