Study protocol for a Prospective, Randomized controlled trial of stEnt graft and Drug-coated bAlloon Treatment for cephalic arch stenOsis in dysfunctional arteRio-venous fistulas (PREDATOR)

BACKGROUND

Treatment of cephalic arch stenosis (CAS) is associated with high risk of failure and complications. Although stent-graft (SG) placement has improved patency rates, stent edge restenosis has been raised as a potential limiting factor for SG usage in CAS. This study aims to evaluate the safety and efficacy of combining stent graft placement with paclitaxel-coated balloon (PCB) angioplasty versus PCB alone in the treatment of CAS.

METHODS

This is an investigator-initiated, prospective, international, multicenter, open-label, randomized control clinical trial that plans to recruit 80 patients, who require fistuloplasty from dysfunctional arteriovenous fistula (AVF) from CAS. Eligible participants are randomly assigned to receive treatment with SG and PCB or PCB alone in a 1:1 ratio post-angioplasty (n = 40 in each arm). Randomization is stratified by de novo or recurrent lesion, and the participants are followed up for 1 year. The primary endpoints of the study are target lesion primary patency (TLPP) and access circuit primary patency (ACPP) rates at 6-months. The secondary endpoints are TLPP and ACPP at 3- and 12-month; target lesion and access circuit assisted primary and secondary patency rates at 3, 6, and 12-months and the total number of interventions; complication rate; and cost-effectiveness.

DISCUSSION

This study will evaluate the clinical efficacy and safety of combination SG and PCB implantation compared to PCB alone in the treatment of CAS for hemodialysis patients.

Clinical Impact of Additional Cilostazol Treatment on Restenosis Risk following Heparin-Bonded Stent Graft Implantation: Sub-Analysis from the Viabahn Stent-Graft Placement for Femoropopliteal Diseases Requiring Endovascular Therapy (VANQUISH) Study

AIM

The present study investigated the effects of additional cilostazol administration on the 12-month risk of restenosis after femoropopliteal heparin-bonded stent graft implantation.

METHODS

This study was a sub-analysis of the Viabahn stent graft placement for femoropopliteal disease reQUIring endovaScular tHerapy (VANQUISH) study, which was a prospective multicenter study investigating patients who received Viabahn stent graft (W.L. Gore & Associates, Flagstaff, AZ, USA) and dual-antiplatelet therapy with aspirin and a thienopyridine. The comparison of clinical outcomes between subgroups with and without cilostazol treatment were performed using the propensity score-matching method to minimize the intergroup differences in baseline characteristics.

RESULTS

Cilostazol-treated patients had a lower 12-month proportion of restenosis than cilostazol-free patients (8.2% vs 27.3%). The odds ratio of cilostazol for the 12-month restenosis was 0.27 [95% CI, 0.08 to 0.97] (p=0.045). Furthermore, the cumulative incidence rates of surgical reconstruction, target lesion revascularization and acute thrombotic occlusion (p values by the log-rank test) were 2.6% versus 1.8% (P=0.43), 5.3% versus 20.5% (P=0.067), and 0.0% versus 11.8% (P=0.0499), respectively. The rates of surgical reconstruction and target lesion revascularization (TLR) were not significantly different between both groups.

CONCLUSIONS

Our study revealed the clinical impact of additional cilostazol treatment on the risk of restenosis and acute thrombotic occlusion following heparin-bonded stent graft implantation, while TLR and surgical reconstruction were not significantly different.

Retrospective multicenter registry for endovascular treatment with newer devices in over 25-cm femoropopliteal artery disease: A retrospective observational study

Background and Aims

Endovascular therapy (EVT) is recommended in femoropopliteal (FP) lesions shorter than 25 cm by current guidelines; however, diffuse FP lesions remains challenging for EVT. The aim of this study was to investigate the efficacy of EVT with the latest devices for FP lesions longer than 25 cm.

Methods

This retrospective multicenter registry analyzed patients presented peripheral artery disease (PAD) having FP lesions longer than 25 cm who underwent EVT using the latest devices between 2017 and 2021. The primary outcome was restenosis 1 year after EVT.

