An article published Online First and in the May edition of The Lancet Neurology by Dr Andrew Molyneux and Richard Kerr, Neurovascular and Neuroradiology Research Unit, John Radcliffe Hospital, Oxford, University of Oxford, UK, and colleagues, reports new findings in neurology. Patients whose aneurysms are coiled instead of clipped have a better survival rate over five years according to a long-term study of the International Subarachnoid Aneurysm Trial (ISAT). The ISAT was funded by the UK Medical Research Council. In both groups, there is a slight danger of rebleeding, but in the first five years the threat is higher for coiled aneurysm.
Between 1994 and 2002, in forty three neurosurgical centers, 2,143 patients with subarachnoid aneurysm* were included in the original ISAT trial. They were assigned at random to clipping (an open surgical intervention in which the aneurysm is clipped) or to 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). Previous research indicated that patients who had coiling had a better survival chance and were completely autonomous after one year. There was a decline of twenty four percent in the risk of death or dependence. More than 2,000 patients who had been monitored for an average of nine years (minimum six and maximum fourteen) were analyzed in the new study.
Findings showed that after only one year of treatment there was a total of twenty four rebleeds, from which thirteen were from the treated aneurysm (ten coiled and three clipped). Four of the rebleeds were from already existing but different aneurysms, and six of them were from new aneurysms, and only one was an unidentified cause. After five years, 11 percent of the coiled group and 14 percent of the clipped group had died. The risk of death was 23 percent lower for patients with coiled aneurysms than clipped aneurysms. However, for the patients alive after five years, the percentage that was autonomous in their everyday activities was similar in both groups (82 percent in the coiled group and 81 percent in the clipped group). In comparison to the general population, there was still a 57 percent increase in the risk of death for patients who had any of the treatments after one year.
“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 authors write in conclusion.
“The ISAT follow-up for a mean of nine years (range 6-14 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 standardized mortality rate, conditional on survival at one year, is increased in patients treated for ruptured aneurysms compared with the general population.”
Dr Joseph Broderick, Department of Neurology, College of Medicine, University of Cincinnati, USA, in a related Reflection and Reaction note, points out that the findings highlight how patients requiring such difficult care need to be handled in centres providing both treatment options.
Dr Broderick says in conclusion: “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.”
*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.
Written by Stephanie Brunner (B.A.)