Introduction: The importance of a framing coil (FC), the first coil inserted into an aneurysm during endovascular coiling, is widely recognized. We previously demonstrated that the percentage of FC volume in total coil volume (FCP) >32% was an independent predictor of long-term outcomes including recanalization and retreatment. However, factors affecting successful insertion of FCs are not well-established, and thus we aimed to identify them in our retrospective cohort.
Methods: A retrospective review of patients who underwent endovascular coiling for unruptured intracerebral aneurysms from 2008 to 2015 in a single center identified 247 patients with a minimum two-year follow-up. They were classified into the two groups: cases with failed attempts to place FCs that were initially selected (Group A, n=63, 25.5%) and those without (Group B, n=184). Data on aneurysmal volume, FCs, reasons for unsuccessful initial attempts, strategies adopted to overcome them, framing coil volume packing density (FVPD, FC volume/aneurysm volume), and FCP are collected and statistically analyzed.
Results: No significant differences in baseline characteristics were identified between the groups. Among the 63 cases, 13 cases were attributed to excessive coil length and thus required decreases in length (Figure 1). In aneurysms<7mm, FVPD>18% had sensitivity of 71.4% and specificity of 87.8% for detecting failure due to excessive coil length, whereas FVPD>10% had sensitivity of 66.6% and specificity of 65.2% in aneurysms>7mm. The AUC of FVPD for detecting excessive coil length was 0.867 in aneurysms<7mm (p<0.001, Figure 2A), 0.676 in aneurysms>7mm (p=0.385, Figure 2B), and 0.742 in all aneurysms (p<0.001). A linear correlation was identified between FVPD and FCP (p<0.001, Figure 2C). There were four incidents of intraoperative aneurysmal rupture, none of which were attributable to FC insertion.
Conclusions: To successfully insert FCs and also improve long-term outcomes, prospectively calculating FVPD prior to selecting FCs and thereby maximizing FVPD and FCP might be beneficial.
Patient Care: By prospectively calculating FVPD prior to selecting FCs and maximize FCP, we can predict the largest, insertable FCs and thereby improve the long-term outcomes of endovascular coiling for patients with unruptured aneurysms such recanalization and retreatment.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of framing coils in endovascular coiling for unruptured intracerebral aneurysms with special attention to FVPD, 2) Discuss, in small groups, how to select an appropriate framing coil, and 3) Identify an effective treatment forunruptured intracerebral aneurysms
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2. Misaki K, Uchiyama N, Nambu I, et al. Optimizing the Volume of the Initial Framing Coil to Facilitate Tight Packing of Intracranial Aneurysms. World Neurosurg. 2016;90:397-402.
3. Ishihara H, Ishihara S, Niimi J, et al. Risk factors for coil protrusion into the parent artery and associated thrombo-embolic events following unruptured cerebral aneurysm embolization. Interv Neuroradiol. 2015;21(2):178-183.
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