Results

The present study enrolled a total of 504 PAD patients with 614 lesions undergoing EVT for diffuse FP lesions. The Kaplan-Meier analysis showed that the rates of freedom from restenosis and clinically-driven target lesion revascularization were 79.3% and 82.4% 1 year after EVT, respectively. The multivariate Cox proportional hazards regression analysis showed that clinical features associated independently with restenosis risk were cilostazol use (adjusted hazard ratio, 0.49 [0.32-0.74]; p = 0.001), reference vessel diameter (RVD) (0.72 [0.58-0.89] per 1-mm increase; p = 0.002), and P3 segment involvement (2.08 [1.33-3.26]; p = 0.001). The Kaplan-Meier analysis was conducted to compare the primary patency between cases with and without a small RVD, P3 involvement, and/or lack of cilostazol; any risk factors were related to a worse primary patency rate, compared with cases without risk factors.

Conclusion

In the current EVT era, the primary patency at 1 year was acceptable at 79.3% in patients with FP lesions longer than 25 cm. A small vessel and P3 segment involvement might be associated with a poor 1-year patency rate after EVT, whereas cilostazol administration might contribute to reducing restenosis.

Endovascular bypass as a strategy for long femoropopliteal lesions

INTRODUCTION

Endovascular treatment has become the predominant treatment modality for femoropopliteal lesions. In longer and more complex lesions advanced technology is often required to improve results, with the endovascular bypass being one of them.

EVIDENCE ACQUISITION

A systematic review of the literature was performed to determine the clinical and technical outcomes of the latest generation endoprosthesis, with heparin bioactive surface and contoured proximal edge.

EVIDENCE SYNTHESIS

13 articles were enrolled: 3 randomized controlled trials, 4 prospective multicenter trials and 6 retrospective studies. The VIASTAR trial showed that the endoprosthesis has a better two-year primary patency compared to bare metal stenting, especially in long lesions (62% vs. 27%, P=0.004). The SUPERB trial showed that the endoprosthesis had similar results compared to bypass surgery, albeit with less complications (31% vs. 55%, P=0.048). The RELINE study showed that treatment with an endoprosthesis had a better one-year primary patency compared to balloon angioplasty for in-stent restenosis (75% vs. 28%, P<0.001). In the cohort studies one-year patency rates ranged from 61% to 86% for primary patency, from 65% to 92% for primary assisted patency, and from 83% to 95% for secondary patency.

CONCLUSIONS

For long femoropopliteal lesions, the heparin-bonded endoprosthesis is related to better outcomes compared to bare nitinol stents, and comparable outcomes as with the femoropopliteal bypass, but with less complications. There is a wide range in primary patency rates, with consistent high secondary patency rates. The endovascular bypass can be considered an appropriate strategy in these patients.

State-of-the-Art Endovascular Therapies for the Femoropopliteal Segment: Are We There Yet?

Peripheral arterial disease is an increasingly prevalent condition with significant associated morbidity, mortality, and health care expenditure. Endovascular interventions are appropriate for most patients with either ongoing symptoms of intermittent claudication despite lifestyle and medical optimization or chronic limb-threatening ischemia. The femoropopliteal segment is the most common arterial culprit responsible for claudication and the most commonly revascularized segment. Endovascular approaches to revascularization of the femoropopliteal segment are advancing with an evolving landscape of techniques for arterial access, device-based therapies, vessel preparation, and intraprocedural imaging. These advances have been marked by debate and controversy, notably related to the safety of paclitaxel-based devices and necessity of atherectomy. In this review, we provide a critical overview of the current evidence, practice patterns, emerging evidence, and technological advances for endovascular intervention of the femoropopliteal arterial segment.

