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Predicting Amputation using Local Circulating Mononuclear Progenitor Cells in Angioplasty-treated Patients with Critical Limb Ischemia
Published on: September 22, 2020
Pedal arterial calcification score is associated with the risk of major amputation in chronic limb-threatening
Iris H Liu1, Bian Wu1, Viktoriya Krepkiy1
1Division of Vascular and Endovascular Surgery, Department of Surgery, University of California, San Francisco, San Francisco, Calif.
Insights
A higher medial arterial calcification (MAC) score, indicating more inframalleolar calcification, is a strong predictor of major amputation risk in patients with chronic limb-threatening ischemia (CLTI). This simple radiographic tool aids in risk stratification for CLTI patients.
Area of Science:
- Vascular Surgery
- Radiology
- Cardiovascular Medicine
Background:
- Chronic limb-threatening ischemia (CLTI) poses a significant risk of major amputation.
- Assessing the burden of inframalleolar calcification is crucial for CLTI management.
- The medial arterial calcification (MAC) score offers a potential metric for calcification burden.
Purpose of the Study:
- To investigate the association between the MAC score and the risk of major amputation in patients with CLTI.
- To determine if the MAC score is an independent predictor of major amputation.
- To evaluate the utility of the MAC score in stratifying risk within CLTI patient subgroups.
Main Methods:
- Retrospective study of 250 patients undergoing infrainguinal revascularization for CLTI.
- Calculation of MAC scores (0-5) from foot radiographs by a blinded reviewer.
- Analysis of MAC score association with major amputation risk using Cox proportional hazards regression, adjusting for relevant clinical factors.
Main Results:
- A higher MAC score was significantly associated with an increased risk of major amputation (P < .0001).
- The MAC score independently predicted major amputation risk (MAC score 5: HR 4.9; MAC score 2-4: HR 3.4).
- The MAC score effectively stratified amputation risk in patients with advanced WIfI stage or diabetes.
Conclusions:
- The MAC score is a simple, practical, and independent predictor of major amputation in CLTI patients.
- It provides valuable clinical data not captured by current CLTI staging systems.
- The MAC score can enhance outcomes stratification and treatment strategy decisions for CLTI.
Objective:
The medial arterial calcification (MAC) score is a simple metric that describes the burden of inframalleolar calcification using a plain foot radiograph. We hypothesized that a higher MAC score would be independently associated with the risk of major amputation in patients with chronic limb-threatening ischemia (CLTI).
Methods:
We performed a single-institution, retrospective study of 250 patients who had undergone infrainguinal revascularization for CLTI from January 2011 to July 2019 and had foot radiographs available for MAC score calculation. A single blinded reviewer assigned MAC scores of 0 to 5 using two-view minimum plain foot radiographs, with 1 point each for calcification of >2 cm in the dorsalis pedis, plantar, and metatarsal arteries and >1 cm in the hallux and non-hallux digital arteries.
Results:
The MAC score was 0 in 36%, 1 in 5.2%, 2 in 8.4%, 3 in 14%, 4 in 14%, and 5 in 21%. The MAC score was trichotomized to facilitate analysis and clinical utility (mild, MAC score 0-1; moderate, MAC score 2-4; and severe, MAC score 5). The variables independently associated with a higher MAC score were male sex, diabetes, end-stage renal disease, and the global limb anatomic staging system pedal score. The MAC score was not associated with the Society for Vascular Surgery WIfI (wound, ischemia, foot infection) grade or overall WIfI stage (P = .58). The median follow-up was 759 days (interquartile range, 264-1541 days). A higher MAC score was significantly associated with the risk of major amputation (P < .0001). In a Cox proportional hazards multiple regression model for major amputation that included the trichotomized MAC score, diabetes, end-stage renal disease, and WIfI stage (1-3 vs 4). The MAC score (MAC score 5: hazard ratio [HR], 4.9; 95% confidence interval [CI], 1.9-13.1; P = .001; MAC score 2-4: HR, 3.4; 95% CI, 1.3-8.8; P = .01) and WIfI stage (WIfI stage 4: HR, 2.1; 95% CI, 1.1-3.9; P = .03) were significantly associated with the risk of major amputation. In the subsets of patients with the most advanced WIfI stage of 3 to 4 (191 of 250; 76%) and patients with diabetes (185 of 250; 74%), the MAC score further stratified the risk of major amputation on univariate and multivariate analyses.
Conclusions:
The MAC score is a simple, practical tool and a strong independent predictor of major amputation in patients with CLTI. It provides novel clinical data that are currently unmeasured using any validated CLTI staging system. The MAC score is a promising standardized measure of inframalleolar disease burden that can be used in conjunction with the WIfI staging system to help improve outcomes stratification and determine the optimal treatment strategies for patients with CLTI.
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