Role of Bypass with Preoperatively Diagnosed Small Caliber Veins in Chronic Limb-Threatening Ischemia

Background: In chronic limb-threatening ischemia (CLTI), although recent studies suggested that limbs classified as a higher Wound, Ischemia, foot Infection (WIfI) stage would benefit more from bypass surgery than endovascular therapy (EVT), graft unavailability is a major limitation for bypass. However, such graft unavailability is not clearly defined. This study aimed to assess whether bypass with veins judged as small by preoperative ultrasound is acceptable to achieve wound healing. Methods: Ninety-five limbs classified as WIfI stage 3/4 that underwent infrainguinal bypass with veins were enrolled and divided into two groups based on the preoperative inner diameter of veins. Those with a diameter < 2.5 mm were classified as small caliber grafts (SMGs, n = 28) and those with a diameter >= 2.5 mm as sufficient caliber grafts (SUGs, n = 67), and wound-related outcomes were evaluated. Wound healing rate (WHR) was analyzed in all cohort, and wound recurrence-free rate (WRF) and wound recurrence-free amputation-free survival rate (WRAFS) were calculated for limbs that achieved wound healing. A propensity score matched analysis was also performed to minimize the background difference, and 21 matched pairs were included for the analysis. Results: Although the primary patency rate was significantly worse in SMGs (1-year patency, Crude model: 82.1% in SUGs and 51.0% in SMGs, P = 0.0003; matched model: 77.7% in SUGs and 41.6% in SMGs, P = 0.005), the secondary patency rate was maintained in the equivalent level (1-year patency, Crude model: 81.8% in SUGs and 83.1% in SMGs, P = 0.26; matched model: 77.7% in SUGs and 78.4% in SMGs, P = 0.24). One-year WHR was equivalent between the groups in both crude and matched models (Crude model: 87.0% in SUGs and 83.8% in SMGs, P = 0.13; matched model: 66.3% in SUGs and 61.4% in SMGs, P = 0.65). One-year WRF and WRAFS were also equivalent (Crude model: WRF, 95.9% in SUGs and 100% in SMGs, P = 0.71; WRAFS, 87.2% in SUGs and 88.0% in SMGs, P = 0.78. Matched model: WRF, 100% in SUGs and 100% in SMGs, P = 0.85; WRAFS, 92.9% in SUGs and 78.6% in SMGs, P = 0.38). Conclusions: Although bypass with small caliber veins showed an infer ior pr imary patency rate, WHR and WRF were equally good if grafts are maintained patent. Bypass with small caliber vein grafts would be an important option to achieve wound healing.