What's the safer procedure with better outcomes for an aneurysm patient? Is the best treatment with coil embolization or standard surgical clipping?

That question was the driving force behind Boston Scientific's (Natick, Massachusetts) ISAT clinical trial. Yesterday, Boston Sci released results from the multicenter, prospective, randomized controlled clinical trial. Results were published in the most recent issue of The Lancet Neurology.

Patients were primarily treated with the early generation of Boston Scientific's Guglielmi Detachable Coils; some as far back as 14 years when technology, angiographic imaging equipment and physician experience differed significantly from today. The coils are bare-platinum and detachable according to the company.

Results show that patients with a ruptured intracranial aneurysm treated with endovascular coil embolization are 23% less likely to die within five years compared to patients who undergo surgical clipping.

The study specifically looked at 2,143 patients with ruptured intracranial aneurysms who were enrolled between 1994 and 2002 at 43 neurosurgical centers.

The findings were reported by Andrew Molyneux, MD, and Richard Kerr, MD, from the Neurovascular and Neuroradiology Research Unit of the John Radcliffe Hospital and the University of Oxford (both Oxford, UK). ISAT data assessed the risk of death and re-bleeding after treatment in more than 2,000 patients with a mean follow-up of nine years.

At five years post-treatment, 14% of surgically clipped patients had died compared to 11% of patients treated with endovascular coiling, representing a 23% relative reduction in risk of death for coiled patients. The percentage of patients characterized as independent in their daily activities at five years post-treatment was similar for both groups (82% for coiling vs. 81% for clipping).

Nearly 24 rebleeds had occurred more than 1 year after treatment. Of these, a little more than half were from the treated aneurysm. There were 8,447 person-years of follow-up in the coiling group and 8,177 person-years of follow-up in the clipping group. Four rebleeds occurred from a pre-existing aneurysm and six from new aneurysms.

At 5 years, 11% (112 of 1,046) of the patients in the endovascular group and 14% (144 of 1,041) of the patients in the neurosurgical group had died. The risk of death at 5 years was significantly lower in the coiling group than in the clipping group, but the proportion of survivors at 5 years who were independent did not differ between the two groups: endovascular 83% (626 of 755) and neurosurgical 82% (584 of 713). The standardized mortality rate, conditional on survival at 1 year, was increased for patients treated for ruptured aneurysms compared with the general population.

"The recently published ISAT data are reassuring to both patients and physicians," said Molyneux.

"The risk of late bleeding from a coiled aneurysm is very low, which has been a clinically unanswered question in the medical community. Although there was a slightly greater chance of re-bleeding from a coiled aneurysm in the first five years, fewer coiled patients died at five years, and there have been no observed hemorrhages from a coiled aneurysm in these patients after five years," Molyneux said.

The primary objective of ISAT was to determine whether endovascular treatment reduced the rates of patient death or dependency at one year compared with surgical treatment.

Endovascular coiling is a minimally invasive procedure in which tiny, platinum coils are inserted via catheter through the blood vessels into the aneurysm to prevent further bleeding into the brain. Surgical clipping is an open intervention involving a significantly longer recovery time, in which a small clip is placed across the aneurysm.

At press time, Boston Scientific could not be directly reached for comment by Medical Device Daily regarding the trial and its outcomes.