STEAMBOAT SPRINGS, Colo.—High-risk patients with asymptomatic severe carotid stenosis may be successfully managed medically, delegates at the winter meeting of the Vascular & Endovascular Surgery Society (VESS) held in Steamboat Springs, Colorado, Jan. 30–Feb. 2, were told.
That was the nub of findings delivered by Jeffrey Siracuse, MD, of the division of vascular and endovascular surgery, Boston Medical Center, Boston University School of Medicine, Boston, in a presentation entitled, “Selective non-operative and delayed management of severe asymptomatic carotid artery stenosis.”
“Reasons for non-operative and delayed operative management of severe asymptomatic carotid stenosis were commonly due to comorbidities and advanced age,” Siracuse et al found. “However, a subset of patients was never referred to vascular surgeons or interventionalists. Adverse neurologic events due to carotid stenosis were not observed during follow-up and patients had relatively high long-term survival.”
Randomized controlled trials, such as the Asymptomatic Carotid Stenosis Trial-1 (ACST-1), have shown the benefit of intervention in asymptomatic patients with carotid artery stenosis, Siracuse considered, but patients with a greater degree of stenosis have been shown to benefit more from carotid endarterectomy [CEA] than medical therapy. “However, these data are older and may not reflect the contemporary patient population and modern medical therapy regimens.”
Extrapolating on the background to his research, Siracuse continued with discussion that asymptomatic patients on modern medical therapy have a lower ipsilateral stroke rate compared to historical cohorts. As such, he went on, some providers have advocated for only medical management of asymptomatic carotid disease. But several single-center studies have demonstrated that medical therapy alone may be inadequate given that almost 25% of patients with moderate to severe carotid stenosis develop symptoms.
“Additionally, the threshold of stenosis severity at many centers to treat asymptomatic carotid disease has changed over time.”
The paper on which the talk was based was a single institution retrospective analysis that looked at 35 internal carotid arteries in 35 patients with severe asymptomatic carotid (80–99%) stenosis on duplex ultrasound from 2011–2018 that did not undergo intervention.
“Reasons for no/delayed intervention were classified as severe medical comorbidities (48.6%), no referral for intervention (14.3%), advanced age (11.4%), patient refusal (11.4%), other severe concomitant cerebrovascular disease (8.6%), and active/advanced cancer (5.7%),” they wrote. “Over a median follow-up of 35.2 months, no patients experienced TIAs [transient ischemic attacks]/strokes attributable to carotid stenosis.”
Siracuse and colleagues had set out to assess the reasons for and outcomes of non-operative/delayed operative management of asymptomatic severe carotid stenosis.
They utilized institutional vascular laboratory data from across the eight-year period outlined, looking for all patients who underwent a carotid duplex ultrasonography.
They included patients with severe asymptomatic carotid stenosis (80– 99%), defined “by an end diastolic velocity >140cm/sec on duplex ultrasound in patients without TIA/strokes <six months prior to imaging.” The authors went on to explain that non-operative/delayed operative management was defined as not having undergone CEA or carotid artery stenting (CAS) <six months after imaging. “Reasons for non-operative management or delayed intervention as well as subsequent TIA/stroke and survival were determined.”
Among 225 patients with severe asymptomatic carotid stenosis, 35 (15.5%) were managed non-operatively or with delayed operation. The mean age in this subset was 72.6±11.4 years, with the majority female (57.1%).
Furthermore, the group had a smoking history (74.3%) and were on statins (62.9%) at the time of index duplex ultrasound. “One patient had a multifocal bilateral stroke after a cardiac arrest and prolonged resuscitation,” the authors noted. “No patients developed carotid occlusion. A subset of patients underwent delayed CEA (8.6%) or CAS (2.9%). Four-year survival after initial imaging was 79%.”
The investigators delved into the literature. “Previous studies have looked at those who had delayed intervention after detection of carotid stenosis,” they found. “One single institution study used a more liberal definition (70–99%) and found that 24.6% developed symptoms with 45% of these being strokes.
“The majority developed neurological symptoms within the first year of image detection. This rate is much higher than what we see in our analysis with a longer follow-up time and what has been reported in other asymptomatic patients. Survival in this cohort was 69.8% at five years, similar to our analysis.”
Although they recommended intervention, Siracuse et al pointed out, “preservation of patient autonomy is important, especially since CEA or CAS are prophylactic operations with potentially devastating complications and given disagreement on the best course of action.”
They continued: “Additionally there was a subset of patients who were not referred. It is unclear if these patients had appropriate risk-benefit discussion with their primary care provider, if the results were not followed up on, or if there was a misinterpretation of the results or what the available options were during that time. Concomitant disease was also another reason for delayed referral. These patients with tandem lesions and proximal common carotid disease have been shown to be at high risk for intervention of asymptomatic disease.”
The research team pointed out some of the limitations to study. They included the fact that medication compliance throughout the study could not be determined; carotid duplexes are routinely obtained during follow-up at their institution but patients whose lesions progressed in between scans may not have been captured; and patients who were seen during follow-up without additional duplexes were considered not to have documented progression.
“Additionally,” they noted, “practice varies amongst physicians which may impact treatment and follow-up provided to patients. Plaque detail that could be obtained from MRI [magnetic resonance imaging] was not available for this retrospective study as many of our patients only have duplex as their imaging modality.”
Still, Siracuse et al were convinced that their research produced robust evidence. “Despite these limitations, our study reflects contemporary medical management of patients with asymptomatic severe ICA [internal carotid artery] stenosis,” the researchers noted.