Journal of Endovascular Therapy

As the number of patients afflicted by chronic limb-threatening ischemia (CLTI) continues to grow, new solutions are necessary to provide effective, durable treatment options that will lead to improved outcomes. The diagnosis of CLTI remains mostly clinical, and endovascular revascularization remains mostly balloon-based. Multiple innovative techniques and technologies are in development or in early usage that may provide new solutions. This review categorizes areas of advancement, highlights recent developments in the management of CLTI and looks forward to novel devices that are currently under investigation.

Despite recent guideline updates on peripheral artery disease (PAD) and critical limb ischemia (CLI) treatment, the optimal treatment for CLI is still being debated. As a result, care is inconsistent, with many CLI patients undergoing an amputation prior to what many consider to be mandatory: consultation with an interdisciplinary specialty care team and a comprehensive imaging assessment. More importantly, quality imaging is critical in CLI patients with below-the-knee disease. Therefore, the CLI Global Society has put forth an interdisciplinary expert recommendation for superselective digital subtraction angiography (DSA) that includes the ankle and foot in properly indicated CLI patients to optimize limb salvage. A recommended imaging algorithm for CLI patients is included.

Endovascular revascularization has been increasingly utilized to treat patients with chronic limb-threatening ischemia (CLTI), particularly atherosclerotic disease in the infrapopliteal arteries. Lesions of the infrapopliteal arteries are the result of 2 different etiologies: medial calcification and intimal atheromatous plaque. Although several devices are available for endovascular treatment of infrapopliteal lesions, balloon angioplasty still comprises the mainstay of therapy due to a lack of purpose-built devices. The mechanism of balloon angioplasty consists of adventitial stretching, medial necrosis, and dissection or plaque fracture. In many cases, the diffuse nature of infrapopliteal disease and plaque complexity may lead to dissection, recoil, and early restenosis. Optimal balloon angioplasty requires careful attention to assessment of vessel calcification, appropriate vessel sizing, and the use of long balloons with prolonged inflation times, as outlined in a treatment algorithm based on this systematic review. Further development of specific devices for this arterial segment are warranted, including devices for preventing recoil (eg, dedicated atherectomy devices), treating dissections (eg, tacks, stents), and preventing neointimal hyperplasia (eg, novel drug delivery techniques and drug-eluting stents). Further understanding of infrapopliteal disease, along with the development of new technologies, will help optimize the durability of endovascular interventions and ultimately improve the limb-related outcomes of patients with CLTI.

Purpose: To assess the utility of intravascular ultrasound (IVUS) during below-the-knee (BTK) interventions for patients with chronic limb-threatening ischemia (CLTI). Materials and Methods: This retrospective single-center study included 216 symptomatic patients (mean age 74.2±9.5 years; 167 men) with CLTI and BTK steno-occlusive disease who underwent successful balloon angioplasty between January 2016 and August 2018. Data from 88 vessels (58 patients) treated with IVUS-guided procedures were compared with corresponding values from 242 vessels (158 patients) treated with angiography-guided procedures. The primary outcomes included procedure-related variables of balloon size, contrast dose, and complication rates, as well as changes in ankle-brachial index (ABI) and skin perfusion pressure (SPP). Secondary outcomes included IVUS determination of vessel size, wire route, and calcification severity, as well as technical success and clinically-driven target lesion revascularization (TLR), limb salvage, and wound healing rates in the Rutherford category 5/6 patients as evaluated by propensity score matching analysis. Results: The patient and lesion characteristics were similar in both groups. The mean balloon size for IVUS-guided procedures was significantly larger (2.45±0.4 mm) compared with that for angiography-guided procedures (2.23±0.4 mm; p<0.001). The technical success (p=0.56) and complication rates (p=0.16) were similar between the groups. The postprocedure dorsal and plantar SPP and change in dorsal SPP improved more in the IVUS-guided group (p<0.001, p=0.015, and p=0.02, respectively). The IVUS-guided group had a significantly better wound healing rate than the angiography-guided group (p=0.006), although the freedom from TLR and limb salvage rates were similar between the groups (p=0.16 and p>0.99, respectively). Conclusion: IVUS-guided interventions for BTK lesions were safe and effective in accurately assessing the lesions. The results suggest that IVUS guidance of endovascular procedures has the potential to influence better clinical outcomes than angiography-guided angioplasty.

