Trends in Preoperative Imaging Prior to Elective Carotid Endarterectomy in the Southern California Vascular Outcomes Improvement Collaborative.

Background: Duplex ultrasound (DUS) has been an important imaging modality for carotid bifurcation disease due to its low cost and noninvasive nature. Over the past decade, computed tomography angiography (CTA) has replaced conventional angiography (CA) due to safety and availability. There are significant differences in cost and patient exposures between CTA and DUS. The objective of this study is to analyze the trends in preoperative imaging modalities in the Southern California region for elective carotid endarterectomies (CEA).

Methods: A retrospective review of the Southern California Vascular Outcomes Improvement Collaborative (SoCal VOICe) was performed. All elective CEA procedures were identified from January 2011 through May 2020. Data included all preoperative imaging modalities used. An analysis was performed of the types and numbers of studies obtained. The trends in the usage of single and multiple preoperative studies and the trends in use of DUS versus CTA were analyzed.

Results: From January 2011 to May 2020, 2,519 elective CEAs were entered into the regional database. Of the 2,336 eligible cases (183 excluded due to incomplete data), 38% were for symptomatic (Sx) and 62% for asymptomatic (ASx) carotid disease. Preoperative imaging studies ordered included 56% DUS, 28% CTA, 6% magnetic resonance angiography, and 10% CA. Single imaging studies were used in 56.3% of cases, 2 studies in 40.4%, and >2 studies in 3.3%. A majority of both Sx and ASx patients undergoing elective CEA had only a single preoperative imaging study. ASx patients were more likely to have a single study than Sx patients (P = 0.0054). DUS was the most frequent single study ordered in both Sx and ASx patients, 37.4% and 41.4%, respectively. The trend over time shows a decreasing use of DUS and an increasing use of CTA for both Sx and ASx patients. In 2020, CTA overtook duplex as the most frequently ordered study for Sx patients. The average number of imaging studies per procedure per year for both Sx and ASx patients has not changed substantially at approximately 1.5 studies. In addition, the overall trend shows that although a single preoperative study was more common than 2 or more studies for elective CEA, single studies were more common for ASx patients, whereas the use of 2 or more studies was more common for Sx patients. The overall trend among three different time periods, 2011-2013, 2014-2016, and 2017-2020 shows that for both Sx and ASx patients, the use of single DUS studies has decreased over time (P < 0.001), whereas the use of single CTA studies has increased over time (P < 0.001). The use of CTA varied widely by a study center ranging from 12-53% for Sx and 10.5-75% for ASx patients.

Conclusions: Over the past decade, most patients undergoing elective CEA in the SoCal VOICe had only a single preoperative imaging study with DUS as the most frequent sole study in both Sx and ASx patients. However, as a single study, CTA is becoming more frequently used than DUS. Further investigation into the variation in practice may help standardize imaging prior to CEA and control healthcare costs.