Objective: Pedal medial arterial calcification (pMAC) is associated with major amputation in patients with chronic limb-threatening ischemia (CLTI). We hypothesize that this association would be related to unresolved distal ischemia. We investigated relationships across pMAC score, hemodynamic change, and major amputation after infrainguinal revascularization for CLTI.
Methods: This is a single-institution, retrospective study of 306 patients who underwent technically successful infrainguinal revascularization for CLTI (2011-2020) and had foot x-rays for blinded pMAC scoring (0-5). A total of 136 (44%) patients had toe pressure measurements performed within 90 days before and 60 days after revascularization. Ischemia grade (0-3) was assigned using the Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) system.
Results: The revascularization approach was open bypass in 118 (38%) and endovascular in 188 (62%) patients. pMAC scores were trichotomized (0-1 [125; 41%], 2-4 [116; 38%], 5 [65; 21%]). Post-revascularization WIfI ischemia grade was improved in 78 of 136 (57%) and unchanged/worsened in 58 of 136 (43%). A lower pMAC score was associated with hemodynamic improvement (P = .004). Failure to improve the ischemia grade was associated with major amputation (P = .0002). In the endovascular subgroup, WIfI ischemia grade was improved in 43 of 90 (48%) with available measurements, and 37 of 188 (20%) underwent major amputation. In a multivariate logistic model, pMAC 5 was the only factor independently associated with unimproved ischemia grade after endovascular treatment (odds ratio: 4.0 [1.1-16.6], P = .04). In a Cox proportional hazards model, factors independently associated with major amputation after endoluminal revascularization were WIfI stage 4 (hazard ratio [HR]: 2.7 [1.3-5.7], P = .007) and pMAC score (pMAC: 2-4: HR: 10.6 [1.4-80.7], P = .02; pMAC: 5: HR: 15.5 [2.0-119], P = .008). In the bypass subgroup, WIfI ischemia grade was improved in 35 of 46 (76%) with available measurements but was not associated with pMAC score (P = .88) or any other baseline patient or limb characteristics. A total of 19 of 118 (16%) patients underwent major amputation. In a Cox proportional hazards model including bypass conduit, WIfI stage, and pMAC score, the only factor independently associated with major amputation after bypass was use of nonautologous conduit (HR: 5.6 [1.8-17.6], P = .003).
Conclusions: The pMAC score is independently associated with persistent distal ischemia and major amputation after technically successful revascularization for CLTI. These data suggest that pMAC may be a marker for hemodynamic response to revascularization and risk of limb loss, and it may have a stronger influence on the outcome of endoluminal interventions.
Keywords: Amputation; Chronic limb-threatening ischemia; Monckeberg medial calcific sclerosis; Peripheral arterial disease; Vascular calcification.