Published online before print February 9, 2007, 10.1148/radiol.2431060006
(Radiology 2007;243:500-508.)
© RSNA, 2007
Intracranial Aneurysms: Treatment with Bare Platinum Coils—Aneurysm Packing, Complex Coils, and Angiographic Recurrence1
Michel Piotin, MD, PhD,
Laurent Spelle, MD, PhD,
Charbel Mounayer, MD,
Marco T. Salles-Rezende, MD,
Daniel Giansante-Abud, MD,
Ricardo Vanzin-Santos, MD, and
Jacques Moret, MD
1 From the Department of Interventional Neuroradiology, Hôpital de la Fondation Ophtalmologique Adolphe de Rothschild, 25-29 rue Manin, 75940 Paris, Cedex 19, France. Received January 3, 2006; revision requested March 2; revision received April 22; accepted May 25; final version accepted August 25.
Address correspondence to J.M. (e-mail: jmoret{at}fo-rothschild.fr).
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ABSTRACT
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Purpose: To retrospectively assess, with three-dimensional rotational angiography, the relationship between packing, complex coils, and angiographic recurrence of aneurysms treated with coils.
Materials and Methods: Informed consent was waived by the institutional review board that approved the study. Results at follow-up angiography of 255 aneurysms in 223 patients (161 female and 62 male patients; mean age, 48 years) were dichotomized into presence or absence of recurrence. The degree of packing of aneurysms treated with complex coils alone, with complex and helical coils, and with helical coils only was compared for significant differences. With generalized estimating equations analysis, relative risk (RR) for recurrence was calculated for mode of manifestation, duration of follow-up, aneurysm volume, packing, initial angiographic result, percentage of complex coils, aneurysm location, and multiplicity of aneurysms.
Results: Follow-up angiography revealed recurrence in 28.6% of aneurysms at a mean follow-up of 12 months; 5.5% were amenable to re-treatment. Aneurysms treated with complex and those treated with helical coils only had a mean packing of 27% and 26%, respectively. There was no significant difference between packing of aneurysms treated with complex and those treated with helical coils (P = .538). Recurring and stable aneurysms both had a mean packing of 27%. Generalized estimating equations analysis showed significant differences between duration of follow-up and recurrence (P = .001, RR = 3.39), between aneurysm volume and recurrence (P < .001, RR = 6.15), and between hemorrhagic manifestation and recurrence (P = .002, RR = 3.17). There was no significant difference between packing and recurrence, between initial angiographic result and recurrence, between percentage of complex coils and recurrence, between aneurysm location and recurrence, or between multiplicity of aneurysms and recurrence.
Conclusion: More angiographic recurrences are detected over time. Complex coils do not augment aneurysm packing. Packing is not related to protection against recurrence.
© RSNA, 2007
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INTRODUCTION
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Endovascular treatment (EVT) with coils is effective in preventing rebleeding after aneurysmal rupture (1,2). Conversely, surgical treatment or EVT versus conservative management of unruptured aneurysms is still debated (3). However, it is more likely that aneurysm remnants and recurrences are more frequent after coil placement than after surgical clipping, although reports of surgical series with follow-up angiography are scarce (4). A main concern with EVT is the possibility that the aneurysm will reopen after coil placement, which exposes patients to the risk of hemorrhage. The relationship between packing—the ratio between the volume of the inserted coils and the volume of the aneurysm sac—and angiographic recurrence in coiled aneurysms has been studied previously, but many series (5–9) included a relatively small number of patients, sometimes with short-term follow-up. Nevertheless, results of these studies demonstrated that packing of more than 20%–25% was found to protect against recurrence. Recently, Sluzewski et al (8) found that, at 6-month follow-up, if 24% or more of the aneurysm volume was packed, recurrence did not occur in lesions with a volume less than 600 mm3. In aneurysms with a volume less than 200 mm3, recurrence did not occur when packing was more than 20% (8). Recently, Slob et al (10) demonstrated that using complex coils resulted in significantly better packing than that achieved with helical coils.
