Limb-based patency as a measure of effective revascularization for chronic limb-threatening ischemia

Advanced Wound, Ischemia, and Foot Infection stage is associated with poor outcomes in the BEST-CLI trial

OBJECTIVE

Wound, Ischemia, and foot Infection (WIfI) staging was established to provide objective classification in patients with chronic limb-threatening ischemia (CLTI) and to predict 1-year major amputation risk. Our goal was to validate WIfI staging using data from the Best Endovascular vs Best Surgical Therapy in Patients with CLTI (BEST-CLI) trial.

METHODS

Data from the BEST-CLI Trial, a prospective randomized trial comparing surgical revascularization (OPEN) and endovascular revascularization (ENDO), were used to assess the association of WIfI stage on long-term outcomes in an intention-to-treat analysis. Patients were prospectively allocated to two cohorts, which included patients with and without adequate single-segment greater saphenous vein, respectively. The primary outcome of this analysis was major amputation.

RESULTS

There were 1568 patients analyzed, representing 86% of the entire trial population; of these 35.5%, 29.6%, and 34.9% were categorized as WIfI stage 4, WIfI stage 3, and WIfI stage 1/2, respectively. There were 1223 patients (606 OPEN, 617 ENDO) and 345 patients (OPEN 172, ENDO 173) in cohorts 1 and 2, respectively. On unadjusted Kaplan-Meier analysis, WIfI clinical stages 4 and 3, compared with WIfI stage 1/2, were associated with higher rates of major amputation (21.4%, 16.2% vs 10.7%), death (33.5%, 35.7% vs 24.6%), amputation/death (44.9%, 44.5% vs 31.3%), major adverse limb events (MALEs)/death (34.4%, 33.9% vs 29.5%), and reintervention/amputation/death (69.9% vs 69% vs 60.4%) (P < .05 for all) at 3 years. On risk-adjusted analysis, compared with WIfI stage 1/2, major amputation was associated with WIfI stage 4 (hazard ratio [HR], 2.06; 95% confidence interval [CI], 1.44-2.96; P < .001) and WIfI stage 3 (HR, 1.62; 95% CI, 1.1-2.37; P = .013) stages. Death was associated with WIfI stage 4 (HR, 1.3; 95% CI, 1.03-1.63; P = .027) and WIfI stage 3 (HR, 1.42; 95% CI, 1.13-1.79; P = .003). MALE/death was associated with WIfI stage 4 (HR, 1.29; 95% CI, 1.02-1.63; P = .036. Reintervention amputation/death was associated with WIfI stage 4 (HR, 1.28; 95% CI, 1.09-1.50; P = .03) and WIfI stage 3 (HR, 1.22, 99% CI 1.03-1.43) ; P = .018). When examining OPEN vs ENDO revascularization by each WIfI stage, OPEN intervention was favored in cohort 1 for MALE/death for each stage.

CONCLUSIONS

In BEST-CLI, WIfI stage was strongly associated with major amputations, death, and MALEs/death after revascularization for CLTI. Cohort 1 patients, with an adequate preoperative single segment greater saphenous vein, had lower MALE/death with OPEN intervention across all WIfI stages. This validation of WIfI score in a prospective multicenter trial reinforces its importance in shared-decision making, informed consent, and prognostication.

Comparative outcomes of arterial bypass using the human acellular vessel and great saphenous vein in patients with chronic limb ischemia

OBJECTIVE

The Human Acellular Vessel (HAV) is a novel, off-the-shelf biologic conduit being evaluated for arterial reconstructions. Regulatory studies in peripheral arterial disease (PAD) to date have consisted of single-arm cohorts with no comparator groups to contrast performance against established standards. This study aimed to compare outcomes of the HAV with autologous great saphenous vein (GSV) in patients with advanced PAD undergoing infrageniculate bypass.

METHODS

Patients with advanced PAD and no autologous conduit who underwent bypass with the 6-mm diameter HAV (Group 1; n = 34) (March 2021-February 2024) were compared with a multicenter historical cohort who had bypass with single-segment GSV (group 2; n = 88) (January 2017-December 2022). The HAV was used under an Investigational New Drug protocol issued by the Food and Drug Administration (FDA) under the agency's Expanded Access Program.

