Rajani, Ravi R.

Background To evaluate the short-term clinical performance of Symvess (acellular tissue engineered vessel-tyod), formerly known as human acellular vessel, or HAV, compared with autologous vein for the treatment of extremity arterial injury. Methods Subjects treated with acellular tissue engineered vessel (ATEV) from two clinical trials were propensity score-matched on a 1:2 basis to PROspective Observational Vascular Injury Trial (PROOVIT) registry subjects with the same injured artery and treated with autologous vein. Matching characteristics included age, sex, trauma type (penetrating vs blunt), injury severity score, mangled extremity severity score, concomitant fracture, shunt use, and ischemia duration>6 hours. Incidence of outcomes (primary/secondary patency, amputation, conduit infection, reintervention for thrombosis/stenosis, pseudoaneurysm, and death) was assessed by a generalized linear model. Outcomes were assessed at Day 30 (ATEV group) or during initial hospitalization (autologous group). Results ATEV subjects lacking suitable autologous vein (n=67) and PROOVIT subjects treated with autologous vein (n=134) suffered injuries to axillary, brachial, femoral, popliteal, and posterior tibial arteries. Subgroups were clinically similar; Injury Severity Score, Mangled Extremity Severity Score, and duration of follow-up (16 vs 30 days) were higher for the ATEV subgroup. Primary patency for the ATEV versus autologous group was 86.6% versus 91.8%, secondary patency: 91.0% versus 97.7%; amputation: 7.5% versus 8.2%; conduit infection: 1.5% versus 0%; reintervention for thrombosis or stenosis: 6.0% versus 8.2%; and death 4.5% versus 4.5%, respectively. No cases of pseudoaneurysm, true aneurysm, or significant differences between the ATEV and autologous groups for any outcome were observed. Conclusions Short-term outcomes were similar between ATEV subjects without feasible autologous vein, and propensity score-matched autologous vein recipients from the PROOVIT registry. The ATEV may provide effective and safe revascularization in subjects with extremity arterial injury without feasible autologous vein. Level of evidence Level 3, Therapeutic/Care Management

Importance Vascular injuries require urgent repair to minimize loss of limb and life. Standard revascularization relies on autologous vein or synthetic grafts, but alternative options are needed when adequate vein is not feasible and when clinical conditions preclude safe use of synthetic materials. Objective To evaluate the performance of the acellular tissue engineered vessel (ATEV) in the repair of extremity arterial injuries. Design, Setting, and Participants Two open-label, single-arm, nonrandomized clinical trials, including 1 prospective civilian study (CLN-PRO-V005 [V005]) and 1 retrospective observational study in a war zone (CLN-PRO-V017 [V017]), were conducted from September 2018 to January 2024 (follow-up ongoing) at 19 level 1 trauma centers in the US and Israel and 5 frontline hospitals in Ukraine. Patients had vascular injury, no autologous vein available for emergent revascularization, and risk factors for wound infection. Data include the subset of patients with extremity injuries and were analyzed from September 2023 to January 2024. Intervention The ATEV is a bioengineered vascular conduit grown from human vascular cells, available off the shelf, and implantable without immunosuppression. Main Outcomes and Measures Primary patency at day 30 was the primary outcome. Secondary outcomes included limb salvage, graft infection, and patient survival. A systematic literature review identified synthetic graft benchmarks in the treatment of arterial trauma for the same end points. Results The arterial extremity injury subset included 51 of 69 participants in V005 and 16 of 17 participants in V017. The majority were male (V005, 38 [74.5%]; V017, 16 [100%]), the mean (SD) ages were similar (V005, 33.5 [13.6] years; V017, 34.2 [9.0] years), and the mean (SD) Injury Severity Scores were similar (V005, 20.8 [10.5]; V017, 20.1 [18.9]). Penetrating injuries dominated (V005, 29 patients [56.9%]; V017, 14 patients [87.5%]). At day 30 for the V005 and V017 trials, respectively, ATEV primary patency was 84.3% (95% CI, 72.0%-91.8%) and 93.8% (95% CI, 71.7%-98.9%); secondary patency was 90.2% (95% CI, 79.0%-95.7%) and 93.8% (95% CI, 71.7%-98.9%); amputation rate was 9.8% (95% CI, 4.3%-21.0%) and 0% (95% CI, 0.0%-19.4%); ATEV infection rate was 2.0% (95% CI, 0.4%-10.3%) and 0% (95% CI, 0.0%-19.4%); and death rate was 5.9% (95% CI, 2.0%-15.9%) and 0% (95% CI, 0.0%-19.4%) (no deaths attributed to the ATEV at day 30). Day 30 synthetic graft benchmarks were as follows: secondary patency, 78.9%; amputation, 24.3%; infection, 8.4%; and death, 3.4%. Conclusions and Relevance Results of analysis in the subset of patients with vascular extremity injuries in 2 single-arm trials in civilian and real-world military settings suggest that the ATEV provides benefits in terms of patency, limb salvage, and infection resistance. Comparing ATEV outcomes with synthetic graft benchmarks demonstrated improved outcomes in the treatment of acute vascular injuries of the extremities. The analyses reported herein are limited to the subset of 67 patients with vascular extremity injuries out of 86 patients enrolled in 2 trials and excluded 19 patients with iatrogenic and torso injuries. Had these 19 patients been included in these analyses, the efficacy and safety findings could have been attenuated. Trial Registration ClinicalTrials.gov Identifiers: NCT03005418 , NCT05873959