Importance of Limb Severity on Primary Graft Patency of Ipsilateral Single Saphenous Vein Grafts for Lower Extremity Artery Bypass in Chromic Limb-threatening Ischemia

Abstract

Approximately 30% of infrainguinal vein bypasses fail within 2 years after placement. A previous study demonstrated limb severity influenced cellular responses of saphenous veins used for lower extremity arterial bypass. The aim of this study was to assess the impact of wound, ischemia, and foot infection (WIfI) on primary graft patency of ipsilateral saphenous vein grafts. This is a retrospective, observational cohort study of autogenous vein bypass for chromic limb-threatening ischemia. Between 2014 and 2019, 201 (of 253) limbs receiving ipsilateral single great saphenous vein grafts were enrolled as research subjects. The outcome of interest was loss of primary graft patency >1 month after surgery because of occlusion or intervention for graft stenosis. Perioperative graft failure due to technical error successfully repaired by revision surgery were included; however, perioperative unrepaired failed graft and patients dying within 30 days after surgery were excluded, leaving 191 vein grafts for analysis of 2-year primary graft patency. Factors associated with loss of graft patency were predicted by Cox regression modeling based on patients’ background and limb severity. Seventy-six grafts (40%) lost primary patency at 2 years after surgery. The highest stage of WIfI classification had significantly lower primary graft patency than a bundle of other lower stages (49% vs 66%; P = .04). When focusing on the three factors of WIfI, higher wound grade (2 and 3) significantly impaired graft patency compared with lower grade (49% vs 68%; P = .016) and existence of foot infection (grade 1-3) also impaired primary graft patency rate (49% vs 63%; P < .05). There was a trend to lower patency for ischemia grade 3 than grade 2 (54% vs 65%; P = .06). Female sex (hazard ratio [HR], 1.6; 95% confidence interval [CI], 1.0-2.6; P = .04), chronic heart failure (HR, 2.0; 95% CI, 1.2-3.2; P < .01), higher wound grade (HR, 1.9; 95% CI, 1.1-3.1; P = .01) were significant by multivariate analysis. Intriguingly, the impact of wound and foot infection grade on loss of primary patency was not significant for men (n = 129 limbs) (P = .35 for wound and P = .30 for foot infection); however, it was for women (n = 62 limbs) (P = .018 for wound and P = .059 for foot infection). Limb severity as classified by WIfI, especially wound grade, was associated with loss of primary graft patency. This impact was weighted in women, not men; hence, further basic investigation will be needed with focus on differing cellular responses of saphenous vein stratified by sex.