Landmark Brain Aneurysm Trial Finds Better Patient Outcomes with Endovascular Coiling

MOUNTAIN VIEW, CA, Oct. 30– Compelling evidence from the International Subarachnoid Aneurysm Trial (ISAT) demonstrates that minimally invasive endovascular coiling produces better overall outcomes for patients suffering from ruptured brain aneurysms than neurosurgical clipping. The study, published October 26, 2002 in The Lancet, indicates that the risk of death or significant disability at one year for patients treated with endovascular coils was 22.6 percent lower than for those treated with the neurosurgical clipping option. The trial was halted early after enrolling 2,143 of the expected 2,500 patients because the independent data monitoring committee found that the evidence was significantly in favor of endovascular coiling.

ISAT is the first and only multi-center, prospective, randomized trial that has compared endovascular coiling of ruptured brain aneurysms to neurosurgical clipping. In this study, patients eligible for either treatment were randomized to have endovascular coiling or neurosurgical clipping. The first patient was enrolled in 1994, with the majority of patients enrolled from 1997 to May 2002, when the trial was halted. ISAT involved 2,143 patients enrolled at 43 centers in Europe, North America and Australia, and was headed by Dr. Andrew Molyneux, a consultant neuroradiologist and Mr. Richard Kerr, a consultant neurosurgeon, both at the Radcliffe Infirmary in Oxford, England. An aneurysm is a "bulge" or weakening in the artery wall. If this "bulge" ruptures, blood flows into the space surrounding the brain, resulting in a subarachnoid hemorrhage. Every year between 6 and 8 people out of 1000 will suffer a subarachnoid hemorrhage.

In traditional neurosurgical clipping, a metal clip is placed at the base of the aneurysm to stop the bleeding into the brain. This is performed through a craniotomy, or an opening through the skull into the brain. In the minimally invasive endovascular procedure, a small opening is made in the patient’s femoral artery, which is located in the groin area. A small catheter under x-ray guidance is guided up the leg and into the brain, where small platinum coils are placed in the aneurysm to keep the aneurysm from bleeding into the brain.

"This trial has produced a groundbreaking result that will change medical practice", Dr. Molyneux recently told The Lancet. "While it is important to make clear that there will be some patients for whom surgery is still the most appropriate treatment, coiling should be suitable for 8 out of 10 people who suffer an subarachnoid hemorrhage from an aneurysm".
Mr. Kerr added that what the results mean for patients in the future is "potentially, out of every 100 patients treated around seven could expect to be better off one year on if they received endovascular treatment rather than conventional surgery. For many patients this could mean the difference between a return to normal life or substantial disability."

"For the first time, we have clear and objective evidence that endovascular coiling is an option that should be considered for all patients with ruptured brain aneurysm", said Michel Mounier, President and CEO of Micrus Endovascular. "Whereas the vast majority of patients still undergo the potentially more traumatic craniotomy, the ISAT results support the notion that both possibilities should be made available and evaluated on a case by case basis at the treatment centers, with the final decision made on the basis of all available knowledge".

While the Lancet article on ISAT reflects survival and disability data, additional data on cost effectiveness, quality of life, neuropsychological, angiographic findings, and rebleed rates are still being collected and analyzed for release in 2003. In order to continue evaluating the long-term follow-up data, the Medical Research Council of Great Britain has granted funding for ISAT through 2007.

The Micrus MicroCoil System, designed and manufactured by Micrus Endovascular, was approved for and included in the ISAT trial. Micrus Endovascular, with offices in Mountain View, CA, and Yverdon, Switzerland, is a worldwide company that develops, manufactures and markets medical devices used in the field of interventional neuroradiology.

This press release contains forward-looking statements. Micrus Endovascular 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.