Practical Applications of Tack Implants for Infrainguinal Dissection Repair: A Single-Center Experience

A Novel Angiographic Risk Score for Femoropopliteal Interventions

PURPOSE

To present a novel angiographic scoring system that stratifies the risk of restenosis after endovascular therapy (EVT) to inform the decision to use paclitaxel-eluting devices in the femoropopliteal segment.

MATERIALS AND METHODS

A prospective, multicenter registry including 1799 limbs of 1578 patients (mean age 74±9 years; 1090 men) with symptomatic peripheral artery disease undergoing intravascular ultrasound-supported femoropopliteal EVT was used as the basis for developing the angiographic score. Multivariable analysis identified baseline patient and limb characteristics associated with restenosis at 12 months. These risk factors for 12-month restenosis were explored using a generalized linear mixed model with a logit-link function in which the inter-institutional and inter-subject variability were treated as random effects. The multiple imputation method was adopted to address missing data. Results of the regression analysis are presented as the odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Twelve-month primary patency was estimated to be 65.1% (95% CI 62.7% to 67.5%). After multivariable analysis, distal reference vessel diameter per 1 mm (OR 0.71, 95% CI 0.62 to 0.81, p<0.001), lesion length per 10 cm (OR 1.39, 95% CI 1.19 to 1.62, p<0.001), and chronic total occlusion (OR 1.56, 95% CI 1.15 to 2.10, p=0.004) were independently associated with the 12-month restenosis risk, whereas baseline patient risk factors were not. Compared to bare nitinol stent implantation, plain angioplasty (OR 2.31, 95% CI 1.67 to 3.18, p<0.001) was independently associated with a higher risk of 12-month restenosis, while drug-eluting stents (OR 0.65, 95% CI 0.43 to 0.99, p=0.045) and stent-grafts (OR 0.24, 95% CI 0.12 to 0.50, p<0.001) were independently associated with a lower risk of 12-month restenosis. The angiographic score, which was developed by using the 3 angiographic factors but not the TransAtlantic Society Consensus II (TASC) class, was significantly and independently associated with 12-month restenosis.

CONCLUSION

The current study demonstrated a novel angiographic score for 12-month restenosis after femoropopliteal EVT in a real-world clinical practice. The developed score was significantly and independently associated with the 12-month restenosis risk, but the TASC class was not.

Twelve-Month Results of Tack-Optimized Balloon Angioplasty Using the Tack Endovascular System in Below-the-Knee Arteries (TOBA II BTK)

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.

Balloon Angioplasty of Infrapopliteal Arteries: A Systematic Review and Proposed Algorithm for Optimal Endovascular Therapy

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.

Optimal Vessel Sizing and Understanding Dissections in Infrapopliteal Interventions: Data From the iDissection Below the Knee Study

Purpose:

To investigate if imaging with intravascular ultrasound (IVUS) yields a more accurate estimate of vessel diameter and the presence of dissections than angiography after intervention in the infrapopliteal arteries.

Materials and Methods:

A prospective, single-center study enrolled 20 consecutive patients (mean age 74.1±12.4 years; 12 women) with infrapopliteal disease who were treated with percutaneous transluminal angioplasty (PTA; n=10) or orbital atherectomy (OA) followed by PTA (n=10). The majority of patients were hypertensive and half were diabetic. The overall lesion length was 7.3±6.3 cm, and the diameter stenosis was 80.3%±22.1%. The baseline characteristics did not differ between the groups. Vessel diameters were measured using IVUS from the internal elastic lamina (IEL) to the IEL. IVUS was performed at baseline, post PTA or OA, and post OA+PTA. Quantitative vascular angiography (QVA) and IVUS were analyzed by a core laboratory. Dissections on cine images were categorized based on the National Heart Lung and Blood Institute (NHLBI) classification, while the arc and depth were used to characterize dissections on IVUS images.

Results:

Mean vessel diameter by QVA was 2.9±0.6 vs 4.0±1.0 mm by IVUS according to the core laboratory (mean difference 1.1±0.9, p<0.001). On angiography, there were 7 dissections after PTA (6 C, 1 D), 1 dissection after OA (1 B), and 2 dissections after OA+PTA (1 A, 1 B; p=0.028 vs post PTA). IVUS uncovered 3.8 times more dissections than seen on angiography. There were 23 dissections after PTA (18 intima, 3 media, 2 adventitia), 12 dissections after OA (8 intima, 1 media, 3 adventitia), and 11 dissections following OA+PTA (7 intima, 1 media, 3 adventitia; p=0.425 vs PTA). Bailout stenting (all due to angiographic dissections ≥C) was necessary in 6 of the PTA cohort and none of the OA+PTA group.

Conclusion:

In addition to underestimating the infrapopliteal vessel diameter by ~25%, angiography underappreciated the presence and severity of post-intervention dissections vs IVUS, particularly in the OA+PTA group.