Whether or not complex coils reduce the frequency of angiographic recurrence remains to be proved. Thus, the purpose of our study was to retrospectively assess, by using three-dimensional (3D) rotational angiography, the relationship between packing, complex coils, and angiographic recurrence of aneurysms treated with coils.
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MATERIALS AND METHODS
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Patient Demographics
Informed consent was waived by our institutional review board, which approved our study. From January 2002 to July 2005, 385 aneurysms in 339 consecutive patients were treated selectively with platinum coils. One hundred two patients (112 aneurysms) were not followed up for various reasons (Table 1). Twenty additional aneurysms were excluded—13 because they were not imaged with 3D rotational angiography prior to EVT, three because the poor quality of 3D images did not allow volumetric measurement, two traumatic aneurysms because they did not have proper boundaries, and two partially thrombosed aneurysms because coils were obviously penetrating the thrombus during EVT.
Our study thus consisted of 223 patients with 255 aneurysms (128 unruptured, 127 ruptured). There were 161 female and 62 male patients, with a mean age of 48 years (median age, 49 years; age range, 17–81 years). Seventy-seven unruptured aneurysms were discovered out of any context of hemorrhage, 44 were discovered in addition to an aneurysm that had ruptured, five had symptoms of mass effect, and two were embolized after failed surgery. The aneurysms had various locations (Table 2). From estimation of maximum diameter, 222 aneurysms were small (<10 mm), and 33 were large (
10 mm). At least one angiographic follow-up examination was performed for each aneurysm (range, 1–43 months).
Volume Measurement of Aneurysms
Aneurysm volumes were determined on 3D images obtained with rotational angiography (Integris Allura; Philips, Best, the Netherlands). The aneurysm was manually segmented from the parent artery, and volume was calculated by using the volumetric measurement feature of the system software. The manual outlining and segmentation of the aneurysm from the parent artery was performed by the same physician (M.P., who had 6 years of experience in interventional neuroradiology) for all aneurysms.
Endovascular Procedure
All procedures were performed by one of four physicians (J.M., C.M., M.P., or L.S., who had 3–20 years of experience in interventional neuroradiology) with the use of general anesthesia and full anticoagulation (a bolus of 5000 IU of heparin [Héparine CHOAY; Sanofi-Aventis, Paris, France], followed by continuous infusion of 2500–3000 IU/h). Anticoagulation was aimed at keeping the activated clotting time at two to three times above the normal value (around 100 seconds) during catheterization and coil placement. In addition, in all patients with no history of subarachnoid hemorrhage within the previous 4 weeks, 250 mg of aspirin was given intravenously. Heparin was discontinued after embolization in the majority of patients.
Rotational angiography, followed by 3D reconstruction of the original projections, was performed just before starting embolization. Reconstruction gave the operator one to two working projections that provided the best achievable view(s) of the aneurysm neck. Four different brands of coils were used; each brand was available in helical or complex shapes (GDC-10, Boston Scientific/Target Therapeutics, Fremont, Calif; Sapphire, EV3/Micro Therapeutics, Irvine, Calif; Trufill/DCS, Cordis, Miami Lakes, Fla; Microplex, Microvention, Aliso Viejo, Calif). Coils were inserted until aneurysmal circulatory exclusion was achieved or until no more coils could be delivered. The choice of the type (helical vs complex) and brand of coil used was up to the physician performing the procedure. Generally, complex coils were used first in larger aneurysms with a broad neck, while smaller aneurysms were treated preferentially with helical coils. One hundred fifty-five (60.8%) of 255 aneurysms were treated with a combination of complex and helical coils, 86 (33.7%) were embolized with helical coils, and 14 (5.5%) were occluded with complex coils only. At the end of the procedure, angiograms in frontal, lateral, and working projections were obtained.
