Hydrocoil Endovascular aneurysm occLusion and Packing Study - HELPS


The goal of the trial was to evaluate treatment with hydrogel-coated coils compared with bare platinum coils among patients with a previously untreated ruptured or unruptured cerebral aneurysm.


Hydrogel-coated coils will improve angiographic and clinical outcomes.

Study Design

  • Randomized
  • Blinded
  • Parallel
  • Stratified

Patient Populations:

  • Patients 18-75 years of age with a previously untreated ruptured or unruptured cerebral aneurysm (2-25 mm in diameter)

    Number of enrollees: 499
    Duration of follow-up: 18 months


  • Cerebral anatomy not amenable to coiling
  • Pregnancy
  • More than one cerebral aneurysm requiring treatment

Primary Endpoints:

  • Composite of procedure-related death or morbidity, or major cerebral aneurysm recurrence at 18 months

Secondary Endpoints:

  • Clinical outcome at 3 and 18 months, measured by the modified Rankin Scale
  • Rates of rebleeding and retreatment
  • Aneurysm packing density

Drug/Procedures Used:

Patients with cerebral aneurysm suitable for coiling were randomized to treatment with hydrogel-coated coils (n = 249) versus bare platinum coils (n = 250).

Principal Findings:

Overall, 499 patients were randomized. At 18 months, the primary composite outcome occurred in 28% of the hydrogel-coated coil group versus 36% of the bare platinum coil group (p = 0.13).

Major aneurysm recurrence occurred in 24% versus 33% (p = 0.049), respectively. Among patients with a ruptured aneurysm, outcomes were better in the hydrogel-coated coil group (p for interaction = 0.014). Aneurysms that were intermediate in size (5-9.9 mm) also tended to do better with hydrogel-coated coils; however, this did not reach significance (p for interaction = 0.46).


Among patients with previously untreated ruptured or unruptured cerebral aneurysm, treatment with hydrogel-coated coils is at least as good as and possibly better than treatment with bare platinum coils. While hydrogel-coated coils failed to improve the primary composite outcome, they reduced the rate of major cerebral aneurysm recurrence. In subgroup analysis, patients with a previously untreated ruptured aneurysm did better with hydrogel-coated coils.


White PM, Lewis SC, Gholkar A, et al. Hydrogel-coated coils versus bare platinum coils for the endovascular treatment of intracranial aneurysms (HELPS): a randomised controlled trial. Lancet 2011;377:1655-62.

Clinical Topics: Vascular Medicine

Keywords: Embolization, Therapeutic, Follow-Up Studies, Aneurysm, Ruptured, Hydrogels, Platinum, Intracranial Aneurysm

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