Carotid calcium burden and perivascular fat density on computed tomography angiography as predictors of outcomes after carotid endarterectomy

Objective: Atherosclerotic disease of the extracranial internal carotid artery affects over 1.5% of the global population and poses major health risks, including ischemic stroke and mortality. Although carotid endarterectomy (CEA) reduces these risks, it carries a 2% to 6% risk of major complications. Improved risk stratification beyond stenosis severity is needed. This study aimed to evaluate whether the carotid calcium score, as a marker of plaque stability, and perivascular fat density, as a marker of inflammatory activity, independently predict clinical outcomes after CEA. The assessed outcomes included all-cause mortality, cardiovascular mortality, major adverse cardiac events (MACE), neurological events, and restenosis. Methods: This single-center retrospective cohort study included 178 patients who underwent CEA between 2015 and 2021 and had preoperative computed tomography angiography within 6 months of surgery. The modified Agatston calcium score was calculated bilaterally using patient-specific attenuation thresholds, and perivascular fat density (Hounsfield units) was measured in standardized regions of interest. Statistical analysis included correlation testing, Kaplan-Meier survival analysis, and Cox proportional hazard models. Results: Preoperative imaging biomarkers (stenosis degree, calcium score, and fat density) were not interrelated and did not predict early postoperative complications. However, lower calcium scores were associated with improved long-term outcomes, including lower risk of MACE (P = .041) and lower cardiovascular mortality (P = .023). At 4 years, survival for all-cause mortality was higher in the low calcium group (63.6% vs 58.0%, P = .008). In asymptomatic patients, differences were even greater for MACE (79.3% vs 48.1%; P = .005) and all-cause mortality (78.2% vs 54.9%; P = .004). The carotid calcium score independently predicted the risk of MACE (hazard ratio [HR] = 1.63; 95% confidence interval [CI]: 1.15-2.33; P = .007) and cardiovascular mortality (HR = 3.12; 95% CI: 1.01-9.58; P = .047), after adjustment for confounding variables. Higher fat density was associated with increased risk of restenosis (HR = 5.69; 95% CI: 1.18-27.4; P = .030), though this was not an independent predictor. Conclusions: High ipsilateral carotid artery calcium score independently predicted the risk of MACE and cardiovascular mortality after CEA and was associated with a trend toward increased all-cause mortality up to 4 years of follow-up. Predictive values were even stronger in asymptomatic patients. Perivascular fat density seems to be relevant to predict restenosis. These plaque characteristics may help identify patients most likely to benefit from CEA and those who may require intensified postoperative cardiovascular risk management due to elevated complication risk.