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

Abstract

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.

Keywords: balloon angioplasty; chronic limb-threatening ischemia; critical limb ischemia; dissection; endovascular revascularization; infrapopliteal disease; peripheral artery disease; restenosis.

Figure 1.

Tack Implant and Tack Endovascular System (4F).

Figure 2.

Patient enrollment and follow-up. D, day; M, month; RC, Rutherford category.

Figure 3.

Kaplan-Meier curves for freedom from major adverse limb events (MALE) + postoperative death (POD) in intent-to-treat (ITT) subjects. RC, Rutherford category.

Figure 4.

Kaplan-Meier curves for (A) Tacked segment patency, (B) target lesion patency, (C) target limb salvage, and (D) amputation-free survival in intent-to-treat (ITT) subjects up to 12 months. RC, Rutherford category.

Figure 5.

Sustained improvement in the ankle-brachial index (ABI) and toe-brachial index (TBI). D, day; M, month.

Figure 6.

Sustained improvement in the Rutherford category (RC) status.

Figure 7.

Post hoc Kaplan-Meier analyses in intent-to-treat subjects by dissection grade of (A) freedom from major adverse limb events (MALE) and perioperative death (POD), (B) Tacked segment patency, (C) target limb salvage, and (D) target lesion patency.