Standardized evaluation and reporting of stent fractures in clinical trials of noncoronary devices

Outcomes and Comparative Analysis of the Initial Results of Standard Balloon Angioplasty Versus Drug-Coated Balloons Alone Versus in Association With Laser-Excimer Atherectomy in the Treatment of Femoropopliteal Artery In-Stent Restenosis (INTACT)

BACKGROUND

Despite improved patency with newer-generation nitinol stents, one-half of patients will require secondary interventions for in-stent restenosis (ISR). The best treatment strategy remains unclear. This study aimed to compare drug-coated balloons (DCBs) used alone or in association with excimer laser atherectomy (ELA) to simple percutaneous transluminal angioplasty (PTA) in the treatment of femoropopliteal-ISR.

METHODS

The INTACT trial is a multicenter, prospective, triple-arm randomized trial conducted across 14 centers from December 2015 to November 2019. Patients Rutherford Class 2-5 with ISR≥70% were followed-up for 18 months. The primary efficacy endpoint was recurrent ISR>70% by duplex ultrasound analysis. The primary safety endpoint was major adverse events (MAEs) defined as death, major amputation, or target lesion revascularization (TLR).

RESULTS

Around 134 subjects were randomized to PTA alone (n=41), PTA+DCB (n=43) or PTA+ELA+DCB (n=50). Procedural success was similar (p=.74), as was clinical success (p=.17). The number of recurrent ISR>70% decreased after PTA+ELA+DCB (30.0%; p=.04) and PTA+DCB (30.2%; p=.05) compared to PTA alone (51.2%). Primary patency was higher after PTA+ELA+DCB (log-rank p=.04) and PTA+DCB (log-rank p=.02) compared to PTA alone at 12 months (78.7% and 70.4% vs 61.5%) and 18 months (61.6% and 67.7% vs 37.3%). Freedom from MAEs was lower after PTA+DCB (27.9%) compared to PTA alone (53.7%; p=.02) but did not differ with PTA+ELA+DCB (40.0%). It was primarily driven by TLR; 2 major amputations occurred after PTA+ELA+DCB (4.0%; p=.18).

CONCLUSION

This independent study demonstrated a decrease in recurrent ISR>70% and increase in primary patency up to 18 months after PTA+ELA+DCB and PTA+DCB compared to PTA alone in the treatment of FP-ISR. It did not show an increase in MAEs but could have lacked power.

CLINICAL IMPACT

This multicenter, prospective, triple-arm randomized, controlled trial focuses on the results of adjunctive therapies, such as excimer laser atherectomy (ELA) and/or drug-coated balloons (DCBs) in the treatment of in-stent restenosis (ISR) in femoropopliteal lesions in 134 patients. It has the originality of being an independent study funded by a grant from the French Ministry of Health. This study confirms a significant decrease in recurrent ISR >70% and increase in primary patency up to 18 months after the use of ELA+DCB and DCBs compared to simple percutaneous transluminal angioplasty in the treatment of femoropopliteal ISR without an increase in major adverse events.

Outcomes of Using Balloon-Expandable Covered Stent for Percutaneous Treatment of Access-Site Vascular Injury after Transfemoral Aortic Valve Implantation: A Single Center Experience

BACKGROUND

Access-site vascular injury (ASVI) remains a challenge for transfemoral transcatheter aortic valve implantation (TAVI). Although surgery is the gold standard, endovascular therapy gains growing acceptance as primary treatment option for ASVI. The aim of this study was to analyze the safety and efficacy of covered balloon-expandable stents (BXSs) placement for ASVI after transfemoral TAVI.

METHODS

All patients treated with a covered BXS between January 2018 and December 2020 for access-site related bleeding complications following femoral TAVI were included in this single center retrospective study. Primary measure outcome of this study was the primary patency at 12 months. Technical success, limb clinical worsening and device related complications were additionally analyzed.

RESULTS

During the study period, 576 percutaneous femoral TAVIs were performed. Of these, 36 patients (6%) underwent covered stent deployment for a femoral access-site complication (19 men, median age 83 years old). Procedural success was 97%. The median follow-up was 12 months (interquartile range [IQR] = 9.7, range 0-36 months). One patient was lost to follow-up. The primary patency rates at 6 and 12 months were 100% and 95% respectively. No clinical deterioration or stent fracture was described during this period.

CONCLUSIONS

Our results suggest that covered BXS deployment is a safe and effective alternative to surgery and may be a promising option for treating ASVI after femoral TAVI.

Treatment of Long Femoropopliteal Lesions With Self-Expanding Interwoven Nitinol Stent: 24 Month Outcomes of the STELLA-SUPERA Trial

PURPOSE

The performance of self-expanding interwoven nitinol stent (Supera) in femoropopliteal interventions has been proven through trials with short lesions and with relatively low proportion of occlusions. There is limited evidence of Supera stent in long lesions. The aim of this study was to assess the clinical safety and efficiency of the Supera stent in the treatment of long femoropopliteal lesions (Trans-Atlantic Inter-Society Consensus [TASC] C/D) in patients with symptomatic peripheral arterial disease (PAD).

METHODS

The STELLA SUPERA (STEnting Long de L'Artère fémorale superficielle par le stent métallique Supera) is a prospective, 2-center, single-arm study. Patients with symptomatic (Rutherford stages 2-6) de novo and TASC C/D lesions of the femoropopliteal segment were treated with Supera stent. The primary endpoint was the primary sustained clinical improvement at 12 months. Follow-up included clinical examination, duplex scan, and biplane X-ray up to 24 months.

RESULTS

Between December 2016 and October 2018, 48 symptomatic patients with 49 femoropopliteal lesions (TASC D = 32, 65%) were treated. The mean lesion length was 234 ± 123 mm, and 78% were total occlusion. The mean stented lesion length was 273 ± 127 mm. At 12 and 24 months, the primary sustained clinical improvement rate was 87.2% and 79.7%, respectively. The Rutherford category assessment was significantly improved at 24 months compared with baseline (p=0.02). At 24 months, the primary patency and freedom from target lesion revascularization (TLR) rates were 77.9% and 86.9%, respectively. The ankle-brachial pressure index increased from 0.62 ± 0.15 at baseline to 0.93 ± 0.15 at 24 months (p<0.0001). There were no stent fractures at 24 months.

