Analysis of wound healing time and wound-free period as outcomes after surgical and endovascular revascularization for critical lower limb ischemia

Background: Traditional end points, such as amputation-free survival, used to assess the clinical effectiveness of lower limb revascularization have shortcomings because they do not account independently for wound nonhealing and recurrence or patient survival. Wound healing process and maintenance of a wound-free state after revascularization were not well-studied. The aim of this study was to elucidate the long-term clinical course of ischemic wounds after revascularization. We focused on initial wound healing process as well as the maintenance of a wound-free state after achievement of wound healing. We introduced a wound-free period (WFP; the period during which limbs maintained an ulcer-free state) and Wound Recurrence and Amputation-free Survival (WRAFS) as parameters and tested their effectiveness in evaluating clinical outcomes of limbs treated using endovascular therapy (EVT) and surgical revascularization. Methods: The medical records of patients developing lower critical limb ischemia with tissue loss who underwent surgical or endovascular revascularization of the infrainguinal vessels between 2009 and 2013 were reviewed retrospectively. The risk factors for achieving wound healing and WRAFS were analyzed using Kaplan-Meier survival curves and Cox regression model. Risk factors to prolong wound healing time (WHT) and reduce WFP were determined by the least squares method. Results: In total, 233 patients underwent 278 limb revascularizations; 138 endovascular and 140 surgical procedures were performed as first treatments. The proportion of healed wounds 1, 2, and 3 years after primary revascularization was 64.0%, 69.7%, and 70.5%, respectively. Significant risk factors for wound healing were an EVT-first strategy (risk ratio [RR], 2.47), congestive heart failure (RR, 2.05), and wound, ischemia, and foot infection wound grade (RR, 1.59). The mean WHT was 143.7 days. An EVT-first strategy and wound infection contributed to significantly longer WHT. The mean WFP was 711.0 days. An EVT-first strategy, history of coronary artery disease, and dialysis dependence were associated with significantly shorter WFPs. WRAFS at 1 and 2 years after achievement of wound healing were 76.9% and 64.2%, respectively. Significant risk factors against WRAFS were a history of coronary artery disease (RR, 1.68), dialysis dependence (RR, 2.03), and being wheel chair bound (RR, 1.64). Conclusions: EVT revascularization was associated with longer WHT, reduced wound healing rate, and a shorter WFP compared with surgical revascularization. wound, ischemia, and foot infection grade was associated with longer WHT and reduced wound healing rate, but not associated with a shorter WFP. Systemic conditions such as dialysis dependence, congestive heart failure, and being wheel chair bound were associated with reduced wound healing rate and shorter WFP, presumably because they limited life expectancy. WHT and WFP are useful criteria for evaluating limb outcomes in patients with critical limb ischemia.