Purpose: To report the outcomes of bypass grafting (BG) vs endovascular therapy (EVT) in patients with non-dialysis-dependent chronic kidney disease (CKD) and chronic limb-threatening ischemia (CLTI). Materials and Methods: The CRITISCH Registry is a prospective, national, interdisciplinary, multicenter registry evaluating the current practice of all available treatment options in 1200 consecutive CLTI patients. For the purposes of this analysis, only the 337 patients with non-dialysis-dependent CKD treated by either BG (n=86; median 78 years, 48 men) or EVT (n=251; median age 80 years, 135 men) were analyzed. The primary composite outcome was amputation-free survival (AFS); secondary outcomes were overall survival (OS) and amputation-free time (AFT). All outcomes were evaluated in Cox proportional hazards models; the results are reported as the hazard ratio (HR) and 95% confidence interval (CI). Results: The Cox regression analysis revealed a significantly greater hazard of amputation or death after BG (HR 1.78, 95% CI 1.05 to 3.03, p=0.028). The models for AFT and overall survival also suggested a higher hazard for BG, but the differences were not significant (AFT: HR 1.66, 95% CI 0.78 to 3.53, p=0.188; OS: HR 1.41, 95% CI 0.80 to 2.47, p=0.348). The absence of runoff vessels (HR 1.73, 95% CI 1.15 to 2.60, p=0.008) was associated with a decreased AFS. The likelihood of amputation was higher in male patients (HR 2.21, 95% CI 1.10 to 4.45, p=0.027) and was associated with a lack of runoff vessels (HR 1.95, 95% CI 0.96 to 3.95, p=0.065) and myocardial infarction (HR 3.74, 95% CI 1.23 to 11.35, p=0.020). Death was more likely in patients without runoff vessels (HR 1.76, 95% CI 1.11 to 2.80, p=0.016) and those with a higher risk score (HR 1.73, 95% CI 1.03 to 2.91, p=0.038). Conclusion: This analysis suggested that BG was associated with poorer AFS than EVT in patients with non-dialysis-dependent CKD and CLTI. Male sex, previous myocardial infarction, and the absence of runoff vessels were additionally identified as predictors of poorer outcomes.

Purpose: To report an experience with the Absorb bioresorbable vascular scaffold (BVS) in an Asian cohort with chronic limb-threatening ischemia (CLTI) from the DISAPEAR (Drug Impregnated Bioresorbable Stent in Asian Population Extremity Arterial Revascularization) registry. Materials and Methods: A retrospective analysis was conducted of 41 patients (median age 64 years; 23 men) with CLTI owing to >50% de novo infrapopliteal lesions (n=53) treated with the Absorb BVS between August 2012 and June 2017. The majority of patients (37, 90%) had diabetes, 24 (59%) had ischemic heart disease, and 39 (95%) had Rutherford category 5/6 ischemia with tissue loss. The mean lesion length was 22.7±17.2 mm; 10 (24%) lesions were severely calcified. Assessments included technical success, primary patency, freedom from clinically-driven target lesion revascularization (CD-TLR), amputation-free survival, limb salvage, complete wound healing, resolution of rest pain, and resolution of CLTI without TLR at 6 and 12 months after the index intervention. Results: Overall, 69 scaffolds were implanted in the 53 lesions, with 100% technical success. There were no deaths within 30 days of the index procedure. The primary patency rates at 6 and 12 months were 95% and 86%, respectively. The corresponding rates of freedom from CD-TLR were 98% and 93%, respectively. Freedom from major amputation was 98% at both time points, and amputation-free survival was 93% and 85% at 6 and 12 months after the index procedure. Wound healing occurred in 31 patients (79%) with Rutherford category 5/6 ischemia by the end of 12 months. Conclusion: The Absorb BVS demonstrated good 1-year patency and clinical outcomes in CLTI patients with complex infrapopliteal disease.

