Why is disease progression more rapid in the proximal segments of grafted coronary arteries?

Coronary artery segments proximal to the site of graft placement are prone to accelerated atherosclerosis. This has been generally (and somewhat simplistically) attributed to competitive flows between the graft and the native vessel. A more plausible mechanism, linking the rapid induction and progression of atherosclerosis to abnormal flow patterns, and the consequent deleterious alterations in shear stress, is presented here.