RS05 - Calcified Plaque Volume as a Predictor of Combined Stroke and Death After Transcarotid Artery Revascularization (TCAR)

Objectives: Within the cardiology literature, coronary calcium scores have been established as an easily automated way to utilize cross-sectional imaging to predict cardiovascular events and death. No analog exists within the vascular surgical literature. Utilizing cross-sectional imaging on patients undergoing trans-carotid arterial revascularization (TCAR), we utilized a previously published standardized, semi-automated technique to obtain atherosclerotic plaque calcium quantification. We examined the impact of carotid calcium volume percent on postoperative stroke/death, hypothesizing that increased calcium burden would be associated with increased stroke/death.

Methods: Patients undergoing TCAR from 2015-2023 were stratified into high- or low-calcium volume percent using the median value. Stroke and mortality dates were obtained from patient records. The primary outcome was composite stroke/death. Patient factors and outcomes were compared using Student’s t-test, Pearson’s chi-square, Fisher’s exact test, and Mann-Whitney testing. Kaplan-Meier analysis was performed for three-year freedom from stroke/death and Cox proportional hazards modeling for factors associated with stroke/death.

Results: 242 patients underwent TCAR from December 2015-January 2023 at our institution. The high-calcium group had more female patients (38.0% versus 24.0%, p=0.03), was older (74.6±7.9 versus 70.5±9.4 years, p< 0.01), and had higher rate of hypertension (95.0% versus 86.0%, p=0.03). Rates of symptomatic disease were similar between groups (41.7% high calcium versus 51.2% low calcium, p=0.17). The mean calcium volume was 2.9±2.8% for low calcium versus 20.7±9.7% in the high calcium group (p < 0.01). 30-day stroke/death occurred only in the high calcium group and was equivalent when stratified by symptomatic status (1.7% asymptomatic versus 3.3% symptomatic, p=0.23). At three years, the low-calcium group demonstrated greater freedom from stroke/death (p=0.03) (Figure 1). Mortality rate was higher in the high-calcium group (20.7% versus 9.1%, p=0.02) though with fewer strokes (0.0% versus 2.5%, p=0.25). Cox proportional hazards analysis showed factors associated with stroke/death were congestive heart failure (hazard ratio (HR):4.5, 95% confidence interval (CI):2.3-9.0; p< 0.01) and chronic kidney disease (HR:2.2, 95% CI:1.1-4.3, p=0.03). Low calcium volume percent (HR:0.5, 95% CI:0.3-1.0, p=0.05) was protective.

Conclusions: Using a novel volumetric technique for quantification of carotid plaque calcium burden, we demonstrated lower calcium volume percent is associated with lower combined stroke/death rate at 3 years. This may reflect that higher carotid calcium burden is associated with greater systemic calcification and thus higher cardiovascular risk. Additionally, a patient’s comorbid profile is strongly associated with stroke/death in the mid-term. These data provide additional anatomic-based data to aid with risk-benefit analysis in patients undergoing minimal access carotid surgery.