SLR - January 2024 - Hogan
Title: Medial arterial calcification score is associated with increased risk of major limb amputationReference: DiBartolomeo AD, Browder SE, Bazikian S, Thapa D, Kim S, Tohann A, Armstrong DG, McGinigle KL. Medial arterial calcification score is associated with increased risk of major limb amputation. J Vasc Surg. 2023 Nov;78(5):1286-1291
Level of Evidence: III
Reviewed By: Steven Hogan, DPM
Residency Program: Emory University School of Medicine, Atlanta, GA
Podiatric Relevance: Chronic limb-threatening ischemia (CLTI) is an increasingly common component of peripheral vascular disease that involves pain at rest with possible tissue ulceration and gangrene. Ultimately, affected patients carry a high risk of major limb amputation and mortality. Classification systems such as the Wound, Ischemia, and Foot Infection scoring tool rely on ABIs and/or toe pressures which may be inaccurate in the setting of extensive calcific disease. A pedal medial arterial calcification (MAC) scoring system has been developed to risk stratify patients with inframalleolar small vessel disease for risk of major limb loss. This study attempts to validate the MAC scoring system across multiple institutions as it has previously demonstrated its ability to independently predict major limb loss in a single-center analysis.
Methods: A multi-institution, retrospective cohort study of patients who underwent prior revascularization for CLTI from 2010-2022 were included. Criteria included ABIs <.5, ankle pressures <70 mmHg, or toe pressure <50 mmHg with pain at rest, ulceration, or gangrene. Patients without two-view foot X-Rays, prior amputation at the level of the metatarsals, or revascularization for acute limb ischemia were excluded. MAC scores 0-5 were based on the extent of calcification with 1 point given for a >2 cm continuous calcific segment in the dorsalis pedis, lateral plantar, or first metatarsal artery and 1 point given for segments >1 cm to any digital artery. The primary outcome was above the ankle amputation at 6 months.
Results: A cohort of 740 patients were identified with 176 patients being included in the final analysis. The average age was 66.2 and 96.7% presented with a wound. Of note, 23.4% had ESRD, 15.2% had CKD 3b to 5, and 77% were diabetic. No calcific changes were noted in 40.8% (MAC score 0) while a relatively even distribution of scores 1-5 were noted to the remaining study population. In total, there were 26 major limb amputations and 16 deaths within 6 months of the initial revascularization. At the end of the study period, major limb amputation-free survival was 92.9% for MAC scores 0-1, 87.3% for MAC scores 2-4, and 73.8% for a MAC of 5. Patients with a MAC score of 5 were significantly more likely to have a major amputation than those with MAC 0-1 or MAC 2-4.
Conclusions: The pedal MAC scoring system is a reproducible and generalizable measurement of inframalleolar arterial disease. As an adjunct to current classification systems it can add prognostic value for risk of limb loss despite revascularization in patients with CLTI. As the scoring system relies on X-ray examination there is minimal impact of cost or time to the patient or physician. Selection bias may exist as all patients underwent revascularization with no available comparison for those who did not. Additionally, the majority of excluded patients did not have X-rays so the study is likely biased towards those with foot wounds. Finally, as a retrospective study the analysis may be underpowered highlighting the need for possible prospective studies in the future.