Preimplant vein intimal thickness is not a predictor of bypass graft stenosis

Preimplant vein morphology has been implicated as a risk factor for subsequent vein graft failure. It is controversial whether microscopic intimal thickening in random saphenous vein biopsy specimens is associated with an increased risk of graft failure. The purpose of this study was to determine the incidence of preexisting intimal thickening in a macroscopically normal preimplant vein, and to evaluate whether preimplant vein intimal thickness was predictive of future vein graft stenosis.

As part of an ongoing protocol, samples of preimplant veins were obtained at the time of the primary leg bypass. Routine duplex surveillance identified 14 patients who required operative revision for severe graft stenosis (n = 12) or graft occlusion (n = 2). Verhoeff's staining of specimens was performed to delineate the internal elastic lamina. Morphometric analysis of preimplant vein specimens was performed. The results were compared to a control group of 13 preimplant vein specimens selected from patients whose grafts have remained patent and stenosis-free by duplex.

Preoperative risk factors were identical between the two groups. Mean intimal thickness in all 27 specimens was measured by two blinded observers. Almost 50% of specimens exhibited marked intimal thickening (>0.08 mm). The mean preimplant intimal thickness of the stenosis group was 0.108 mm +/- 0.155 compared to 0.100 mm +/- 0.064 for the control group (P = 0.866, NS).

Although grossly normal preimplant veins often exhibit prominent microscopic intimal thickening, preimplant vein intimal thickness determined from a random saphenous vein biopsy at the time of primary leg bypass is not predictive to the subsequent development of vein graft stenosis.