RESUMEN
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.
RESUMEN
Ankle brachial pressure index (ABPI) is the first-line test to diagnose peripheral artery disease (PAD). Its adoption in clinical practice is poor and its validity, particularly in diabetes, is limited. We hypothesised that ABPI can be accurately and precisely estimated based on cuffless Doppler waveforms. Retrospective analysis of standard ABPI and handheld Doppler waveform characteristics (n = 200). Prospective analysis of angle-corrected Doppler acceleration index (AccI, n = 148) and standard ABPI with testing of performance to diagnose PAD as assessed with imaging reference standards in consecutive patients. The highest AccI from handheld Doppler at ankle arteries was significantly logarithmically associated with the highest standard ABPI (E[y] = 0.32 ln [1.71 ∗ x + 1], p < 0.001, R2 = 0.68, n = 100 limbs). Estimated ABPI (eABPI) based on AccI closely resembled ABPI (r = 0.81, p < 0.001, average deviation −0.01 ± 0.13 [SD], n = 100 limbs). AccI from angle-corrected Doppler in patients without overt media sclerosis (ABPI ≤ 1.1) improved ABPI prediction (E[y] = 0.297 ∗ ln[0.039 ∗ x + 1], R2 = 0.92, p = 0.006, average deviation 0.00 ± 0.08, n = 100). In a population (n = 148 limbs) including diabetes (56%), chronic limb-threatening ischaemia (51%) and media sclerosis (32%), receiver operating characteristics analysis of (angle-corrected) eABPI performed significantly better than standard ABPI to diagnose PAD defined by ultrasound (ROC AUC = 0.99 ± 0.01, p < 0.001; sensitivity: 97%, specificity: 96%) at the ≤0.9 cut-off. This was confirmed with CT angiography (ROC AUC = 0.98, p < 0.001, sensitivity: 97%, specificity: 100%) and was independent of the presence of diabetes (p = 0.608). ABPI can be estimated based on ankle Doppler AccI without compression, and eABPI performs better than standard ABPI to diagnose PAD independent of diabetes. eABPI has the potential to be included as a standard component of lower extremity ultrasound.