Purpose: To report the 12-month safety and efficacy outcomes of the investigational device exemption trial evaluating an implantable below-the-knee (BTK) dissection repair device. Materials and Methods: The prospective, multicenter, single-arm Tack-Optimized Balloon Angioplasty (TOBA) II BTK study (ClinicalTrials.gov identifier NCT02942966) evaluated the Tack Endovascular System in the BTK arteries vs objective performance goals derived from a systematic review of BTK angioplasty literature. Patients presenting with Rutherford category 3–5 ischemia were eligible and were enrolled during the procedure if angioplasty resulted in dissection(s) of the BTK arteries. Between February 2017 and December 2018, the study enrolled 233 patients (mean age 74.4±10.0 years; 157 men). Most lesions (93.8%) were de novo; almost half (118/248, 47.6%) were total occlusions. Mean target lesion length was 80±49 mm. Moderate to severe calcium was present in 89 (35.8%) lesions. The 30-day primary safety endpoint was a composite of major adverse limb events (MALE) and all-cause perioperative death (POD). The primary efficacy endpoint was a composite of MALE at 6 months and 30-day POD. These safety and efficacy endpoints were assessed at 12 months as observational endpoints along with amputation-free survival (AFS), freedom from clinically-driven target lesion revascularization (CD-TLR), vessel patency, and changes from baseline in clinical and quality of life measures. Results: All patients had post-PTA dissection and received at least 1 Tack implant (range 1 to 16). The angiographic core laboratory noted successful resolution of 100% of the 341 treated dissections. At 12 months, 93.4% (170/182) of patients remained free of the composite endpoint of MALE + POD. Tacked segment patency was 81.3% and limb salvage was 96.8% at 12 months; freedom from CD-TLR and AFS were 83.1% and 89.3%, respectively. Sustained Rutherford category improvement was reported in 82.4% of evaluated patients, with 62.4% improving ≥3 categories (p<0.001). Ninety of 124 index wounds (72.5%) healed or improved. Conclusion: The Tack Endovascular System is safe and effective in the treatment of post-angioplasty BTK dissections. Twelve-month outcome data from the TOBA II BTK study demonstrate high rates of patency, limb salvage, and wound healing.

Purpose: To investigate the prognostic impact of infrapopliteal (IP) artery anatomic severity according to the Global Limb Anatomic Staging System (GLASS) on delayed wound healing in patients with chronic limb-threatening ischemia (CLTI). Materials and Methods: This study retrospectively analyzed 639 limbs with tissue loss in 484 CLTI patients (mean age 74±10 years; 300 men) presenting IP lesions treated with endovascular therapy between April 2010 and December 2015. Two-thirds of patients had diabetes (323, 67%) and over half were on hemodialysis (255, 53%). More than a third of the limbs (251, 39%) were classified as clinical stage 4 according to the Wound, Ischemia, and foot Infection (WIfI) system. IP anatomic severity was classified based on preprocedural angiography according to the GLASS. Severity of arterial calcification was assessed using high-intensity fluoroscopy and classified into 3 groups: none (grade 0), unilateral (grade 1), and bilateral (grade 2). Poor below-the-ankle (BTA) runoff was defined as the lack of a pedal arch with 0 to 1-vessel runoff within the dorsal pedis artery and the lateral and medial plantar arteries. The outcome measure was 1-year wound healing. The association of anatomic characteristics with delayed wound healing was evaluated using Cox proportional hazards regression analysis. Outcomes are presented as the adjusted hazard ratio (HR) with 95% confidence interval (CI). Results: During a mean follow-up of 22±19 months, the 1-year cumulative wound healing rate was estimated to be 59.0% (95% CI 54.5% to 63.5%). Multivariable analysis demonstrated independent associations between delayed wound healing and IP calcification grade (HR 1.24, 95% CI 1.02 to 1.50, p=0.027) and poor BTA runoff (HR 1.39, 95% CI 1.04 to 1.85, p=0.025) but not the GLASS IP grade (HR 0.92, 95% CI 0.82 to 1.14, p=0.21). Conclusion: The current study revealed that IP arterial calcification and poor BTA runoff were significantly associated with delayed wound healing, whereas the GLASS was not predictive of wound healing.

Purpose: To investigate the safety and efficacy of drug-coated balloons (DCB) for the treatment of femoropopliteal or infrapopliteal lesions in patients with chronic limb-threatening ischemia (CLTI). Materials and Methods: A systematic literature search was conducted in PubMed, Scopus, and Cochrane Central up to January 2020 to identify randomized trials and observational studies presenting data on the effectiveness and safety of DCBs in the treatment of femoropopliteal or infrapopliteal lesions. A meta-analysis utilizing random effects modeling was conducted to investigate primary patency and all-cause mortality at 12 months; the results are reported as the odds ratios (ORs) and 95% confidence intervals (CIs). Secondary outcomes were procedural success, bailout stenting, target lesion revascularization (TLR), reocclusion, major amputation, wound healing, and major adverse limb events. Results: Twenty-six studies, 12 retrospective and 14 prospective, comprising 2108 CLTI patients treated with DCBs for femoropopliteal (n=1315) or infrapopliteal (n=793) lesions were analyzed. The average lesion lengths were 121±44 and 135±53 mm, respectively. The overall 12-month all-cause mortality and major amputation rates were 9% (95% CI 6% to 13%) and 5% (95% CI 2% to 8%), respectively. Primary patency rates were 82% (95% CI 76% to 87%) and 64% (95% CI 58% to 70%), respectively. A sensitivity analysis of the infrapopliteal lesions demonstrated no difference between DCB and balloon angioplasty in terms of primary patency, TLR, major amputation, or mortality over 12 months. However, patients with infrapopliteal lesions undergoing DCB angioplasty did have a significantly lower risk for reocclusion (10% vs 25%; OR 0.38, 95% CI 0.21 to 0.70, p=0.002). Conclusion: DCB angioplasty of femoropopliteal and infrapopliteal lesions in patients with CLTI results in acceptable 12-month patency rates, although comparative data have not shown a patency benefit for infrapopliteal lesions. The 12-month mortality rate of DCB vs balloon angioplasty was not significantly different, but studies with longer-term outcomes are necessary to determine any association between DCB use and mortality in patients with CLTI.