Image Evaluation
Angiographic images obtained immediately after EVT were compared with those obtained at each follow-up examination. Mean duration of follow-up was 15 months (median, 15 months; range, 1–43 months). One hundred thirty-three (52.2%) of 255 aneurysms were imaged with only one follow-up angiographic examination at a mean follow-up time of 10 months (median, 7 months; range, 1–41 months).
One hundred five (41.2%) of 255 aneurysms were imaged with two follow-up angiographic examinations at a mean follow-up interval of 19 months (median, 17 months; range, 7–40 months). Seventeen aneurysms (6.7%) were imaged with three follow-up angiographic examinations at a mean follow-up interval of 33 months (median, 36 months; range, 18–43 months). The volume of the coils inserted was calculated with a spreadsheet. Packing was calculated as the ratio of coil volume to aneurysm volume, and aneurysm volume was multiplied by 100. Follow-up angiograms were reviewed, and aneurysm recurrence was dichotomized as absent or present by the same physician (M.P.).
Angiographic results were evaluated and classified as described by the Montreal group (11). A class 1 result meant complete obliteration, including the neck of the aneurysm. A residual neck (class 2) was defined as the persistence of any portion of the original defect of the arterial wall as seen on any single projection but without opacification of the aneurysmal sac. Any opacification of the sac was classified as indicating a residual aneurysm (class 3). At follow-up, an aneurysm was considered recurrent if a previously totally occluded aneurysm had a partial recurrence of the neck and/or sac. In addition, an aneurysm was considered to have remnant regrowth if a subtotally occluded aneurysm was found to have an increasing neck remnant or residual aneurysm. The recurrence was qualified as sizable if its size would theoretically permit re-treatment with coils. The time between treatment and the first follow-up angiographic examination with recurrence results was noted.
Statistical Analysis
Statistical analysis was performed with software (SAS, version 8.2; SAS, Cary, NC). Packing (the ratio between the volume of the inserted coils and the volume of the aneurysm) of aneurysms treated with complex coils, with complex and helical coils, and with helical coils only; of aneurysms that exhibited angiographic recurrence; and of those that remained stable was compared for a statistically significant difference by using a nonparametric test (Mann-Whitney). We calculated relative risk with standard error of estimate for recurrence with generalized estimating equations for the following factors: volume of complex coils versus total volume of coils introduced, aneurysm location (according to the three most frequent anatomic locations: middle cerebral, anterior communicating, and supraclinoid internal carotid arteries), packing, aneurysm volume, initial angiographic result, duration of angiographic follow-up, mode of manifestation (hemorrhagic vs nonhemorrhagic), multiplicity of aneurysms, and the number of aneurysms harbored by the patient. The relationships between recurrence and initial angiographic result, duration of angiographic follow-up, packing, aneurysm volume, volume of complex coils, aneurysm location, mode of manifestation, and multiplicity of aneurysms were then studied with 
2 tests. The relationship between aneurysm volumes and packing was further clarified by dividing aneurysm volumes into two packing categories that highlighted the relationship between these two variables.
The same analysis was performed for the relationship between aneurysm volume and recurrence. For this purpose, aneurysms were divided into two groups: those with a volume less than 66 mm3, a value corresponding to the median volume of all 255 aneurysms (n = 126), and those with a volume of 66 mm3 or greater (n = 129). The corresponding spherical diameter for an aneurysm with a volume of 66 mm3 was 5.3 mm.
Finally, the aneurysms were divided into two packing categories: those with packing less than 24% and those with packing of 24% or greater. This division of packing groups was chosen because aneurysms with packing of 24% or greater were found not to show coil compaction in a previous study (8). P values of less than .05 were considered to indicate a statistically significant difference.
