The Source for Neurovascular News and Education

August 11, 2020


The new coils are softer, contain less hydrogel, and expand more slowly than earlier-generation options.


Second-generation hydrogel stents for the coiling of ruptured and unruptured intracranial aneurysms produce better outcomes than do bare-platinum stents, according to a European randomized trial published online February 6, 2018, ahead of print in Stroke.


Previous studies have demonstrated a link between packing density and recanalization rate following endovascular coil embolization of intracranial aneurysms, Christian A. Taschner, MD (University Hospital Freiburg, Germany), and colleagues note. Coated coils have therefore been developed in an effort to increase packing density and thus reduce recanalization rates.


“A different approach consists of platinum coils coupled with hydrogel, which expands once in contact with liquids, resulting in increased packing density,” they write. The HELPS trial revealed fewer major recurrences with the hybrid hydrogel-coated platinum detachable coil known as HydroCoil (MicroVention), but use of this device was limited by technical issues, including coil stiffness and time restriction for placement.


The present study evaluated the safety and efficacy of the HydroSoft and HydroFrame second-generation hydrogel coils (MicroVention), which are softer, contain less hydrogel, and expand more slowly than their predecessor.


At 22 centers in France and Germany, Taschner et al conducted a trial in which 513 patients with ruptured or unruptured intracranial aneurysms (4-12 mm in diameter) were randomized, with stratification by rupture status, to treatment using a hydrogel coil (n = 256) or a bare-platinum coil (n = 257).


After exclusions due to missing informed consent and treatment-related criteria, data on 484 patients (43% had ruptured aneurysms) were included in the final analysis: 243 were treated with a hydrogel stent and 241 of with a bare-platinum stent. Assist devices were allowed as clinically required. An independent imaging core laboratory that was masked to allocation assessed outcomes.


The primary endpoint was a composite outcome measure that included major aneurysm recurrence, aneurysm retreatment, morbidity that prevented angiographic controls, and any death during treatment and follow-up. Final endpoint data were available for 456 patients and revealed better outcomes among patients treated with the hydrogel coils.




(n = 226)

Bare Platinum

(n = 230)

Major Recurrence, Retreatment, Morbidity, and Mortality




After adjusting for rupture status, this difference between groups amounted to an 8.4% reduction in the proportion of patients experiencing an unfavorable composite primary outcome with use of hydrogel coils (P = 0.036). Rates of adverse and serious adverse events were similar for both groups of patients.


“Our results suggest that endovascular coil embolization with second-generation hydrogel coils may reduce the rate of unfavorable outcome events in patients with small- and medium-sized intracranial aneurysms.” write the authors.



Taschner CA, Chapot R, Costalat V, et al. Second-generation hydrogel coils for the endovascular treatment of intracranial aneurysms: A randomized controlled trial. Stroke. 2018;Epub ahead of print.



  • Taschner reports receiving grants and support from MicroVention.
  • The study was funded by MicroVention.