MicroVention's HydroCoil Studied for Treating Medium-Sized Ruptured Brain Aneurysms

February 11, 2015—The American Stroke Association (ASA) announced that research presented at its International Stroke Conference 2015 in Nashville, Tennessee, demonstrated that the HydroCoil (MicroVention, Inc, a Terumo Group company) significantly improved healing of medium-sized ruptured aneurysms compared to treatment with a standard platinum coil. The HydroCoil combines a gel-like substance with the standard platinum coil. When the substance comes into contact with blood, the gel expands to block blood flow to the aneurysm.

According to the ASA, the study investigators analyzed data from the previous HELPS (HydroCoil Endovascular Aneurysm Occlusion and Packing Study) clinical study examining the effectiveness of HydroCoils compared to standard coils. The original HELPS trial, which was funded by MicroVention, was composed of 500 patients with aneurysm sizes ranging from 2 to 25 mm, with 84% of all aneurysms in the medium and large in size. In May 2011, the company announced that the final 18-month HELPS data were published by Philip M. White, MD, et al in The Lancet (2011;377;1655–1662). 

In the current study of the 288 patients with medium-sized (5–10 mm) ruptured aneurysms who were enrolled in the HELPS study, 70% were female, and most were 55 years old or younger. Half of the patients were randomly assigned to receive one of the two treatments. The investigators then performed brain-imaging studies at 15- to 18-month follow-up to determine whether the aneurysms had ruptured again or remained intact. The substudy investigators found that among patients with ruptured, medium-sized aneurysms, the major recurrence rate was significantly lower (< 20%) for those patients treated with HydroCoils compared to the rates of those treated with bare platinum coils (> 30%).

By contrast, in the original HELPS trial of 500 patients with the wider range of aneurysm sizes, the results showed a decrease of 8.6% in major aneurysm recurrence with the HydroCoil system arm as compared to the bare-platinum control arm.

In the ASA announcement, the study’s lead investigator Waleed Brinjikji, MD, commented, “We think that one of the reasons that the HydroCoil had better outcomes than the bare platinum coil in the ruptured aneurysms is that a ruptured aneurysm can have a little bit more of a complex or irregular shape; the expansion of the hydrogel likely allows for filling of some of these irregular outpouchings and rupture sites. The advantage of the HydroCoil is that it will expand to fill in that irregular shape.” Dr. Brinjikji is a radiologist at the Mayo Clinic in Rochester, Minnesota.

The investigators advised that because the study included only a subgroup of patients, the results could be due to chance, so further research is critical before changing the recommended treatment for aneurysms.

Dr. Brinjikji added, “We hope that these results help inform the development of future clinical trials. Since small aneurysms generally respond well to the bare platinum coils, and large aneurysms are difficult to treat with coils alone, clinicians should try to focus on enrolling patients with medium-sized, ruptured aneurysms in future trials. Only if these results can be replicated should they be used to change clinical management.”