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Stent Graft Versus Balloon Angioplasty for Failing Dialysis-Access Grafts - Stent Graft Versus Balloon Angioplasty for Failing Dialysis-Access Grafts
Description:
Although hemodialysis access is traditionally done with native fistulas, especially the first time, prosthetic grafts are often used to create permanent access hemodialysis circuits. Prosthetic arteriovenous (AV) graft failure is related to stenosis at the venous site of the anastomosis, usually due to neointimal hyperplasia. Traditionally, balloon angioplasty has been used to treat these stenoses, but is associated with a high secondary failure rate (approximately 50% at 3 years). The current trial sought to compare outcomes after balloon angioplasty alone versus balloon angioplasty with endovascular stenting with a stent graft made of the same material as the graft.
Hypothesis:
Treatment of prosthetic hemodialysis access graft stenosis with an expanded polytetrafluoroethylene (PTFE) stent graft would be noninferior to balloon angioplasty alone.
Study Design
- Parallel
Patients Enrolled: 190
Mean Follow Up: 6 months
Mean Patient Age: 61 years
Female: 64
Mean Ejection Fraction: CHF (25%)
Patient Populations:
- Age of 18-90 years and a hemodialysis access consisting of a synthetic AV access graft located in the arm
- Angiographic evidence of ≥1 stenoses, ≤7 cm in length and ≥50%, at the graft-vein anastomosis of a synthetic AV access graft, with the entire lesion located within 7 cm of the anastomosis, such that approximately 1 cm of the stent graft will be extended into a nondiseased vein and approximately 1 cm, but no more than 2 cm, of the stent graft will be extended into a nondiseased AV graft
- Clinical evidence of a hemodynamically significant stenosis
- Percutaneous endovascular therapy thought by the investigator to have been the best treatment choice for the identified lesion
- Synthetic AV access grafts implanted >30 days before enrollment and ≥1 successful hemodialysis sessions performed
- During primary balloon angioplasty, full expansion of an appropriately sized angioplasty balloon, in the operator’s judgment
Exclusions:
- Concomitant disease (e.g., terminal cancer) or other medical condition likely to result in death within 6 months after the time of implantation
- Stenosis with a corresponding thrombosis treated within 7 days before enrollment
- A second lesion in the access circuit (area from the arteriovenous access graft arterial anastomosis to the superior vena cava–right atrial junction), ≤3 cm from the edges of the primary lesion, either treated within 30 days before enrollment or ≥30%
- The presence of a second lesion in the access circuit >3 cm from the edges of the primary lesion that was ≥30%
- Second lesions that were ≥30% must have been treated before patient inclusion to reduce the percent stenosis to <30%
- Being unwilling or unable to return for follow-up visits or reason to believe that adherence to follow-up visits would be irregular
- A stent placed at the target lesion site
- A blood coagulation disorder or sepsis
- Requirement that the stent graft would have to cross an angle (between the inflow vein and synthetic AV access graft) of >90 degrees
- Requirement that the stent graft would have to be deployed fully across the elbow joint (which is identified radiographically as a combination of the humeroulnar joint and the humeroradial joint)
- A contraindication to the use of contrast medium
- Infected AV access graft
- Current or scheduled enrollment in other conflicting studies
- Procedural use of another investigational device
- Pregnancy
Primary Endpoints:
- 6-month primary patency of a stenotic venous anastomosis in the treatment area
Secondary Endpoints:
- Safety endpoints
- Procedural success (successful percutaneous insertion of the stent graft)
- Primary patency of the access circuit at 2 months and 6 months
- Percent stenosis of the treatment area at 2 months and 6 months
- Freedom from subsequent intervention
Drug/Procedures Used:
The stent graft was an investigational device, which consisted of a self-expanding nitinol stent covered in carbon-impregnated expanded PTFE (Flair Endovascular Stent Graft, Bard Peripheral Vascular). Two stent-graft configurations were used: tubular (straight) and flared. The stent graft was deployed with a 9F delivery catheter. Balloon angioplasty was performed using standard methods.
Concomitant Medications:
Anticoagulants (40%), antiplatelet agents (9%). A single, intravenous dose of prophylactic antibiotic—usually cefazolin sodium, in patients who did not have an allergy—was administered in the stent graft arm.
Principal Findings:
A total of 190 patients were randomized, 93 to balloon angioplasty and 97 to stent grafting. A total of 125 stent grafts were implanted in 97 patients; 67% of the stent grafts were flared, 16% were straight, and 17% consisted of overlapping straight and flared grafts. Baseline characteristics were fairly similar between the two arms. The mean age of the dialysis grafts was 2.4 years. The majority of grafts were located in the left arm (76%). Arterial anastomoses were predominantly the brachial artery (95%), while venous anastomoses were mainly the basilic vein (57%) or the axillary vein (28%). Previous access was mainly venous anastomosis (68%), or AV access graft (58%). The mean target lesion length was about 36 mm, while the mean lesion diameter was about 2.35 mm. Mean preprocedure stenosis was about 72%.
While immediate hemodynamic success was noted in 100% of patients in both groups, anatomical (94% vs. 73%, p < 0.001) and procedural (94% vs. 73%, p < 0.001) success was higher in the stent graft group. At 6 months, the incidence of the primary endpoint of primary patency of the treatment area was significantly greater in the stent graft group, as compared with the balloon angioplasty group (51% vs. 23%, p < 0.001). Primary patency of the access circuit was also higher in the stent graft group (38% vs. 20%, p = 0.008). At 210 days, the stent graft group had a higher freedom from subsequent re-interventions (p = 0.03).
Adverse events were infrequent, but numerically higher in the stent graft arm, as compared with the balloon angioplasty arms, although this was not statistically significant. This included infection (6% vs. 2%, p = 0.28), thrombotic occlusion (33% vs. 21%, p = 0.1), pseudoaneurysm formation (5% vs. 2%, p = 0.45), hematoma (2% vs. 0%, p = 0.5), and congestive heart failure (CHF) (4% vs. 2%, p = 0.7). Overall mortality was similar (5% vs. 6%, p = 1.0). There were no embolic episodes in either arm.
Interpretation:
The results of this trial indicate that balloon angioplasty along with the use of an endovascular stent graft is superior to balloon angioplasty alone in the treatment of prosthetic AV hemodialysis graft stenosis. These results are encouraging, since balloon angioplasty alone has a high recurrence rate of 50% at 3 years, and other methods such as the use of cutting and ultra-high pressure balloons, brachytherapy, cryotherapy, bare-metal stents, etc., have all showed no benefit over balloon angioplasty.
Note that, although not significant, most complications tended to be higher in the stent graft arm, despite experienced operators in this trial. It is possible that unselected operators may experience a higher rate of complications, thus negating some of the benefits of this approach.
References:
Haskal ZJ, Trerotola S, Dolmatch B, et al. Stent graft versus balloon angioplasty for failing dialysis-access grafts. N Engl J Med 2010;362:494-503.
Keywords: Aneurysm, False, Brachial Artery, Axillary Vein, Constriction, Pathologic, Hematoma, Hyperplasia, Angioplasty, Balloon, Coronary, Peripheral Vascular Diseases, Hemodynamics, Stents, Polytetrafluoroethylene, Renal Dialysis, Research Personnel, Heart Failure, Cryotherapy, Brachytherapy, Fistula
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