3.3 Carotid Artery Intervention: Comparative Outcomes of Micromesh Stents and TCAR and Are They Better Than CEA?

These proceedings summarize the educational activity of the 17th Biennial Meeting of the International Andreas Gruentzig Society held January 30 to February 2, 2024 in Chiang Rai, Thailand.

Faculty Disclosures     Vendor Acknowledgments

2024 IAGS Summary Document

Statement of the problem or issue

Stroke incidence and the number of stroke-affected patients will increase over the next 20 years. Medical therapies alone are not sufficient to reduce the risk of stroke in patients with carotid artery stenosis. The difficulty with medical therapies is: (1) the efficacy or “strength” of pharmacologic agents is low; (2) patient compliance is suboptimal. Carotid artery revascularization is and will be needed to reduce the risk of carotid-related stroke in many patients with carotid artery stenosis. Risk stratification tools are here today to help identify the patients who may need carotid revascularization – and they are improving.

The surgical approach to revascularization, carotid endarterectomy (CEA), removes the atherosclerotic plaque material. With carotid artery stenting (CAS), the concept is to stabilize the plaque. Ideally, we would like to totally isolate the plaque with CAS to achieve an effect similar to vascular surgery. The first generation of stents consisted of a single layer. Those stents had a “cheese grater” effect that allowed atherosclerotic debris to “squeeze through.” Today we have second generation dual layer carotid stents called micromesh stents, which have documented anti-embolic effects (Figure 1).

Figure 1. Micromesh dual layer carotid artery stent.

Additionally, there is a hybrid strategy called transcarotid artery revascularization (TCAR). In this approach, there is surgical exposure of the common carotid artery for access, followed by catheter-based stent delivery. It is an evolving technique that is likely to lead to safer carotid artery revascularization in the future.

Gaps in current knowledge

Carotid artery stent trials have not been designed well. Historical trial data, dating from 15 to 20 years ago, are of no value today. An analysis of earlier trials and registries found that more comorbid patients, as well as symptomatic and medically high-risk patients, were treated with CAS rather than CEA, leading to large differences in outcomes that were unfavorable to CAS.^1,2 We do not have a randomized trial powered for clinical endpoints; not a single one. With adverse event rates at approximately 1%, an adequately powered trial would require thousands of patients. Furthermore, it would be enormously expensive.

Possible solutions and future directions

The CARMEN collaborators recently performed a large meta-analysis of contemporary trials and studies of CAS that employed second generation (micromesh) carotid stents, comparing clinical outcomes to a large cohort of patients undergoing CEA during the same time frame.³ There were approximately 103,000 CAS patients and 95,000 CEA patients included. Clinical outcomes are shown in Figure 2. The results were very favorable for CAS. The future is hopeful.

Figure 2. Forest plots of clinical outcomes of CAS and CEA in the CARMEN collaborators meta-analysis. From: J Cardiovasc Surg (Torino). 2023;64(6):570-582.

References

1. Gaba KA, Halliday A, Bulbulia R, Chana P. Procedural risks of carotid intervention in 19,000 patients. Ann Vasc Surg. 2021;70:326-331. doi: 10.1016/j.avsg.2020.06.030 PMID: 38385840
2. Columbo JA, Stone DH, Martinez-Camblor P, et al. Adoption and diffusion of transcarotid artery revascularization in contemporary practice. Circ Cardiovasc Interv. 2023;16(9):e012805. doi: 10.1161/CIRCINTERVENTIONS.122.012805 PMID: 37725675
3. Mazurek A, Malinowski K, Sirignano P, et al (CARMEN) Collaborators. Carotid artery revascularization using second generation stents versus surgery: a meta-analysis of clinical outcomes. J Cardiovasc Surg (Torino). 2023;64(6):570-582. doi: 10.23736/S0021-9509.24.12933-3 PMID: 32599106