CONCLUSION

The use of Supera stent in long lesions (TASC C/D) is a safe and effective endovascular alternative. These results reinforce the need for randomized clinical trials to assess the value of interwoven stents for long femoropopliteal lesions.

Midterm and Long-Term Outcomes following Dedicated Endovenous Nitinol Stent Placement for Symptomatic Iliofemoral Venous Obstruction: Three- to 5-Year Results of the VIRTUS Study

PURPOSE

To assess the midterm patency and long-term safety of placement of a dedicated venous stent (Vici Venous Stent System) for the treatment of venous lesions of the iliofemoral outflow tract.

MATERIALS AND METHODS

Patients with unilateral obstructive disease of the iliofemoral veins and a Clinical, Etiological, Anatomical, Pathophysiological class of 3 or higher or a Venous Clinical Severity Score of 2 or greater were enrolled in this prospective, multicenter, single-arm study at 23 sites in the United States and Europe. The patients were followed up for 36 months after the index procedure for the assessment of patency and up to 60 months for the assessment of safety. The clinical outcomes in 11 patients with a stent fracture were assessed.

RESULTS

A total of 200 patients enrolled in 2 cohorts (ie, feasibility cohort, n = 30; pivotal cohort, n = 170) were combined for this analysis. The overall 36-month primary patency rate was 71.7% (86/120), and the 36-month primary patency rate was 96.4% (27/28) for the nonthrombotic group and 64.1% (59/92) for the postthrombotic group. The freedom from major adverse events was 81.2% (53/65) through 60 months. The 60-month Kaplan-Meier estimate of freedom from target vessel revascularization (TVR) was 84.3%. In 9 of the 11 patients who had a stent fracture (1 patient with nonthrombotic etiology and 10 patients with postthrombotic etiology) identified at 12 months, the stents extended into the common femoral vein. The TVR rates and clinical outcomes were similar between patients with and without a stent fracture.

CONCLUSIONS

The results of the VIRTUS study demonstrated good midterm patency and long-term safety following the placement of a dedicated venous stent for iliofemoral obstruction.

One-year results of long femoropopliteal lesions stenting with fasciotomy lamina vastoadductoria

OBJECTIVE

Fasciotomy can increase the mobility of the superficial femoral artery and decrease the incidence of stent fractures. This study aimed to compare the long-term patency of drug-eluting nitinol stents with and without fasciotomy in patients with prolonged SFA occlusions.

METHODS

A randomized clinical trial was conducted in 60 (1:1) patients with long femoropopliteal steno-occlusive lesions more than 200 mm. Patients in group 1 (Zilver) underwent recanalization of femoropopliteal artery occlusion with stenting. In group 2 (ZilverFas), the femoropopliteal occlusion was recanalized with stenting and fasciotomy of Gunter's canal. The follow-up assessment of the patency took place after 6, 12 months.

RESULTS

12-month primary patency in Zilver and ZilverFas groups was 51% and 80%, respectively (p = 0.02). The freedom from target revascularization (TLR) in Zilver and ZilverFas groups was 50% and 76%, respectively (p = 0.04). At one-year, primary-assisted and secondary patency for the ZilverFas and Zilver groups were 83% versus 62% (p = 0.07), 86% versus 65% (p = 0.05), respectively. In Zilver and ZilverFas groups, the number of stents fractures was 14 and 7, respectively (p = 0.05). The multivariables Cox regression indicated that the stent fracture and diabetes mellitus were the independent predictors of restenosis and reocclusion. Fasciotomy reduced the risk of reocclusion and restenosis by 2.94 times.

CONCLUSIONS

Our study has shown that a decompressing the stented segment with fasciotomy significantly improves the patency of the femoropopliteal segment and significantly reduces the number and severity of stent fractures.

Hybrid surgery techniques for the treatment of in-stent restenosis after 5 years of femoral artery self-expanding bare-metal stent implantation: A case report

RATIONALE

Lower extremity arteriosclerosis obliterans (ASO) disease is caused by the formation of atherosclerotic plaque in the femoral artery, which causes the stenosis and occlusion of lower legs, and then leads to chronic limb ischemia. Stent intervention is the most common treatment for ASO in the lower extremities, although there is a risk of overstretching or fracturing the stent, resulting in stent rupture. We provide a unique method for treating stent rupture.

PATIENT CONCERNS

A 79-year-old male presented with intermittent claudication of the left lower limb for 6 months. Five years ago, a stent was placed in the lower extremity femoral artery. According to the examination, the stent suffered a modest torsional fracture.

DIAGNOSIS

The case was diagnosed with lower extremity ASO.

INTERVENTIONS

We performed a combination of femoral endarterectomy and interventional surgery.

OUTCOMES

Blood flow was restored after the hybrid operation has been used to treat arterial stenosis in the lower limbs.

CONCLUSION

Integrating vascular interventional surgeries can shorten surgical procedures time and increase success rates.

Common Femoral Artery Stenting: Computed Tomography Angiography Based Long-Term Patency

BACKGROUND

Despite considerable morbid-mortality rates, common femoral endarterectomy is still considered the gold standard for atherosclerotic common femoral artery (CFA) disease. The aim of this study was to demonstrate computed tomography angiography based long-term patency after CFA stent placement and to analyze associated risk factors for restenosis.

METHODS

A retrospective and observational study was carried out in consecutive patients treated with endovascular stent placement in CFA lesions. A clinical follow-up and imaging study was performed using MD-CTA to assess different degrees of in stent restenosis (ISR) and primary, assisted, and secondary patency rates.

RESULTS

In a 5-year period, 35 extremities were treated in 33 patients with self-expandable nitinol stents. The technical success was 100% without complications related to the procedure. The mean follow-up (FU) was 32.2 months, and 8 limbs were lost. The degree of CFA stenosis was reduced from 79.69 ± 26.47% to 11.23 ± 24.53%. ISR < 20%, 20-70%, and ≥ 70% was evident in 15 (55.6%), 9 (33.3%), and 3 (11.1%) limbs, respectively. Estimated primary, assisted, and secondary patency was 79.5, 96.3, and 96.3%, respectively, after 24 months and 79.5, 96.3, and 96.3%, respectively after 60 months, with a freedom of clinical driven target lesion revascularisation rate of 87.8%.

