Every Day

May - July 2006 Issue

Carotid Stenting Technology Evolves Quickly

Sam O. Zaidat, MD, MSc

Medical College of Wisconin Neurointerventional Stroke Critical Care Specialist
Director, Neurointerventional Program

The technology behind carotid stenting continues to evolve, opening the doors to better understanding of this relatively new procedure to help reduce the risk of disabling stroke in selected patients. Sam O. Zaidat, MD, describes his latest research, hopeful new developments and whether carotid stenting may one day be a preferred treatment for more patients.

Q. How effective are carotid stents in preventing stroke?

Stenting of the carotid artery is meant to prevent neurological events, namely stroke and transient ischemic attacks (TIA). It is a way to improve brain perfusion and reduce the likelihood of future stroke. It is one means by which we are able to prevent recurrent strokes in patients with significant blockage in their carotid artery. Recent studies showed that carotid stenting is effective in preventing stroke when compared to the open surgical method in a group of patients who are considered high risk to undergo the surgery. But, it is not a 100 percent cure; we are far from achieving that goal. It reduces the likelihood of subsequent strokes and improves the chances of stroke-free survival.

Q. How have carotid stents evolved in recent years?

Carotid stenting is a moving target. Clinically, things are evolving and more and more patients are being treated with carotid stenting. More studies are under way to compare carotid stenting to open surgery in patients who are a candidate for both procedures. Technology is evolving rapidly with filter baskets to protect the patient from any debris traveling up to the brain arteries and allowing us to avoid stroke during the procedure. The use of those protection devices is becoming the standard of care and I routinely use a protection device during carotid stent placement. Specifically designed carotid stents are being used, rather than using stents invented for other arteries in the body. In the earliest procedures, we used renal arteries and biliary stents. The first stents designed specifically for use in carotid arteries were designed in the late 1990s. The technology is still young, and enhancement and improvement in the specification of the carotid stent is happening every day.

Currently, the FDA has approved two specifically designed carotid stents, and both are available at Froedtert and are used in our routine clinical practice.

Q. What research are you currently working on with regard to stents and their use?

At Froedtert we are conducting several parallel clinical and technical studies. We are looking at outcomes on patients older than 80 who underwent the stent procedure and the method to enhance the outcome in this population. We are evaluating the safety and efficacy of carotid stenting in this age group. We are hoping to obtain neuropsychological evaluation before and after stenting to assess for any improvement in cognitive function following carotid artery stenting. We are also assessing the use of blood-thinning medication before and after the procedure to prevent procedure-related complications. We acquired a machine in our catheterization lab where we can assess the effect of aspirin and other blood-thinning medications on blood clotting and adjust those medications accordingly. Our goal is to find out if by making an adjustment we would improve patient outcomes.

Q. Do you have any preliminary findings?

We are waiting to analyze our data on the outcomes in this group of patients and will publish it very soon. From our preliminary results, the use of instant testing of aspirin and other thinning medications may play a role in improving patient outcomes and reducing the incidence of procedure-related strokes.

Q. What do you hope that research will tell you?

We hope to answer questions such as the following:

What is the final verdict on stenting versus surgery in low-risk operative patients? What is the optimum blood-thinning medication that will make the procedure safer, and for how long after the procedure do we need to keep the patients on a certain regimen?
What is the safest carotid stent and filter basket combination in a given patient with a given plaque in the carotid artery?
Will advances in medical therapy for preventing plaque formation or halting the progression of atherosclerosis (hardening in the arteries) make it more challenging for interventional and open surgical therapy to show benefit over future advances in medical conservative therapy?

Q. How will that help in the treatment of younger patients?

In younger patients with carotid disease, we hope to make the best recommendation for them on the best approach for preventing future strokes. Currently, the mainstay for patients with such disease is open surgery — with low surgical complication risk — performed by a surgeon. The comparison of stenting versus surgery in healthy young patients is currently being studied and the data will be available in the next several years. There is one European study that was published that showed equivalency between stenting and surgical endarterectomy in this low surgical population of patients; though there has been some criticism for the study’s method and design.

Q. What do you plan to study next in regard to carotid stenting?

I am focusing on looking into things that would make the procedure safer; intraoperative management; and the best medical management before and after the procedure including controlling blood pressure and lipid and blood thinning agents. Treatment is not over once the stent is placed in the carotid artery.

Q. Where is stenting headed clinically?

I am not sure yet, but with newer technology; the carotid stenting may become safer and safer and may have a significant role. We hope to be able to provide the patient with the benefit of the procedure without its associated risk and complications. Physician judgment and a team approach remain the key to good patient outcomes.

Q. What does the next generation of stents look like?

Changes are constant with carotid stent technology. Newer filters to prevent escape of debris into the brain have been developed and established. Newer, enhanced stents with different shapes and designs are also available, and more research is going into how to prevent or at least lessen procedure related complications.

Q. Are there other applications down the road?

The main indication now is to prevent stroke in those with blocked carotid arteries. Other uses may be implemented in repairing arterial tear after traumatic injury to the carotid artery or to assist in repairing low lying aneurysm in the carotid artery.

Q. What kinds of changes might there be in carotid stents a year from now?

This is a technical/engineering question, but the goal would be to have a stent that creates the least disturbances to the plaque and is therefore less likely to cause strokes.

Q. Will carotid stenting ever become the first choice to treat carotid artery disease in the average patient?

NO. The current answer is no. Carotid stenting is a technology in progress and evolution. Only time and studies will tell the rest of the story. I think the biggest challenge for both surgery and stenting is medical therapy and advances in atherosclerosis prevention and stroke prevention. As we have more efficacious medical agents, it will become harder to show benefit over a non-interventional approach.

Q. Who are the best candidates for carotid stenting?

In summary, the indication is for those with severe stenosis with or without stroke with medical or anatomical/technical contraindication for open surgery. Currently, that includes those with significant heart, lung or kidney diseases. Those with prior surgery on their neck or recurrent stenosis after prior carotid surgery, those with any sort of neck radiation and patients with injured nerves in the neck or hoarseness in their voice, may be a candidate for carotid stent. In addition, patients who may have blockage high up in their neck or low down in the chest where the surgeon may have difficulty in reaching those areas to clean the arteries may also be good candidates for carotid stenting.

Q. What else should people know about carotid stenting?

It is an effective procedure in preventing stroke for those with blocked arteries who are felt to be a candidate by an expert team. It is performed through a needle puncture in the groin artery. It requires, for most patients, an overnight stay in the hospital. Patients need to take a combination of blood-thinning medications before and after the procedure to keep the stent open. Patients may also need to know that experts in performing this procedure may come from different backgrounds. An interventional neurologist is usually a neurologist trained in stroke and neurovascular clinical care and is subsequently trained in performing the carotid stenting and other neurovascular procedures. Other specialists may include endovascular neurosurgeons, vascular surgeons, interventional cardiologists and interventional radiologists.

Source: Every Day

Date: May - July 2006 Issue