Effect of expanded polytetrafluoroethylene thickness on paclitaxel release and edge stenosis in stent graft

Stent grafts have been widely used to treat lower extremity arterial stenosis or occlusion. However, there are major issues with edge stenosis and loss of patency over time. Paclitaxel-coated stent grafts have been proven to be effective in preventing edge stenosis, but the insufficient amounts of paclitaxel released may limit the effectiveness of drug-eluting stent grafts. In this study, we examined whether paclitaxel-coated expanded polytetrafluoroethylene (ePTFE) stent graft thickness influences paclitaxel release properties and inhibits edge stenosis. Low-, medium-, and high-thickness paclitaxel-coated stent grafts were prepared by varying the thickness of inner and outer ePTFE layers. Surface morphologies of the stent grafts were analyzed using a scanning electron microscope. The stent grafts were then implanted in the iliac arteries of 20 healthy swine. Twelve pigs were used to assess edge stenosis, and digital subtraction angiography was performed at day 30 (n = 4), 90 (n = 4), and 180 (n = 4). Histological evaluation of the treated arteries was also performed. Eight pigs were used for pharmacokinetic analysis, and the treated arteries were obtained at day 1 (n = 2), 30 (n = 2), 90 (n = 2) and 180 (n = 2). Scanning electron microscopy confirmed that the mean pore size of the stent grafts decreased with increasing thickness. The results of angiographic and histological evaluation demonstrated that low-thickness ePTFE-stent grafts resulted in edge stenosis and apparent intimal hyperplasia at 180 days, whereas for medium-thickness ePTFE-stent grafts, no obvious edge stenosis and intimal hyperplasia was noted in the similar time period. The results of pharmacokinetic evaluation showed that at 180 days, the paclitaxel concentration of treated arteries of the medium group was 36 ± 53 ng/g, while concentrations in the low group was not detectable. Stent grafts with increased ePTFE thickness appear to allow for more delayed release of paclitaxel compared to low-thickness ePTFEs.

Inhibition of edge stenosis of endografts in swine iliac arteries by a novel endograft with biodegradable coating at both ends

Objective

This study evaluated the effectiveness and safety of a novel endograft with a biodegradable coating at both ends in preventing edge stenosis in swine iliac arteries. The biodegradable coating was composed of polylactide and paclitaxel.

Methods

Four types of endograft were implanted in the iliac arteries of healthy swine: an endograft without coating (control group) and endografts with polylactide and paclitaxel coating containing 0.1, 0.3, or 3.6 μg/mm² of paclitaxel. The edge stenosis of these endografts in swine iliac arteries was assessed using angiographic image data at 30, 90, and 180 days after the operation. After terminal angiography, histologic evaluation of the treated arteries was performed. The treated sections of iliac arteries and blood samples were obtained at 1, 7, 30, 90, and 180 days for pharmacokinetic analysis.

Results

The results of angiographic and histologic evaluation demonstrated that intimal hyperplasia contributed to edge stenosis and polylactide-paclitaxel coating effectively inhibited edge stenosis. At 30 days, edge stenosis was observed at both the proximal and distal edges of the endograft without coating. At 90 days, edge stenosis was detected for the endograft coated with 0.1 μg/mm² paclitaxel, and ectasia dilation occurred at the proximal and distal edges of the endograft coated with 3.6 μg/mm² paclitaxel. No edge stenosis or other adverse effects were observed at 90 and 180 days for the endograft coated with 0.3 μg/mm² paclitaxel. In addition, for the endograft coated with 0.3 μg/mm² paclitaxel, a pharmacokinetic analysis showed that the paclitaxel concentration of treated segments decreased from 14 264 ± 1020 ng/g at day 1 to 80 ± 70 ng/g at day 90, and 20 ± 40 ng/g at day 180. The plasma paclitaxel concentration was low at day 1 and no longer detected after 7 days.

Conclusions

Polylactide and paclitaxel coating containing 0.3 μg/mm² paclitaxel at both ends of endografts effectively and safely inhibits edge stenosis in swine iliac arteries.