CONCLUSION

Endovascular treatment with self-expandable nitinol stents in CFA lesions had a high technical success rate and was related to few complications. A mild form of intimal hyperplasia was observed in a considerable number of cases. However, long-term patency was high; therefore, CFA stent placement might be a suitable therapeutic alternative in selected patients.

Pre-procedural color duplex ultrasound evaluation predicts restenosis after long-segment superficial femoral artery stenting

OBJECTIVES

Restenosis after stenting for superficial femoral artery atherosclerotic disease remains a significant clinical problem, especially for long-segment lesions. We assessed predictors of in-stent restenosis in patients with long-segment superficial femoral artery disease and hypothesized that pre-procedural ultrasound assessment would predict in-stent restenosis.

METHODS

This single-center study retrospectively analyzed 283 limbs in 243 patients who treated with superficial femoral artery nitinol stent placement for long-segment (≥15 cm) lesions between 2015 and 2018. Color duplex ultrasound was performed pre-procedure and post-procedure at 3, 6, 12, 24, and 36 months. The endpoint was ≥50% in-stent restenosis in the superficial femoral artery. Primary patency rates were analyzed with Kaplan-Meier survival analysis and compared using the log-rank test. A multivariable Cox proportional hazards model was used to evaluate the risk factors for in-stent restenosis.

RESULTS

The median length of lesions was 25.8 ± 8.1 cm. The cumulative freedom from ≥50% in-stent restenosis at 3, 6, 12, 24, and 36 months was 95.3%, 78.3%, 56.0%, 30.6%, and 15.9%, respectively. Univariate and multivariate Cox regression analysis showed that cumulative lesion length ≥ 25 cm (hazard ratio 1.681; p = 0.003), calcified plaque (hazard ratio 1.549, p = 0.006), poor runoff scores >10 (hazard ratio 1.870, p = 0.003), and chronic renal failure (hazard ratio 2.075, p = 0.009) were independent risk factors for in-stent restenosis. The agreement rate between ultrasound and angiography was 92.6% for cumulative lesion length (κ 0.851) and 91.9% for runoff score (κ 0.872).

CONCLUSIONS

The results indicate that pre-procedural color duplex ultrasound evaluation is helpful for the selection of appropriate candidates for superficial femoral artery stent placement. Cumulative lesion length ≥25 cm, plaque calcification, poor distal runoff, and chronic renal failure independently predicted in-stent restenosis.

Simplified Trans-Axillary Aortic Valve Replacement Under Local Anesthesia - A Single-Center Early Experience

BACKGROUND

The axillary artery is an alternative route for patients with comorbidities and unfavorable femoral arteries who need transcatheter aortic valve replacement (TAVR). Simplified trans-axillary transcatheter aortic valve replacement (TAx-TAVR) implies a completely percutaneous approach under local anesthesia and arteriotomy closure with vascular closure techniques. Herein, we report on early experience with simplified TAx-TAVR under local anesthesia.

METHODS

We enrolled all consecutive patients who underwent simplified TAx-TAVR in our center. Main study parameter was the incidence of axillary access related major vascular complications within 30 days. Secondary parameters included a composite early safety endpoint, axillary access-site related vascular/bleeding complications and short-term mortality. Post TAVR axillary stent patency was evaluated during follow-up by CT-analysis.

RESULTS

Between July 2018 and April 2020, Tax-TAVR was attempted in 35 patients with a mean age of 79 years. Local anesthesia and conscious sedation were used in 91.4% (n = 32) and 8.6% (n = 3) respectively. A covered stent was needed for complete axillary hemostasis in 44.1% (n = 15). Device success was achieved in 91.2% (n = 31/34). The 30-day axillary artery major vascular and ≥major bleeding complication rates were 14% (n = 5) and 11% (n = 4). The early safety endpoint was reached in 22.9% (n = 8). Mortality rates at 30 days and six months were 2.9% and 11.6%. Computed tomography (CT) confirmed axillary stent patency during follow-up in 82% (n = 9/11).

CONCLUSIONS

In patients with high/prohibitive surgical risk and unsuitable femoral access, simplified TAx-TAVR under local anesthesia offers a valuable alternative for transfemoral TAVR but requires advanced access site management techniques including covered stents. Our data suggest an unmet clinical need for dedicated TAx closure devices.

Stents in the femoropopliteal territory: prevalence of fractures and their consequences

OBJECTIVE

Endovascular treatment for femoropopliteal arterial disease has made revascularization procedures less invasive, but the self-expanding stents used can suffer great wear in arteries with extreme mobility. To evaluate the prevalence of fractures in stents implanted in the femoropopliteal segment, to identify predisposing factors and consequences on arterial patency.

METHOD

between March and June 2019, thirty patients previously operated for femoropopliteal obstruction underwent stent X-rays in anteroposterior and lateral views to detect fractures and Doppler to analyze arterial patency.

RESULTS

we observed 12 cases with fractures (33.3%): 1 type I (2.8%), 3 type II (8.3%), 5 type III (13.9%), 3 type IV (8.3%) and no type V. According to the TASC II we had 1 in group B (8.3%), 6 in group C (50%) and 5 in group D (41.6%) p <0.004. The number of stents per limb was 3.1 (± 1.3) in cases of fracture versus 2.3 (± 1.3) in cases without fracture (p = 0.08). The extension was 274.17mm (± 100.94) in cases of fracture and 230.83mm (± 135.44) in cases without fracture (p = 0.29). On Doppler we had: 17 patients (47.2%) without stenosis, 9 patients (25%) with stenosis> 50% and 10 patients (27.8%) with occlusion (p = 0.37). There was no correlation between fracture and arterial obstruction (p = 0.33).

CONCLUSION

stent fractures are a frequent finding in the femoropopliteal area (33.3%), being more prevalent in cases of more advanced disease (C and D). There was no association between the finding of fracture and arterial obstruction.

Bare Stents for Iliac Chronic Total Occlusions ("TELIS"): A Prospective Cohort Study with a Midterm Follow-up

BACKGROUND

This study aims to assess primary bare stenting for iliac chronic total occlusions (CTOs) with midterm follow-up.

