Michelle Christina Johansen, MD

Choi JC, Johnston SC, and Kim AS. Early Outcomes After Carotid Artery Stenting Compared With Endarterectomy for Asymptomatic Carotid Stenosis. Stroke. 2014

The number of patients referred for evaluation of asymptomatic carotid artery stenosis will only increase as imaging technology improves and the population ages over the ensuing decades. The number 70%, signifying severe stenosis and warranting intervention, has been indelibly etched in the mind of neurologists. But what about the patients who are symptom free? Are their stenosed vessels ticking time bombs? And if a procedure is chosen which should be given preference, a stent or open surgery?

Choi et al attempt to shine additional light on an already hotly debated topic. The investigators used multivariable logistic regression, propensity score matching and a grouped-treatment approach (with adjustments for baseline characteristics) to compare in-hospital death and postoperative stroke after either carotid artery stenting (CAS) or carotid endarterectomy (CEA). A cohort of 17,716 patients with asymptomatic carotid stenosis treated with CEA and 3,962 patients treated with CAS at 186 different academic medical centers which participate in the University Health System Consortium were reviewed. The patients were identified using ICD 9 codes between the years 2010-2012. Patient information, such as demographics, was obtained from the medical record. They examined the annual volume of both CAS and CEA at each hospital as well as the volume and outcomes of patients undergoing each procedure per physician. The primary outcome was defined as a composite of postoperative stroke or in-hospital death with secondary outcome including any postoperative stroke, myocardial infarction (MI) or in-hospital death. They also looked at 30 day readmission data.

Initial unadjusted analysis showed that the primary outcome was more frequent after CAS than after CEA (4% vs 1.5% p<0.001). Even when considered separately, stroke, 30 day readmission for stroke and in-hospital mortality were all significantly more frequent in CAS patients. There was no difference however in the occurrence of postoperative MI. Even after adjusting for demographics and comorbidity (age, sex, race, hypertension, coronary artery disease, atrial fibrillation, peripheral artery disease, smoking status, congestive heart failure, hyperlipidemia, diabetes mellitus, chronic kidney or lung disease) the primary outcome remained significantly higher in the stented patients (OR 2.5; 99% CI 2.1-3.1; p<0.001). When using a multilevel mixed-effects model, the investigators found that hospitals which perform a higher proportion of revascularization procedures using CAS have significantly higher postoperative stroke or in-hospital death rates even after adjusting for demographics and the comorbidities listed above.

The authors conclude that CAS is associated with more than a two-fold greater risk of postoperative stroke or death than CEA even after adjusting for all baseline characteristics. So are we to conclude that all patients with high grade asymptomatic carotid stenosis should be referred for an endarectomy?

The question remains as appropriately posed by the author: Is invasive intervention of any kind warranted in these patients? The stroke risk in patients with asymptomatic carotid stenosis varies in the literature but has been documented around 1-3% with higher rates cited with increasing degrees of stenosis. As shown above, the risk in undergoing either a stenting procedure or an endarterectomy is not insignificant. Another important consideration is that our medical management only continues to improve, i.e., with continually evolving antiplatelet, antihypertensive and lipid lowering drugs, one wonders if there is indeed any role for intervention in patients who are truly asymptomatic. Some literature has cited a stroke rate as low as 1% per year if intensive medical therapy is used among those with asymptomatic carotid stenosis. In light of the results of Choi et al, the need for new studies (CREST-2) becomes even more apparent as physicians strive to “do no harm” especially in patients who are symptom free.