Coated vs. Bare-Platinum Coils for Endovascular Treatment of Intracranial Aneurysms

One limitation of using detachable platinum coils for the endovascular treatment of brain aneurysms is the substantial rate of aneurysm recurrence within a year. Aneurysms can recur when coils become compacted in the aneurysm sac or when the aneurysm wall expands. Larger aneurysms, wider necks, and locations with direct-flow impingement are associated with increased risks for recurrence after treatment with coils. Deciding whether to retreat a recurrent aneurysm depends on anatomic factors, including size, location, and relationship with branch arteries, and on clinical factors, including whether the aneurysm has ruptured in the past. These researchers sought to determine the rate of aneurysm recurrence after endovascular treatment with a hydrogel-coated versus a bare-platinum coil. The manufacturer of the hydrogel coils funded the trial.
About 500 patients with a previously untreated, ruptured or unruptured, intracranial aneurysm (maximum diameter, 2–25 mm) were randomized to undergo endovascular treatment with either type of coil. The primary combined endpoint was angiographically determined recurrence at 18 months after the procedure (a surrogate for clinical recurrence) or procedure-related death or morbidity that prevented follow-up angiography.
Incidence of the primary combined endpoint was statistically similar in the two groups (hydrogel, 28%; bare, 36%), although the difference in the angiographic endpoint alone did reach significance (24% vs. 33%, respectively; P=0.049). Each group had exactly one patient who re-bled and a 3% rate of retreatment. Among patients with ruptured aneurysms, the hydrogel group fared significantly better than the bare-platinum group. Of six patients with unruptured aneurysms who developed hydrocephalus, five were in the hydrogel group.
Comment: Hydrogel coils likely reduce angiographic recurrence, particularly in ruptured aneurysms. However, these findings are ambiguous, owing to the nonsignificant difference between the groups in the primary combined endpoint and the unclear clinical relevance of angiographically determined aneurysm recurrence. The similarly low retreatment rate in both groups is evidence of the latter issue. Although aneurysm occlusion is often incomplete with bare-platinum coils and some aneurysms recur, the rate of rerupture is extremely low, similar to rates with surgical clipping. The risk for hydrocephalus with hydrogel-coated coils also remains a concern. The benefit of hydrogel in ruptured aneurysms is likely related to differences in how aggressively bare-platinum coils are placed in ruptured versus unruptured aneurysms. For now, both types of coils seem to be reasonable options for endovascular treatment of cerebral aneurysms.
— Colin Derdeyn, MD
Dr. Derdeyn is Professor of Radiology, Neurology, and Neurological Surgery, Washington University School of Medicine in St. Louis.
Published in Journal Watch Neurology June 14, 2011
White PM et al. Hydrogel-coated coils versus bare platinum coils for the endovascular treatment of intracranial aneurysms (HELPS): A randomised controlled trial. Lancet 2011 May 14; 377:1655.
Source: Journal Watch Neurology June 14, 2011

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