Medial arterial calcification score is associated with increased risk of major limb amputation

The pedal medial arterial calcification (MAC) score has been associated with risk of major limb amputation in patients with chronic limb-threatening ischemia. This study aimed to validate the pedal MAC scoring system in a multi-institutional analysis to validate its usefulness in limb amputation risk prediction. A multi-institution, retrospective study of patients who underwent endovascular or open surgical infrainguinal revascularization for chronic limb-threatening ischemia was performed. MAC scores of 0 to 5 were assigned based on visible calcified arteries on foot X ray then trichotomized (0-1, 2-4, 5) for analysis. The primary outcome was major limb amputation at 6 months. Adjusted Kaplan-Meier models were used to analyze time-to-major amputation across groups. There were 176 patients with 184 affected limbs (mean age, 66 years; 61% male; 60% White), of whom 97% presented with a wound. The MAC score was 0 in 41%, 1 in 9%, 2 in 13%, 3 in 11%, 4 in 13%, and 5 in 13% of the limbs. There were 26 major amputations (14%) and 16 deaths (8.7%) within 6 months. Patients with MAC 5 had a significantly higher risk of major limb amputation than both the 0 to 1 and 2 to 4 groups (P = .001 and P = .044, respectively), and lower overall amputation-free survival (log-rank P = .008). Pedal MAC score is a reproducible and generalizable measure of inframalleolar arterial disease that can be used with Wound, Ischemia, and foot Infection staging to predict major limb amputation in patients with chronic limb-threatening ischemia.