Long Aortic Part of the Stents as a New Predictor for In-stent Restenosis After Kissing Stenting of the Aortoiliac Arteries

Introduction - Kissing stenting is the preferred, minimally invasive treatment for aortoiliac steno-occlusive disease. However, only a few publications are available about the long-term patency of aortoiliac kissing stents and about the risk factors for in-stent restenosis (ISR), the majority of which have conflicting outcomes. Our aim was to determine the long-term patency rates of aortoiliac kissing stents and to identify predisposing factors for the development of ISR. Methods - One hundred and five patients (64 females; median age: 60.9 [56.3-69.2] years) with symptomatic aortoiliac steno-occlusive disease (Fontaine II, 86.7%; III-IV, 13.3%; TASC A, 49.5%; B, 27.6%; C, 3.8%; D, 19%) who underwent kissing stenting (n = 210 stents; self-expandable, 85.7%; balloon-expandable, 14.3%) between 2001 and 2015 were retrospectively analyzed. Patient, vessel, lesion, and stent characteristics were examined. Follow-up included palpation of peripheral pulses, measurement of ankle-brachial index, and duplex ultrasonography. Mann-Whitney U and Fisher’s exact tests as well as Kaplan-Meier, Cox regression, and receiver operating characteristic (ROC) analyses were used as statistical methods. Results - The median follow-up time was 45 (21-69) months. The primary patency rate was 95%, 93%, 86%, and 77% at 6, 12, 24, and 60 months, respectively. Significant ISR developed in 23 patients (21.9%; unilateral, n = 11; bilateral, n = 12). Univariate Cox regression analysis revealed older age (hazard ratio [HR], 0.5; 95% confidence interval [CI], 0.31-0.81; P = .004), presence of hypertension (HR, 0.15; 95% CI, 0.04-0.54; P = .003), and larger aortic diameter (HR, 0.42; 95% CI, 0.25-0.7; P < .001) to be significant protective factors against ISR, while longer aortic part of the stents (HR, 1.56; 95% CI, 1.16-2.09; P = .003) and larger discrepancy between sum of the stent diameters and aortic diameter (HR, 1.64; 95% CI, 1.01-2.65; P = .043) were associated with worsened long-term patency. Multivariable analysis showed longer aortic part of the stents to be the only significant determinant of ISR (HR, 1.44; 95% CI, 1.02-2.01; P = .035). Regarding the length of aortic part of the stents, 20 mm was identified by ROC analysis as the optimal cut-off value due to its highest sensitivity, specificity, and clinical relevance (sensitivity, 66% [95% CI, 55-76%]; specificity, 74% [95% CI, 52-90%]; area under the curve, 0.69 [95% CI, 0.58-0.81]; P = .004). The length of aortic part of the stents was dichotomized into the categories of ≤ 20 mm and > 20 mm. The primary patency rate was 98%, 97%, 95%, and 89% at 6, 12, 24, and 60 months, respectively, in patients whose aortic stent part was ≤ 20 mm, while it was 91%, 88%, 74%, and 59% at 6, 12, 24, and 60 months, respectively, in patients whose aortic stent part was > 20 mm. The primary patency rates were significantly worse (P < .001) in patients with longer aortic stent part compared to those with shorter aortic stent part. Conclusion - Kissing stent technique can be performed with good long-term patency rates for the treatment of aortoiliac steno-occlusive disease. Patients whose iliac stents protrude too far into the aorta need closer follow-up care.