Predicting factors associated with postoperative hypotension following carotid artery stenting

Background: Prolonged hemodynamic instability after carotid artery stenting (CAS) has been associated with increased incidence of stroke and other major adverse events. The objective of this study is to determine the factors associated with hypotension following CAS. In particular, this study evaluates whether involvement of the carotid bifurcation/bulb and degree of calcification can predict postoperative hypotension. Methods: A retrospective review of 90 CASs performed in 88 patients at a single tertiary center was completed. In patients with proximal internal carotid stenosis involving the carotid bifurcation, the extent of bifurcation/bulb calcification on preoperative computed tomography angiography was assessed using a scoring system. Calcium scores were assigned based on the percent of circumferential calcification of carotid bifurcation as follows: grade 1, < 10%; grade 2, 10-50%; grade 3, 50-90%; and grade 4, > 90%. Perioperative factors associated with prolonged postoperative hypotension requiring vasopressor infusion were analyzed. Results: Overall, postoperative hypotension requiring vasopressors occurred in 26 (28.9%) of CAS. There were no differences in baseline demographics, comorbidities, or CAS indication between patients who required postoperative vasopressors for hypotension and those who did not. The majority of patients (64.4%) were on 2 or more antihypertensive medications preoperatively. Stenosis involved carotid bifurcation in 64 (71.1%) cases. Of these, 27 (42.2%) were grade 1, 19 (29.7%) were grade 2, 10 (15.6%) were grade 3, and 8 (12.5%) were grade 4 based on our calcium scoring system. On risk-adjusted analysis, carotid bifurcation/bulb involvement (adjusted odds ratio [aOR] 4.5, 95% confidence interval [CI] 1.1-18.5) and preoperative regimen of 2 or more antihypertensives (aOR 4.2, 95% CI 1.1-16.0) were independent predictors of hypotension requiring vasopressors following CAS. Among patients with carotid bifurcation involvement, severity of calcium score was not a significant predictor of postoperative hypotension. Conclusions: CAS for carotid stenosis involving the carotid bifurcation/bulb is associated with a higher risk for postoperative hypotension requiring vasopressors. Patients with preoperative hypertension requiring 2 or more antihypertensive medications are also at increased risk. However, severity of carotid bifurcation calcification is not a significant predictor of need for postoperative vasopressors.