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RESULTS
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Aneurysm Volume, Packing, and Recurrence
Mean aneurysm volume was 152 mm3 (median, 66 mm3; range, 4–2619 mm3). Mean packing was 27% (median, 25%; range, 6%–55%). At the end of the procedure, a class 1 result was obtained in 165 (64.7%) of 255 aneurysms, a class 2 result was obtained in 48 (18.8%) aneurysms, and a class 3 result was obtained in 42 (16.5%) aneurysms. Follow-up angiography revealed recurrence in 73 (28.6%) of 255 aneurysms at a mean follow-up interval of 12 months (median, 8 months; range, 3–43 months). Fourteen (5.5%) of 255 aneurysms were amenable to re-treatment. Aneurysms that were treated with complex coils had a mean packing of 27% (median, 25%; range, 6%–55%); those that were treated with helical coils only had a mean packing of 26% (median, 25%; range, 7%–51%). There was no significant difference between the packing of aneurysms treated with complex coils and that of those treated with helical coils only (P = .538). The aneurysms that exhibited recurrence had a mean packing of 27% (median, 25%; range, 7%–55%). Lesions that remained stable had a mean packing of 27% (median, 25%; range, 6%–53%). There was no statistically significant difference in packing between recurring and stable aneurysms (P = .723).
Generalized estimating equations analysis showed a significant difference between duration of angiographic follow-up and recurrence, between aneurysm volume and recurrence, and between hemorrhagic manifestation and recurrence. Conversely, there was no significant difference between packing and recurrence, between initial angiographic result and recurrence, between aneurysm location and recurrence, between the percentage of complex coils and recurrence, and between multiplicity of aneurysms and recurrence (Tables 3, 4; Figs 1, 2).
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Figure 1a: Images (working projection, close to oblique projection) in 40-year-old woman with unruptured right middle cerebral artery aneurysm. (a) Angiogram in right internal carotid artery shows 68-mm3 middle cerebral artery aneurysm (arrow). (b) Angiogram in right internal carotid artery at end of procedure shows class 1 angiographic result. (c) Unsubtracted view of angiogram just before contrast material administration at end of procedure shows cast of coils inserted into aneurysm. Corresponding calculated packing is 43%; 63% of coils used were complex coils. (d) Angiogram in right internal carotid artery at 38-month follow-up shows aneurysm recurrence (arrow). (e) Conventional radiograph of skull at 38-month follow-up shows substantial modification of the aspect of the cast of coils when compared with c.
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Figure 1b: Images (working projection, close to oblique projection) in 40-year-old woman with unruptured right middle cerebral artery aneurysm. (a) Angiogram in right internal carotid artery shows 68-mm3 middle cerebral artery aneurysm (arrow). (b) Angiogram in right internal carotid artery at end of procedure shows class 1 angiographic result. (c) Unsubtracted view of angiogram just before contrast material administration at end of procedure shows cast of coils inserted into aneurysm. Corresponding calculated packing is 43%; 63% of coils used were complex coils. (d) Angiogram in right internal carotid artery at 38-month follow-up shows aneurysm recurrence (arrow). (e) Conventional radiograph of skull at 38-month follow-up shows substantial modification of the aspect of the cast of coils when compared with c.
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Figure 1c: Images (working projection, close to oblique projection) in 40-year-old woman with unruptured right middle cerebral artery aneurysm. (a) Angiogram in right internal carotid artery shows 68-mm3 middle cerebral artery aneurysm (arrow). (b) Angiogram in right internal carotid artery at end of procedure shows class 1 angiographic result. (c) Unsubtracted view of angiogram just before contrast material administration at end of procedure shows cast of coils inserted into aneurysm. Corresponding calculated packing is 43%; 63% of coils used were complex coils. (d) Angiogram in right internal carotid artery at 38-month follow-up shows aneurysm recurrence (arrow). (e) Conventional radiograph of skull at 38-month follow-up shows substantial modification of the aspect of the cast of coils when compared with c.