Provisional focal stenting of complex femoropopliteal lesions using the Multi-LOC multiple stent delivery system – 12-month results from the LOCOMOTIVE EXTENDED study

Summary: Background: This study aimed to evaluate a Multiple Stent Delivery System for provisional focal stenting of the femoropopliteal artery. Patient and methods: The LOCOMOTIVE EXTENDED study (Multi-LOC for flOw liMiting Outcomes after plain old balloon angioplasty and/or drug-coated balloon Treatment in the infrainguinal position with the objectIVE to implant multiple stent segments) is a prospective, single-arm, multicentre observational study. The Multi-LOC Multiple Stent Delivery System (B.Braun, Melsungen, Germany) was used for provisional focal stenting of the femoropopliteal artery. We enrolled 357 patients with 449 femoropopliteal lesions; all had flow-limiting dissections or recoil following angioplasty. Eligibility included Rutherford classification 2 to 5 with a de novo or non-stented restenotic femoropopliteal lesion undergoing plain balloon or drug-coated balloon angioplasty. The 6- and 12-month efficacy endpoints encompassed target lesion revascularisation and primary patency rates. Results: The mean patient age was 71 ± 10 years. The mean lesion length was 16.0 ± 9.7 cm; 44.5% were TASC II C/D lesions and 31.4% were chronic total occlusions. By operator choice, 45% of the patients underwent drug-coated balloon angioplasty. On average, 4.0 stents (each 13 mm long) were placed in each lesion, resulting in a scaffolding proportion of 56% of the total lesion length with a technical success rate of 98.3%. At 6 and 12 months, the freedom from clinically driven target lesion revascularisation was 95.5% and 88.7% and the primary patency rates were 88.7% and 82.3%, respectively. At 12 months, significant improvements were noted in Rutherford categories and ankle-brachial indices. In multiple regression analyses, both diabetes mellitus and no distal run-off vessel showed a trend toward worse TLR, while other factors such as DCB predilation or the lesion length were not predictive. Conclusions: The LOCOMOTIVE EXTENDED study demonstrated the safety and efficacy of the Multi-LOC stent system for focal provisional stenting of complex femoropopliteal lesions.

Patients with failed femoropopliteal covered stents are more likely to present with acute limb ischemia than those with failed femoropopliteal bare metal stents

OBJECTIVE

Covered stents (CS) to treat superficial femoral artery (SFA) occlusive disease have become more common. However, concerns about patients presenting with acute limb ischemia (ALI) after failure due to coverage of important collaterals have been raised. Herein, we determine if CS are associated with ALI after failure.

METHODS

Vascular Quality Initiative peripheral vascular intervention and infrainguinal bypass datasets were queried from 2010 to 2020 for patients who underwent SFA stenting with a bare metal stent (BMS) or CS and who also had a subsequent ipsilateral SFA endovascular reintervention or bypass recorded in the Vascular Quality Initiative. The initial SFA stenting procedure will be referred to as the index procedure and the subsequent procedure will be referred to as the reintervention. Patients with aneurysmal pathology, prior infrainguinal bypass, and ALI at the index procedure were excluded. Patients with pre-index inflow/outflow procedures were not excluded. The primary outcome was ALI at reintervention. Other outcomes included higher degree of ischemia (claudication vs rest pain vs tissue loss vs ALI) and reoperative factors. Predictors of the primary outcome were determined with multivariable logistic regression. The index treatment length and pre-index ankle-brachial index were forced into the model.

RESULTS

There were 3721 patients: 3338 with index BMS, 383 with index CS. The mean patients age was 66.3 ± 11.0 years and 59.2% were male. Baseline covariates were similar between the groups; during the index procedure, more patients with BMS underwent plain balloon angioplasty (68.7% vs 62.1%; P = .001) and had shorter total index treatment length (median, 15.0 cm [interquartile range, 10.0-25.0 cm] vs 20.0 cm [interquartile range, 12.0-30.0 cm]; P < .001). At reintervention, ALI was the presenting symptom for 12.0% of the CS cohort vs 6.3% of the BMS cohort (P < .001). More patients with an index CS underwent major amputation at the time of reintervention (2.6% vs 1.0%; P = .006). Reinterventions for the patients with a CS more often used bypass, pharmacologic thrombolysis, and mechanical thrombolysis. CS at the index procedure was a predictor of ALI at reintervention (odds ratio, 1.87; 95% confidence interval, 1.31-2.65; P = .001) while controlling for age, time difference between procedures, body mass index, chronic obstructive pulmonary disorder, preoperative anticoagulation and antiplatelet, prior carotid intervention and major amputation, index procedure fluoroscopy time and treatment length, and pre-index ankle-brachial index.