METHODS

From April 2013 to May 2016, all patients presenting with symptomatic iliac CTO were treated endovascularly and included in a prospective single-center cohort. Common iliac CTOs were treated with balloon-expandable bare-metal stents. External iliac lesions were treated with bare self-expandable nitinol stents. Primary end point was primary sustained clinical improvement. A total of 49 iliac CTOs were treated in 46 patients.

RESULTS

A total of 22 lesions were located at the level of the common iliac artery (45%), 20 at the external iliac artery (41%), and 7 extending to both (14%). Mean stenting length was 114.4 ± 49.8 mm. Technical success was 98%. Primary sustained clinical improvement was achieved for 93.4 ± 3.7% of patients at 12 months and 87.7 ± 5.2% at 24 months. Three in-stent thrombosis were observed with no restenosis in the remaining patients at 24 months. Freedom from target lesion revascularization was 93.3% ± 3.7% at 24 months. Three stent fractures were noted, none were symptomatic. Mean quality of life (EQ5D-3L) was significantly improved at 24 months (71.2 ± 20.3 vs. 52.4 ± 22.6, P = 0.001).

CONCLUSIONS

Our results showed that primary bare-metal stenting for iliac CTO is safe and efficient at 24 months and could be considered as a first-line strategy.

Three-Year Efficacy and Safety of the Misago Peripheral Stent for Superficial Femoral Artery Disease: Final Results from the OSPREY Trial

PURPOSE

This study evaluated the long-term outcomes of the Misago peripheral stent trial (Terumo) for atherosclerotic lesions in the superficial femoral artery (SFA) in patients with claudication.

MATERIALS AND METHODS

This was a prospective multicenter, single-arm, clinical trial of primary stent placement for de novo cases of SFA disease conducted in the United States and Asia. The primary endpoint was freedom from clinically driven target lesion revascularization (CD-TLR) at 36 months. Secondary outcomes were ankle-brachial index (ABI), Rutherford score, Walking Impairment Questionnaire (WIQ), a quality of life survey, and rate of device fracture.

RESULTS

A total of 276 patients (64.4% male; mean age, 69.3 ± 10.1 years) were enrolled. Freedom from CD-TLR was 78.5% (95% confidence interval [CI], 73.0%-83.0%) at 24 months and 75.4% (95% CI, 69.6%-80.2%) at 36 months. Baseline ABI was 0.7 ± 0.1 and 0.98 ± 0.20 (P < .001) at 30 days after the procedure. Baseline Rutherford score was 3.6 ± 0.6 and 1.6 ± 1.0 30 at 30 days after the procedure (P < .001). Mean (and changed) ABI and Rutherford score at 36 months compared to day 30 after the procedure were, respectively, 0.91 (-0.1 ± 0.2) and 1.5 (-0.2 ± 1.1). WIQ score at baseline was 21.49 ± 26.30 and 50.51 ± 38.49 at 30 days after the procedure ( P < .001). The mean WIQ score at 2 years was 46.65 ± 37.31 (P = .12). Stent fracture rate at 36 months was 2.0% (4 of 202 patients).

CONCLUSIONS

OSPREY (Occlusive-Stenotic Peripheral Artery Revascularization Study) 36-month data demonstrated persistent freedom from CD-TLR and sustained improvement in ABI and Rutherford score with primary stent placement for SFA lesions.

Long-term follow-up after stent graft placement for access-site and access-related vascular injury during TAVI - The Bonn-Copenhagen experience

AIMS

Stent graft placement is a safe and effective treatment option for vascular complications in the context of transcatheter aortic valve implantation (TAVI). This study aimed to provide long-term angiological follow-up of stent grafts used for this indication.

METHODS AND RESULTS

Seventy-one patients (64.8% female, log EuroScore 14.7 ± 6.8%) who had undergone TAVI between March 2010 and October 2015 with implantation of a Viabahn or Fluency stent graft to treat access-site or access-related vascular injury (ASARVI) were analyzed. Implantations were mostly due to access-site bleeding complications (83.1%) in the common femoral artery (97.1%). Follow-up was performed with duplex sonography in all patients after a median of 3.9 years after TAVI (interquartile range [IQR]: 895-1749 days). Ultrasound revealed tri- or biphasic flow patterns in 16.9% and 77.6%, respectively. Stent graft patency was 100% without signs of stent graft stenosis (mean peak velocity ratio 1.0 ± 0.2). Pseudo-aneurysms or endoleaks were diagnosed in 5.6% of patients. Additional fluoroscopic and/or computed tomography (CT)-imaging was available in 36.6% of patients and did not reveal any stent fracture.

CONCLUSION

Self-expanding stent grafts provide excellent long-term function with few complications when implanted in the context of TAVI-related ASARVI.

Ex vivo assessment and in vivo validation of non-invasive stent monitoring techniques based on microwave spectrometry

Some conditions are well known to be directly associated with stent failure, including in-stent re-occlusion and stent fracture. Currently, identification of these high-risk conditions requires invasive and complex procedures. This study aims to assess microwave spectrometry (MWS) for monitoring stents non-invasively. Preliminary ex vivo data are presented to move to in vivo validation. Fifteen mice were assigned to receive subcutaneous stent implantations (n = 10) or sham operations (n = 5). MWS measurements were carried out at 0, 2, 4, 7, 14, 22, and 29 days of follow-up. Additionally, 5 stented animals were summited to micro-CT analyses at the same time points. At 29 days, 3 animals were included into a stent fracture subgroup and underwent a last MWS and micro-CT analysis. MWS was able to identify stent position and in-stent stenosis over time, also discerning significant differences from baseline measures (P < 0.001). Moreover, MWS identified fractured vs. non-fractured stents in vivo. Taken together, MWS emerges as a non-invasive, non-ionizing alternative for stent monitoring. MWS analysis clearly distinguished between in-stent stenosis and stent fracture phenomena.

Use of the Gore Tigris Vascular Stent in Advanced Femoropopliteal Peripheral Arterial Disease

PURPOSE

To prospectively evaluate the safety and efficacy of using the Tigris vascular stent (Gore, Flagstaff, Arizona) alone or in combination with the Viabahn stent (Gore) for revascularizing femoropopliteal Trans-Atlantic Intersociety Consensus (TASC) type B-D lesions with varying degrees of calcification.