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Figure 1d: Images (working projection, close to oblique projection) in 40-year-old woman with unruptured right middle cerebral artery aneurysm. (a) Angiogram in right internal carotid artery shows 68-mm3 middle cerebral artery aneurysm (arrow). (b) Angiogram in right internal carotid artery at end of procedure shows class 1 angiographic result. (c) Unsubtracted view of angiogram just before contrast material administration at end of procedure shows cast of coils inserted into aneurysm. Corresponding calculated packing is 43%; 63% of coils used were complex coils. (d) Angiogram in right internal carotid artery at 38-month follow-up shows aneurysm recurrence (arrow). (e) Conventional radiograph of skull at 38-month follow-up shows substantial modification of the aspect of the cast of coils when compared with c.
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Figure 1e: Images (working projection, close to oblique projection) in 40-year-old woman with unruptured right middle cerebral artery aneurysm. (a) Angiogram in right internal carotid artery shows 68-mm3 middle cerebral artery aneurysm (arrow). (b) Angiogram in right internal carotid artery at end of procedure shows class 1 angiographic result. (c) Unsubtracted view of angiogram just before contrast material administration at end of procedure shows cast of coils inserted into aneurysm. Corresponding calculated packing is 43%; 63% of coils used were complex coils. (d) Angiogram in right internal carotid artery at 38-month follow-up shows aneurysm recurrence (arrow). (e) Conventional radiograph of skull at 38-month follow-up shows substantial modification of the aspect of the cast of coils when compared with c.
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Figure 2a: Images (working projection, close to submental projection) in 66-year-old man with ruptured anterior communicating artery aneurysm. (a) Angiogram in left internal carotid artery shows 77-mm3 anterior communicating artery aneurysm (arrow). (b) Angiogram in left internal carotid artery at end of procedure shows class 1 angiographic result. Corresponding calculated packing is 16%; 25% of coils used were complex coils. (c) Angiogram in left internal carotid artery at 16-month follow-up shows aneurysm stability with persisting complete occlusion (arrow).
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Figure 2b: Images (working projection, close to submental projection) in 66-year-old man with ruptured anterior communicating artery aneurysm. (a) Angiogram in left internal carotid artery shows 77-mm3 anterior communicating artery aneurysm (arrow). (b) Angiogram in left internal carotid artery at end of procedure shows class 1 angiographic result. Corresponding calculated packing is 16%; 25% of coils used were complex coils. (c) Angiogram in left internal carotid artery at 16-month follow-up shows aneurysm stability with persisting complete occlusion (arrow).
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Figure 2c: Images (working projection, close to submental projection) in 66-year-old man with ruptured anterior communicating artery aneurysm. (a) Angiogram in left internal carotid artery shows 77-mm3 anterior communicating artery aneurysm (arrow). (b) Angiogram in left internal carotid artery at end of procedure shows class 1 angiographic result. Corresponding calculated packing is 16%; 25% of coils used were complex coils. (c) Angiogram in left internal carotid artery at 16-month follow-up shows aneurysm stability with persisting complete occlusion (arrow).
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Recurrence according to Initial Angiographic Result
Lesions with class 1 results did not have a lower risk for developing a recurrence (P = .142). When aneurysms were divided into two groups according to packing categories, aneurysms with higher packing were not at lower risk for developing a recurrence, but class 2 results conferred a higher risk of recurrence, though not a significantly higher risk (Table 5). When aneurysms were divided into two groups according to volume categories, aneurysms with higher volumes were at higher risk for developing a recurrence when the aneurysm had a persisting neck opacification, although not a significantly higher risk (Table 6).
Recurrence according to Duration of Follow-up
When patients were divided into two groups according to length of angiographic follow-up, the group followed up for less than 12 months was at less risk for a recurrence than the group followed up for more than 12 months (Table 7).
Recurrence according to Packing
When aneurysms were dichotomized according to a 24% packing threshold, the numbers of recurring lesions were not significantly different between the two groups (Table 8).