RESULTS

Demographics were comparable between groups (mean age 69 ± 10 years; 71% male). Group 1 had higher rates of tobacco use (37 pack-years vs 28 pack-years; P = .059), coronary artery disease (71% vs 43%; P = .007), and prior coronary artery bypass grafting (38% vs 14%; P = .003). Group 1 had more patients classified as wound, ischemia, and foot infection clinical stage 4 (56% vs 33%; P = .018) and with previous index leg revascularizations (97% vs 53%; P < .001). Both groups had a similar number of patients with chronic limb-threatening ischemia (Rutherford class 4-6) (88% vs 86%; P = .693) and Global Anatomic Staging System stage III (91% vs 96%; P = .346). Group 1 required a composite conduit (two HAV sewn together) in 85% of bypasses. The tibial vessels were the target in 79% of group 1 and 100% of group 2 (P < .001). Group 1 had a lower mean operative time (364 minutes vs 464 minutes; P < .001). At a median of 12 months, major amputation-free survival (73% vs 81%; P = .55) and overall survival (84% vs 88%; P = .20) were comparable. Group 1 had lower rates of primary patency (36% vs 50%; P = .044), primary-assisted patency (45% vs 72%; P = .002), and secondary patency (64% vs 72%; P = .003) compared with group 2.

CONCLUSIONS

Implanted under Food and Drug Administration Expanded Access provisions, the HAV was more likely to be used in redo operations and cases with more advanced limb ischemia than GSV. Despite modest primary patency, the HAV demonstrated resilience in a complex cohort with no autologous conduit options, achieving good secondary patency and providing major amputation-free survival comparable with GSV at 12 months.

Intraoperative Transit-Time Flow as a Predictor of Failure after Infrainguinal Revascularization with Heparin-Bonded Expanded Polytetrafluoroethylene Graft

BACKGROUND

The heparin-bonded expanded polytetrafluoroethylene (He-ePTFE) conduit is an option for patients requiring infrainguinal revascularization (iIR), but the risk of failure may be unpredictable, especially in cases with poor run-off. Intraoperative transit-time flow (TTF) provides an automated and quantitative analysis of flow and may serve as an adjunct evaluation during surgical revascularization. The aim of this study was to assess TTF in patients undergoing iIR with He-PTFE at 3 referral hospitals and to establish a predictive flow threshold for graft occlusion.

METHODS

A prospective registry initiated in 2020 enrolled patients undergoing iIR using He-PTFE for critical limb ischemia or severe claudication, and TTF measurement was analyzed. Preoperative assessments of anatomical and clinical characteristics were available for all patients. The HT353 Optima Meter (Transonic Systems Inc., Ithaca, NY, USA) was used in all procedures according to a standardized protocol. The institutional ethics committee approved the study. A predictive model using receiver operating characteristic curve analysis was utilized to establish the threshold of flow, and variables were compared. Anatomical and clinical evaluation were reported according to Rutherford grade, Global Limb Anatomic System and Wound, Ischemia, and foot Infection classification. The main outcome considered was the correlation between TTF and graft occlusion. Secondary outcomes included survival, other predictors of graft occlusion, freedom from major adverse cardiovascular events, and freedom from major amputation.

RESULTS

Among 68 patients, 55.8% had Rutherford 5-6, 45.6% had Global Limb Anatomic System 3 and 73.5% had Wound, Ischemia, and foot Infection 3-4. Distal anastomosis was at tibial level in 23.5% and mean diameter of conduit was 6.4 mm. Basal and postoperative TTF were 27.8 ± 15.6 ml/min and 109.0 ± 53.0 ml/min, respectively. After a mean follow-up of 18 ± 13 months, 7 (10.9%) patients presented graft occlusion and 5 (7.8%) required major amputation. TTF threshold = 80 ml/min revealed a sensitivity and specificity of 81.8% (95% confidence interval 48.2-97.7) and 80.7% (95% confidence interval 68.1-90.0) respectively, and it was selected as cut-off for graft occlusion. Freedom from graft occlusion in patients with TTF >80 ml/min vs. TTF ≤80 ml/min at 6, 12, and 24 months was 95.7% (standard error (SE) = 0.030) vs. 65.5% (SE = 0.115), 95.7% (SE = 0.030) vs. 58.9% (SE = 0.120) and 90.9% (SE = 0.054) vs. 51.6% (SE = 0.126), P = 0.0003. No statistical difference in primary patency, secondary patency and limb salvage was observed. At multivariate analysis, distal anastomosis at tibial vessel (odds ratio 8.50) and TTF ≤80 ml/min (odds ratio 9.39) were independent predictors of graft occlusion.