CONCLUSIONS

In patients undergoing reintervention for failed SFA stents, CS are more likely to present with ALI than those with failed SFA BMS.

Outcomes after Endovascular Stent Placement for Long-Segment Superficial Femoral Artery Lesions

BACKGROUND

Endovascular intervention is commonly pursued as first-line management of symptomatic, long-segment superficial femoral artery (SFA) disease. The relative effectiveness and comparative long-term outcomes among bare metal stents (BMS), covered stents (CS), and drug-eluting stents (DES) for long-segment SFA lesions remain uncertain.

METHODS

A retrospective cohort study identified patients with symptomatic SFA lesions measuring at least 15 cm in length who successfully received an endovascular stent (BMS, CS, or DES). The outcomes were patency, patient presentation upon stent occlusion, amputation-free survival (AFS), and all-cause mortality. Proportional hazards regressions and a multinomial logistic regression model were used to control for significant confounders.

RESULTS

A total of 226 procedures were analyzed (BMS: 95 [42%]; CS: 74 [33%]; DES: 57 [25%]). There were no significant differences among the 3 stent types with respect to age, prevalence of either diabetes or end-stage renal disease, or smoking history. The median length of the SFA lesion varied across the cohorts (BMS: 28 cm [interquartile range, IQR 20-30]; CS: 26 cm [IQR 20-30]; DES: 20 cm [IQR 16-25]; P = 0.002). The unadjusted primary patency of BMS at 12, 24, and 48 month following index stent placement was 57%, 47%, and 44%, respectively. This is compared to 62%, 49%, and 42% for CS, and 81%, 66%, and 53% for DES, respectively (log-rank P = 0.044). In adjusted models, however, there were no significant differences in primary patency among the stent types. Compared to CS however, DES was associated with improved primary-assisted patency (hazard ratio [HR] for patency loss: 0.35, P = 0.008) and secondary patency (HR: 0.32, P = 0.011). Across the entire follow-up period, stent occlusions occurred in 38 (40%) BMS cases, 42 (57%) CS, and 11 (19%) DES (P < 0.001). Of these, acute limb ischemia (ALI) occurred in 2 (5%) BMS cases, 14 (33%) CS, and 1 (9%) DES (P = 0.010). After adjustment, the relative risk of presenting with ALI as opposed to claudication was 27 times greater among patients re-presenting with occluded CS compared to BMS (P = 0.020). There were no significant differences in AFS or all-cause mortality across the 3 cohorts.

CONCLUSIONS

For long-segment SFA lesions, DES is associated with improved primary-assisted and secondary patency over long-term follow-up. In the event of stent occlusion, CS is associated with an increased risk of ALI.

Drug-coated balloon angioplasty for the treatment of edge stenosis after self-expanding covered stent placement for superficial femoral artery occlusive disease

BACKGROUND

Edge stenoses are the predominant limitation of self-expanding covered stent treatment of superficial femoral artery (SFA) occlusive disease, necessitating reinterventions. Angioplasty of an edge stenosis is associated with a high recurrence rate. Drug-coated balloon (DCB) treatment of edge stenoses might improve outcomes by decreasing the incidence of restenosis.

PURPOSE

The aim of this study was to evaluate the outcomes of using a DCB for the treatment of edge stenoses after self-expanding covered stent placement for SFA occlusive disease.

METHOD

We performed a retrospective analysis of patients treated with a DCB for edge stenoses after self-expanding covered stent placement. The primary endpoint was primary patency at one year. The secondary endpoints included procedure-related complications, secondary patency, and freedom from target lesion revascularization (TLR).

