Cath Lab Digest

Describe the inclusion criteria for patients in the RESILIENT trial

Patients were included in the trial if they had lifestyle-limiting claudication (Rutherford categories 1–3) of at least 6 months’ duration and were candidates for angioplasty or stenting. They had to have de-novo or restenotic (not stented) lesions in the superficial femoral artery (SFA) and/or proximal popliteal artery.

What types of lesions were treated in this trial?

The target lesion(s) had to meet the following criteria: (a) De-novo or restenotic lesion(s) located within the native SFA (1 cm below the origin of the profunda femoris artery) and/or proximal popliteal artery (3 cm above the knee joint). If the lesion(s) was/were restenosed or reoccluded, prior percutaneous transluminal angioplasty (PTA)-only treatment (no previous stent placement) must have occurred > 6 months prior to the study procedure. (b) The target lesion(s) had angiographic evidence of stenosis or restenosis ≥ 50% or occlusion and was/were amenable to PTA alone or primary stenting. The target vessel reference diameter was ≥ 4.0 mm and ≤ 7.0 mm and therefore appropriate for treatment with stent diameters of 6.0 and 7.0 mm. The total length of the lesion or series of lesions was ≤ 150 mm, and there was angiographic evidence of at least one vessel runoff to the foot.

How long will these patients be followed?

Data reported in the current manuscript (Circulation: Cardiovascular Interventions) were through 12 months (6 and 12 months). Patients in the RESILIENT study were followed through 3 years (6, 12, 24 and 36 months). Subsequent analysis of the longer-term data will be completed and submitted for publication at a later date.

How many centers participated in the RESILIENT trial? What were the operator requirements for participation?

Twenty-four sites in the United States and Europe participated in the randomized portion of the RESILIENT study. All operators were experienced stent users and experienced in peripheral endovascular procedures. Operators included interventional cardiologists, interventional radiologists and vascular surgeons.

Tell us about the various subanalyses of the RESILIENT results. What do these analyses tell us about bare-metal stenting in the SFA and popliteal artery?

The RESILIENT trial was designed as an intention-to-treat study to compare the results of angioplasty to a primary stent strategy. Patients were randomized to either the angioplasty group or primary stent group following successful crossing of the most distal lesion with a guidewire and uninflated angioplasty balloon. Patients who were randomized to the angioplasty group, but the PTA procedure either resulted in a flow-limiting dissection or significant elastic recoil with a residual stenosis of > 30%, could be treated with a stent (i.e., bailout stent). Per protocol, angioplasty patients who failed repeated PTA attempts and required a bailout stent were considered a target lesion revascularization (TLR) and a failure of primary patency.

Although not designed or powered to study the provisionally stented patients (i.e., bailout stent group), two post-hoc subset analyses were performed. The first post-hoc subset analyzed patients according to the treatment received; that is, angioplasty versus the combined stent group (primary stent patients and provisional/bailout-stented patients). The second post-hoc analysis compared the results of PTA and PTA plus provisional stenting to the primary stent group. This analysis was the same as the a priori intention-to-treat analysis except that the bailout/provisional-stent patients were not treated as PTA failures.

The as-treated analysis demonstrated that the patients who were successfully treated with angioplasty alone had relatively short lesions compared to the combined stent group (47.7 ± 32.6 mm vs. 63.3 ± 41.9 mm; p < 0.01). Patients in the PTA-only group had less calcified lesions and less severe symptoms of claudication. Primary patency was better for the combined-stent group both at 6 months (94.4% vs. 79.3%; p = 0.03) and 12 months (80.4% vs. 61.5%; p = 0.03). The RESILIENT study confirmed that shorter lesions (mean lesion length ≤ 48 mm) responded adequately to PTA (61.5% primary patency at 12 months), but the combined stent group performed better overall.

The post-hoc intention-to-treat analysis compared the results of PTA and PTA with provisional stenting to the primary stent group. Although in this analysis stented patients were included in the PTA control arm and improved the revascularization and primary patency rates of the PTA group, the primary stent group performed better through 12 months. The freedom from TLR rate at 12 months was 87.3% for the primary stent group compared to 77.3% for the PTA and PTA with provisional stent group (p = 09), while the primary patency at 12 months for the primary stent group was 81.3% versus 66.9% for the PTA and PTA with provisional stent group (p = 0.05).

Describe the LifeStent’s design and deployment. Are there unique features to this stent?

The LifeStent® Vascular Stent System (Bard Peripheral Vascular, Inc., Tempe, Arizona) is composed of a nitinol self-expanding stent pre-loaded on a tri-axial delivery catheter with an ergonomic deployment handle. The nitinol stent is designed with a multidimensional helical architecture. The stent struts form a true helix and are connected by angled bridges, each offset from the previous bridge. Since the bridges connect a helical structure, their pattern is also helical. This unique design is engineered to conform to the bending, compression and torsion of the SFA and proximal popliteal arteries. Its dynamic vessel conformability and flexible helical design may afford some degree of fracture resistance, demonstrated by the low fracture rate in the RESILIENT study at 12 months (3.1%).