Iliac Artery Calcification Score Stratifies Mortality Risk Estimation in Patients with Chronic Limb-Threatening Ischemia Undergoing Revascularization.

BACKGROUND: Patients with chronic limb-threatening ischemia (CLTI) are at high risk for adverse limb outcomes and mortality. Using the Vascular Quality Initiative (VQI) prediction model to estimate mortality after revascularization can assist with clinical decision-making. We aimed to improve the discrimination of the 2-year VQI risk calculator by incorporating a common iliac artery (CIA) calcification score based on computed tomography (CT) scans.

METHODS: This was a retrospective analysis of patients who underwent infrainguinal revascularization for CLTI from 1/2011 to 6/2020 and had a CT scan of the abdomen/pelvis 2 years before or up to 6 months after revascularization. CIA calcium morphology, circumference, and length were scored. Bilateral scores were summed for the total calcium burden (CB) score, which was trichotomized (mild:0-15, moderate:16-19, severe:20-22). The VQI CLTI model was used to categorize patients as low-, medium-, or high-risk for mortality.

RESULTS: 131 patients with mean age of 69±12 years were included in the study, and 86 (66%) were men. CB scores were mild in 52 (40%), moderate in 26 (20%) and severe in 53 (40%) patients. Older patients (p=0.0002) and those with coronary artery disease (p=0.06) had higher CB scores. Patients with severe CB scores were more likely to undergo infrainguinal bypass compared to those with mild or moderate CB scores (p=0.006). The 2-year VQI mortality risk was calculated to be low in 102 (78%), medium in 23 (18%) and high in 6 (4.6%) patients. In the "low-risk" VQI mortality subgroup, 46 (45%) patients had mild, 18 (18%) had moderate, and 38 (37%) had severe CB scores, and patients with severe CB scores had significantly higher risk of mortality compared to those with mild or moderate scores [HR 2.5 (1.2-5.1), p=0.01]. In this "low-risk" VQI mortality subgroup, CB score further stratified the risk of mortality (p=0.04).

CONCLUSIONS: Higher total CIA calcification was significantly associated with mortality in patients undergoing infrainguinal revascularization for CLTI, and preoperative assessment of CIA calcification may help with perioperative risk stratification and guide clinical decision making in this population.