RESULTS

A total of 21 patients with 28 edge stenoses were included. The time from primary treatment to treatment of the edge stenosis was 19 months (interquartile range (IQR) 8; 52 months). Primary patency and assisted primary patency at one year were 66.7% with a secondary patency of 90.9%. Freedom from TLR was 86.1%, and freedom from clinically driven TLR was 89.4%. Four patients presented with a hemodynamically significant restenosis, and three of those patients had an occlusion. Median time to failure was six months (IQR 3.5; 7.0 months), and median time to occlusion was four months (IQR 3.0; 6.0 months).

CONCLUSION

The treatment of edge stenoses using a DCB is associated with a safe one-year outcome; however, this has to be confirmed in larger prospective studies. The continuous surveillance of patients is indicated.

Risk Factors for Early and Late Iliac Limb Occlusions of Stent Grafts Extending to the External Iliac Artery after Endovascular Abdominal Aneurysm Repair

BACKGROUND

Iliac limb stent grafting to the external iliac artery (EIA) is a commonly performed procedure in various situation during endovascular abdominal aneurysm repair (EVAR). However, this procedure is associated with a risk of graft occlusion. We evaluated risk factors affecting occlusion among patients who underwent iliac limb stent-graft extension to the EIA.

MATERIALS AND METHODS

We compared occluded limbs with patent limbs during the follow-up period using variables, including anatomical values, demographics, and other factors. Thereafter, we divided the occluded limbs into early and late occlusion subgroups. The main and subgroup analyses used the same variables. Survival analysis was performed to evaluate time-dependent risk factors for late limb occlusion.

RESULTS

From 2007 to 2016, 766 iliac limbs from 383 patients who underwent EVAR were initially included in our analysis. Among them, 134 iliac limbs underwent limb extension to the EIA. The limb extension was a significant risk factor for occlusion (hazard ratio = 6.34, P < 0.001). Occlusion occurred in 10 patients who underwent iliac limb extension. The size of common iliac artery (CIA) was associated with occlusion. The most significant factor was iliac bifurcation diameter (patent vs. occluded limbs, 21.6 ± 7.6 vs. 27.5 ± 9.5 mm, P = 0.005). Subgroup analysis revealed that the CIAs of the early occlusion subgroup were generally more tortuous (1.16 ± 0.33 vs. 1.47 ± 0.25, P = 0.091) and longer (53 ± 24 vs. 74 ± 9, P = 0.01) than those of the patent limb group. In addition, the EIA diameters of the late occlusion subgroup were narrower than those of the patent limb group (10.9 ± 1.6 mm vs. 9.1 ± 0.8 mm, P = 0.011). Using the log-rank test, those patients with an EIA diameter narrower than 10.1 mm had a higher risk for late limb occlusion (log-rank χ² = 5.73, P = 0.017) and the patients who did not take at least a single antiplatelet agent had a significantly higher chance of limb occlusion (log-rank χ² = 11.029, P = 0.001). In addition, the patients who did not take a statin had a higher risk for late limb occlusion (log-rank χ² = 7.41, P = 0.007).

CONCLUSIONS

Among patients who underwent EVAR with iliac limb extension, the CIA length affected early limb occlusion and predisposed patients to vessel injury or stent-graft kinking, and there was the possibility that CIA tortuosity was associated with a higher risk. The late occlusion subgroup had narrower EIAs than the patent limb group. Appropriate antiplatelet and statin therapy is expected to play a key role in the prevention of late limb occlusion after EVAR.

