The collateral circulation of the heart

Table 2 Factors that have been tested to improve collateral circulation

Method (references)	Positive effect^a	Application	Remarks
Exercise [50], [51]	Yes		No randomized data, increase in CFI.
External counterpulsation [47]	Yes		One randomized controlled trial (RCT), observational studies, increase in CFI, improvement of angina symptoms
GM-CSF [45, 52]	Yes	Intracoronary, subcutaneous	Two small RCTs (n = 21, n = 12). Stopped early because of potential plaque destabilization. Increase in CFI.
G-CSF [44]	Yes	Subcutaneous	One small randomized trial (n = 52). Increase in CFI.
Dipyridamole [53]	Yes		Very small trial (n = 30); angiographic collateral assessment, which is not very accurate
VEGF [54]	No	Intracoronary	No difference in angina symptoms or exercise tolerance
FGF4 (adenovirus) [55]	No	Intracoronary	No change in exercise tolerance

^aBased on a random effects meta-analysis model if more than one study.
CFI, collateral flow index; FGF4, fibroblast growth factor 4; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte-macrophage colony-stimulating factor (GM-CSF); VEGF, vascular endothelial growth factor.

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