BACKGROUND:
The anterior communicating artery (AcoA) is the most common location for intracranial aneurysms.
OBJECTIVE:
To present occlusion outcomes, complication rate, recurrence rate, and predictors of recurrence in a large cohort with AcoA aneurysms treated primarily with endosaccular embolization. We also attempt to present data on the most effective treatment modality for recurrent AcoA aneurysms.
METHODS:
This is a retrospective, single-center study, reviewing the outcomes of 463 AcoA aneurysms treated endovascularly between 2003 and 2018.
RESULTS:
The study cohort consisted of 463 patients. Adequate immediate occlusion was achieved in 418 (90.3%). Independent functional status at discharge was observed in 269 patients (58.0%), and the mortality rate was 6.8% (31). At 6 months, adequate occlusion was achieved in 418 (90.4%). Of all the patients, recurrence was observed in 101 cases (21.8%), and of those, 98 (22.4%) underwent retreatment. The combined frequency of retreatment for the coiling group was 42.4%, which was significantly higher than the 0 incident of retreatment in the clipping group (P < .0001). Among the retreatment cohort, there was a significantly higher subsequent retreatment rate in the endovascular group (0% in the clipping group vs 42.4% in the endovascular group, P < .0001).
CONCLUSION:
Coiling with and without stent/balloon assistance is a relatively safe and effective modality for the treatment of AcoA aneurysms; however, in the setting of recurrence, microsurgical reconstruction leads to improved outcomes regarding durable occlusion, thus avoiding the potential for multiple interventions in the future.
KEY WORDS: Aneurysm, Microsurgical reconstruction, Endovascular embolization, Recurrence, Anterior communicating artery
ABBREVIATIONS:
- EVT
endovascularly treated
- ISUIA
International Study of Unruptured Intracranial Aneurysms.
Endovascular treatment of ruptured brain aneurysms has become more prevalent in the last decade. This shift in practice occurred following the International Subarachnoid Aneurysm Trial (ISAT), showing that endovascular treatment effectively prevents aneurysm rerupture and is associated with favorable outcomes compared with clipping at 1-year follow-up.1,2 The ongoing dilemma is identifying the most effective treatment modality of unruptured or recurrent aneurysms that achieves durable, long-term results.3 Moreover, despite extensive advancements in endovascular devices, minimal improvement in complete occlusion rates has been achieved.4-11 It is imperative to have an accurate representation of populations at high risk of recurrence meriting strict follow-up and retreatment.
The anterior communicating artery (AcoA) is the most common location for intracranial aneurysms, and their rupture in this location accounts for approximately 40% of aneurysmal subarachnoid hemorrhage (SAH) in adults.12-15 In this article, we present occlusion outcomes, complication rate, recurrence rate, and predictors of recurrence in a large cohort with AcoA aneurysms treated primarily with endosaccular embolization. We also attempt to present data on the most effective treatment modality for recurrent AcoA aneurysms.
METHODS
This is a retrospective, single-center study, reviewing the outcomes of 463 AcoA aneurysms treated endovascularly between 2003 and 2018. The inclusion criteria included (1) AcoA aneurysms treated primarily endovascularly with simple coils with or without adjunctive techniques and (2) both ruptured and nonruptured status. The exclusion criterion was failed treatment attempt primarily and patients who underwent clipping as the initial modality of treatment.
The study protocol was reviewed and approved by the institutional review board. The institutional review board waived the patient's consent because of the study design. The method section is available as Supplemental Digital Content, http://links.lww.com/NEU/C880.
Data Sharing Statement
The relevant anonymized patient-level data are available on reasonable request from the authors.
RESULTS
Participants
The study cohort consisted of 463 patients with a mean age of 55.6 ± 12.7 years, 95% CI 55.4 to 58.0, and 249 (53.7%) were female. Regarding comorbidities, 272 patients (58.8%) suffered from hypertension, and 175 (37.7%) were smokers. Three hundred sixty-nine aneurysms (79.7%) were ruptured, and of those aneurysms, 110 (29.8%) were high-grade H&H (Table 1A).
TABLE 1A.