CONCLUSIONS

These results suggest that TTF may serve as a valuable tool in the management of iIR. A TTF measurement of ≤80 ml/min should be regarded as a predictor of graft occlusion, prompting consideration of additional intraoperative maneuvers to enhance arterial flow. Caution should be exercised in patients requiring direct tibial artery revascularization, as it represents a predictor of failure independent of TTF levels. Larger cohorts of patients and longer follow-up periods are necessary to confirm these findings.

Validation of the global limb anatomical staging system in Vietnamese patients treated for chronic limb-threatening ischemia

BACKGROUND

Chronic limb-threatening ischemia (CLTI) is the most severe clinical form of peripheral artery disease (PAD), accounting for approximately 11%, and is strongly associated with the incidence of amputation, cardiovascular events, and mortality. The Global Vascular Guideline (GVG) proposed a new Global Anatomic Staging System (GLASS) for evaluating the anatomic complexity of arterial lesions. However, more research is required to evaluate outcomes after endovascular intervention in CLTI patients using the GLASS.

OBJECTIVE

Our study aimed to describe clinical characteristics, arterial lesions, and endovascular interventions according to three grades of GLASS in the Vietnamese population. We evaluated the technical success, mortality rate, and probability to preserve the limb according to the GLASS.

METHODS

All patients were diagnosed with CLTI and underwent infrainguinal endovascular intervention at the Department of Thoracic and Vascular Surgery, University Medical Center, Ho Chi Minh City from June 2020 to June 2022. All patients were evaluated before intervention and follow-up at 6 and 12 months after intervention. Patients were divided into three groups according to the GLASS, thereby comparing the technical success, mortality, and amputation rates. This retrospective study describes a series of cases.

RESULTS

The study sample evaluated 82 lower limbs of 82 patients, in which GLASS class I, II, and III lesions accounted for 36.6%, 43.9%, and 19.5% of the patients, respectively. The rates of technical success in the groups gradually decreased according to the complexity of the lesions (90%, 86.11%, and 56.25% for GLASS I, II, and III, respectively; p = 0.012). Notably, limb-based patency (LBP) at 12 months was significantly lower in the GLASS III group than in the GLASS I and II groups (22.22% vs 88.89% and 67.74%, respectively; p = 0.001). The amputation rates at 12 months in GLASS groups I, II, and III were 13.3%, 22.2%, and 50%, respectively (p = 0.021), while the mortality rates at 12 months were 0%, 8.33%, and 25%, respectively (p = 0.015).

CONCLUSION

In patients with CLTI of higher GLASS stages, the rates of technical success were lower and the amputation and mortality rates were higher.

Using machine learning to predict outcomes following suprainguinal bypass

OBJECTIVE

Suprainguinal bypass for peripheral artery disease (PAD) carries important surgical risks; however, outcome prediction tools remain limited. We developed machine learning (ML) algorithms that predict outcomes following suprainguinal bypass.

METHODS

The Vascular Quality Initiative database was used to identify patients who underwent suprainguinal bypass for PAD between 2003 and 2023. We identified 100 potential predictor variables from the index hospitalization (68 preoperative [demographic/clinical], 13 intraoperative [procedural], and 19 postoperative [in-hospital course/complications]). The primary outcomes were major adverse limb events (MALE; composite of untreated loss of patency, thrombectomy/thrombolysis, surgical revision, or major amputation) or death at 1 year following suprainguinal bypass. Our data were split into training (70%) and test (30%) sets. Using 10-fold cross-validation, we trained six ML models using preoperative features (Extreme Gradient Boosting [XGBoost], random forest, Naïve Bayes classifier, support vector machine, artificial neural network, and logistic regression). The primary model evaluation metric was area under the receiver operating characteristic curve (AUROC). The best performing algorithm was further trained using intra- and postoperative data. Model robustness was evaluated using calibration plots and Brier scores. Performance was assessed on subgroups based on age, sex, race, ethnicity, rurality, median Area Deprivation Index, symptom status, procedure type, prior intervention for PAD, concurrent interventions, and urgency.

