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Home > Vascular Annual Meeting > PP31. Does Nitinol Stent Design Influence Long-Term...

PP31. Does Nitinol Stent Design Influence Long-Term Patency and Integrity in Long Femoro-Popliteal Occlusions?

Massimo Lenti1, Enrico Cieri1, Paola De Rango1, Giacomo Isernia1, Paolo Bonanno1, Mathias Fischer2, Piergiorgio Cao1
1Vascular and Endovascular Surgery Unit,University of Perugia, Perugia, Italy; 2Interventional Radiology Unit,University of Perugia, Perugia, Italy

OBJECTIVES: Changes in nitinol stent design and conformation have been introduced to increase radial force and avoid loss of integrity in femoro-popliteal (F-P) occlusions. To compare long-term patency and frequency of fractures in different nitinol F-P stents .

METHODS: Two Groups of nitinol F-P stent were compared: Group I, continuous elicoidal covered (ePTFE) stent and Group II, bare no-spiral stents. All stents implanted for F-P obstruction in 2001-2008 were reviewed. Patency was investigated by duplex ultrasound and Stent integrity using double projection x-ray with high-resolution images with Extended and flexed leg position. The association between fractures and patency, timing from implantation, calcification, lesion length and patients’ characteristic was compared.

RESULTS: A total of 102 F-P lesions were stented (mean age 70.6years, males 66%): 59 in Group I and 43 in Group II. The 2 Groups were similar for baseline characteristics, lesion morphology and indications. Mean lesion length was 132mm (IQR 80-180). At 32 months, assisted patency was 68%, without no differences between II Groups. Sixty-nine patients were available for stent integrity analysis. Twenty-five (36%) stent fractures were detected, more frequent in Group I (20/41; 49%) than in Group II (5/28; 18%), 95% CI 1.39-13.8; OR 4.3, p=0.01. Overall, 15 (21.7%) fractured stents were still patent. In patients available for stent integrity, assisted patency rate at 32 months was 73% in Group I vs. 65% Group II (p=0.88).

Logistic regression showed that longer lesions (HR 1.11; 95% CI1.00-1.024; p 0.013) were the only strongly negative predictors of patency in Group II while, failed to confirm any statistically association between length of lesion and patency in Group I.

CONCLUSIONS: Different design in F-P stents, spiral or not, offers the same patency in mid and long term. Nevertheless, spiral stent deals better in longer lesions but the high radial force increasing the fracture rate is a major concern. Further design research and improvement of material resistance are required to achieve satisfactory long-term results in F-P area.

AUTHOR DISCLOSURES: M. Lenti, None; E. Cieri, None; P. De Rango, None; G. Isernia, None; P. Bonanno, None; M. Fischer, None; P. Cao, None.