Baseline Patient's Characteristics
| Variables | N (%) Mean (SD, 95% CI, range) |
|---|---|
| Total no. of patients | 463 |
| Sex (female) | 249 (53.7) |
| Age | 55.6 ± 12.7, 55.4-58.0, 20-90 |
| Hypertension | 272 (58.8) |
| Smoker | 175 (37.7) |
| Ruptured | 369 (79.7) |
| Hunt and Hess scale | |
| Low grade | 259 (70.2) |
| High grade | 110 (29.8) |
SD, standard deviation.
Aneurysm Characteristics
AcoA anatomy was normal in 276 patients (59.7%). One hundred fifty-eight patients (34.1%) had A1 hypoplasia, 11 (2.4%) had azygous A1, 8 (1.7%) had bihemispheric A1, 4 (0.9%) had a trifurcated A1, 4 (0.9%) were asymmetric AcoA, and finally 1 (0.2%) had a fenestrated A1 and 1 (0.2%) had an accessory AcoA.
Concerning the dome orientation, 264 aneurysms (57.1%) pointed superiorly and 427 (92.3%) pointed anteriorly. Most aneurysms had a saccular morphology 439 (94.6%), while the remaining were in the following distributions: 15 (3.2%) were fusiform, 7 (1.5%) were dissected, and 2 (0.5%) were blister. Similarly, the majority (371% and 80.2%) had a regular dome wall.
Regarding aneurysm dimensions, the median largest diameter was 5.0 ± 3.1 mm. The median neck size was 2.6 ± 0.9 mm, the median dome size was 4.3 ± 2.3 mm, and the median dome to neck ratio was 1.6 ± 0.8. Stratifying aneurysm sizes based on the International Study of Unruptured Intracranial Aneurysms (ISUIA) Investigators trial, 367 aneurysms (79.2%) were less than 7 mm, 85 (18.4%) were between 7 and 12 mm, 10 (2.2%) were between 13 and 24 mm, and 1 (0.2%) was larger than 25 mm (Table 1B).
TABLE 1B.
Baseline Aneurysm Characteristics
| Variables | N (%) median ± SD | |
|---|---|---|
| Total no. of patients | 463 | |
| Anatomy | ||
| Normal | 276 (59.7) | |
| A1 hypoplasia | 158 (34.1) | |
| Azygous | 11 (2.4) | |
| Bihemispheric | 8 (1.7) | |
| Asymmetric ACOM complex | 4 (0.9) | |
| Trifurcation | 4 (0.9) | |
| Fenestrated | 1 (0.2) | |
| Accessory ACOM | 1 (0.2) | |
| Orientation | ||
| Superior | 264 (57.1) | |
| Inferior | 199 (42.9) | |
| Orientation | ||
| Anterior | 427 (92.3) | |
| Posterior | 36 (7.8) | |
| Form | ||
| Saccular | 439 (94.6) | |
| Fusiform | 15 (3.2) | |
| Dissecting | 7 (1.5) | |
| Blister | 2 (0.5) | |
| Dome wall | ||
| Regular | 371 (80.2) | |
| Irregular | 92 (19.8) | |
| Largest dimension (mm) | 5.0 ± 3.1 | |
| Neck size (mm) | 2.6 ± 0.9 | |
| Dome size (mm) | 4.3 ± 2.3 | |
| Dome to neck ratio | 1.6 ± 0.8 | |
| Size according to ISUIA (mm) | ||
| <7 | 367 (79.2) | |
| 7-12 | 85 (18.4) | |
| 13-24 | 10 (2.2) | |
| >25 | 1 (0.2) | |
ACOM, anterior communicating artery; ISUIA, International Study of Unruptured Intracranial Aneurysms; SD, standard deviation.
Treatment Characteristics, Complications, Length of Hospital Stay, and Functional Status
The initial modality of treatment was simple coiling in 402 aneurysms (86.8%), balloon-assisted coiling in 50 aneurysms (10.9%), and stent-assisted coiling in 11 cases (2.4%). Occlusion right after treatment per modified Raymond Roy Classification were as such; 276 (59.6%) grade I, 142 (30.7%) grade II, 35 (7.6%) grade IIIa, and 10 (2.1%) grade IIIb.
