Predictive Ability of the Pedal Medial Arterial Calcification Score for Major Adverse Limb Events Among Patients with Chronic Limb-Threatening Ischemia

Abstract

ObjectivePedal medial arterial calcification (pMAC) is a potential predictor of major adverse limb events (MALE) among patients with critical limb-threatening ischemia (CLTI). This study aims to validate the prognostic value of the pMAC score in predicting major lower limb amputation (MLLA) and need for re-do revascularisation. MethodsA single centre study involving 196 patients diagnosed with CLTI, reviewed between 2012 and 2022. Patients’ pMAC scores were obtained through X-ray assessments. Correlations between pMAC scores and the incidence of MALE and re-do revascularisation, were analysed. A power analysis using G* Power 3 software determined a needed sample size of 157 participants. Statistical analysis employed SPSS 26, utilising descriptive statistics, Chi Square, Mann-Whitney, Kaplan-Meier with log-rank test, and Cox regression for predictor identification. ResultsThe cohort was predominantly male (79.1%) and diabetic (59.2%). Re-do revascularisation need was 15.3%, increasing with pMAC scores: 3.3% (low), 24.5% (medium), and 50% (high) (p<0.001). MLLA frequency also rose with pMAC scores: 6.7%, 27.5%, and 50% respectively (p<0.001). Higher pMAC scores correlated with a higher incidence of MALE (p=0.029). Multivariate analysis showed medium pMAC (HR 4.159, p=0.002), high pMAC (HR 7.366, p=0.015), and GLASS stage 3 (HR 3.529, p=0.011) as independent MLLA predictors. Re-do revascularisation predictors included female sex (HR 2.106, p=0.063), Black race (HR 64.498, p=0.001), medium pMAC (HR 6.812, p=0.002), high pMAC (HR 11.455, p=0.008), and GLASS stage 3 (HR 2.899, p=0.037). ConclusionThe pMAC score effectively predicts MALE in CLTI patients and enhances risk stratification. Using both, pMAC scores and GLASS stages enhances predictive accuracy, identifying patients at higher risk for MLLA, Informing clinical decision-making and therapeutic strategies.