ZILVER-PTX - ZILVER-PTX

Description:

Endovascular options for the treatment of femoropopliteal peripheral arterial disease are limited. Current standard of care is usually to perform a percutaneous transluminal angioplasty (PTA) with provisional bare-metal stent (BMS) as needed. The current trial sought to study the safety and efficacy of stenting with a polymer-free paclitaxel-eluting Zilver PTX stent, as compared with PTA alone for the treatment of such lesions.

Hypothesis:

Zilver PTX stenting would be superior to PTA alone in the treatment of patients with symptomatic femoropopliteal disease.

Study Design

  • Blinded
  • Parallel
  • Randomized

Patient Populations:

  • Total lesion length ≤14 cm
  • Symptomatic disease of the above-the-knee femoropopliteal artery (Rutherford-Becker class ≥2 symptoms)
  • Reference vessel diameter 4-9 mm

    Number of enrollees: 498
    Duration of follow-up: 1 year
    Mean patient age: 68 years
    Percentage female: 35%

Exclusions:

  • In-stent restenosis

Primary Endpoints:

  • Safety: Freedom from death, amputation, target lesion revascularization, or worsening Rutherford score (by 2 classes or to class 5 or 6) at 12 months
  • Efficacy: Primary patency on duplex ultrasonography, patent = PSVR (peak systolic velocity ratio) <2.0 (or angiography if available, patent = diameter stenosis <50%)

Drug/Procedures Used:

Patients were randomized in a 1:1 fashion to either Zilver PTX stent or PTA. Patients with suboptimal PTA results were further randomized in a 1:1 fashion to provisional stenting with either the Bare Zilver stent or the Zilver PTX stent.

Concomitant Medications:

Aspirin and clopidogrel were mandated for a minimum of 60 days.

Principal Findings:

A total of 498 lesions in 474 patients were randomized, 251 to PTA alone, and 247 to Zilver PTX. Of the 251 PTA-treated lesions, an optimal result was noted in 126 (50.2%) of lesions. Lesions with suboptimal results were further randomized to provisional Bare Zilver (62 lesions) or provisional Zilver PTX (64 lesions). Baseline characteristics were fairly similar between the two arms. About 45% had diabetes mellitus, and 85% were current or former smokers. Mean lesion length was 6.5 cm, with a mean diameter stenosis of 79%; 27% of these were total occlusions. Lesions in the Zilver PTX arm were more likely to have moderate calcification (35% vs. 22%, p < 0.01).

The primary safety endpoint of event-free survival was higher in the Zilver PTX arm, as compared with the PTA arm (90.4% vs. 82.6%, p < 0.01). The primary efficacy endpoint of primary patency was significantly higher in the Zilver PTX arm at 1 year, as compared with the PTA arm (83.1% vs. 32.8%, p < 0.01). Even in lesions with an optimal PTA result, Zilver PTX still demonstrated a higher primary patency rate (83.1% vs. 65.3%, p < 0.01). On per-protocol analysis, Zilver PTX was superior to standard of care measures (PTA with provisional BMS stenting for suboptimal results) at 12 months (83.1% vs. 67.0%, p < 0.01). Restenosis rates were 16.9% and 33.0%, respectively. Even when used provisionally, Zilver PTX was also noted to be superior to the Zilver BMS stent for 12-month restenosis (10.1% vs. 27.0%, p < 0.05). The Zilver PTX stent fracture rate was about 0.9% at 12 months.

Interpretation:

This is the largest trial to date on the endovascular treatment of peripheral arterial disease. The results of this trial indicate that the Zilver PTX polymer-free paclitaxel-eluting stent is safe and efficacious, and is superior to PTA alone in maintaining primary patency in patients with symptomatic femoropopliteal disease. Further, a strategy of predetermined or provisional stenting with Zilver PTX appears to be superior to provisional stenting with BMS in patients with suboptimal PTA.

One limitation of this trial is that patency evaluation was done by duplex ultrasonography alone, and not with routine angiography. Further, lesions included in this trial were relatively short (≤14 cm) and in-stent restenosis was an exclusion criterion. However, these results are very interesting, and clinical outcomes data, including with longer-term follow-up, and full publication of these results are eagerly awaited.

References:

Presented by Dr. Michael Dake at the Transcatheter Cardiovascular Therapeutics Meeting (TCT 2010), Washington, DC, September 24, 2010.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Interventions and Vascular Medicine

Keywords: Paclitaxel, Follow-Up Studies, Metals, Polymers, Standard of Care, Disease-Free Survival, Peripheral Arterial Disease, Constriction, Pathologic, Angioplasty, Diabetes Mellitus, Stents


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