The median length of hospital stay was 14.5 + 12.5 days. Complications were observed in 88 cases (19.1%). Independent functional status at discharge was observed in 269 patients (58.0%), and the mortality rate was 6.8 (31%) (Table 1C).
TABLE 1C.
Treatment Characteristics, Immediate Occlusion Outcome, and Morbidity and Mortality
| Variables | N (%) median ± SD |
|---|---|
| Total no. of patients | 463 |
| Initial modality of treatment | |
| Simple coiling | 402 (86.7) |
| Balloon-assisted coiling | 50 (10.9) |
| Stent-assisted coiling | 11 (2.4) |
| Immediate modified Raymond–Roy classification | |
| Class I | 276 (59.6) |
| Class II | 142 (30.7) |
| Class IIIa | 35 (7.6) |
| Class IIIb | 10 (2.1) |
| Complications | 88 (19.1) |
| Length of stay (d) | 14.5 ± 12.5 |
| >15 | 235 (50.8) |
| <15 | 228 (49.2) |
| Modified Rankin Scale at discharge | |
| 0-2 | 269 (58.0) |
| 3-6 | 194 (42.0) |
| Mortality | 31 (6.8) |
SD, standard deviation.
Angiographic and Functional Outcome at Follow-up and Recurrence Rate
The median duration of follow-up was 7 months ± 84. Independent functional outcome at 90 days was observed in 377 patients (81.4%). Angiographic outcomes at 6 months per mRRC were according to the following: 285 (61.6%) grade I, 133 (28.8%) grade II, 28 (6.1%) grade IIIa, and finally 16 (3.5%) grade IIIb.
Of all the patients, recurrence was observed in 101 cases (21.8%), and of those, 98 (22.4%) underwent retreatment. Of all 463 aneurysms, 365 patients (78.8%) required a single treatment, 75 (16.2%) required 2 treatments, 18 (3.8%) required 3 treatments, 4 (0.9%) required 4 retreatments, and 1 patient required 5 treatments (0.2%). The final modality of retreatment consisted of clipping in 46 patients (48.9%), coiling in 22 (23.4%), coiling then clipping in 16 (17.0%), balloon-assisted coiling in 3 (3.2%), and stent-assisted coiling in 7 cases (7.4%). Of all retreatments, clipping was the final modality of retreatment in 62 cases (70.6%). The morbidity rate was 1.5 (2%) in the retreated group (Table 1D).
TABLE 1D.
Angiographic and Functional Outcome at Follow-up and Recurrence Rate
| Variables | N (%) median ± SD |
|---|---|
| Total no. of patients | 463 |
| Time to follow-up (mo) | 7 ± 84 |
| Modified Rankin Scale at 3 mo | |
| 0-2 | 377 (81.4) |
| 3-6 | 86 (18.6) |
| Modified Raymond–Roy classification at 6 mo | |
| Class I | 285 (61.6) |
| Class II | 133 (28.8) |
| Class IIIa | 28 (6.1) |
| Class IIIb | 16 (3.5) |
| Recurrence | 101 (21.8) |
| Final modality of retreatment (n = 94)a | |
| Clipping | 46 (48.9) |
| Coiling | 22 (23.4) |
| Coiling/balloon-assisted coiling then clipping | 16 (17.0) |
| Balloon-assisted coiling | 3 (3.2) |
| Stent-assisted coiling | 7 (7.4) |
| Clipping as final modality of retreatment | 62 (70.6) |
| Total no. of treatments | |
| 1 | 365 (78.8) |
| 2 | 75 (16.2) |
| 3 | 18 (3.8) |
| 4 | 5 (0.9) |
| 5 | 1 (0.2) |
| Complication of retreatment (n = 128) | 2 (1.56) |
SD, standard deviation.
Four procedures failed.
