RSNA News - March 2005

New Stroke Prevention Therapy as Effective as Invasive Surgery

It's essential that only experienced interventional experts perform these procedures.
—Gianluca Piccoli, M.D.

New research demonstrates two important radiographic findings about stroke. In one study, angioplasty and stenting were found to be as successful as surgery in treating carotid stenosis. In a second study, gender differences were found in carotid stenosis response and treatment.

Angioplasty and Stenting

Gianluca Piccoli, M.D.

Santa Maria della Misericordia Hospital, Udine, Italy

Gianluca Piccoli, M.D., an interventional radiologist at the Santa Maria della Misericordia Hospital of Udine in Italy, presented the findings of his study at RSNA 2004.

Directed by Daniele Gasparini, M.D., the researchers studied 222 patients with carotid artery disease who underwent angioplasty and stenting. They found that these patients had a lower rate of complication and approximately the same outcome as patients who underwent the more invasive carotid endarterectomy.

The accumulation of plaque in the carotid artery can lead to stroke either by decreasing the blood flow to the brain or by having plaque break free and lodge in arteries supplying the brain or other areas of the head. The American Stroke Association reports that stroke is the third leading cause of death in the United States behind heart disease and cancer. Stroke is also a leading cause of serious, long-term disability with an estimated direct and indirect cost of $53.6 billion in 2004.

In August 2004, the FDA approved the first carotid stenting system for use in the United States. A second system is under review.

Dr. Piccoli said use of a protective filter is essential for reducing the risk of embolization.

"Although the filter is static, the carotid artery changes diameter so the filter cannot protect the entire diameter of the carotid but probably can transform a major stroke or fatal stroke to a minor stroke," he said. In surgery they usually clamp the carotid artery to prevent embolization, but this is a problem because you see ischemia in the lateral part of the brain because you have no flow during the intervention."

Dr. Piccoli's study showed that patients who underwent carotid angioplasty and stenting had a lower rate of acute complications (2.2 percent) than those undergoing surgery (3.0 percent). Six months later, his team found the angioplasty/stenting group had a four percent rate of restenosis, which is about the same as patients treated with surgery.

Because the procedure is relatively new, Dr. Piccoli stressed the importance of a multidisciplinary approach. "It's essential that only experienced interventional experts perform these procedures," he explained. "Radiology needs to work with angiology and neurology to help quickly recognize a complication and focus medical therapy."

The cost of the materials used in carotid angioplasty and stenting is high, but the overall price of the procedure is similar to surgery once the cost of an operating room and a longer hospital stay are included. Dr. Piccoli pointed out the advantages of the less invasive procedure, including shorter hospital stays, use of local anesthesia and no need for an incision in the neck.

He said his results are encouraging and demonstrate a need for further, randomized tests. "I think our results are in line with bigger studies," he said. "Our research is going forward and, in 2005, we hope to present more data and have more information about the patients we discussed today."

ACT I Trial

Patient enrollment is expected to begin early this year in a separate study—the asymptomatic carotid trial (ACT I). The multicenter, randomized trial will compare carotid artery stenting to carotid artery surgery in asymptomatic patients. It will involve up to 50 hospitals and as many as 1,500 patients in the United States.

Carotid Artery Disease in Men vs. Women

Meanwhile, research presented at the recent Annual International Symposium on Endovascular Therapy (ISET) in Miami Beach, Fla., showed that carotid artery disease in men should be treated differently than carotid artery disease in women.

Anthony Comerota, M.D., director of the Jobst Vascular Center in Toledo, Ohio, said that blood flow velocities in the carotid arteries of women are generally about nine percent higher than they are in men.

"For stenoses above 50 percent, the difference was 15 percent increased velocity in women compared to men," explained Dr. Comerota, who is also a clinical professor of surgery at the University of Michigan, Ann Arbor. "This means that women naturally have higher blood flow velocities in their carotid arteries than men do, so we ought to recognize this and revise our diagnostic standards. If we use the same standards, we'll be over-diagnosing disease in women. Many people undergo surgery based on the non-invasive test alone, so you can see how important this becomes."

He added that at his clinic, they generally treat carotid disease when the carotid duplex shows a 50-percent stenosis in symptomatic patients and an 80-percent stenosis in asymptomatic patients.

"It's important to realize that the diagnostic criteria were established in patient populations in which women were underrepresented, such as patients at the Veterans Administration and in university hospitals with predominantly male populations," he explained.

Some of the differences that have been found in men and women include:

• At any age, the risk for stroke is greater in men than in women
• At similar degrees of carotid stenosis, the risk for stroke is higher in men than in women
• After carotid endarterectomy, the risk for stroke is higher in women with asymptomatic disease than in men with asymptomatic disease
• After carotid endarterectomy, women have a higher incidence of carotid restenosis than do men

Dr. Comerota said the data add even further weight to the evidence that non-invasive velocity criteria should be adjusted in women to more accurately reflect the underlying disease and offer a better fit with their risk for carotid atherosclerosis as well as the risks and benefits of intervention.

Cautious Reaction from Interventional Radiology

Barry T. Katzen, M.D.

Baptist Cardiac & Vascular Institute, Miami

Barry T. Katzen, M.D., an interventional radiologist who was the program director for ISET, said radiologists should be aware of the information but the results need to be confirmed by a prospective study. "I think it would be premature to start recalibrating our duplex criteria before this study is confirmed. It was a retrospective study with different qualities of angiography over a 10-year period, and the ability to correlate that with high-quality imaging is not the same as if you did a prospective study today," he said.

"When you see a woman with increased velocities, you definitely want to make sure she's in a critical category before you do anything," said Dr. Katzen, the founder and medical director of the Baptist Cardiac & Vascular Institute in Miami. "It's probably not reasonable to treat asymptomatic women in the 60 to 80 percent occlusion range, and it's even more imperative that we wait until they get to that critical category of over 80 percent. I do think there's enough in all of this that we should increase the baseline on which we operate on asymptomatic women, but we need to be very cautious about raising the bar on which women we treat."

Tight atherosclerotic stenosis imaged with 3D volume-rendered CT, 2D CT MIP image and digital subtraction angiography.

The Piccoli story was adapted from an article that appeared in the RSNA 2004 Daily Bulletin.