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INTRODUCTION: Since the time of the Asymptomatic Carotid Artery Stenosis (ACAS) trial, medical management of carotid stenosis has improved significantly. With the widespread use of antiplatelet agents and statins, it is no longer clear that patients with 60% internal carotid artery (ICA) stenosis will benefit from carotid endarterectomy (CEA). The Vascular Quality Initiative registry has shown that there are wide practice variations across the country regarding the degree of stenosis that prompts consideration for surgical intervention. Despite being in the stroke belt, the surgeons in the Carolinas region have a very high threshold for offering CEA. We sought to determine the clinical outcomes of the >60% carotid stenosis patients who are treated with medical management alone.
METHODS: We identified all patients with ICA stenosis >60% based on hemodynamic criteria in our peripheral vascular lab from January 2013 through December 2014. Based on previous evaluations performed at our institution to correlate duplex derived velocities and carotid angiogram derived carotid stenosis, we use an ICA end diastolic velocity of 110 cm/sec as our definition of > 60% ICA stenosis. With retrospective chart review, demographics, comorbid conditions, medications, relevant radiographic studies, clinical follow up, interventions, and outcomes through July 2016 were all recorded. Descriptive statistics were used to define these variables. Medical management and surgical management groups were compared with Fisher’s exact test.
RESULTS: From January 2013 to December 2014, 169 patients (203 carotids) were identified with >60% ICA stenosis based on hemodynamic criteria on duplex ultrasound. The mean age was 66 years, 49% were male, and 78% were white. 97% were taking aspirin, 89% were taking a statin, and 51% had hypertension controlled to <140/90. Approximately half (87 patients) underwent carotid endarterectomy or carotid stenting and had mean peak systolic/end diastolic velocity (PSV/EDV) 402/163. The other half (82 patients) were managed medically and had a mean PSV/EDV 410/152.
The patients that underwent surgical intervention experienced far fewer cerebrovascular events (2% vs 13%, p = .008). The odds of having an ipsilateral stroke is 6.52 times higher with medical management alone.
CONCLUSIONS: Despite good adherence to current recommendations for maximal medical therapy, many patients are developing symptomatic carotid disease and have a risk of stroke similar to that reported in ACAS. This data supports the concept that changes in medical management since the ACAS trial have not resulted in reduced stroke rates in asymptomatic patients with high-grade carotid stenosis managed medically. CEA provides significant risk reduction and should be considered more often in this patient population.

Table 1. Occurrence of stroke in surgically vs medically managed severe carotid stenosis

	Surgical (n=87)	Medical (n=82)	p-value
Stroke, n (%)	2 (2.3%)	11 (13.4%)	0.008
No stroke, n (%)	85 (97.7%)	71 (86.6%)	--