Abstract No. 100: A retrospective comparison of available self-expanding covered stents in dialysis fistulas including acute occlusion rate, primary patency, and primary assisted patency

Abstract

PurposeStenosis at the venous anastomosis or the outflow vein is a common cause of failure of arteriovenous fistulas and grafts in dialysis patients. These lesions are commonly treated with covered self-expanding stents, the most common of which are Flair (Fla), Fluency (Flu), and Viabahn (V). The aim of this retrospective study is to compare these three stents in terms of acute occlusion, primary patency, and primary assisted patency.Materials and MethodsThe IR database was reviewed over the last 4 years and all covered stents that were placed in a venous anastamosis or peripheral venous outflow in dialysis access sites were placed into one of three groups: Fla, Flu, or V. The following data was recorded: number of acute occlusions (defined as clotted access within 30 days), primary patency (defined as days until reintervention), and primary assisted patency(defined as total follow up days until an endpoint was reached). Endpoints include last follow-up, access failed, kidney transplant, or death. Other data including stent diameter and total number of interventions were also recorded.Results51 patients out of 536 patients treated with fistulograms over the last 4 years were included in the study. While trends favored superiority of the Flu stent in every category, statistical significance was not achieved. Post-hoc sample size calculations revealed that with an alpha = 0.05 significance and a desired power of 80%, with the sizes observed for primary patency and primary assisted patency we would need approximately 110 patients per group to detect a significant difference.ConclusionTabled 1Flair (n=20)Fluency (n=23)Viabahn (n=18)p-value# of interventions3.45 + 3.023.87 + 3.523.06 + 2.180.95671Occluded in 30 days30.00% (6/20)13.04% (3/23)27.78% (5/18)0.379221st intervention (Primary patency)114.90 + 115.01183.13 + 216.4297.11 + 120.070.33501Total follow-up (primary assisted patency)215.20 + 161.86370.22 + 390.88234.22 + 221.850.669411) p-value derived using the non-parametric Kruskal-Wallis test 2) p-value derived using Fisher's Exact test. Open table in a new tab PurposeStenosis at the venous anastomosis or the outflow vein is a common cause of failure of arteriovenous fistulas and grafts in dialysis patients. These lesions are commonly treated with covered self-expanding stents, the most common of which are Flair (Fla), Fluency (Flu), and Viabahn (V). The aim of this retrospective study is to compare these three stents in terms of acute occlusion, primary patency, and primary assisted patency. Stenosis at the venous anastomosis or the outflow vein is a common cause of failure of arteriovenous fistulas and grafts in dialysis patients. These lesions are commonly treated with covered self-expanding stents, the most common of which are Flair (Fla), Fluency (Flu), and Viabahn (V). The aim of this retrospective study is to compare these three stents in terms of acute occlusion, primary patency, and primary assisted patency. Materials and MethodsThe IR database was reviewed over the last 4 years and all covered stents that were placed in a venous anastamosis or peripheral venous outflow in dialysis access sites were placed into one of three groups: Fla, Flu, or V. The following data was recorded: number of acute occlusions (defined as clotted access within 30 days), primary patency (defined as days until reintervention), and primary assisted patency(defined as total follow up days until an endpoint was reached). Endpoints include last follow-up, access failed, kidney transplant, or death. Other data including stent diameter and total number of interventions were also recorded. The IR database was reviewed over the last 4 years and all covered stents that were placed in a venous anastamosis or peripheral venous outflow in dialysis access sites were placed into one of three groups: Fla, Flu, or V. The following data was recorded: number of acute occlusions (defined as clotted access within 30 days), primary patency (defined as days until reintervention), and primary assisted patency(defined as total follow up days until an endpoint was reached). Endpoints include last follow-up, access failed, kidney transplant, or death. Other data including stent diameter and total number of interventions were also recorded. Results51 patients out of 536 patients treated with fistulograms over the last 4 years were included in the study. While trends favored superiority of the Flu stent in every category, statistical significance was not achieved. Post-hoc sample size calculations revealed that with an alpha = 0.05 significance and a desired power of 80%, with the sizes observed for primary patency and primary assisted patency we would need approximately 110 patients per group to detect a significant difference. 51 patients out of 536 patients treated with fistulograms over the last 4 years were included in the study. While trends favored superiority of the Flu stent in every category, statistical significance was not achieved. Post-hoc sample size calculations revealed that with an alpha = 0.05 significance and a desired power of 80%, with the sizes observed for primary patency and primary assisted patency we would need approximately 110 patients per group to detect a significant difference. ConclusionTabled 1Flair (n=20)Fluency (n=23)Viabahn (n=18)p-value# of interventions3.45 + 3.023.87 + 3.523.06 + 2.180.95671Occluded in 30 days30.00% (6/20)13.04% (3/23)27.78% (5/18)0.379221st intervention (Primary patency)114.90 + 115.01183.13 + 216.4297.11 + 120.070.33501Total follow-up (primary assisted patency)215.20 + 161.86370.22 + 390.88234.22 + 221.850.669411) p-value derived using the non-parametric Kruskal-Wallis test 2) p-value derived using Fisher's Exact test. Open table in a new tab 1) p-value derived using the non-parametric Kruskal-Wallis test 2) p-value derived using Fisher's Exact test.