Combination therapy of heparin-bonded covered stent and bare-nitinol stent assessed by intravascular ultrasound

To examine clinical outcomes for combination therapy of heparin-bonded covered stent [VIABAHN™ stent (VIA)] and bare-nitinol stent (BNS), and to determine independent predictors of restenosis after VIA implantation assessed by intravascular ultrasound (IVUS). A retrospective analysis was conducted on VIA use in the femoropopliteal artery of 71 patients (81 lesions) treated between June 2012 and November 2018. We divided the treated lesions into two groups; that is, whether BNS was added at the proximal site of the VIA or not (combination of VIA and BNS group [COM; n = 21] vs. VIA group [n = 60]). The median follow-up duration was 21.6 months (interquartile range, 13.2-28.8 months). Restenosis at 2 years was observed in 5 lesions (33%) in COM group and 17 lesions (38%) in VIA group (log-rank, P = 0.74). In VIA group, 14 lesions developed restenosis within 12 months. Multivariate logistic regression analysis of VIA group revealed that the proximal plaque burden was an independent predictor of restenosis within 12 months after VIA implantation (odds ratio 1.15, 95% confidence interval 1.01-1.30, P = 0.01), with the optimal cutoff value of 43% (area under the receiver operator characteristic curve 0.79, sensitivity 91%, specificity 69%). A remaining plaque of > 43% at the proximal reference segment was an independent predictor of restenosis after VIA implantation. When residual stenosis is observed at the proximal site of SFA after VIA implantation, combination therapy of VIA and BNS would be an optimal management.

Distal Edge Stenosis After Stent Placement for Isolated Superior Mesenteric Artery Dissection: Mechanisms and Risk Factor Analysis

PURPOSE

To analyze factors potentially associated with the occurrence of distal edge stenosis after stent placement for isolated superior mesenteric artery dissection (ISMAD).

MATERIALS AND METHODS

Cases of consecutive patients who were diagnosed with spontaneous ISMAD between February 2010 and July 2018 were retrospectively identified. Of the 123 cases identified, 45 patients (42 men; three women) underwent endovascular stent placement and were included in the study. Univariate and multivariate analyses were used to assess factors potentially associated with distal edge stenosis.

RESULTS

The technical success rate among study patients was 100%. During 26.7 ± 17.3 months of follow-up, CT angiography demonstrated good distal edge patency in 25 patients (55.6%) and evidence of distal edge stenosis in 20 patients (44.4%). In univariate analysis, stent length (odds radio [OR] 1.03; 95% confidence interval [CI] 1.01, 1.06; P = .02), stent-to-vessel (S/V) diameter ratio (OR 2.27; 95% CI 1.35, 3.82; P < .01), and angulation at the distal edge (OR 1.05; 95% CI 1.00, 1.10; P =.03) were significantly associated with distal edge stenosis; only S/V diameter ratio (OR 3.36; 95% CI 1.41, 7.99; P < .01) and angulation at the distal edge (OR 1.12; 95% CI 1.01, 1.23; P =.03) retained this significance in multivariate analysis.

CONCLUSIONS

Distal edge stenosis after stent placement for ISMAD is common. S/V diameter ratio and angulation at the distal edge are independent risk factors for distal edge stenosis in patients with ISMAD who undergo stent placement.

Exaggerated arterial curves due to endovascular interventions: Novel concept that describes how curves in the arterial wall affect the formation of neointimal hyperplasia, and explains why the long-term results of endovascular interventions are inferior to the long-term results of open surgical procedures

Despite the vast advancement made in endovascular practice, it is still lacking the long-term success of open surgery in treating critical limb ischemia. In Bypass surgery excess length of the graft is cut to straighten it between the arterial anastomoses to avoid any excess length, in order to make sure that there will be no curves, but in endovascular approach this option is not available. In endovascular procedures, there are factors affecting negatively the long-term results. These factors contribute to excess length of the arterial wall, which is exaggerated after balloon dilatation. With deployment of stent, the stent straightens the arterial segment, so any extra length shifts proximal and distal to this segment leading to exaggeration of curves in arterial wall which affect hemodynamics of blood flow leading to neointimal hyperplasia and restenosis even at the edges of stent. This explains neointimmal hyperplasia and restenosis at the edges of stent graft although its edges are landing on a normal artery. New solution for this durability problem of endovascular procedures is to avoid excess length. It can be achieved through a kind of stent that abolishes curves from the arterial tree.