RESULTS

Overall, 16,832 patients underwent suprainguinal bypass, and 3136 (18.6%) developed 1-year MALE or death. Patients with 1-year MALE or death were older (mean age, 64.9 vs 63.5 years; P < .001) with more comorbidities, had poorer functional status (65.7% vs 80.9% independent at baseline; P < .001), and were more likely to have chronic limb-threatening ischemia (67.4% vs 47.6%; P < .001) than those without an outcome. Despite being at higher cardiovascular risk, they were less likely to receive acetylsalicylic acid or statins preoperatively and at discharge. Our best performing prediction model at the preoperative stage was XGBoost, achieving an AUROC of 0.92 (95% confidence interval [CI], 0.91-0.93). In comparison, logistic regression had an AUROC of 0.67 (95% CI, 0.65-0.69). Our XGBoost model maintained excellent performance at the intra- and postoperative stages, with AUROCs of 0.93 (95% CI, 0.92-0.94) and 0.98 (95% CI, 0.97-0.99), respectively. Calibration plots showed good agreement between predicted and observed event probabilities with Brier scores of 0.12 (preoperative), 0.11 (intraoperative), and 0.10 (postoperative). Of the top 10 predictors, nine were preoperative features including chronic limb-threatening ischemia, previous procedures, comorbidities, and functional status. Model performance remained robust on all subgroup analyses.

CONCLUSIONS

We developed ML models that accurately predict outcomes following suprainguinal bypass, performing better than logistic regression. Our algorithms have potential for important utility in guiding perioperative risk mitigation strategies to prevent adverse outcomes following suprainguinal bypass.

Bypass surgery versus endovascular revascularization for occlusive infrainguinal peripheral artery disease: a meta-analysis of randomized controlled trials for the development of the Italian Guidelines for the treatment of diabetic foot syndrome

To report a review and meta-analysis of all randomized controlled trials (RCTs) comparing bypass surgery (BS) and endovascular treatment (ET) in infrainguinal peripheral arterial disease (PAD) for several endpoints, such as major and minor amputation, major adverse limb events (MALEs), ulcer healing, time to healing, and all-cause mortality to support the development of the Italian Guidelines for the Treatment of Diabetic Foot Syndrome (DFS). A MEDLINE and EMBASE search was performed to identify RCTs, published since 1991 up to June 21, 2023, enrolling patients with lower limb ischemia due to atherosclerotic disease (Rutherford I-VI). Any surgical BS or ET was allowed, irrespective of the approach, route, or graft employed, from iliac to below-the-knee district. Primary endpoint was major amputation rate. Secondary endpoints were amputation-free survival major adverse limb events (MALEs), minor amputation rate, all-cause mortality, ulcer healing rate, time to healing, pain, transcutaneous oxygen pressure (TcPO2) or ankle-brachial index (ABI), quality of life, need for a new procedure, periprocedural serious adverse events (SAE; within 30 days from the procedure), hospital lenght of stay, and operative time. Twelve RCTs were included, one enrolled two separate cohorts of patients, and therefore, the studies included in the analyses were 13. Participants treated with ET had a similar rate of major amputations to participants treated with BS (MH-OR 0.85 [0.60, 1.20], p = 0.36); only one trial reported separately data on patients with diabetes (N = 1), showing no significant difference between ET and BS (MH-OR: 0.67 [0.09, 5.13], p = 0.70). For minor amputation, no between-group significant differences were reported: MH-OR for ET vs BS: 0.83 [0.21, 3.30], p = 0.80). No significant difference in amputation-free survival between the two treatment modalities was identified (MH-OR 0.94 [0.59, 1.49], p = 0.80); only one study reported subgroup analyses on diabetes, with a non-statistical trend toward reduction in favor of ET (MH-OR 0.62 [0.37, 1.04], p = 0.07). No significant difference between treatments was found for all-cause mortality (MH-OR for ET vs BS: 0.98 [0.80, 1.21], p = 0.88). A significantly higher rate of MALE was reported in participants treated with ET (MH-OR: 1.44 [1.05, 1.98], p = 0.03); in diabetes subgroup analysis showed no differences between-group for this outcome (MH-OR: 1.34 [0.76, 2.37], p = 0.30). Operative duration and length of hospital stay were significantly shorter for ET (WMD: - 101.53 [- 127.71, - 75.35] min, p < 0.001, and, - 4.15 [- 5.73, - 2.57] days, p < 0.001 =, respectively). ET was associated with a significantly lower risk of any SAE within 30 days in comparison with BS (MH-OR: 0.60 [0.42, 0.86], p = 0.006). ET was associated with a significantly higher risk of reintervention (MH-OR: 1.57 [1.10, 2.24], p = 0.01). No significant between-group differences were reported for ulcer healing (MH-OR: 1.19 [0.53, 2.69], p = 0.67), although time to healing was shorter (- 1.00 [0.18, 1.82] months, p = 0.02) with BS. No differences were found in terms of quality of life and pain. ABI at the end of the study was reported by 7 studies showing a significant superiority of BS in comparison with ET (WMD: 0.09[0.02; 0.15] points, p = 0.01). The results of this meta-analysis showed no clear superiority of either ET or BS for the treatment of infrainguinal PAD also in diabetic patients. Further high-quality studies are needed, focusing on clinical outcomes, including pre-planned subgroup analyses on specific categories of patients, such as those with diabetes and detailing multidisciplinary team approach and structured follow-up.

