An Economic Analysis of Stent Grafts for Treatment of Vascular Access Stenosis: Point-of-Care and Medicare Perspectives in the United States

Six-Month Outcomes from the Prospective, Multi-Center, Non-Randomized Clinical Study of the COVERA(™) Arterio VeNous (AV) Stent Graft in the Treatment of Stenosis in the VEnous OutfloW of AV Fistula Access Circuits (AVeNEW PAS)

PURPOSE

The AVeNEW Post-Approval Study (AVeNEW PAS) follows upon results from the AVeNEW IDE clinical trial and was designed to provide additional clinical evidence of safety and effectiveness using the Covera™ Vascular Covered Stent to treat arteriovenous fistula (AVF) stenoses in a real-world hemodialysis patient population.

MATERIALS AND METHODS

One hundred AVF patients were prospectively enrolled at 11 clinical trial sites in the USA and treated with the covered stent after angioplasty of a clinically significant target stenosis. The primary safety outcome was freedom from any adverse event that suggests the involvement of the AV access circuit evaluated at 30 days. The primary efficacy outcome was Target Lesion Primary Patency (TLPP) at six months, determined by an independent core laboratory. Secondary outcome measures included technical success defined as successful deployment to the intended location and access circuit primary patency (ACPP).

RESULTS

Safety was 94.9% with no device-related deaths nor in-patient hospitalization. Technical success was 100%. TLPP rates at 1, 3, and 6 months were 100, 89.7, and 82.2%. ACPP rates at 1, 3, and 6 months were 98, 76.3, and 60.0%. Target stenoses were 81% restenotic, and 75% located in the cephalic vein arch. There were 35% non-target stenoses treated with angioplasty during the index procedure.

CONCLUSION

The 6-month results of the AVeNEW PAS confirm results from the AVeNEW IDE clinical trial and demonstrate safety and efficacy using the Covera(™) Covered Stent in a real-world US hemodialysis patient population.

TRIAL REGISTRATION

NCT04261686.

LEVEL OF EVIDENCE

3 - prospective, multicenter.

Salvage treatment of forearm arteriovenous fistula with small caliber inflow distal artery by percutaneous transluminal angioplasty

BACKGROUND

Dysfunctional distal arteriovenous fistulas (AVFs) with small caliber distal inflow arteries theoretically require percutaneous transluminal angioplasty (PTA) throughout the entire arterial length. However, in clinical practice, whole distal inflow arterial PTA is not frequently performed due to concerns about possible arterial rupture. Therefore, we investigated the safety and efficacy of this procedure at our center, comparing it with the standard venous PTA.

METHODS

From March 2017 to December 2022, 48 cases of distal AVF salvaged by whole distal inflow arterial PTA were assigned into a treatment group and 121 cases of distal AVF salvaged by venous standard PTA not involving the whole inflow artery were assigned into a control group. These two groups were then compared.

RESULTS

Those in the treatment group (who received whole distal inflow arterial PTA) were older than those in the control group (mean age, 69 vs 59 years, p < 0.001). Otherwise, differences between the two groups were unremarkable. After the salvage treatment, primary patency seemed to decrease in the treatment group with whole distal inflow arterial PTA compared to the control group with conventional PTA, although such decrease was not significant (p = 0.072). However, primary assisted patency and secondary patency were comparable between the two groups (p = 0.350 and p = 0.590, respectively). And in the treatment group, only one arterial dissection occurred, which was successfully managed with balloon tamponade so that no distal AVF was abandoned due to complications following whole distal inflow arterial PTA.

CONCLUSION

Whole distal inflow arterial PTA is an effective and safe option for distal AVF salvage with a narrowed inflow artery, frequently refractory to conventional venous PTA.

Nitric oxide in the cardio-cerebrovascular system: Source, regulation and application

Nitric oxide (NO) plays a crucial role as a messenger or effector in the body, yet it presents a dual impact on cardio-cerebrovascular health. Under normal physiological conditions, NO exhibits vasodilatory effects, regulates blood pressure, inhibits platelet aggregation, and offers neuroprotective actions. However, in pathological situations, excessive NO production contributes to or worsens inflammation within the body. Moreover, NO may combine with reactive oxygen species (ROS), generating harmful substances that intensify physical harm. This paper succinctly reviews pertinent literature to clarify the in vivo and in vitro origins of NO, its regulatory function in the cardio-cerebrovascular system, and the advantages and disadvantages associated with NO donor drugs, NO delivery systems, and vascular stent materials for treating cardio-cerebrovascular disease. The findings provide a theoretical foundation for the application of NO in cardio-cerebrovascular diseases.

