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National Variation in Preoperative Imaging, Duplex Ultrasound Criteria, and Intervention Threshold for Asymptomatic Carotid Artery Stenosis
Edward J. Arous, MD1, Jessica P. Simons, MD MPH1, Julie M. Flahive, MS1, Adam W. Beck, MD2, David H. Stone, MD3, Andrew W. Hoel, MD4, Louis M. Messina, MD1, Andres Schanzer, MD1.
1University of Massachusetts Medical School, Worcester, MA, USA, 2University of Florida College of Medicine, Gainesville, FL, USA, 3Dartmouth Hitchcock Medical Center, Hanover, NH, USA, 4Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
Objective
Carotid endarterectomy (CEA) for asymptomatic carotid stenosis is among the most common procedures performed in the United States. However, there is lack of consensus regarding optimal preoperative imaging, carotid duplex ultrasound criteria, and ultimately, threshold for surgery. We sought to identify national variation in preoperative imaging, duplex ultrasound criteria, and surgical intervention threshold for asymptomatic CEA.
Methods
The Society for Vascular Surgery Vascular Quality Initiative (VQI) database was used to identify all CEA procedures performed for asymptomatic carotid artery stenosis between 2003 and 2014. VQI currently captures 100% of CEA procedures performed at over 270 centers by over 2,000 physicians nationwide. Three analyses were performed to quantify the variation in 1) preoperative imaging modality, 2) duplex ultrasound criteria, and 3) degree of stenosis threshold used for CEA.
Results
Of 35,695 CEA procedures in 33,488 patients, 19,610 (55%) were performed for asymptomatic disease. The preoperative imaging modality varied widely with 53% of patients receiving a single imaging study (Duplex Ultrasound 41%, CT-Angiography 8.3%, MR-Angiography 2.5%, Cerebral Angiography 1.1%) and 47% receiving multiple preoperative imaging studies. Of the 16,997 (87%) asymptomatic patients who underwent a preoperative duplex ultrasound, there was significant variability between centers in the degree of stenosis (50-69%, 70-79%, 80-99%) designated for a given peak systolic velocity, end diastolic velocity, and ICA:CCA ratio. While the majority of asymptomatic CEA procedures were performed for an 80-99% stenosis (68% of patients), 26% were for a 70-79% stenosis, and 4.1% were for a 50-69% stenosis. At the center level, institutions range in the percent of CEA procedures performed for a <80% asymptomatic carotid artery stenosis from 2.8% to 86%. At the surgeon level, surgeons range in the percent of CEA procedures performed for a <80% asymptomatic carotid artery stenosis from 0.6% to 88%.
Conclusion
Despite CEA being an extremely common procedure, there is widespread variation in the three primary determinants - preoperative imaging, duplex ultrasound criteria, and treatment threshold - of whether CEA is performed for asymptomatic carotid stenosis. The observed variation likely has significant downstream effects that influence health care quality and health care costs, which may be improved with increased standardization of care.
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