In-stent neo-intimal hyperplasia after stem cell mobilization by granulocyte-colony stimulating factor Preliminary intracoronary ultrasound results from a double-blind randomized placebo-controlled study of patients treated with percutaneous coronary intervention for ST-elevation myocardial infarction (STEMMI Trial).

The influence of treatment with granulocyte-colony stimulating factor (G-CSF) on the development of in-stent intimal hyperplasia is not known. We aimed to study this phenomenon in patients who had stents implanted in the course of an acute ST-elevation infarction and successively were treated with G-CSF. We performed angiography and intracoronary ultrasound follow-up after 5 months in 41 consecutive patients in the STEMMI trial, which is a randomized double-blind placebo-controlled study on the effect of G-CSF injections on the myocardial function following acute myocardial infarction in patients treated with primary percutaneous coronary stent implantation. The intracoronary ultrasound images were analyzed by a blinded and independent core laboratory. There were no differences in in-stent neo-intimal hyperplasia determined by intracoronary ultrasound between patients treated with G-CSF compared to patients treated with placebo. Neo-intimal hyperplasia per mm of stent was 1.87 (+/-1.41) and 1.89 (+/-1.39), respectively (p = 0.97). Angiographic in-segment restenosis (>50% diameter stenosis) was found in 28% of patients (24% in the G-CSF group and 33% in the placebo group; p = 0.55). G-CSF treatment following coronary stent implantation in primary PCI treated AMI patients does not increase in-stent restenosis excessively and it does not seem warranted to limit further study of effects of G-CSF for that reason.