Is Carotid Artery Stenting a Fair Alternative to Carotid Endarterectomy for Symptomatic Carotid Artery Stenosis?

Systematic Review of Guidelines for the Management of Asymptomatic and Symptomatic Carotid Stenosis

BACKGROUND AND PURPOSE

We systematically compared and appraised contemporary guidelines on management of asymptomatic and symptomatic carotid artery stenosis.

METHODS

We systematically searched for guideline recommendations on carotid endarterectomy (CEA) or carotid angioplasty/stenting (CAS) published in any language between January 1, 2008, and January 28, 2015. Only the latest guideline per writing group was selected. Each guideline was analyzed independently by 2 to 6 authors to determine clinical scenarios covered, recommendations given, and scientific evidence used.

RESULTS

Thirty-four eligible guidelines were identified from 23 different regions/countries in 6 languages. Of 28 guidelines with asymptomatic carotid artery stenosis procedural recommendations, 24 (86%) endorsed CEA (recommended it should or may be provided) for ≈50% to 99% average-surgical-risk asymptomatic carotid artery stenosis, 17 (61%) endorsed CAS, 8 (29%) opposed CAS, and 1 (4%) endorsed medical treatment alone. For asymptomatic carotid artery stenosis patients considered high-CEA-risk because of comorbidities, vascular anatomy, or undefined reasons, CAS was endorsed in 13 guidelines (46%). Thirty-one of 33 guidelines (94%) with symptomatic carotid artery stenosis procedural recommendations endorsed CEA for patients with ≈50% to 99% average-CEA-risk symptomatic carotid artery stenosis, 19 (58%) endorsed CAS and 9 (27%) opposed CAS. For high-CEA-risk symptomatic carotid artery stenosis because of comorbidities, vascular anatomy, or undefined reasons, CAS was endorsed in 27 guidelines (82%). Guideline procedural recommendations were based only on results of trials in which patients were randomized 12 to 34 years ago, rarely reflected medical treatment improvements and often understated potential CAS hazards. Qualifying terminology summarizing recommendations or evidence lacked standardization, impeding guideline interpretation, and comparison.

CONCLUSIONS

This systematic review has identified many opportunities to modernize and otherwise improve carotid stenosis management guidelines.

Bias in the use of randomized trials for carotid stenosis management

Background

Carotid artery procedures, such as surgery and stenting, although associated with significant risks and costs, are often recommended in guidelines which cite12- to 34-year-old randomized trial evidence of benefit; however, these recommendations exist although there is no evidence these procedures benefit patients who receive only current optimal medical treatment  (encouragement of a healthy lifestyle and appropriate use of medication).

Objective

To examine whether bias exists in the use of randomized trial evidence and its impact on guideline recommendations.

Material and methods

Examples of how bias underpins endorsement of carotid procedures for patients with asymptomatic or symptomatic carotid stenosis were sought from available literature. .

Results

Many forms of procedural bias were identified involving the need for randomized trials, and their design and interpretation. Fundamental problems included failure to first adequately measure outcomes with non-invasive treatment alone, lack of appreciation of quality non-randomized trial measurements of risk in determining need for randomized trials and their applicability in routine practice, poor randomized trial methods with biased comparisons, inaccurate definitions of target populations, confusion of efficacy and safety outcomes, too much reliance on statistical rather than clinical significance and biased use of terminology to make procedures sound more effective.

Conclusion

Procedural bias in design and interpretation of randomized trials has resulted in widespread loss of understanding of how to optimize outcomes in patients with carotid artery stenosis. Current guidelines reflect the cumulative impact of this bias and are an excellent starting point for efforts to improve prevention of stroke and other vascular disease complications; however, there is also need for clinicians, policy makers, health service funding bodies, educators and the general public to assist.

Why the United States Center for Medicare and Medicaid Services (CMS) should not extend reimbursement indications for carotid artery angioplasty/stenting

In recent years, many important discoveries have been made to challenge current policy, guidelines, and practice regarding how best to prevent stroke associated with atherosclerotic stenosis of the origin of the internal carotid artery. The United States Center for Medicare and Medicaid Services (CMS), for instance, is calling for expert advice as to whether its current policies should be modified. Using a thorough review of literature, 41 leading academic stroke-prevention clinicians from the United States and other countries, have united to advise CMS not to extend current reimbursement indications for carotid angioplasty/stenting (CAS) to patients with asymptomatic carotid stenosis or to patients with symptomatic carotid stenosis considered to be at "low or standard risk from carotid endarterectomy (CEA)." It was concluded that such expansion of reimbursement indications would have disastrous health and economic consequences for the United States and any other country that may follow such inappropriate action. This was an international effort because the experts to best advise CMS are relatively few and scattered around the world. In addition, US health policy, practice, and research have tended to have strong influences on other countries.