Portland, Ore.

International clinical trial halted after compelling results suggest new effective treatment for deadliest form of stroke

Clinical trial results released this week demonstrate that a less invasive surgical approach to the deadliest form of stroke leads to better outcomes than the current more invasive standard treatment. The results of the International Subarachnoid Aneurysm Trial (ISAT) will be published in the medical journal The Lancet on Oct. 26. The study demonstrated that less invasive endovascular treatment using detachable platinum coils produces better outcomes for patients suffering from ruptured brain aneurysms than more invasive neurosurgical clipping. The study showed that the risk of death or significant disability for patients treated endovascularly with coils was 22.6 percent lower than for those treated neurosurgically with clipping after one year. Results from interim analysis of the data was so compelling that the trial was halted early after enrolling 2,143 of the planned 2,500 patients. The trial's steering committee determined it was no longer ethical to randomize patients to neurosurgical clipping.

When a brain aneurysm ruptures, blood flows into the space surrounding the brain resulting in a subarachnoid hemorrhage, the deadliest form of stroke. In the United States it is estimated that as many as 18 million people will develop a brain aneurysm during their lifetime. Health care analysts suggest that as many as 75 percent of patients with brain aneurysms are currently treated by neurosurgical clipping, where a surgical clip is placed at the base of the aneurysm.

Endovascular treatment, which was introduced in the early 1990s, involves insertion of a catheter into the femoral artery in the patient's leg and navigating it through the vascular system, under X-ray guidance, into the head and into the aneurysm. Tiny platinum coils are then threaded through the catheter and deployed into the aneurysm, obstructing blood flow into the aneurysm and preventing further damage.

Oregon Health & Science University (OHSU) is one of a handful of institutions across the country that offer aneurysm treatment using endovascular coils. During the past decade, approximately 350 OHSU Hospital patients have had coils implanted for the treatment of their aneurysms. In fact, OHSU took part in clinical trials prior to ISAT, investigating the efficacy of endovascular coils for the treatment of aneurysms.

"Currently, the standard of treatment for a burst aneurysm is neurosurgical clipping. While this procedure is effective, it involves a craniotomy, or temporary removal of a section of the skull, which often results in longer recuperation periods," said Stanley L. Barnwell, M.D., Ph.D., associate professor of neurological surgery, and diagnostic and interventional radiology in the OHSU School of Medicine. "By comparison, coils are less invasive, hospital stays are typically reduced and as these new study results show patient outcomes are significantly better."

Thanks to endovascular coiling, Helen Gross' life is back to normal. Physicians detected an unruptured brain aneurysm in the 45-year-old St. Helens woman following an MRI she received for an unrelated health matter.

"The doctors told me I was a perfect candidate for coiling due to the size of my aneurysm, its location, my age and other factors," she said. "Following surgery, my hospital stay lasted only one day, and within two weeks I was back at work."

Three months following her surgery, Gross rarely thinks about her aneurysm. She occasionally has follow-up visits at OHSU to confirm the success of her treatment.

"We believe the results of this trial will have a significant impact on patient care", said Gary M. Nesbit, M.D., an associate professor of diagnostic and interventional neuroradiology in the OHSU School of Medicine. "More than 30,000 people suffer from ruptured brain aneurysms each year in the United States, of those 30 percent die with another 30 percent disabled. If we can treat these patients and treat those with aneurysms found incidentally on MRI or CT with less risk, this will be significant."

"This study was designed to provide results that will help guide physician practice," said Richard Kerr, M.D., neurosurgical principal investigator of ISAT and a consultant neurosurgeon with the Department of Neurosurgery at the Radcliffe Infirmary in Oxford, England. "Patients had to be suitable for both treatments to be included in the trial, and once in the trial, patients were systematically randomized so that the two treatment arms were comparable in terms of age, gender, patient condition and aneurysm location. For patients with ruptured brain aneurysms suitable for both treatments, endovascular coiling is significantly more likely to leave patients alive and free of disability. However, as in any study, long-term follow-up will be essential to evaluate the substantial early advantage of endovascular coil treatment."

Funded by the Medical Research Council of Great Britain in 1997, ISAT systematically compared endovascular coiling to neurosurgical clipping. Forty-three neurosurgical centers in Europe, North America and Australia participated, enrolling patients who were deemed suitable for either treatment.

The study's primary objective was to determine whether endovascular coiling reduces the number of patients with poor outcomes compared to neurosurgical clipping. Following a planned interim review, the study was halted on May 2, 2002 because the difference in outcomes between the two procedures was so great that it was no longer deemed ethical to randomize patients to neurosurgical clipping.

"This landmark trial clearly demonstrates that all patients with ruptured brain aneurysms should be thoroughly evaluated for endovascular coiling," said Jim Feenstra, president of Boston Scientific's Target division, which manufactures coils, guidewires and catheters used to treat brain aneurysms. "Although Boston Scientific has helped to introduce endovascular coiling to more than 300 major medical centers in the United States, fewer than 25 percent of ruptured brain aneurysm patients are admitted to hospitals where endovascular coiling is available. The ISAT findings suggest that when medically possible, all ruptured brain aneurysm patients should be transferred to -- and treated primarily at -- hospitals that provide both therapeutic options."

About Boston Scientific:
Boston Scientific (NYSE: BSX) is a worldwide developer, manufacturer and marketer of medical devices whose products are used in a broad range of interventional medical specialties.

This press release contains forward-looking statements. The company wishes to caution the reader of this press release that actual results may differ from those discussed in the forward-looking statements and may be adversely affected by, among other things, risks associated with clinical trials, the regulatory approval process, reimbursement policies, competitive offerings, physician preference, intellectual property, commercialization of new technologies and other factors described in the company's filings with the Securities and Exchange Commission:

ADDITIONAL CONTACTS:
Media Relations
Boston Scientific Corporation

Sheila Rasu/Jill Hoffman
FischerHealth, Inc.
310 577-7870, ext. 151/113
srasu@fischerhealth.com
 

After-hours contacts:
Sheila Rasu 213 447-0987
Jill Hoffman 310 738-1212
jhoffman@fischerhealth.com

PARTICULARS:
Stanley L. Barnwell, M.D., Ph.D., associate professor of neurological surgery, and diagnostic and interventional radiology in the OHSU School of Medicine and the Dotter Interventional Institute at OHSU; neurointerventional director of the Stroke Treatment Program in the Oregon Stroke Center at OHSU

Gary M. Nesbit, M.D., associate professor of diagnostic and interventional neuroradiology in the OHSU School of Medicine and the Dotter Interventional Institute at OHSU

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