Congratulations to our combined UNC and USC team led by Kate McGinigle and Alex DiBartolomeo. This provides further data supporting the use of medial arterial calcification (MAC) score as a useful surrogate for risk.
Alexander D DiBartolomeo 1, Sydney E Browder 2, Sebouh Bazikian 1, Diwash Thapa 2, Sooyeon Kim 2, Avital Yohann 2, David G Armstrong 1, Katharine L McGinigle 3
Objective: 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.
Methods: 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 0-5 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.
Results: There were 176 patients with 184 affected limbs (mean of 66 years old, 61% male, 60% white), of which 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 (14%) major amputations and 16 (8.7%) deaths within 6 months. Patients with MAC 5 had a significantly higher risk of major limb amputation than both the 0-1 and 2-4 groups (p=0.001, p=0.044, respectively), and lower overall amputation-free survival (log-rank p=0.008).
Conclusions: 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.
Keywords: amputation; chronic limb threatening ischemia; lower extremity revascularization; medial arterial calcification.