Comparison of Superwoven and Helical Nitinol Stents for the Femoropopliteal Artery

Purpose: Certain regions of the femoropopliteal artery, such as the proximal popliteal artery, subject stents to greater torsion, bending and axial/radial compression. These mechanical forces can lead to higher rates of restenosis and strut fractures. To address this, novel stent designs have been developed to withstand these forces. The purpose of this study is to compare the outcomes of superwoven nitinol stents and 3D helical stents in the femoropopliteal artery.

Materials and Methods: A retrospective review was performed of all patients at a single university hospital undergoing femoropopliteal stenting by interventional radiology in whom either 1) Supera (Abbott Vascular, Santa Clara, CA) superwoven nitinol stent(s) or 2) Biomimics (Veryan Medical, Galway, Ireland) 3D helical stent(s) were placed. Primary, assisted primary, and secondary patency was compared between the two groups, as well as amputation-free survival at 1 and 2 years.

Results: Patient demographics did not differ significantly between the two groups (Superwoven (n=72 stents): 72 years of age, 51% male; 3D Helical (n=45 stents): 73 years of age, 54% male). The proportion of patients with chronic limb-threatening ischemia (CLTI) was also not significantly different (Superwoven: 93%; 3D Helical 81%). However, lesions stented with the 3D helical stent were significantly longer than those with the superwoven stent (121 ± 18 mm vs 56 ± 10 mm, p < 0.001).

Median primary unassisted patency for superwoven stents (62% in popliteal artery) at 6-months, 1- and 2-years was not significantly different from 3D helical stents (69% in popliteal artery): 65 ± 13%, 58 ±14%, and 50 ± 15% vs. 83 ± 14%, 63 ± 19%, and 54 ± 20%, respectively (p= 0.1, log-rank test). Similarly, median primary assisted patency was not significantly different between Supera stents (60±14% at 1-year) and 3D helical stents (77 ±18% at 1-year, p=0.1). In contrast, secondary patency of 3D helical stents (100 ± 0% at one year) was significantly higher than that of superwoven stents (69 ± 14% at 1-year, p=0.005).

Among CLTI patients (89% of the total cohort), amputation-free survival was 81±12% and 77 ±13% at 1- and 2-years for superwoven stents, compared to 95 ± 9% and 95 ± 9% at 1 and 2 years for 3D helical stents (p=0.3). Strut fractures were observed in 2% of patients with superwoven stents compared to 4% of patients with 3D helical stents.

Conclusion: Patency and limb salvage rates were similar between superwoven and 3D helical stents, with no significant difference in the incidence of strut fractures or limb salvage.