Results released from the International Subarachnoid Aneurysm Trial (ISAT) demonstrate that less-invasive endovascular treatment with detachable platinum coils produces better outcomes for patients suffering from ruptured brain aneurysms than neurosurgical clipping. The study showed that the risk of death or significant disability at one year for patients treated endovascularly with coils was 22.6 per cent lower than for those treated neurosurgically with clipping. 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 because the Trial Steering Committee determined it was no longer ethical to randomize patients to neurosurgical clipping.

As the only multi-center, prospective, randomized trial comparing endovascular coiling of ruptured brain aneurysms to neurosurgical clipping, ISAT demonstrated that in patients equally suited for either treatment, coiling provides better outcomes in terms of survival free of disability at one year.

When a brain aneurysm ruptures, blood flows into the space surrounding the brain (the subarachnoid space), 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. Every year it is estimated that more than 30,000 people suffer from ruptured brain aneurysms. Ten to 15 per cent of these patients will die before reaching the hospital. More than 50 per cent will die within the first 30 days after rupture. Of those who survive, approximately half suffer some permanent neurological deficit.

Health care analysts suggest that as many as 75 per cent of patients with brain aneurysms in the United States are currently treated by neurosurgical clipping, which involves performing a craniotomy (removing a section of the skull) and placing a surgical clip at the neck 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.

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 by the Data Monitoring Committee, the Trial Steering Committee halted the trial on May 2 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.

Target is a leading developer of less-invasive medical technologies for endovascular neurosurgery and interventional neuroradiology. It manufactures coils, guidewires and catheters used to treat brain aneurysms. All of the endovascular patients in the study with one-year follow-up were treated using Target's GDC coil.