NEW YORK (Reuters Health) – Stent-assisted coiling of intracranial aneurysms significantly reduces angiographic recurrence, new research shows.

But using stents also increases the risk of permanent neurologic complications and procedure-related mortality, compared to coiling without stents, according to the retrospective study.

Definitive conclusions on the advantages of stents will require longer follow-up, lead author Dr. Michel Piotin, from Foundation Rothschild Hospital, Paris, and colleagues note in the January issue Stroke, and improvements in technology will also be needed to reduce complications.

They explain that the goal of stenting in these procedures is to divert blood flow, diminish intra-aneurysmal flow, and to create a mesh at the neck of the aneurysm to be colonized and covered by endothelial cells.

The article describes their experience with 1137 consecutive patients and 1325 aneurysms coiled with (n = 216) or without (n = 1109) stent assistance, between 2002 and 2009. Mean follow-up periods were 22 months for nonstented aneurysms and 14 months for stented aneurysms

Immediately after the procedure, angiography showed that 63.5% of aneurysms in the no-stent group were totally occluded, versus 46.3% in the stent group, the investigators report. Stented aneurysms were more likely to show delayed occlusion on the first follow-up angiogram, most likely due to the use of dual antiplatelet therapy plus heparin during the procedure.

The researchers analyzed recurrence according to aneurysm size, but recurrence rates were significantly lower with stented coiling in all comparisons. Specifically, recurrence rates with small (<10 mm) aneurysms were 2.9% in the stented group and 28.8% in the nonstented group. For large (10 mm or greater) aneurysms, recurrence rates were 32.6% with stents and 55.1% in nonstented cases. Permanent neurological complications occurred in 42 of 1109 procedures without stents (3.8%) and in 16 of 216 procedures with stents (7.4%, p = 0.027). The corresponding rates of mortality were 1.2% and 6.0% (p = 0.002). Again, they suggest that the use of strong antiplatelet therapy, plus guidewire exchange maneuvers, may have been to blame, as well as balloon-expandable stents that tend to be more traumatic to the arterial wall than self-expandable stents. Based on their observations, Dr. Piotin’s group concludes that “improvement in stent technology is still warranted to diminish complications.” Dr. Johnny C. Pryor, Director of Interventional Neuroradiology at the Massachusetts General Hospital in Boston, disagrees with the paper’s suggestion that complications were due to earlier versions of aneurysmal stents. “We have seen an increase in severe and lethal complications even recently with the generation of stents now available,” he told Reuters Health, noting that none are FDA approved but are used under a humanitarian device exception. “A lot of people believe stents make coiling more durable,” he added, conceding that they’re appropriate in some cases. However, placement of a stent increases the risk of having it “clot off” or having platelets that colonize the surface enter the circulation and cause a stroke. Add that to the risk of dual antiplatelet therapy in addition to a blood thinner, and “when a complication occurs, their blood is so thinned that it becomes more severe — or even lethal – than if the stent had not been there,” Dr. Pryor said. Reference:
Stroke 2010.