Does rich coronary collateral circulation distal to chronically occluded left anterior descending artery compete with graft flow?

In coronary artery bypass grafting (CABG), graft flow distal to a mild stenosis can compete with relatively preserved native flow through the stenosis and the competition can result in graft stenosis. In chronic total occlusion (CTO), coronary collateral circulation, which is essential to maintain myocardial viability distal to CTO, varies in extent among patients and the extent can be scored by Rentrop grade in coronary angiography. We investigated whether rich collateral circulation distal to CTO competes with distally anastomosed graft flow in association with Rentrop grade.