Risk of death at 5 years is lower, but bleeding risk slightly higher

March 27, 2009

Long-term follow-up of the International Subarachnoid Aneurysm Trial (ISAT)* has shown that patients whose aneurysms are coiled rather than clipped are less likely to die within five years. There is a small risk of rebleeding in both groups, with the risk slightly higher for coiled aneurysms in the first five years. The findings are reported in an Article published Online First and in the May edition of The Lancet Neurology, written by Dr Andrew Molyneux and Richard Kerr, Neurovascular and Neuroradiology Research Unit, John Radcliffe Hospital, Oxford, and University of Oxford, UK, and colleagues.

The original ISAT trial looked at 2143 patients with subarachnoid aneurysm** recruited between 1994 and 2002 at 43 neurosurgical centres, who were randomly assigned to clipping (an open surgical intervention in which the aneurysm is clipped) or coiling (an endovascular intervention where a coil is inserted through the blood vessels into the aneurysm in the brain to seal the place where the leak has occurred). In a previous report they had shown that patients who had coiling were more likely to be alive and fully independent at one year, with a reduction in the risk of death or dependence of 24%. In this new study, the researchers analysed just over 2000 of these patients who have been followed up for a mean of nine years (minimum six, maximum 14).

They found that a total of 24 rebleeds had occurred more than 1 year after treatment, during more than 16000 patient-years of follow-up. Of these, 13 were from the treated aneurysm (10 coiled, three clipped). Four rebleeds occurred from pre-existing but different aneurysms and six from new aneurysms, while one was of unknown origin. At five years, 11% of the coiled group and 14% of the clipped group had died -- with the relative risk of death 23% lower for patients whose aneurysms were coiled rather than clipped. However, of those who were alive at five years the proportion who were independent in their daily activities was similar in the two groups (82% coiled vs 81% clipped). Overall, patients who had had either treatment and had survived one year still had a 57% increased risk of death compared with the general population.

The authors conclude: "For patients with suitable aneurysms, coiling is more likely than clipping to result in improved clinical outcomes at one year, and these data suggest that although the early clinical benefits are reduced over time, they are not lost over the subsequent four years.

"The ISAT follow-up for a mean of nine years (range 6�� years) demonstrates that the risk of rebleeding from a treated aneurysm is low. There were more rebleeds from the treated aneurysm in the coiling group than in the clipping group, but there was no difference between the groups in the number of deaths due to rebleeding. The risk of death at five years was significantly lower in the coiled group than it was in the clipping group. The probability of independent survival for those patients alive at five years is the same in the two groups. The standardised mortality rate, conditional on survival at one year, is increased in patients treated for ruptured aneurysms compared with the general population."

In an accompanying Reflection and Reaction comment, Dr Joseph Broderick, Department of Neurology, College of Medicine, University of Cincinnati, USA, says the findings emphasise the need for patients with such a complicated care pathway to be managed in centres where both treatment options are available.

He concludes: "The initial decision with regard to coiling or clipping is only the first step in the management of patients who have an active cerebrovascular disease that might recur, and imaging of any persistent aneurysms and aggressive modification of risk factors are crucial for long-term management."
Dr Andrew Molyneux and Richard Kerr, Oxford Neurovascular and Neuroradiology Research Unit, John Radcliffe Hospital, Oxford, and University of Oxford, UK T) +44 (0)1865 234755 E) onnru@nds.ox.ac.uk

Dr Joseph Broderick, Department of Neurology, College of Medicine, University of Cincinnati, USA T) please complete telephone number E) joseph.broderick@uc.edu

For full Article and Reflection and Reaction comment, see: http://press.thelancet.com/tlnisatfinal.pdf

Notes to editors:

*ISAT was funded by the UK Medical Research Council

**an aneurysm is a localized, blood-filled dilation (balloon-like bulge) of a blood vessel caused by disease or weakening of the vessel wall. Aneurysms most commonly occur in arteries at the base of the brain.


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