G-CSF in patients suffering from late revascularized ST elevation myocardial infarction: Analysis on the timing of G-CSF administration

Objective Granulocyte colony-stimulating factor (G-CSF) improves myocardial function after infarction in vivo. Placebo-controlled clinical studies failed to show beneficial effects on myocardial function. Recent data demonstrate that the time point of treatment initiation may be crucial for the efficacy of G-CSF. We investigated the influence of the timing of G-CSF treatment on myocardial function and perfusion in a subgroup study of the G-CSF–ST Elevation Myocardial Infarction trial. Materials and Methods Patients with late revascularized myocardial infarction (n = 44) were treated with either G-CSF or placebo over 5 days after successful percutaneous coronary intervention (PCI). Of the G-CSF group, 13 patients had received G-CSF early treatment started within 24 hours after PCI (mean: 16 ± 6 hours). In 10 patients, G-CSF was initiated late (>24 hours after PCI, mean: 49 ± 26 hours). Global and regional myocardial function and perfusion were assessed from baseline to 3 months after PCI using magnetic resonance imaging in 37 patients who completed magnetic resonance follow-up. Results G-CSF was safe when used early or late after PCI. Early G-CSF administration resulted in significantly improved perfusion at rest 1 month after PCI when compared to placebo (Up-slope, signal intensity 1.2 [0.4–1.8] vs 0.6 [0.1–1.3], p = 0.03). Timing of G-CSF had no influence on global and regional function. Conclusion This post-hoc analysis indicates that timing of G-CSF after myocardial infarction does not improve myocardial function but myocardial perfusion if the cytokine is given early. This urges the need to investigate alternative dosage regimens or combination with novel therapeutics promoting mobilization and homing.