Long-term Outcomes and Risk Stratification of Patency Following Nitinol Stenting in the Femoropopliteal Segment: Retrospective Multicenter Analysis

Abstract

Purpose

To investigate the long-term outcomes of nitinol stenting in femoropopliteal lesions and to determine the factors associated with restenosis.

Methods

Between December 2003 and December 2009, 861 patients (603 men; mean age 72 years) underwent nitinol stenting of the femoropopliteal segment in 1017 limbs. A quarter (26%) of the patients had critical limb ischemia. Mean lesion length was 152±93 mm. Stent patency was assessed by either duplex ultrasound or angiography and analyzed by Kaplan-Meier estimation. The determinants of restenosis were explored with Cox proportional hazard regression analyses; the results are presented as the hazard ratio (HR) and 95% confidence interval (CI). Risk stratification of primary patency was subsequently analyzed using a score based on the significant prognostic factors identified in the multivariate model.

Results

Stent fracture occurred in 10% (104 limbs) of the lesions. At 1, 3, and 6 years, the primary patency rates were 77%, 67%, and 63%; secondary patency rates were 91%, 87%, and 87%; freedom from femoropopliteal bypass grafting was 99%, 97%, and 96%, respectively. Multivariate Cox regression analysis identified female gender (HR 1.899; 95% CI 1.318 to 2.737, p<0.001), ankle-brachial index <0.6 (HR 1.921; 95% CI 1.348 to 2.736, p<0.001), TASC II C/D lesion (HR 2.068; 95% CI 1.346 to 3.177, p=0.0009), stent fracture (HR 1.937; 95% CI 1.203 to 3.118, p=0.006), and the absence of cilostazol administration (HR 2.102; 95% CI 1.394 to 3.172, p<0.001) as strong independent factors associated with restenosis. After assigning a risk score based on the outcomes of the multivariate regression analysis (1 each for female gender, ABI <0.6, TASC II C/D, stent fracture, and absence of cilostazol therapy), primary patency was found to be lower in limb groups with a higher cumulative score (12-month primary patency: score 0: 93%, score 1: 80%, score 2: 73%, score 3; 47%, score 4: 0%, respectively; p<0.001).

Conclusions

Endovascular therapy using nitinol stents for FP lesions yielded acceptable outcomes up to 6 years. Risk stratification for patency can play an important role in estimating future occurrence of restenosis after nitinol stent implantation in FP lesions.