Prognostic nomogram for the patency of wrist autologous arteriovenous fistula in first year

Autologous arteriovenous fistula (AVF) is preferred in hemodialysis patients. Maintaining its patency is a critical problem. This study aimed to create a nomogram model for predicting 1-year primary patency of AVF. Consequently, a total of 414 patients were retrospectively enrolled and randomly allocated to training and validation cohorts. Risk factors were identified by multivariable logistic regression and used to create a nomogram model. Performance of the model was evaluated by receiver operating characteristic (ROC) curve, Hosmer-Lemeshow test, and calibration curve. The results suggested that diameter of cephalic vein, low-density lipoprotein, glycosylated hemoglobin (%), and C-reactive protein were risk factors which could predict the patency of AVF. Area under ROC curves for training and validation cohorts were 0.771 and 0.794, respectively. Calibration ability was satisfactory in both cohorts. Therefore, present nomogram model could predict the 1-year primary patency of AVF.

Impact on Hospital Resource Utilization of Endoluminal Bypass Using the Viabahn Endoprosthesis with Heparin Bioactive Surface Compared With Surgical Femoropopliteal Bypass

OBJECTIVE

To assess the impact of heparin-bonded endoprosthesis compared with femoropopliteal bypass on key hospital resources and revenues up to 1-year follow-up.

DESIGN

A 2-arm scenario resource consumption data analysis was modeled based on a multicentre prospective randomized controlled trial.

SETTING

Six centers in the Netherlands.

PARTICIPANTS

A total of 100 patients were assigned to 2 arms (50 each arm). The first arm evaluated endovascular treatment using the heparin-bonded Viabahn endoprosthesis and the second the femoropopliteal bypass. Resource consumption rates were compared between arms.

PRIMARY AND SECONDARY OUTCOMES MEASURES

Resource consumption rates, including hospital stay for bypass procedure, operating room time, type of anesthesia, number of used (endo)grafts, use of different types of bed locations (vascular ward, medium or intensive care), readmission for wound infections, and reinterventions over a period of 12 months.

RESULTS

Endovascular repair used fewer hospital resources, with an overall difference of €149.983. Hospital stay was 118 days less (261 vs 379), including 21 fewer days in medium/intensive care (5 vs 26) and 50 fewer operating room hours (100 vs 150). Fewer patients required general anesthesia (31 vs 39), and there were less surgical site infections (3 vs 12). In the surgical bypass group, there were 18 fewer days of hospital stay related to reinterventions (80 vs 62), and the cost of the devices was €309.996, cheaper. The total monetary difference was € 160.013, in favor of the femoropopliteal bypass (€3.200, per patient).

CONCLUSIONS

Endovascular repair of the superficial femoral artery reduces the use of valuable hospital resources. Its major limitation is the cost of the devices, which should be balanced against the reduction in peri-procedural morbidity and faster recovery. In the context of shortage of hospital beds, it offers capacity benefits, allowing for the treatment of more patients overall. These benefits may outweigh the fewer reinterventions in the surgical bypass group.

REGISTRATION

The SuperB Trial was registered in clinicaltrials.gov; NCT-ID: NCT01220245.

CLINICAL IMPACT

Modeling is a useful technique to predict the impact of treatment modalities on hospital resources and revenue. This study uses real-world data from the SuperB Trial to compare two treatment strategies of superficial femoral artery disease, reflecting actual clinical practice and patient outcomes. The analysis focused on direct costs associated with hospital resources and device usage without considering indirect costs or long-term cost-effectiveness. The analysis showed that endovascular repair reduces the use of valuable hospital resources. Its major limitation is device costs, which should be balanced against the reduction in peri-procedural morbidity and faster recovery. In the context of shortage of hospital beds, it offers capacity benefits, allowing for the treatment of more patients overall.

Pre-emptive or reactive treatment, angioplasty or stent-graft? The outcome for interventions for venous stenosis in early-cannulation arteriovenous grafts

BACKGROUND

Early-cannulation arteriovenous grafts (ecAVG) have good initial patency, but frequent episodes of reintervention for venous stenosis (VS) and thrombosis limit their use. Stent grafts (SG) have shown promise in reducing re-interventions and improving functional patency for dysfunctional ecAVG and recurrent VS. There is little data on the impact of stent grafts as the first elective procedure for VS. The aim of this study was to determine firstly, if treating VS whilst asymptomatic has a better outcome than treating after presentation with thrombosis; and secondly, to determine the best initial treatment for asymptomatic VS: SG or angioplasty.

