Predicting Major Lower Limb Amputations in Chronic Limb-Threatening Ischemia: The Role of Pedal Medial Arterial Calcification.

Objective: The Pedal Medial Arterial Calcification (pMAC) score is a radiographic tool that quantifies arterial calcification in the foot, providing a novel approach to predict outcomes in chronic limb-threatening ischemia (CLTI). This study investigates the association of pMAC scores with clinical outcomes in patients undergoing major lower limb amputations (MLLA). Methods: This retrospective study analyzed data from the National Vascular Registry (NVR) for the Southeast Wales Vascular Network (SEWVN) from July 2022 to June 2024. Patients undergoing MLLA with available preoperative radiographs were included. pMAC scores were categorized into low (0-1), medium (2-3), and high (4-5). Cox proportional hazards regression assessed the impact of pMAC on time to amputation, while additional analyses evaluated its association with revascularization outcomes and systemic comorbidities. Results: A total of 119 patients were included after excluding cases with insufficient imaging. Higher pMAC scores were associated with male gender (P = 0.009) and chronic kidney disease (P = 0.017), though not with preoperative blood test parameters. Each unit increase in pMAC score was associated with a 22% higher risk of amputation over time (HR = 1.22, P = 0.049). Medium pMAC scores correlated with shorter time to MLLA (P = 0.0516). Revascularization type did not significantly impact time to amputation (P = 0.66). Conclusions: pMAC predicts amputation risk in CLTI patients, independent of revascularization type. Integrating pMAC into clinical workflows may refine risk stratification and guide postoperative care. Prospective validation is warranted to establish its role in vascular surgery decision-making.