RESILIENT
PubMed • Full text • ClinicalTrials.gov
Clinical Question
Among patients with symptomatic disease of the superficial femoral artery, is implantation of a self-expanding nitinol stent for moderate length lesions superior to percutaneous transluminal angioplasty only (PTA) in regards to angiographic results and patency?
Bottom Line
In the patient population having symptomatic disease of the superficial femoral artery (SFA), primary treatment with flexible nitinol stent for moderate-length lesions in the SFA and in the proximal popliteal artery may be preferred over angioplasty alone given improved clinical outcomes, better acute angiographic results, and low adverse event rate.
Major Points
The standard care of treatment for patients with symptomatic disease of the SFA and proximal popliteal artery is percutaneous transluminal angioplasty (PTA). PTA works particularly well for focal lesions in the SFA. However, PTA patency rates decrease as the lesion increases in length. Stenting is a promising intervention as it should provide a better initial result. However, the first generation of stents had underwhelming data. The second generation nitinol stents have had conflicting evidence prior to this study in regards to efficacy of stenting compared to only PTA. This study set out to compare the placement of nitinol stents to a more traditional PTA in patients with obstructive lesions of the SFA and proximal popliteal artery. The multicenter 2010 Randomized Study Comparing the Edwards Self-Expanding Lifestent versus Angioplasty Alone in LEsions INvolving the SFA and/or Proximal Popliteal Artery (RESILIENT) trial randomized 206 adults in Europe & the United States with obstructive lesions of the SFA and proximal popliteal artery and intermittent claudication to nitinol stent placement or PTA only. Freedom from target lesion revascularization (TLR) was better in the stent group than the PTA group at 6 months (98.5% vs 52.6%) and 12 months (87.3% vs 45.1%). Clinical success was improved for the nitinol stent group at 6 months (81.4% vs. 30.9) and 12 months (72.3% vs. 32.3%) as compared to the PTA group. Primary patency was also increased at 6 month (94.2% vs. 47.3%) and 12 month (72.3% vs. 32.3%) intervals in the nitinol stent group as compared to the PTA group.
There is some concern about the fracture potential of nitinol stents. While none of the fractures in this study (3.1% of stents implanted) resulted in loss of patency or TLR, there is risk of increased in-stent restenosis and reocclusion rate. [1] (1) Additionally, there was a high crossover rate (40.3%) in this study, leaving only 43 patients who solely received a PTA. 29 of the original 72 patients in the PTA group underwent secondary bailout stenting procedures. These lesions were significantly longer and more calcified than the lesions that were treated with PTA alone.
Guidelines
No guidelines have been published that reflect the results of this trial.
Design
- Multicenter, randomized, prospective, 24 centers (Europe & U.S.)
- N=206
- Nitinol Stent (n= 134)
- PTA = 72
- Setting: 24 centers in Europe & the U.S.
- Enrollment: 2004-2006
- Mean follow-up: 6 & 12 months
- Analysis: Intention-to-treat
- Primary outcome: rate of target lesion revascularization (TLR) at 12 months post procedure.
Population
Inclusion Criteria
- Age ≥ 18 years with intermittent claudication symptoms
- Candidates for angioplasty or stenting due to occlusive lesions in the SFA or proximal popliteal artery and had at least 1 patent infrapopliteal runoff vessel to the foot
- Target lesion had stenosis ≥50% and a total lesion length of ≤ 150mm. Multiple lesions could be treated if total length was ≤ 150mm
- Restenosed lesions could only be treated if previous intervention was >6 months prior and did not include stenting
Exclusion Criteria
- Critical limb ischemia (Rutherford categories 4 to 6)
- Patients with sensitivity to contrast media
- Known allergies to materials used in the study
- Renal failure or hepatic insufficiency
- Previous bypass surgery on target limb
- Extensive PVD
- Aneurysmal disease
- Unresolvable thrombus in treatment area
- Patients receiving immunosuppressive therapy
- Patients receiving dialysis
- Angiographic evidence of poor inflow unlikely to support bypassed vessel
Baseline Characteristics
Patient Demographics
From the stenting group.
