The effect of in-stent restenosis on hemodialysis access patency.

Endovascular stents have recently been shown to extend access patency in thrombosed and stenotic arteriovenous grafts (AVG). Concern remains over the frequency and severity of in-stent restenosis, though this has not been rigorously defined to date. The study was a retrospective analysis of hemodialysis patients referred for access dysfunction during a 2-year period. Using a prospectively collected, vascular access database, we identified 76 patients seen for follow-up angiography due to access dysfunction after stent placement. We compared the effect of in-stent restenosis vs. de novo lesions in patients with previously placed endovascular stents. Measured outcomes were primary assisted patency and frequency of in-stent and de novo lesions. Thirty-five (46.1%) patients had de novo lesions, while 41 (53.9%) had in-stent restenosis. In-stent restenosis was found to be the only factor associated with severity of luminal stenosis (beta=0.35, 95% confidence interval 2.21-15.48, P=0.01). In-stent restenosis was associated with increased primary patency among AVGs (hazards ratio 3.10; 95% confidence interval 1.35-7.10; P=0.008). Primary patency of in-stent restenosis vs. de novo lesions for AVGs were respectively: 78% vs. 94% at 1 month, 56% vs. 42% at 3 months, 33% vs. 6% at 6 months. For arteriovenous fistulae, the difference in primary patency of in-stent vs. de novo lesions was not statistically significant. In-stent restenosis is associated with higher percent luminal diameter lesions, while de novo lesions rather than in-stent restenosis are associated with higher risk of AVG access failure and reduced primary patency.