METHODS

A retrospective study was performed of 259 ecAVG with a sutured anastomosis. The case-mix and outcomes of 153 who presented with VS was analysed by presentation (elective at surveillance or emergency following thrombosis), and then for only elective patients, by treatment (SG vs angioplasty).

RESULTS

There was no significant difference in case-mix and time to presentation by mode of presentation (100 elective and 53 with thrombosis) other than a higher rate of pro-thrombotic disorders in thrombosed ecAVG. Thrombosed ecAVG had poorer outcomes with increased re-intervention rates and thrombosis in the following year, and reduced long-term functional patency. In patients presenting electively, primary SG rather than angioplasty led to significantly reduced thrombosis rates, a longer time to re-intervention in the following year, and superior long-term functional patency. The use of SG was the same in both groups. Both the mode of presentation and the type of intervention performed were independently predictive of a poorer subsequent functional patency.

CONCLUSIONS

Primary elective stent-grafting may be the optimal strategy to reducing maintenance costs with ecAVG.

Comparison of Clinical Outcomes in Patients Undergoing a Salvage Procedure for Thrombosed Hemodialysis Arteriovenous Grafts

Background

The major limitation of arteriovenous graft access is the high incidence of thrombotic occlusion. This study investigated the outcomes of our salvage strategy for thrombosed hemodialysis arteriovenous grafts (including surgical thrombectomy with balloon angioplasty) and evaluated the efficacy of intragraft curettage.

Methods

Salvage operations were performed for 290 thrombotic occluded arteriovenous grafts with clinical stenotic lesions from 2010 to 2018. Of these, 117 grafts received surgical thrombectomy and balloon angioplasty from 2010 to 2012 (group A), and 173 grafts received surgical thrombectomy and balloon angioplasty, with an additional salvage procedure using a curette and a graft thrombectomy catheter, from 2013 to 2018 (group B). Outcomes were described in terms of post-intervention primary patency and secondary patency rates.

Results

The post-intervention primary patency rates in groups A and B were 44.2% and 66.1% at 6 months and 23.0% and 38.3% at 12 months, respectively (p=0.003). The post-intervention secondary patency rates were 87.6% and 92.6% at 6 months and 79.7% and 85.0% at 12 months, respectively (p=0.623). Multivariate Cox regression analysis demonstrated that intragraft curettage was a positive predictor of post-intervention primary patency (hazard ratio, 0.700; 95% confidence interval, 0.519-0.943; p=0.019).

Conclusion

Surgical thrombectomy and balloon angioplasty showed acceptable outcomes concerning post-intervention primary and secondary patency rates. Additionally, intragraft curettage may offer better patency to salvage thrombotic occluded arteriovenous grafts with intragraft stenosis.

First Clinical Results of the Merit WRAPSODY™ Cell-Impermeable Endoprosthesis for Treatment of Access Circuit Stenosis in Haemodialysis Patients

PURPOSE

This prospective, observational first in human study evaluated the safety and effectiveness of WRAPSODY^TM Cell-impermeable Endoprosthesis (Merit Medical Systems, Inc.) in the treatment of arteriovenous fistula and arteriovenous graft access circuit stenosis.

MATERIALS AND METHODS

Investigators conducted a prospective analysis of 46 patients with access circuit stenosis from three centres. Treatment sites included the peripheral outflow veins (e.g. cephalic arch, basilic vein swing point; 16 fistula and 10 graft patients); the graft-vein anastomosis (9 patients); and the central veins (up to, but not including the SVC; 11 patients). Primary outcome measures included 30-day freedom from access circuit-related safety events and 30-day target lesion primary patency. Secondary outcome measures included procedural success; device- and procedure-related adverse events; target lesion primary patency; access circuit primary patency; and secondary patency. In-person follow-up was scheduled at 1, 3, 6, and 12 months. An independent data monitoring/clinical event committee adjudicated all reinterventions and device/procedure-relatedness for adverse events.

RESULTS

All initial procedures were successful. All but one patient was free from safety events through the first 30 days (97.8% (45/46)). This event was not device-related. Over the remainder of the study, one adverse event was adjudicated as possibly device-related. Six- and 12-month target lesion primary patency rates were 97.7% (42/43) and 84.6.% (33/39), respectively. Six- and 12-month access circuit primary patency rates were 84.4% (38/45) and 65.9% (29/44), respectively.

CONCLUSION

Results suggest that the study device is safe and effective for treatment of stenoses in the peripheral and central veins of arteriovenous access circuits.

LEVEL OF EVIDENCE

Level 2b, cohort study.