MATERIALS AND METHODS

Patients with Rutherford stage ≥ 3 and TASC type ≥ B were included in the study. From January 2015 to April 2017, 31 segments in 31 patients (21 men, ovarall mean age 73.3 ± 9.2 years) were treated. The breakdown by TASC type and Rutherford stage were TASC B (n = 12), C (n = 6), and D (n = 13), and Rutherford 3 (n = 28) and 4 (n = 3). The lesions were located in the common femoral artery (n = 1), superficial femoral artery (SFA; n = 20), distal SFA to P1 (n = 3), popliteal P1 (n = 1), popliteal P1-3 (n = 3), popliteal P2-3 (n = 2), and 1 femoropopliteal bypass. There were 18 occlusions (58.1%) and 13 stenoses (41.9%). The mean diseased segment length was 15.5 ± 9.9 cm with 80.6% of moderate/severe calcification. The follow-up consisted of color Doppler ultrasound and clinical assessment at 1, 3, 6, 9, 12, and 15 months.

RESULTS

Technical success was 100%. There were no periprocedural or postprocedural complications. The mean stented lesion length was 17.2 ± 10.5 cm with a mean follow-up of 13.1 ± 6.9 months. Primary patency rates at 6, 9, 12, and 15 months were, respectively, 100% (24/31 patients), 90.5% (21/31 patients), 88.9% (20/31 patients), and 80% (15/31 patients). The median postprocedural Rutherford stage was 1. Three occlusions occurred at 7, 9, and 14 months, leading to a target lesion revascularization of 9.7% and a secondary patency of 100% at 15 months. Logistic analysis results demonstrated that lesion length (P = .003) was associated with reocclusion. Amputation-free survival at 15 months was 100%. Intrastent restenosis was observed in four cases (12.9%) but none were associated with worsening of symptoms. No stent fractures were observed.

CONCLUSIONS

The Tigris stent used alone or in combination with a Viabahn stent for femoropopliteal TASC B-D lesions demonstrated acceptable 12-month primary patency with a low reintervention rate.

Novel Nitinol Stent for Lesions up to 24 cm in the Superficial Femoral and Proximal Popliteal Arteries: 24-Month Results From the TIGRIS Randomized Trial

PURPOSE

To evaluate the safety and effectiveness of the TIGRIS stent for lesions up to 24 cm in the superficial femoral and proximal popliteal arteries (SFA/PPA).

METHODS

This prospective, multicenter, randomized study enrolled 274 subjects at 36 sites in the United States and Europe. Subjects were randomly assigned in a 3:1 ratio to treatment with the TIGRIS stent (n=197; mean age 66.7±9.28 years; 141 men) or LifeStent (n=70; mean age 67.9±8.87 years; 49 men). The primary safety endpoint was 30-day freedom from major adverse events (MAE). The primary efficacy endpoint was primary patency at 12 months. Secondary endpoints included target lesion revascularization (TLR) and stent fracture. Clinical success and quality of life were also assessed.

RESULTS

Mean lesion length (107.6 vs 117.9 mm, p=0.29), procedure success (99.5% vs 97.1%, p=0.17), and freedom from MAE (99.5% vs 100%, p>0.99) were similar for the TIGRIS and control groups, respectively. Likewise, there was no difference in primary patency at 12 months (60.6% vs 63.2%, p=0.73) or 24 months (56.3% vs 50.2%, p=0.60) or in TLR at the same time points (76.6% vs 80.6%, p=0.49; 70.5% vs 67.2%, p=0.85). There were no differences in the changes in Rutherford category or the ankle/brachial index through 24 months. The rate of stent fracture was lower for TIGRIS compared with LifeStent (0% vs 32.7%, p<0.001).

CONCLUSION

The TIGRIS stent and LifeStent were similarly effective for the treatment of lesions in the SFA and PPA. The high flexibility and zero fracture rate associated with the TIGRIS stent make this device favorable for use in high-flexion arteries.

Fracture of a Supera Interwoven Nitinol Stent After Treatment of Popliteal Artery Stenosis

Purpose: To present a Supera stent fracture following treatment of popliteal artery stenosis. Case Report: A 60-year-old man previously treated with angioplasty/stenting of a popliteal artery lesion with a Supera stent presented at 8 months with in-stent occlusion that proved to be secondary to stent fracture. Conclusion: Supera interwoven nitinol stents, despite having higher radial force and conformability than classic tube stents, are not free from fracture. Moreover, due to their peculiar structure, a break in these stents results in complete loss of integrity and consequent device collapse, thus jeopardizing endovascular recanalization and relining.

Zilver PTX Post-Market Surveillance Study of Paclitaxel-Eluting Stents for Treating Femoropopliteal Artery Disease in Japan: 12-Month Results

OBJECTIVES

This multicenter, prospective, post-market surveillance study in Japan evaluates the paclitaxel-coated Zilver PTX stent in real-world patients with complex lesions.

BACKGROUND

The Zilver PTX stent is the first drug-eluting stent (DES) approved for the superficial femoral artery. Previously, results from a large randomized study and a complementary, large single-arm study supported the safety and effectiveness of the DES.

METHODS

There were no exclusion criteria, and consecutive patients with symptomatic peripheral artery disease (PAD) treated with the DES were enrolled in the study. Clinically driven target lesion revascularization (TLR) was defined as reintervention performed for ≥50% diameter stenosis after recurrent clinical symptoms of PAD. Clinical benefit was defined as freedom from persistent or worsening symptoms of ischemia. Patency was evaluated by duplex ultrasound where physicians considered this standard of care.

RESULTS

In this study, 907 patients were enrolled at 95 institutions in Japan. There were numerous comorbidities including high incidences of diabetes (58.8%), chronic kidney disease (43.8%), and critical limb ischemia (21.5%). Lesions were also complex, with an average length of 14.7 cm, 41.6% total occlusions, and 18.6% in-stent restenosis. In total, 1,861 DES were placed in 1,075 lesions. Twelve-month follow-up was obtained for >95% of eligible patients. Freedom from TLR was 91.0%, and clinical benefit was 87.7% through 12 months. The 12-month primary patency rate was 86.4%.

CONCLUSIONS

Despite more challenging lesions, results from the current study are similar to outcomes from the previous Zilver PTX studies, confirming the benefit of the Zilver PTX DES in a real-world patient population. (Zilver PTX Post-Market Study in Japan; NCT02254837).