Presenting limb severity is associated with long-term outcomes after infrainguinal revascularization for chronic limb-threatening ischemia

OBJECTIVE

The SVS Wound, Ischemia, foot Infection (WIfI) limb staging system was established to estimate risk of major amputation in chronic limb-threatening ischemia (CLTI) and better stratify outcomes comparisons. There is little data on treatment outcomes beyond 1 year based on presenting WIfI stage.

METHODS

This is a single-institution retrospective study of 413 patients who underwent infrainguinal revascularization for CLTI (2011-2021) with data available for WIfI staging. Patient characteristics and outcomes were gathered from the electronic medical record. Data were analyzed based on presenting WIfI stage and initial treatment received at our center.

RESULTS

Presenting WIfI stages were 1 to 2 (23%), 3 (27%), and 4 (50%). Index revascularization approach was endoluminal (59%), autogenous vein bypass (29%), or non-autogenous bypass (13%). Operative mortality within 30 days was 2.9% and was not associated with WIfI stage or revascularization approach. Median limb follow-up time was 502 days (interquartile range [IQR], 112-1256 days), and median survival follow-up time was 932 days (IQR, 343-1770 days). Major amputation or death occurred in 19% and 46% of patients at median times of 119 days (IQR, 28-314 days) and 739 days (IQR, 204-1475 days), respectively. WIfI stage was independently associated with major amputation (P = .001), as was initial revascularization approach (P = .01). In a Cox proportional hazards model, factors independently associated with major amputation were male sex (hazard ratio [HR], 1.4; 95% confidence interval [CI], 1.04-2.0; P = .03), diabetes (HR, 1.8; 95% CI, 1.3-2.5; P = .001), WIfI stage 4 (HR, 2.3; 95% CI, 1.5-3.5; P < .001), and non-autogenous bypass (HR, 2.9; 95% CI, 2.1-4.2; P < .001). In a Cox proportional hazards model for mortality, independently associated factors were age (HR, 1.04; 95% CI, 1.02-1.05; P < .001), end-stage renal disease (HR, 2.8; 95% CI, 1.9-4.0; P < .001), congestive heart failure (HR, 1.9; 95% CI, 1.4-2.5; P < .001), chronic obstructive pulmonary disease (HR, 1.5; 95% CI, 1.1-2.1; P = .02), and WIfI stage 4 (HR, 1.6; 95% CI, 1.04-2.2; P = .03). Among those presenting with WIfI stage 4 limbs, Kaplan-Meier estimated rates of freedom from major amputation or death at 2 years were 71% ± 3.7% and 68% ± 3.5%, respectively. In an inverse propensity weighted Cox proportional hazards model, non-white race (HR, 1.5; 95% CI, 1.01-2.2; P = .047), diabetes (HR, 2.0; 95% CI, 1.2-3.3; P = .008), Global Anatomic Staging System infrapopliteal grade (HR, 1.2; 95% CI, 1.05-1.3; P = .005), non-autogenous bypass (HR, 3.2; 95% CI, 1.9-5.3; P < .001), and endoluminal revascularization (HR, 2.6; 95% CI, 1.6-4.3; P < .001) were independently associated with major amputation in the WIfI stage 4 subgroup.

CONCLUSIONS

Presenting WIfI stage is strongly associated with long-term risks of major amputation and death following infrainguinal revascularization for CLTI and should be used to stratify outcomes comparisons. Effective revascularization is critical in WIfI stage 4 disease, and autogenous vein bypass provides durable long-term limb preservation.