The total number of patients who required retreatment was 98, and they underwent 128 procedures (Figure). From the 128 procedures, 62 (48.4%) were clipping, 55 (42.9%) were simple coiling, 7 (5.4%) were stent-assisted coiling, and 4 (3.1%) were balloon-assisted coiling (baseline and aneurysm characteristics of patients requiring retreatment are summarized in Table 2A). Patients were followed up using digital subtraction angiography at 6 months after retreatment. The combined frequency of retreatment for the coiling group (simple coiling, stent-assisted coiling, and balloon-assisted coiling) was 42.4%, which was significantly higher compared with the 0 incident of retreatment in the clipping group (P < .0001, odds ratio [OR]: infinity). Furthermore, there was no significant difference in major complications (0% vs 3.0%; P = .496), independent functional outcome at the latest follow-up (40, 95.2% vs 21, 84.0%; P = .185), and follow-up duration (52.12 + 35.7 months vs 45.2 + 40.9 months; P = .446) (Table 2B). Outcomes and complication rates were compared between patients presenting with ruptured vs unruptured aneurysms (Table 2C).
TABLE 2A.
Baseline and Aneurysm Characteristics of Patients Requiring Retreatment
| Retreated with coiling | Retreated with clipping | |
|---|---|---|
| Total no. of patients | 25 | 46 |
| Total no. of procedures | 55 | 62 |
| Age | 58.1 ± 9.9, CI: 54.1-62.1, 28-84 | 49.7 ± 10.8, CI: 46.9-52.6, 24-78 |
| Sex (female) | 12 (48) | 32 (70) |
| Hypertension | 17 (68) | 39 (84.8) |
| Smoker | 15 (60) | 26 (56.5) |
| Aneurysm form | ||
| Saccular | 25 (100) | 42 (91.3) |
| Nonsaccular | 0 (0) | 4 (8.7) |
| Aneurysm orientation | ||
| Superior | 9 (36) | 32 (69.6) |
| Inferior | 16 (64) | 14 (30.4) |
| Aneurysm orientation | ||
| Anterior | 22 (88) | 34 (73.9) |
| Posterior | 3 (12) | 12 (26.1) |
| Dome wall | ||
| Smooth | 20 (80) | 40 (87) |
| Irregular | 5 (20) | 6 (13) |
| Maximum diameter (mm) | 6.5 ± 2.8, CI: 5.4-7.7, 2.6-13 | 5.6 ± 2.2, CI: 5.0-6.2, 1.9-11 |
| Neck size (mm) | 2.9 ± 1.1, CI: 2.4-3.4, 1.3-5 | 2.9 ± 0.8, CI: 2.6-3.1, 1.4-5.3 |
| Dome size (mm) | 5.4 ± 2.6, CI: 4.2-6.7, 2.5-10.7 | 5.0 ± 1.9, CI: 4.4-5.5, 1.7-11 |
| Dome to neck ratio | 2.0 ± 0.9, CI: 1.6-2.4, 0.8-3.5 | 1.8 ± 0.8, CI: 1.6-2.0, 0.6-3.8 |
| Aneurysm status | ||
| Ruptured | 18 (72) | 42 (91.3) |
| Unruptured | 7 (28) | 4 (8.7) |
| Hunt and Hess Grade | ||
| 1-3 | 21 (84) | 38 (82.6) |
| 4-5 | 4 (16) | 8 (17.4) |
TABLE 2B.
Efficacy and Safety of the Retreatment Modality (Total No. of Patients is 98)
| Clipping (N = 62) | Coiling (N = 66) | P-value | Odds ratio | |
|---|---|---|---|---|
| Retreatment | 0 (0) | 28 (42.4) | <.0001a | Infinity |
| Major complications | 0 (0) | 2 (3.0) | .496 | |
| mRS 0-2b | 40 (95.2) | 21 (84.0) | .185 | |
| Follow-up duration (mo)b | 52.12 + 35.7 | 45.2 + 40.9 | .446 |
mRS, Modified Rankin Score.
Significant value P < .05.
Based on the final modality of treatment.
TABLE 2C.
