title: HydroCoils Are Associated with Lower Angiographic Recurrence Rates Than Are Bare Platinum Coils in Treatment of "Difficult-to-Treat" Aneurysms: A Post Hoc Subgroup Analysis of the HELPS Trial.
abstract: OBJECTIVE
  The HydroCoil Endovascular Aneurysm Occlusion and Packing Study was a randomized controlled trial that compared HydroCoils to bare platinum coils. Using data from this trial, we performed a subgroup analysis of angiographic and clinical outcomes of patients with "difficult-to-treat" aneurysms, defined as irregularly shaped and/or having a dome-to-neck ratio of <1.5.
  
  
  METHODS
  Separate subgroup analyses comparing outcomes of treatment with HydroCoils to that of bare platinum coils were performed for the following: 1) irregularly shaped aneurysms, 2) regularly shaped aneurysms, 3) aneurysms with a dome-to-neck ratio of <1.5, and 4) aneurysms with a dome-to-neck ratio of ≥1.5. For each subgroup analysis, the following outcomes were studied at the last follow-up (3-18 months): 1) any recurrence, 2) major recurrence, 3) re-treatment, and 4) an mRS score of ≤2. Multivariate logistic regression analysis was performed to determine if the HydroCoil was independently associated with improved outcomes in these subgroups.
  
  
  RESULTS
  Among the patients with an irregularly shaped aneurysm, the HydroCoil was associated with lower major recurrence rates than the bare platinum coils (17 of 66 [26%] vs 30 of 69 [44%], respectively; P = .046). Among the patients with an aneurysm with a small dome-to-neck ratio, the HydroCoil was associated with lower major recurrence rates than the bare platinum coils (18 of 73 [24.7%] vs 32 of 76 [42.1%], respectively; P = .02). No difference in major recurrence was seen between HydroCoils and bare platinum coils for regularly shaped aneurysms (42 of 152 [27.6%] vs 52 of 162 [32.1%], respectively; P = .39) or aneurysms with a large dome-to-neck ratio (41 of 145 [28.3%] vs 50 of 155 [32.3%], respectively; P = .53).
  
  
  CONCLUSIONS
  This unplanned post hoc subgroup analysis found that HydroCoils are associated with improved angiographic outcomes in the treatment of irregularly shaped aneurysms and aneurysms with a dome-to-neck ratio of <1.5. Because this was a post hoc analysis, these results are not reliable and absolutely should not alter clinical practice but, rather, may inform the design of future randomized controlled trials.
authors.affiliation: From the Department of Radiology (W.B., H.J.C., D.F.K.), Mayo Clinic, Rochester, Minnesota brinjikji.waleed@mayo.edu.
authors.forename: W
authors.initials: W
authors.lastname: Brinjikji
authors.affiliation: Institute for Ageing and Health (P.M.W., A.G.), Newcastle University, Newcastle-upon-Tyne, United Kingdom.
authors.forename: P M
authors.initials: PM
authors.lastname: White
authors.affiliation: Department of Clinical Neuroscience (H.N.), University of Edinburgh, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Nahser
authors.affiliation: Walton Centre (J.W., R.S.), Liverpool, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Wardlaw
authors.affiliation: Walton Centre (J.W., R.S.), Liverpool, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Sellar
authors.affiliation: Institute for Ageing and Health (P.M.W., A.G.), Newcastle University, Newcastle-upon-Tyne, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Gholkar
authors.affiliation: From the Department of Radiology (W.B., H.J.C., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: H J
authors.initials: HJ
authors.lastname: Cloft
authors.affiliation: From the Department of Radiology (W.B., H.J.C., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: D F
authors.initials: DF
authors.lastname: Kallmes
mesh_terms: D000368:Aged; D004621:Embolization, Therapeutic / Q000295:instrumentation*; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010984:Platinum; D011859:Radiography; D012008:Recurrence; D016896:Treatment Outcome
chemical_list: D010984:Platinum