Prognostic and predictive value of ultrasound-based estimated ankle brachial pressure index at early follow-up after endovascular revascularization of chronic limb-threatening ischaemia: a prospective, single-centre, service evaluation

Abstract

Background: Ankle brachial pressure index can be estimated (eABPI) using cuffless ankle Doppler ultrasound. We evaluated the prognostic value of eABPI measured during pre- and post-procedural ultrasound exams to predict the clinical outcome after endovascular revascularisations.

Methods: In this prospective, single-centre, service evaluation, consecutive patients with symptomatic peripheral artery disease undergoing lower limb endovascular revascularisations between July, 26 2018 and January, 13 2022 at Surrey and Sussex Healthcare NHS Trust (Redhill, UK) were analysed. eABPI was determined using the higher acceleration index measured with angle-corrected duplex ultrasound in ankle arteries before and ≤1 month post-procedure. Clinical outcomes (mortality, major amputations, amputation-free survival [AFS], clinically driven target lesion revascularization [cdTLR], major adverse limb events [MALE; cdTLR and major amputation], wound healing) were assessed over 1 year.

Findings: Of 246 patients treated, for 219 patients (median 75 [IQR 66-83] years) pre- and post-procedural eABPI (0.50 [0.33-0.59] and 0.90 [0.69-1.0], p < 0.0001) were available, respectively. In n = 199 patients with chronic limb-threatening ischaemia (CLTI) Kaplan-Meier survival analyses showed that higher post-procedural, but not pre-procedural, eABPI was associated with favourable AFS, MALE, cdTLR, and wound healing. This was confirmed in Cox regression analysis and remained significant with adjustment for pre-procedural eABPI, age, sex, co-morbidities, treated levels, wound score, and foot infection. Whereas all clinical outcomes, except for survival, were significantly better at ≥0.7 vs <0.7, wound healing (unadjusted: HR 1.7 (95% CI 1.2-2.6), adjusted: HR 2.1 (95% CI 1.3-3.1), cdTLR, and MALE (unadjusted: HR 0.41 (95% CI 0.18-0.93), adjusted: HR 0.28 (95% CI 0.11-0.74) were significantly improved at ≥0.9 vs <0.9.

Interpretation: Post-procedural eABPI can provide valid, clinically important prognostic and predictive information. Our data indicate that revascularisations should target values of at least 0.9 to achieve optimal outcomes. Future studies need to confirm generalisability and cost-effectiveness in a wider context.

Funding: European Partnership on Metrology, co-financed from European Union's Horizon Europe Research and Innovation Programme and UK Research and Innovation.

Keywords: Angioplasty; Biomarker; Chronic limb-threatening ischaemia; Estimated ankle brachial pressure index; Peripheral artery disease.

Fig. 1

Overview of (A) study design and (B) flowchart of patient groups and analyses (AFS = amputation-free survival, IC = intermittent claudication, CLTI = chronic limb-threatening ischaemia, cdTLR = clinically driven target lesion revascularisation, MALE = major adverse limb event [cdTLR, major amputation]).

Fig. 2

Kaplan-Maier survival analysis for 1-year (A) amputation-free survival, (B) freedom from major adverse limb events (MALE; major amputation and clinically driven target lesion revascularisation [cdTLR]), (C) freedom from cdTLR, (D) freedom from major amputation, (E) overall survival, and (F) wound healing in patients with chronic limb-threatening ischaemia (n = 199, n = 174 with ulcers/gangrene) (Overall p-values are shown, see Table 3 for 95% confidence intervals of individual groups).

Fig. 3

Overview of event rates for endpoints according to technical success and post-procedural eABPI. Based on data detailed in Table 3 and Supplementary Table 2; ∗p < 0.05 vs “technical success”, #p < 0.05 vs ≥0.7, ≥0.8, and ≥0.9, respectively (Kaplan–Meier analysis, Table 3), +p < 0.05 vs ≥0.7, ≥0.8, and ≥0.9, respectively (adjusted Cox regression analysis, Table 4) (AFS = amputation-free survival, MALE = major adverse limb event [cdTLR, major amputation]).