Recurrence according to Aneurysm Volume
When aneurysms were dichotomized according to a 66-mm3 volume threshold, the numbers of recurring lesions were not significantly different between the two groups (Table 9).
Recurrence according to Use of Complex Coils
Whether or not complex coils were used during the treatment did not affect the angiographic stability of the initial angiographic result (Table 10).
Recurrence according to Aneurysm Location
Middle cerebral artery aneurysms were found to recur more frequently than did aneurysms at other locations, but this result did not reach significance (Table 11).
Recurrence according to Mode of Manifestation
Ruptured aneurysms were found to recur more frequently than aneurysms that did not hemorrhage, but the difference between the two groups was not significant (Table 12).
Recurrence according to Multiplicity of Aneurysms
Multiple aneurysms were not found to recur more frequently than single aneurysms (Table 13).
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DISCUSSION
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In France, the vast majority of aneurysms are referred for EVT as a first option, and, consequently, the characteristics of our study population are not similar to the common North American selection of patients referred for EVT. In North America, a high proportion of lesions such as posterior circulation or ophthalmic artery aneurysms are usually referred for EVT rather than being referred for surgical clipping. Our aneurysm population reflects the natural distribution of cerebral aneurysms and does not overrepresent specific aneurysm anatomic locations (12).
Large aneurysms treated with coils have a greater propensity to recur than do smaller aneurysms (8,11,13). Aneurysm volume was identified as a risk factor for angiographic recurrence in our study, even if this was not confirmed with the 2 test. This was due to the fact that the majority of the aneurysms were small lesions. Ruptured aneurysms are more likely to recur than are unruptured lesions (11). This known factor was also found in this series by using generalized estimating equations analysis but was not confirmed with the 2 test. Incomplete aneurysm occlusion has been previously identified as a significant predictor of a recurrence (11). In our study, this factor was not confirmed as being a statistically significant predictor of recurrence, although this might be due to insufficient statistical power and to the fact that the majority of our aneurysms were small. Nevertheless, we found that an initial incomplete occlusion conferred a higher risk of recurrence, especially in the group of aneurysms with larger dimensions. One interpretation is that complete obliteration of the lesion is important to decrease the number of early recurrences, and this can be achieved more frequently with technical advances, such as the use of complex coils or the balloon remodeling technique. However, recurrences might still occur in a delayed fashion, because the magnitude of the recurrence problem varied according to the length of follow-up.
Raymond et al (11) have demonstrated that short periods of follow-up do not guarantee sufficient detection of aneurysm recurrence. We have established a strong relationship between the rate of recurrence and the duration of follow-up. If we limit our evaluation to patients with follow-up periods of 12 months or longer, the percentage of patients with any recurrence is 37.5%. Raymond et al (11) found a similar rate of recurrence, 40%, in their aneurysm population with long follow-up periods.
Interestingly, our overall recurrence rate of 28.6% was not dramatically lower than the quite similar overall recurrence rate (33.6%) of Raymond et al (11), despite the fact that their series included patients treated between 1992 and 2002, which meant that their patients were treated with Guglielmi detachable coils, the majority of which were helical coils. In 1999, the first complex coil (3D Guglielmi detachable coils) was introduced to facilitate coil placement in wide-neck aneurysms (14). This new complex spherical design aimed specifically to bridge the aneurysm neck with coil loops, thereby facilitating retention of additional coils placed within the aneurysm. Later on, Cordis (Trufill-Complex coil), Microvention (Microplex-Complex), and then EV3 (Tetris coil) developed and introduced their own complex coils to ease the treatment of wide-neck aneurysms. Previous studies (15,16) have found that complex coils resulted in higher packing than did helical coils. In our series, the use of complex combined with helical coils did not confer higher packing than helical coils only and did not reduce the frequency of angiographic recurrence.
