HydroCoil embolic system showed superior outcomes compared to bare platinum coils in the treatment of cerebral aneurysms


MicroVention-Terumo announced the final 18-month follow-up data in a landmark international study. The HydroCoil endovascular aneurysm occlusion and packing study (HELPS) published in The Lancet, showed that the HydroCoil embolic system for treating cerebral aneurysms reduced recurrence and retreatment rates and provided improved outcomes in study patients when compared to bare platinum coils. 

HELPS was a prospective, randomised controlled trial that compared the results from the HydroCoil system to results from bare platinum coils. The 500-patient, independently-run, multicentre, multinational 18-month trial was the first comparative adjudicated study completed since the International subarachnoid aneurysm trial (ISAT) which was presented in 2002.


“Our study shows that the non-invasive techniques for treating brain aneurysms are getting better. Hydrogel coated coils offer an improved treatment for ruptured aneurysms and coiling has a faster recovery than having to have brain surgery and come with less risk as well, which is great news for the thousands of people affected by this condition each year,” said Philip White, Western General Hospital in Edinburgh, Scotland and lead author of the study.


The HELPS trial results showed that the HydroCoil system, based on a microporous expandable hydrogel, proved to be a more stable solution for endovascular occlusion of aneurysms than bare platinum. The HydroCoil implant is a non-bioactive coil that combines platinum with an expanding hydrogel polymer which provides the features of greater aneurysm volume filling with biologically inert material for natural tissue proliferation.


Angiographic results from an independent core lab indicated there was a statistically significant

decrease (8.6%) in major aneurysm recurrence with the HydroCoil system arm as compared to bare platinum control arm. Aneurysms in the trial ranged in size from 2mm to 25mm, and 84% of all aneurysms were medium and large in size.


 Key results of the trial demonstrated:


  • HydroCoil implants had statistically significant more stable angiographic results with a significant decrease in major remnant/recurrence rates.
  • The primary composite endpoint, while neutral, showed a strong trend favoring the HydroCoil Embolic System.
  • There was a very low retreatment rate: 3% HydroCoil system arm vs. 4% bare platinum control arm.
  • The effect of the HydroCoil system on outcomes was superior in ruptured aneurysms: 68% HydroCoil implants vs. 50% bare platinum implants.
  • The HydroCoil system had less thromboembolic complications: 5.6% vs. 10% with bare
  • platinum.
  • HydroCoil implants resulted in a higher packing density with less coil length (reduction of 20% as compared to bare platinum) due to its expansion properties: 63.9% for HydroCoil implants and 23.2% for bare platinum implants.
  • Outcomes were superior when the targeted amounts of HydroCoil implants were achieved in aneurysms (≥50% HydroCoil implant length per protocol).


“We are very pleased with the exceptional results from this landmark trial. It continues to validate findings from previous multicentre and single-centre trials, which is that the HydroCoil system provides excellent results in reducing aneurysm recurrence and retreatment in a wide range of cerebral aneurysms as compared to bare platinum coils,” said Richard Cappetta, president and CEO, MicroVention-Terumo.


Procedural safety and efficacy results for HELPS, previously published in 2008, found that the

HydroCoil system can be safely used in a wide spectrum of aneurysms with a risk profile equivalent to thatof bare platinum coils.


Since the HELPS patient enrolment was completed in February 2007, MicroVention-Terumo has continued to innovate the HydroCoil line of coils, including the HydroSoft finishing coil for filling small spaces that provides hydrogel at the neck of the aneurysm, and the HydroFrame framing coil that provides optimal framing of the aneurysm with the clinical benefits of hydrogel.


The trial was based in the United Kingdom and managed by the Lothian Health Board with support from UK’s National Health Service. A total of 24 worldwide medical centres participated. The Core Lab that independently reviewed the results was Centre Hospitalier de l’Université de Montréal (CHUM) in Montreal, Quebec, Canada.


About the HydroCoil embolization system


The HydroCoil embolic system is a unique non-bioactive endovascular embolization device combining the company’s platinum microcoil technology with a proprietary hydrogel. The hydrogel polymer is a biomaterial that begins to swell after a brief period of contact with blood, giving physicians the ability to precisely control delivery of the device. Once the hydrogel swells, it provides improved filling of the aneurysm without exerting pressure onto the aneurysm wall or adjacent coils. The HydroCoil system combines the safety of platinum coils with the filling and mechanical stability of hydrogel. The HydroCoil system offers a therapeutic alternative to the current treatment choices of platinum coils and neurosurgical clipping, and is also being used clinically to treat fistula and peripheral vascular lesions.