Why is this study important?

Transfemoral carotid artery stenting (CAS) has been performed for over 30 years, but clinical equipoise has remained regarding the benefit of carotid stenting for the prevention of stroke in asymptomatic patients. Contemporary questions have arisen regarding the perceived improvement in medical therapy, further reducing the additional benefits of stenting as well as the safety of carotid stenting in broader clinical practice.

What question did the study seek to answer?

The two concurrent randomized multicenter observer-controlled trials. 1,555 sites, 5 countries. 2,485 patients randomized. All had > 70% carotid stenosis. Had excellent medical therapy. Exclusion criteria were standard of care. Operators were evaluated for competence. 45% of the CAS operators were interventional cardiologists. Only 14% of operators who applied were rejected. 70-80% of patients were at goal for medical management. Periprocedural stroke and death 1.3%. Only 7 actual periprocedural strokes. Carotid stenting added to medical therapy reached statistical significance for benefit. Stroke risk went from 1.7% to 0.4%, and it was positive across subgroups. The NNT at 4 years 31 patients. PCSK9 requires treating 90. If curves are divergent and continue to diverge further, your NNT will be even lower. Emphasize this is transferable to general practice. Experience issue is big point. Of the trial operators, only about 20% were “very experienced”. Unique in that it had two control groups.

Trial Design: Unique design with two concurrent randomized multicenter trials: CAS vs medical therapy and carotid endarterectomy (CEA vs. medical therapy). 1555 sites, 5 countries. 2485 patients randomized. All had > 70% carotid stenosis. Aggressive medical therapy with medications provided, compliance monitoring and lifestyle coaching by a third party. Operators were required to demonstrate competence as adjudicated by a selection committee, but were not required to have extensive experience. Minimum prior case volume was 3. 86% of operators who applied were accepted.

What did the study show?

Results: CAS significantly reduced the incidence of stroke. Absolute risk difference = 3.2% (95% CI, 0.6 to 5.9) p=0.016. Relative risk = 2.13 (95% CI, 1.15 to 4.39). Annual Stroke risk post-procedure reduced with CAS from 1.7% to 0.4%, a 75% Reduction. Excellent medical therapy with ~70-80% of patients at the target for risk factor control by the end of the study. Periprocedural stroke rate with CAS was 1.1%. The CEA trial showed a trend to benefit, but was not statistically significant.

Perspective: The NNT at 4 years 31 patients. PCSK9 requires treating 90. If the curves continue to diverge as expected, the NNT will continue to go down. The trial speaks to two of the common critiques of carotid stenting: that it does not add to contemporary excellent medical therapy and that it requires highly experienced operators. It was also notable that interventional cardiologists were the most highly represented specialty among enrolling physicians at 45%. The trial shows that CAS is effective, safe and accessible for patients with asymptomatic carotid artery stenosis >70%.