Purpose: To evaluate the midterm results of patients suffering from no-option chronic limb-threatening ischemia (CLTI) treated with a dedicated system for percutaneous deep venous arterialization (pDVA). Materials and Methods: Thirty-two consecutive CLTI patients (mean age 67±14 years; 20 men) treated with pDVA using the Limflow device at 4 centers between 11 July 2014 and 11 June 2018 were retrospectively analyzed. Of all patients, 21 (66%) had diabetes, 8 (25%) were on immunosuppression, 4 (16%) had dialysis-dependent renal failure, 9 (28%) had Rutherford category 6 ischemia, and 25 (78%) were deemed at high risk of amputation. The primary outcome was amputation-free survival (AFS) at 6 months. Secondary outcomes were wound healing, limb salvage, and survival at 6, 12, and 24 months. Results: Technical success was achieved in 31 patients (96.9%). The median follow-up was 34 months (range 16–63). At 6, 12, and 24 months, estimates were 83.9%, 71.0%, and 67.2% for AFS, 86.8%, 79.8% and 79.8% for limb salvage, and 36.6%, 68.2%, and 72.7% for complete wound healing, respectively. Median time to complete wound healing was 4.9 months (range 0.5–15). The DVA circuit occluded during follow-up in 21 patients; the median time to occlusion was 2.6 months. Reintervention for occlusion was performed in 17 patients: 16 because of unhealed wounds and 1 for a newly developed ulcer. Conclusion: This study represents the largest population of patients with no-option CLTI treated with pDVA using the LimFlow device with midterm results. In this complex group of patients, pDVA using the LimFlow device has been shown to be feasible, with a high technical success rate and AFS at 6 up to 24 months coupled with wound healing. In selected patients with no-option CLTI, pDVA could be a recommended treatment to prevent amputation and heal wounds.

Purpose: To present the 6-month results of the Stromal Cell–Derived Factor-1 Plasmid Treatment for Patients with Peripheral Artery Disease (STOP-PAD) trial. The trial was an attempt to alter the course of chronic limb-threatening ischemia (CLTI) with a biological agent vs placebo after successful arterial revascularization at or below the knee. Materials and Methods: The multicenter, randomized, double-blinded, placebo-controlled, phase 2B STOP-PAD trial (ClinicalTrials.gov identifier NCT02544204) randomized 109 patients (mean age 71 years; 68 men) with Rutherford category 5 or 6 CLTI and evidence of persistent impaired forefoot perfusion following recent successful revascularization to 8- (n=34) or 16-mg (n=36) intramuscular injections of a non-viral DNA plasmid–based treatment vs placebo (n=34). The primary efficacy outcome was the 6-month wound healing score evaluated by an independent wound core laboratory; the primary safety endpoint was major adverse limb events (MALE), a composite of major amputation plus clinically-driven target lesion revascularization at 6 months. Results: Only one-third of the patients had complete wound healing at 6 months in the placebo (31%), 8-mg injection (33%), and 16-mg injection (33%) groups. In addition, the observed increase in the toe-brachial index from baseline to 6 months was statistically significant in each group; however, this did not result in lower rates of MALE at 6 months (24% in the placebo, 29% in the 8-mg injection, and 11% in the 16-mg injection groups). During the 6-month period, 6 patients (6%) died, and 24 patients (23%) had an amputation [only 4 (4%) major]. Conclusion: Combining revascularization and biological therapy failed to improve outcomes in CLTI at 6 months. STOP-PAD has provided insights for future trials to evaluate biological therapy.