Routine Endovascular Treatment With a Stent Graft for Access-Site and Access-Related Vascular Injury in Transfemoral Transcatheter Aortic Valve Implantation

Background—

Access-site and access-related vascular injury (ASARVI) is still a major limiting factor in transcatheter aortic valve implantation and affects the outcome of patients. Management strategies for ASARVI include manual compression, stent grafts, and vascular surgery. We hypothesized that the standard use of a self-expanding stent graft for the management of ASARVI is feasible and safe.

Methods and Results—

Of 407 patients treated by transfemoral transcatheter aortic valve implantation, 110 experienced ASARVI (27.0%). Of these, 96 (87.3%) were managed by the implantation of a self-expanding nitinol stent graft. In the majority of patients, minor vascular complications triggered the implantation of a stent graft (86.5%), mainly because of bleeding (90.6%) and dissection (5.2%) of the common femoral artery with high rates of primary treatment success (97.9%). Patients receiving stent grafts were more often female (62.2 versus 45.6%, P <0.01), had higher body mass indices (27.8±6.7 versus 25.7±4.7, P =0.01), and suffered more often from diabetes mellitus (34.4 versus 24.5%, P =0.04). Angiographic assessment after a median follow-up of 345 days (interquartile range, 23–745 days) revealed only one patient with moderate, asymptomatic instent-stenosis (1.0%). Compared with a propensity score–matched cohort of patients without ASARVI, stented patients had comparable long-term mortality, despite the occurrence of a vascular complication (1-year mortality: 17.7% versus 26.6%; stent versus matched cohort, respectively; P =0.1).

Conclusions—

Routine use of a self-expanding nitinol stent graft in selected patients experiencing ASARVI after transcatheter aortic valve implantation is feasible, safe, and associated with favorable short- and midterm clinical outcome.

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section

The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and tortuosity). Secondary flow structures are vortical flow patterns that occur in curved arteries due to the combined action of centrifugal forces, adverse pressure gradients and inflow characteristics. Such flow morphologies are greatly affected by pulsatility and multiple harmonics of physiological inflow conditions and vary greatly in size-strength-shape characteristics compared to non-physiological (steady and oscillatory) flows (1 - 7). Secondary flow structures may ultimately influence the wall shear stress and exposure time of blood-borne particles toward progression of atherosclerosis, restenosis, sensitization of platelets and thrombosis (4 - 6, 8 - 13). Therefore, the ability to detect and characterize these structures under laboratory-controlled conditions is precursor to further clinical investigations. A common surgical treatment to atherosclerosis is stent implantation, to open up stenosed arteries for unobstructed blood flow. But the concomitant flow perturbations due to stent installations result in multi-scale secondary flow morphologies (4 - 6). Progressively higher order complexities such as asymmetry and loss in coherence can be induced by ensuing stent failures vis-à-vis those under unperturbed flows (5). These stent failures have been classified as "Types I-to-IV" based on failure considerations and clinical severity (14). This study presents a protocol for the experimental investigation of the complex secondary flow structures due to complete transverse stent fracture and linear displacement of fractured parts ("Type IV") in a curved artery model. The experimental method involves the implementation of particle image velocimetry (2C-2D PIV) techniques with an archetypal carotid artery inflow waveform, a refractive index matched blood-analog working fluid for phase-averaged measurements (15 - 18). Quantitative identification of secondary flow structures was achieved using concepts of flow physics, critical point theory and a novel wavelet transform algorithm applied to experimental PIV data (5, 6, 19 - 26).

Structural Mechanics Predictions Relating to Clinical Coronary Stent Fracture in a 5 Year Period in FDA MAUDE Database

Endovascular stents are the mainstay of interventional cardiovascular medicine. Technological advances have reduced biological and clinical complications but not mechanical failure. Stent strut fracture is increasingly recognized as of paramount clinical importance. Though consensus reigns that fractures can result from material fatigue, how fracture is induced and the mechanisms underlying its clinical sequelae remain ill-defined. In this study, strut fractures were identified in the prospectively maintained Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience Database (MAUDE), covering years 2006-2011, and differentiated based on specific coronary artery implantation site and device configuration. These data, and knowledge of the extent of dynamic arterial deformations obtained from patient CT images and published data, were used to define boundary conditions for 3D finite element models incorporating multimodal, multi-cycle deformation. The structural response for a range of stent designs and configurations was predicted by computational models and included estimation of maximum principal, minimum principal and equivalent plastic strains. Fatigue assessment was performed with Goodman diagrams and safe/unsafe regions defined for different stent designs. Von Mises stress and maximum principal strain increased with multimodal, fully reversed deformation. Spatial maps of unsafe locations corresponded to the identified locations of fracture in different coronary arteries in the clinical database. These findings, for the first time, provide insight into a potential link between patient adverse events and computational modeling of stent deformation. Understanding of the mechanical forces imposed under different implantation conditions may assist in rational design and optimal placement of these devices.

Stent Fractures After Superficial Femoral Artery Stenting

Purpose: To determine the risk factors and clinical impact of stent fractures after superficial femoral artery (SFA) stenting. Methods: From May 2009 to June 2012, 171 consecutive patients (mean age 74.5±7.8, years; 106 men) who presented with SFA stenosis or occlusion in 205 limbs underwent stent implantation in the SFA at a single center. Stent fractures were determined by radiography and classified into types I through V. Loss of patency was assessed by duplex ultrasonography (>2.4 peak systolic velocity ratio) or angiography (percent diameter stenosis >50%). Results: The 12- and 24-month primary patency rates were 49.8% and 43.4%, respectively. Stent fractures occurred in 12.5% and 26.8% per limb (6.6% and 19.4% per stent) at 12 and 24 months, respectively. Primary patency was numerically worse in the stent fracture group but not statistically different from the group without fractures at 2 years. Primary patency for different classes of stent fracture were 30.8% (type I), 50.0% (type II), and 31.3% (type III–V). Hyperlipidemia (p=0.001), TransAtlantic Inter-Society Consensus II classification (p=0.007), chronic total occlusion (CTO; p<0.001), proximal lesion location (p=0.008), lesion calcification (p=0.025), total stent length (p=0.005), stent diameter (p=0.001), and number of stents (p=0.001) were statistically significant predictors of stent fracture. Multivariate analysis showed that CTO (hazard ratio 0.173, 95% confidence interval 0.042 to 0.716, p=0.015) was an independent predictor of stent fracture. Conclusion: Stent fractures occur more frequently in patients with CTOs after treatment of longer stented lesions. Although multivariate analysis showed that CTO was the only independent predictor regardless of stent length or number, the stent fracture rate was numerically higher in the severe calcification and proximal SFA lesion subgroups. Stent fracture did not appear to affect long-term patency rates, but this is yet to be confirmed with further follow-up.

