Endovascular Treatment of Atherosclerotic Popliteal Artery Lesions - ETAP

Description:

Popliteal artery lesions are typically treated with percutaneous transluminal angioplasty (PTA) alone due to concern for bending, kinking, and fracturing of stents in this location. The current trial sought to compare outcomes after stenting versus balloon PTA alone in patients with popliteal artery stenosis.

Hypothesis:

Primary stenting with a nitinol stent (Lifestent) would be superior to PTA alone in the treatment of popliteal artery stenosis.

Study Design

  • Randomized
  • Blinded
  • Parallel

Patient Populations:

  • Patients with chronic peripheral arterial disease with Rutherford claudication class 1-4
  • Significant popliteal stenosis
  • No restrictions in lesion lengths

    Number of enrollees: 246
    Duration of follow-up: 2 years
    Mean patient age: 72 years
    Percentage female: 36%

Primary Endpoints:

  • Restenosis rate at 12 months (duplex peak systolic velocity ratio [PSVR] >2.4)

Secondary Endpoints:

  • Restenosis rate at 6 months (PSVR >2.4)
  • Restenosis rate at 24 months (PSVR >2.0)
  • Primary patency rate
  • Secondary patency rate
  • Clinically driven TLR rate
  • Change in Rutherford class claudication
  • Walking distance (treadmill)
  • Ankle-brachial index
  • Major adverse cardiac events
  • Stent fracture rate at 12 and 24 months (plain X-ray)

Drug/Procedures Used:

Patients with popliteal artery stenosis were randomized in a 1:1 fashion to either primary stenting with the Lifestent or balloon PTA alone with bailout stenting, as needed.

Principal Findings:

A total of 246 patients were randomized, 119 to stenting and 127 to balloon PTA alone. Bailout/crossover rate in the PTA arm was 24%. Baseline characteristics were fairly similar between the two arms. About 37% had diabetes, 23% were current smokers, 43% had concomitant coronary artery disease, and 15% had concomitant cardiovascular disease. Approximately 47% of patients had disease in the popliteal artery above the knee joint (proximal popliteal artery) and 7% had disease extending throughout the length of the popliteal artery. The mean lesion length was 42 mm and one-third of all lesions were chronic occlusions. Moderate to severe calcification was noted in 47% of the lesions.

Primary patency was significantly higher in the stent arm as compared with the PTA arm (67.4% vs. 44.9%, p < 0.05). Event-free survival (death, target lesion revascularization [TLR], myocardial infarction [MI], amputation) at 12 months was higher in the stent arm (p < 0.0001). TLR (15.4% vs. 50.4%, p = 0.0001) and change in walking distance (116 m vs. 70 m, p < 0.05) were both significantly improved in the stent arm as compared with PTA. Other endpoints such as death (3.9% vs. 2.1%, p = 0.68), amputation (3% vs. 3%, p = 1.0), and change in ankle-brachial index (0.22 vs. 0.24, p = 0.9) were similar between the two arms. On interim analysis, there were 2 fractures out of 58 stents studied (incidence: 3.4%).

Interpretation:

The results of the ETAP trial indicate that primary stenting of popliteal artery lesions with the Lifestent is associated with improved patency, reduced TLR, and increased walking distance as compared with PTA alone, with a low fracture rate on interim analysis. These results are encouraging, as popliteal artery lesions are relatively common in patients with peripheral arterial disease, but treatment has been limited to PTA alone (with bailout stenting) due to concern for stent fracture. Long-term stent fracture rates and final full publication of these results are awaited. Results from ongoing trials with other stents (e.g., Supira stent) are also awaited.

References:

Presented by Dr. Thomas Zeller at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2012), Miami, FL, October 24, 2012.

Clinical Topics: Diabetes and Cardiometabolic Disease, Invasive Cardiovascular Angiography and Intervention, Prevention, Vascular Medicine, Interventions and Coronary Artery Disease, Interventions and Vascular Medicine, Exercise

Keywords: Intermittent Claudication, Coronary Artery Disease, Myocardial Infarction, Follow-Up Studies, Ankle Brachial Index, Knee Joint, Disease-Free Survival, Peripheral Arterial Disease, Constriction, Pathologic, Angioplasty, Stents, Walking, Popliteal Artery, Diabetes Mellitus


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