Background: Experimentally, activated macrophages have been documented to induce vascular proliferation.
Methods and results: In 21 patients (age 74+/-9 years) with extensive coronary artery disease not eligible for coronary artery bypass surgery, the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF, Molgramostim) on quantitatively assessed collateral flow was tested in a randomized, double-blind, placebo-controlled fashion. The study protocol consisted of an invasive collateral flow index (CFI) measurement immediately before intracoronary injection of 40 microg of GM-CSF (n=10) or placebo (n=11) and after a 2-week period with subcutaneous GM-CSF (10 microg/kg) or placebo, respectively. CFI was determined by simultaneous measurement of mean aortic pressure (P(ao), mm Hg), distal coronary occlusive pressure (P(occl), mm Hg; using intracoronary sensor guidewires), and central venous pressure (CVP, mm Hg): CFI=(P(occl)-CVP)/(P(ao)-CVP). CFI, expressing collateral flow during coronary occlusion relative to normal antegrade flow during vessel patency, changed from 0.21+/-0.14 to 0.31+/-0.23 in the GM-CSF group (P<0.05) and from 0.30+/-0.16 to 0.23+/-0.11 in the placebo group (P=NS). The treatment-induced difference in CFI was +0.11+/-0.12 in the GM-CSF group and -0.07+/-0.12 in the placebo group (P=0.01). ECG signs of myocardial ischemia during coronary balloon occlusion occurred in 9 of 10 patients before and 5 of 10 patients after GM-CSF treatment (P=0.04), whereas they were observed in 5 of 11 patients before and 8 of 11 patients after placebo (P=NS).
Conclusions: This first clinical study investigating the potential of GM-CSF to improve collateral flow in patients with coronary artery disease documents its efficacy in a short-term administration protocol.