Impact of Calcified Plaque Volume on Technical and 3-Year Outcomes After Transcarotid Artery Revascularization (TCAR).

OBJECTIVE: To quantify percent calcification within carotid artery plaques and assess its impact on percent residual stenosis and rate of restenosis in patients undergoing TCAR for symptomatic and asymptomatic carotid artery stenosis.

METHODS: A retrospective review of prospectively collected institutional Vascular Quality Initiative (VQI) data was performed to identify all patients undergoing TCAR from December 2015 to June 2021 (n=210). Patient and lesion characteristics were extracted. Using a semi-automated workflow, pre-operative computed tomography (CT) head and neck angiograms were analyzed to determine the calcified plaque volume in distal common carotid artery and internal carotid artery plaques. Intraoperative digital subtraction angiograms (DSA) were reviewed to calculate the percent residual stenosis post-intervention according to North American Symptomatic Carotid Endarterectomy Trial criteria (NASCET). Peak systolic velocity and end diastolic velocity were extracted from outpatient carotid duplex ultrasounds. Univariate logistic regression was performed to analyze the relationship of calcium volume percent and VQI lesion calcification to percent residual stenosis in completion angiograms. Kaplan-Meier analysis examined the relationship between calcium volume percent and in-stent stenosis over 36 months.

RESULTS: One hundred ninety seven carotid arteries were preliminarily examined. Pre-dilation was performed in 87.4% of cases with a mean balloon diameter of 5.1 ± 0.7 mm and mean stent diameter was 8.8 ± 1.1 mm. Mean calcium volume percent was 11.9 ± 12.4% and the mean percent residual stenosis was 16.1 ± 15.6%. Univariate logistic regression demonstrated a statistically significant difference between calcium volume percent and percent residual stenosis (OR: 1.324, 95% CI 1.005-1.746, p = 0.046). Stratified by quartile, only the top 25% of calcified plaques (>18.7% calcification) demonstrated a statistically significant association with higher percent residual stenosis OR: 2.532, 95% CI: 1.049-6.115, p =0.039). There was no statistical significance with lesion calcification (OR: 1.298, CI: 0.980-1.718, p=0.069). A Kaplan-Meier analysis demonstrated a statistically significant increase in the rate of in-stent stenosis during a 36-month follow-up for lesions containing greater than 8.2% calcium volume (p=0.0069).

CONCLUSIONS: Calcium volume percent greater than 18.7% was associated with higher percent residual stenosis, and a calcium volume percent greater than 8.2% was associated with higher in-stent stenosis at 36 months. There was one clinically diagnosed stroke during the follow-up period, demonstrating the overall safety of the procedure.