Angioplasty of the common femoral artery and its bifurcation

BACKGROUND

To evaluate the efficacy of percutaneous transluminal angioplasty (PTA) of atherosclerotic lesions of the common femoral artery (CFA) and its bifurcation.

METHODS

From 2009 to 2013, 53 patients (43 men, average age, 68 years) were included in a single-center, nonrandomized, prospective study. Indication was disabling intermittent claudication (n = 36) or chronic critical limb ischemia (n = 17). Thirty-four procedures (64%) were isolated CFA PTA, whereas 7 of 53 (13%) involved inflow (including 4 iliac occlusions) and 12 of 53 (23%) involved outflow vessels. Primary stenting was performed in 50 cases (95%). CFA occlusions were recanalized in 4 of 53. Lesions involved the bifurcation in 22 cases (40%). Follow-up consisted of clinical examination and duplex scanning with ankle-brachial index measurement at 1, 6, and 12 months. A biplane X-ray was performed at 1 year. The primary end point was the absence of binary restenosis (>50% reobstruction of the CFA). Secondary end points were freedom from target lesion revascularization (TLR) and stent fracture rate.

RESULTS

Procedural success was achieved in 96% of cases. At a mean follow-up of 24 months (with 1 patient lost of follow-up), the absence of binary restenosis was 92.5%. At the end of follow-up, 82% of patients continued to show clinical improvement. Freedom from TLR was 97%. Stent fracture rate at 1 year was 9%.

CONCLUSIONS

PTA of the CFA and its bifurcation is a reliable technique with good midterm functional results. These results justify performing a randomized study comparing surgery and endovascular treatment.

Microwave spectrometry for the evaluation of the structural integrity of metallic stents

PURPOSE

To assess the feasibility of a method based on microwave spectrometry to detect structural distortions of metallic stents in open air conditions and envisage the prospects of this approach toward possible medical applicability for the evaluation of implanted stents.

METHODS

Microwave absorbance spectra between 2.0 and 18.0 GHz were acquired in open air for the characterization of a set of commercial stents using a specifically design setup. Rotating each sample over 360°, 2D absorbance diagrams were generated as a function of frequency and rotation angle. To check our approach for detecting changes in stent length (fracture) and diameter (recoil), two specific tests were performed in open air. Finally, with a few adjustments, this same system provides 2D absorbance diagrams of stents immersed in a water-based phantom, this time over a bandwidth ranging from 0.2 to 1.8 GHz.

RESULTS

The authors show that metallic stents exhibit characteristic resonant frequencies in their microwave absorbance spectra in open air which depend on their length and, as a result, may reflect the occurrence of structural distortions. These resonances can be understood considering that such devices behave like dipole antennas in terms of microwave scattering. From fracture tests, the authors infer that microwave spectrometry provides signs of presence of Type I to Type IV stent fractures and allows in particular a quantitative evaluation of Type III and Type IV fractures. Recoil tests show that microwave spectrometry seems able to provide some quantitative assessment of diametrical shrinkage, but only if it involves longitudinal shortening. Finally, the authors observe that the resonant frequencies of stents placed inside the phantom shift down with respect to the corresponding open air frequencies, as it should be expected considering the increase of dielectric permittivity from air to water.

CONCLUSIONS

The evaluation of stent resonant frequencies provided by microwave spectrometry allows detection and some quantitative assessment of stent fracture and recoil in open air conditions. Resonances of stents immersed in water can be also detected and their characteristic frequencies are in good agreement with theoretical estimates. Although these are promising results, further verification in a more relevant phantom is required in order to foresee the real potential of this approach.

S.M.A.R.T. self-expanding nitinol stent for the treatment of atherosclerotic lesions in the superficial femoral artery (STROLL): 1-year outcomes

PURPOSE

To assess safety and efficacy of the S.M.A.R.T. Vascular Stent System (Cordis Corp, Fremont, California) in obstructive superficial femoral artery (SFA) disease.

MATERIALS AND METHODS

The single-arm, multicenter STROLL study (S.M.A.R.T. Nitinol Self-Expanding Stent in the Treatment of Obstructive Superficial Femoral Artery Disease) included 250 patients (250 lesions in SFA or proximal popliteal artery). The efficacy endpoint was primary patency defined by freedom from binary restenosis (peak systolic velocity ratio > 2.5) as derived by duplex ultrasound plus clinically driven target lesion revascularization (TLR) at 12 months.

RESULTS

Mean age of patients was 67.7 years ± 10.3; 47.2% of patients had diabetes; distribution of Rutherford/Becker classes 2, 3, and 4 was 45.8%, 51.4%, and 2.8%. Mean lesion length and reference vessel diameter were 77.3 mm ± 35.3 and 4.9 mm ± 0.7, respectively (23.6% cases with total occlusions). The 30-day freedom from major adverse events (death, index limb amputation, clinically driven TLR) was 100%. The 1-year primary patency was 81.7% by Kaplan-Meier estimate. The presence of diabetes or total occlusion had no effect on primary patency. Ankle-brachial index was 0.4-0.8 in 84.6% of patients at baseline and improved to > 0.8 in 81.0% of patients at 12 months. The proportion of patients in Rutherford/Becker class 3-4 was reduced from 54.2% at baseline to 8.0% at 12 months. Four patients (2.0%) experienced single-stent strut fracture (type I) at 1 year, without associated loss of stent patency.

CONCLUSIONS

The S.M.A.R.T. Vascular Stent System proved to be safe and effective for endovascular treatment of obstructive SFA and proximal popliteal artery disease, based on 1-year vessel patency and associated hemodynamic and clinical improvements.

