Time to symptomatic vascular stenosis at different locations in patients with arteriovenous grafts

Most arteriovenous grafts fail due to irreversible thrombosis, superimposed on hemodynamically significant vascular stenosis. Previous studies observed the highest frequency of stenosis at the venous anastomosis, without addressing the timing of stenosis. The present study quantified time to symptomatic stenosis at different vascular locations, and related it to permanent graft failure. A prospective computerized vascular access database was queried retrospectively to identify 309 hemodialysis patients receiving new upper extremity grafts during a 4-year period at a large dialysis center. For each vascular site we calculated the time to symptomatic stenosis using survival techniques. The cumulative likelihood of symptomatic stenosis at 2 years was 67% for venous anastomotic stenosis, 19% for intra-graft stenosis, 16% for venous outlet stenosis, 13% for central vein stenosis, and 5% for arterial anastomotic stenosis. The cumulative risk of graft failure at 2 years was 40%. Stenosis at the venous anastomosis was twice as likely as cumulative graft failure (hazard ratio [HR] 1.95; 95% confidence interval [CI], 1.65-2.52, p < 0.001). In contrast, intra-graft stenosis was half as likely as cumulative graft failure (HR 0.45; 95% CI, 0.36-0.61, p < 0.001). Central vein stenosis was more likely in patients with a previous ipsilateral catheter compared with those without one (HR 2.40; 95% CI, 1.39-5.58, p = 0.004). Symptomatic stenosis occurs much earlier at the venous anastomosis compared with other vascular sites. Moreover, preexisting ipsilateral internal jugular dialysis catheters more than double the risk of central vein stenosis.