Covered stents versus balloon angioplasty for failure of arteriovenous access: a systematic review and meta-analysis

INTRODUCTION

Patients with end-stage renal disease may require arteriovenous (AV) access in the form of arteriovenous fistulae (AVFs) or arteriovenous grafts (AVGs) for haemodialysis. AV access dysfunction requires intervention such as plain balloon angioplasty or covered stents to regain patency.

AIM

To systematically review and meta-analyse the patency outcomes of covered stents in failing haemodialysis AV access, compared with balloon angioplasty.

METHODS

The review was first registered on the International Prospective Register of Systematic Reviews (CRD42018069955) before data collection. We searched six electronic databases to identify relevant randomised controlled trials (RCTs) up until August 2020, without language restriction. Two reviewers assessed the suitability and quality of studies for inclusion using the Consolidated Standards of Reporting Trials guidelines. We meta-analysed data using a random-effects model.

RESULTS

We included seven studies including 1147 patients in the systematic review, of which 867 had AVGs and 280 had AVFs. One study was an ongoing RCT. In the meta-analyses, we assessed patients with failing AVGs only. Overall risk of bias was moderate. Covered stents were associated with lower loss of patency versus angioplasty alone at 6, 12 and 24 months (OR 4.48, 95% CI 1.98 to 10.14, p<0.001; OR 4.07, 95% CI 1.74 to 9.54, p=0.001; OR 2.24, 95% CI 1.17 to 4.29, p=0.01, respectively). Covered stents afforded superior access circuit primary patency compared with angioplasty alone at 6 and 12 months (OR 1.91, 95% CI 1.31 to 2.80, p<0.001; OR 1.97, 95% CI 1.14 to 3.41, p=0.02, respectively). This was not significant at 24 months. There was no significant difference in loss of secondary patency between groups at 12 or 24 months (OR 0.74, 95% CI 0.45 to 1.23, p=0.25; OR 0.67, 95% CI 0.29 to 0.154, p=0.34, respectively).

CONCLUSION

Our results support use of covered stents over angioplasty alone, at 6, 12 and 24 months in failing AVGs. Further clinical trials are warranted.

A comparison of stenting versus hemodialysis reliable outflow graft for hemodialysis patients with recurrent central venous obstructions

BACKGROUND

Central venous occlusive disease is a common cause of upper extremity arteriovenous access dysfunction in hemodialysis patients. When refractory to balloon angioplasty, the treatment options include central venous stenting and hemodialysis reliable outflow (HeRO; Merit Medical, South Jordan, Utah) graft. The purpose of the present study was to evaluate the outcomes of these options.

METHODS

A retrospective review was performed of patients who had undergone central venous stenting or HeRO placement for central venous obstruction from December 2008 to March 2018. The primary outcomes were the reintervention rates, patency, and mortality.

RESULTS

A total of 75 hemodialysis patients were identified after failed balloon angioplasty for central venous obstruction. Of the 75 patients, 44 underwent central venous stenting comprising coverage of the subclavian vein (n = 27), innominate vein (n = 18), and/or superior vena cava (n = 5). Six stent patients later underwent HeRO placement. The stents used were stent grafts in 65% (Viabahn, n = 9; Fluency/Flair, n = 19; iCast, n = 2; and other, n = 1) and bare metal stents in 35% (Wall-stent, n = 6; Protégé, n = 1; Cobalt, n = 1; and other, n = 9). The remaining 31 patients underwent HeRO graft placement. The venous outflow component insertion sites were the internal jugular (n = 20), external jugular (n = 1), subclavian (n = 6), axillary (n = 2), and other (n = 2). The stent and HeRO groups were similar in the previous central venous intervention rates (median, 0.6 [interquartile range (IQR), 0-3.0]; vs median, 3.5 [IQR, 0-10.1] annually; P = .679). After the index procedure, no difference was found between the two groups in the frequency of dialysis circuit interventions annually (median, 2.0 [IQR, 0-6.0]; vs median, 2.0 [IQR, 0-7.0]; P = .291) nor central venous interventions (ie, angioplasty of the central veins or within the portion of the HeRO inside the central veins) annually (median, 2.0 [IQR, 0-4.1]; vs median, 0 [IQR, 0-2.4]; P = .419). The 1-year access circuit primary patency was 8.1% for stenting and 22.2% for HeRO (P = .109). The 2-year access circuit secondary patency was 40.0% for stenting and 52.4% for HeRO (P = .401). The all-cause mortality was similar at 1 year (3.7% vs 4.8%; P = .856) and 2 years (11.8% vs 23.5%; P = .368).