Coronary stent fracture: a recently appreciated phenomenon with clinical relevance

In the stent era, in addition to restenosis, there are many important consequences deserving more attention. Firstly described in peripheral vascular interventions, it took several years for stent fracture to be known as an appreciable complication of coronary intervention. Especially with the introduction of drug eluting stents and the use of coronary stents in more complex cases, its prevalence has raised and new data have been published concerning its mechanism, predictors, diagnosis, clinical course and treatments. This review will discuss the available literature about stent fracture.

Primary stenting of TASC C and D femoropopliteal lesions: results of the STELLA register at 30 months

BACKGROUND

The 1-year results of the prospective register STELLA suggested that primary stenting of long femoropopliteal (FP) lesions (≥15-cm) was a sure and effective treatment. However, the long-term results of this technique remain unknown.

METHODS

STELLA is a prospective monocentric register of patients treated for FP lesions ≥15-cm (Trans-Atlantic Inter-Society Consensus [TASC] C and D) by direct stenting (Flexstar(®), Bard). The patients with de novo atheromatous lesions were included between November 2008 and October 2009 when the guidewire had crossed the lesion. Restenoses were excluded. The follow-up was coordinated by a clinical research assistant. Clinical and ultrasound evaluation were carried out every 3 months for 12 months, then every 6 months up to 30 months. Restenosis was defined by an index of peak systolic velocity >2.4.

RESULTS

Among the 58 patients (62 limbs) included, 40.3% presented an effort ischemia and 59.7% a critical ischemia (CI). The mean age was 71 ± 12 years. The lesions were classified as TASC D in 37.1% of the cases. The median length of the stenting was 26 ± 18 cm. The average follow-up was 26.1 months (1-30). At 30 months, a complete follow-up was obtained in 55 patients (58 limbs). The rate of survival was 79.6%. Nine of the 11 patients deceased presented initially with CI. Death was in connection with CI in 2 cases. At the date of latest news, 98.3% of the patients were under antiaggregating treatment, 20% received antivitamin K treatment, 75% received statins, and 75% received angiotensin-converting-enzyme inhibitors. The rates of maintenance of the primary and secondary clinical improvement were 68.6 ± 6.0% and 82.6 ± 5.1% at 12 months and 65.1 ± 6.2% and 78.4 ± 5.6% at 30 months, respectively. The mean Rutherford index was 4.1 ± 1.0 in preoperative, 0.7 ± 1.2 at 12 months, and 0.6 ± 1.1 at 30 months (P < 0.001). Two major amputations were carried out at 9 and 28 months for patients initially with CI. The mean systolic pressure index was 0.6 ± 0.1 in preoperative and 1.0 ± 0.2 at 1-year and 0.9 ± 0.3 at 30 months (P < 0.001). The rates of primary and secondary patency were 66 ± 6.3% and 80.9 ± 9.5% at 12 months and 62.2 ± 6.6% and 77.2 ± 5.9% at 30 months, respectively. Between 0 and 12 months, 12 (19.3%) intrastent restenosis (ISR) were noted. One ISR was observed after 12 months. At the same period, we observed 11 and 1 target lesion revascularization, respectively.

CONCLUSIONS

In the long run, the primary stenting of long FP lesions (≥15-cm) is a safe and durable treatment. A strong clinical and ultrasound monitoring is indicated during the first year to maintain the clinical improvement.

Percutaneous management of vascular complications in patients undergoing transcatheter aortic valve implantation

OBJECTIVES

This study sought to investigate the feasibility and safety of percutaneous management of vascular complications after transcatheter aortic valve implantation (TAVI).

BACKGROUND

Vascular complications after TAVI are frequent and outcomes after percutaneous management of these adverse events not well established.

METHODS

Between August 2007 and July 2010, 149 patients underwent transfemoral TAVI using a percutaneous approach. We compared outcomes of patients undergoing percutaneous management of vascular complications with patients free from vascular complications and performed duplex ultrasonography, fluoroscopy, and multislice computed tomography during follow-up.

RESULTS

A total of 27 patients (18%) experienced vascular complications consisting of incomplete arteriotomy closure (n = 19, 70%), dissection (n = 3, 11%), arterial perforation (n = 3, 11%), arterial occlusion (n = 1, 4%), and pseudoaneurysm (n = 1, 4%). Percutaneous stent graft implantation was successful in 21 of 23 (91%) patients, whereas 2 patients were treated by manual compression, 2 patients underwent urgent surgery, and 2 patients required delayed surgery. Rates of major adverse cardiac events at 30 days were similar among patients undergoing percutaneous management of vascular complications and those without vascular complications (9% vs. 8%, p = 1.00). After a median follow-up of 10.9 months, imaging showed no evidence of hemodynamically significant stenosis (mean peak velocity ratio: 1.2 ± 0.4). Stent fractures were observed in 4 stents (22%, type I [6%], type II [16%]) and were clinically silent in all cases.

CONCLUSIONS

Vascular complications after TAVI can be treated percutaneously as a bailout procedure with a high rate of technical success, and clinical outcomes are comparable to patients without vascular complications. Stent patency is high during follow-up, although stent fractures require careful scrutiny.

Stent fractures after superficial femoral artery stenting

Stent fracture is one of the major factors compromising implanted stent patency due to its consequences including in-stent restenosis, thrombosis, perforation, and migration. Stent fracture can occur from stress (extrinsic or intrinsic) and biomechanical forces at different implantation sites. We report on 2 cases of stent fractures and pertinent literature. One patient, a 75-year-old male, presented with recurrence of claudication 14 months after superficial femoral artery stenting; a femoral artery occlusion with stent fracture was found, and he underwent femoropopliteal bypass. The other patient, a 72-year-old male presented with recurrence of claudication; a stent fracture was found without femoral artery occlusion, and he was treated with additional femoral artery stenting to secure the fracture site.

Advances in the management of patients with vascular disease

Now in its 9th year, the Vascular Interventional Advances (VIVA) Symposium has demonstrated comprehensive, objective, cutting-edge continuing education in the field of vascular medicine and intervention. With a faculty representing expertise across all specialties, and using a proprietary system of interactive educations (Laptop Learning), attendees listen to presentations and debates, and watch cases demonstrating state-of-the-art interventions from sites around the world. This year, VIVA attracted some of the most important studies presented by international investigators. In this article details regarding new stent technologies in the aorta, peripheral artery and carotid arteries will be highlighted.