The relationship between packing and recurrence in aneurysms treated with coils has been studied previously (5–9). The results of these studies are, however, remarkably different from ours, in that packing of more than 20%–25% was found to protect against recurrence. We were not able to confirm these results, and no packing threshold beyond which no recurrence occurred could be determined. There are several potential explanations that might explain these discrepancies. First, these previous studies included a small number of aneurysms that were followed-up during shorter time periods, thus causing underestimation of the role of time.
Another explanation might be misleading estimation of aneurysm volume. Three-dimensional rotational angiographic technology gives the capability to obtain precise volumetric measurements (7,17,18). Conversely, this capability is not always available, and aneurysm volume calculation is performed given the assumption that the aneurysm is an ellipsoid geometric form. Previous studies (5,6,9) of aneurysm coil packing were conducted on the basis of this ellipsoid approximation, but this approximation has been shown to be inaccurate because the majority of cerebral aneurysms are irregularly shaped (18). This gives the operator a misleading estimation of the actual aneurysm volume (18). Consequently, the resulting calculated coil packing is wrong. For this study, we prospectively used 3D rotational angiography as a method to measure the volume of aneurysms.
The degree of packing is not the only factor involved in predicting aneurysm stability. One possible explanation is that adequate flow diversion at the aneurysm neck may be achieved with a single coil in small aneurysms, and flow diversion allows thrombosis and scar formation at the neck (19). Results of our series suggest that even an aneurysm with low packing can be protected over time. Coil placement causes dramatic flow reduction in the dome of aneurysms (20). The changes in flow produce a proportional reduction in velocity. Because blood is a non-Newtonian fluid, a decrease in flow and velocity causes an increase in viscosity. These changes create an environment that favors thrombosis; the changes are amplified until complete aneurysmal thrombosis occurs. In our study, it appears that packing does not play an important role. Recently, Goddard et al (19), in a series of 22 small (
7 mm) aneurysms with a mean duration of follow-up of 30 months, have shown that lesions treated with a single coil achieved satisfactory stability over time despite having a low average packing. The fact that we did not find a lower limit of packing above which reopening does not occur indicates that a dense coil mesh is not the sole prerequisite to ensure that the subsequent biologic mechanisms leading to occlusion will be effective. In many instances of recurrence, coil compaction does not occur, but coil placement is not sufficient to prevent the aneurysm from continuing to grow despite an initial total occlusion.
Our series was, by definition, biased and thus limited in that only aneurysms treated selectively were included. However, few lesions for which the primary EVT was parent vessel sacrifice were excluded because the recurrence issue does not apply to this subgroup of aneurysms.
Even if in France EVT is considered the first treatment option, many ruptured aneurysms surrounded by compressive hematomas were treated with surgery and were not referred to us for EVT. The majority of the lesions included were small, and, consequently, our results cannot serve in drawing conclusions for larger aneurysms.
Despite improvements in coil design, aneurysm EVT with coils is still followed by recurrence in 28.6% of aneurysms; these recurrences are sizable in 5.5% of aneurysms. More angiographic recurrences can be detected over time. Complex coils do not augment aneurysm packing, and packing does not play a critical role in the recurrence rate.
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ADVANCES IN KNOWLEDGE
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- Endovascular treatment of intracranial aneurysms with bare platinum coils is still followed by recurrence in 28.6% of cases, despite improved coil design.
- More angiographic recurrences can be detected over time.
- Complex coils do not augment aneurysm packing.
- Packing does not play a critical role in recurrence rate.
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ACKNOWLEDGMENTS
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The authors thank Wim N. Makel, BS, (Clinical Research Facilities International, Schaijk, the Netherlands) for his instrumental help in the generalized estimating equations analysis.
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FOOTNOTES
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Abbreviations: EVT = endovascular treatment • 3D = three-dimensional
Authors stated no financial relationship to disclose.
Author contributions: Guarantors of integrity of entire study, M.P., J.M.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, M.P.; clinical studies, all authors; statistical analysis, M.P.; and manuscript editing, M.P.
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ABSTRACT
INTRODUCTION