CONCLUSIONS

Central venous stenting and HeRO were shown to have similar rates of reintervention and patency. The results from the present study suggest that the multiple treatment options available for this problematic disease process can yield similar results when careful patient selection is applied.

Treatment of failing arterio-venous dialysis graft by angioplasty, stent, and stent graft: Two-years analysis of patency rates and cost-effectiveness

The objective of this prospective randomized single-center study was to compare primary and secondary patency rates, number of percutaneous transluminal angioplasty (PTA) interventions and cost-effectiveness among PTA, deployment of a stent, or a stent graft in the treatment of failing arteriovenous dialysis grafts (AVG) due to restenosis in the venous anastomosis or the outflow vein. Altogether 60 patients with failing AVG and restenosis in the venous anastomosis or the outflow vein were randomly assigned to either PTA, placement of a stent (E-Luminexx^®) or stent graft (Fluency Plus^®). After the procedure, patients with stent or stent graft received dual antiplatelet therapy for the next three months. Follow-up angiography was scheduled at 3, 6, and 12 months unless requested earlier due to suspected stenosis or malfunction of the access. Subsequently, angiography was performed only if requested by the clinician. During a median follow-up of 22.4 (IQR=5.7) months patients with PTA, stent, or stent graft required 3.1±1.7, 2.5±1.7, or 1.7±2.1 (P=0.031) secondary PTA interventions. The primary patency rates were 0, 18 and 65% at 12 months and 0, 18 and 37% at 24 months in the PTA, stent, and stent graft group respectively (P<0.0001). The cost of the procedures in the first two years was €7,900±€3,300 in the PTA group, €8,500±€4,500 in the stent group, and €7,500±€6,200 in the stent graft group (P=0.45). We conclude that the treatment of failing dialysis vascular access by the deployment of a stent graft significantly improves its primary patency rates and decreases the number of secondary PTA interventions; however, the reduction in costs for maintaining AVG patency is not significant.

A percutaneous endovascular technique for reducing arteriovenous fistula flow

Reduction of arteriovenous access flow is usually performed by tightening the inflow lumen through an open surgical procedure. A percutaneous endovascular approach can provide a precise and effective reduction of access flow without making a skin incision. After placing a vascular introducer sheath toward the inflow direction of an arteriovenous fistula, a small stent (5 mm diameter × 25 mm length) was deployed in the target area near the anastomosis. A second stent (10 mm × 60 mm) was then deployed inside the first stent, making a corset-shape constraint on the access flow. This newly described endovascular procedure was utilized to reduce the excessive flow of arteriovenous fistula in three patients. Deployment of the constrained stent-graft resulted in reducing the estimated access flow from 1900, 1600, and 1500 mL/min to 1100, 900, and 900 mL/min, respectively. Percutaneous endovascular placement of a constrained stent-graft can narrow the inflow lumen of arteriovenous access to a desired precise diameter of 5 mm and effectively reduce access flow over a long-term period.

Clinical and Economic Benefits of Stent Grafts in Dysfunctional and Thrombosed Hemodialysis Access Graft Circuits in the REVISE Randomized Trial

PURPOSE

To compare reinterventions and associated costs to maintain arteriovenous graft hemodialysis access circuits after rescue with percutaneous transluminal angioplasty (PTA), with or without concurrent Viabahn stent grafts, over 24 months.

MATERIALS AND METHODS

This multicenter (n = 30 sites) study evaluated reintervention number, type, and cost in 269 patients randomized to undergo placement of stent grafts or PTA alone. Outcomes were 24-month average cumulative number of reinterventions, associated costs, and total costs for all patients and in 4 groups based on index treatment and clinical presentation (thrombosed or dysfunctional).

RESULTS

Over 24 months, the patients in the stent graft arm had a 27% significant reduction in the average number of reinterventions within the circuit compared to the PTA arm (3.7 stent graft vs 5.1 PTA; P = .005) and similar total costs ($27,483 vs $28,664; P = .49). In thrombosed grafts, stent grafts significantly reduced the number of reinterventions (3.7 stent graft vs 6.2 PTA; P = .022) and had significantly lower total costs compared to the PTA arm ($30,329 vs $37,206; P = .027). In dysfunctional grafts, no statistical difference was observed in the number of reinterventions or total costs (3.7 stent graft vs 4.4 PTA; P = .12, and $25,421 stent graft and $22,610 PTA; P = .14).

CONCLUSIONS

Over 24 months, the use of stent grafts significantly reduced the number of reinterventions for all patients, driven by patients presenting with thrombosed grafts. Compared to PTA, stent grafts reduced overall treatment costs for patients presenting with thrombosed grafts and had similar costs for stenotic grafts.