- Demographics: Age 68 years with SD ± 10, male 70.9%, Black 9.0%, White 89.6%, Other 1.5%
- Hypertension: 83.6% (compared to 94.4% in control group, which had a p value of 0.03)
- Hypercholesterolemia: 79.9%
- Diabetes: 38.1%
- Smoking status (current or past): 71.6%
- Coronary artery disease: 56.0%
- Myocardial infarction: 20.1%
- Rutherford Claudication Category: 1/Mild 3.0%; 2/Moderate 35.8%, 3/severe 61.2%
- Target limb ABI: 0.71 ± 0.19
- Contralateral limb ABI: 0.88 ± 0.21
(not significantly different from PTA group except for higher rate of hypertension in stenting group 83.6% vs. 94.4%)
Lesion Classifications
From the stenting vs. PTA groups
- Lesions per patient:
- 1: 85.8% vs. 87.5%
- 2: 14.2% vs. 12.5%
- Lesion location: proximal SFA 13.1% vs. 14.8%; middle SFA 32.0% vs. 38.3%; distal SFA 50.3% vs. 45.7%; proximal popliteal 4.6% vs. 1.2%
- Lesion classification: stenosis- de novo 80.4% vs. 79.0%; occlusion 17.0% vs. 18.5%; restenosis 2.6% vs. 2.5%
- Lesion calcification: none or mild 64.7% vs. 65.7%; moderate 10.8% vs. 15.7%; severe 24.5% vs. 18.6%
- Reference vessel diameter, mm: 5.1±0.8
- Minimum lumen diameter, mm: 1.4±0.9
- Degree of stenosis, %: 72.7±17.6 vs. 74.9±18.3
- Lesion length (per patient), mm: 70.5±44.3 vs. 64.4±40.7%
Interventions
Patients were randomized to either group (nitinol stent or PTA). All patients received PTA of the target lesion. All patients received at least 81 mg of aspirin (6 months) and 75 mg of clopidogrel per day (12 weeks). All procedures performed percutaneously by antegrade or crossover approach.
- Nitinol stent - self-expanding nitinol stent is placed after PTA is performed in the target vessel
- PTA only (control) - vessel angioplasty with no stenting. If an appropriate PTA could not be achieved, a bailout stent procedure was performed.
Both groups had follow-ups at 6 and 12 months.
Outcomes
Presented as Nitinol stent vs PTA.
Primary Outcome
- Freedom from target lesion revascularization (TLR) at 12 months post procedure
- 87.3% vs. 45.1% (P<0.0001)
Secondary Outcomes
- Primary patency at 6 and 12 months using DUS
- 94.2% vs. 47.4% at 6 months (P<0.0001)
- 81.3% vs. 36.7% (P<0.0001) at 12 months
- Secondary patency at 6 and 12 months using DUS (patency after reintervention)
- 100.0% vs. 98.3% at 6 months (P<0.31)
- 100.0% vs. 98.3% at 12 months (P<0.31)
- Acute effectiveness
- 95.8% vs. 83.9% for lesion success (P<0.01) (≤ 30% residual stenosis in treatment area)
- 73.0% vs. 56.9% for hemodynamic success (P=0.05)(>0.10 improvement in ABI)
- Freedom from TLR at 6 months
- 98.5% vs. 52.6% (P<0.0001)
- Freedom from Target vessel revascularization (TVR)
- 94.6% vs. 52.6% at 6 months (P<0.0001)
- 83.5% vs. 45.1% at 12 months (P<0.0001)
- Clinical success (improvement of symptoms by > 1 Rutherford category)
- 81.4% vs. 30.9% at 6 months (P<0.0001)
- 72.3% vs. 32.3% at 12 months (P<0.0001)
- Quality of Life (Short Form 8 Question Health Survey score increase from baseline)
- 5.7±11.2 vs. 5.9±11.2 at 12 months
- Walking distance score
- 22.8±24.2 vs. 22.3±.23.2 at 12 months
Subgroup Analysis
There was a post hoc analysis of PTA plus PTA with a bailout stent compared to primary stenting. Bailout stenting wasn’t counted as a TLR. There was still an increased freedom from TLR at 6 months in the primary stenting group compared to the bailout stent group (98.5% vs. 91.2%). There was also increased primary patency at 6 months for the primary stenting group compared to the bailout stent group (81.3% vs. 66.9%).
Adverse Events
No patient deaths during 30 days of the procedure. No statistically differences in major adverse cardiac events (MACE) between the two procedures. There were a total of 9 stent fractures (3.1%) in 12 months. None of these patients lost primary patency or had to undergo a revascularization procedure.
Criticisms
- There was a high crossover rate of 40.3%, leaving only 43 patients who underwent PTA only.
- There are concerns about the fracture potential of nitinol stents.
- There is debate about the optimal peak systolic velocity ratio (PSVR) for the detection of a significant stenosis.
Funding
- Bard Peripheral Vascular, manufacturer of LifeStent Self-Expanding Stent (nitinol).