Comparison of Outcomes Between Patients Presenting With Ruptured vs Unruptured Aneurysms
| Ruptured aneurysms N (%) mean (SD, 95% CI, range) |
Unruptured aneurysms N (%) mean (SD, 95% CI, range) |
|
|---|---|---|
| Total no. of patients | 369 | 114 |
| Complication rates | 81 (22) | 7 (6.1) |
| Immediate modified Raymond–Roy classification | ||
| Class I | 232 (62.9) | 61 (53.5) |
| Class II | 115 (31.2) | 33 (28.9) |
| Class IIIa | 16 (4.3) | 15 (13.2) |
| Class IIIb | 6 (1.6) | 5 (4.4) |
| Modified Rankin Scale | ||
| 0-2 | 184 (49.9) | 92 (80.7) |
| 3-6 | 185 (50.1) | 22 (19.3) |
| Modified Rankin Scale at 6 mo | ||
| 0-2 | 233 (63.1) | 93 (81.6) |
| 3-6 | 136 (36.9) | 21 (18.4) |
| Recurrent (yes) | 91 (24.7) | 12 (10.5) |
SD, standard deviation.
FIGURE.
Diagram tree showing the division of retreatment modalities of the 98 patients with anterior communicating artery aneurysms who were initially coiled and then required one or more retreatments. BAC, balloon-assisted coiling; SAC, stent-assisted coiling.
Univariate and Multivariate Predictors of Aneurysm Recurrence
On univariate analysis, variables associated with aneurysm recurrence were younger age (OR: 1.0; 95% CI: 0.9-1.0; P = <.001) and smoking status (OR: 1.8; 95% CI: 1.2-2.9; P = .010). Variables associated with protection from recurrence were unruptured aneurysm status (OR: 0.4; 95% CI: 1.1-4.2; P = .029) and balloon-assisted coiling as a primary treatment (OR: 0.3; 95% CI: 0.1-0.9; P = .030).
On multivariate analysis, hypertension (OR: 1.9; 95% CI: 1.1-3.5; P = .031) and increasing aneurysm size (OR: 2.0; 95% CI: 1.1-3.6; P = .026) were independent predictors of aneurysm recurrence. On the other hand, unruptured aneurysm status (OR: 0.3; 95% CI: 0.2-0.7; P = .031), balloon-assisted coiling as a primary treatment (0.2; 95% CI: 0.04-0.9; P = .034), and increasing age (OR: 1.0; 95% CI: 0.9-1.0; P = .016) were independent predictors of protection against aneurysm recurrence (Table 3).
TABLE 3.
Univariate and Multivariate Predictors of Aneurysm Recurrence
| Variable | Univariate | Multivariate | ||||
|---|---|---|---|---|---|---|
| OR | 95% CI | P-value | OR | 95% CI | P-value | |
| Sex | 1.2 | 0.7-1.8 | .491 | |||
| Age | 1.0 | 0.9-1.0 | <.001a | 1.0 | 0.9-1.0 | .016a |
| Hypertension | 1.4 | 0.9-2.3 | .141 | 1.9 | 1.1-3.5 | .031a |
| Smoker | 1.8 | 1.2-2.9 | .010a | |||
| Anatomy | 1.2 | 0.8-1.9 | .406 | |||
| Orientation (superior) | 0.8 | 0.5-1.3 | .345 | |||
| Orientation (anterior) | 0.9 | 0.3-2.2 | .764 | |||
| Saccular | 0.7 | 0.3-1.8 | .432 | |||
| Wall (irregular) | 0.9 | 0.5-1.7 | .763 | |||
| Size ISUIA | 1.4 | 0.9-2.2 | .101 | 2.0 | 1.1-3.6 | 0.026a |
| Neck (mm) | 1.2 | 0.9-1.5 | .188 | |||
| Dome (mm) | 1.1 | 1.0-1.2 | .166 | |||
| Dome to neck ratio | 1.1 | 0.8-1.5 | .600 | |||
| Unruptured | 0.4 | 1.1-4.2 | .029a | 0.3 | 0.2-0.7 | 0.031a |
| Balloon used | 0.3 | 0.1-0.9 | .030a | 0.2 | 0.04-0.9 | 0.034a |
| Stent used | 1.5 | 0.4-5.9 | .534 | |||
ISUIA, International Study of Unruptured Intracranial Aneurysms; OR, odds ratio.
Significant value P < .05.
DISCUSSION
Key Results
AcoA aneurysms are the most common cerebral aneurysms comprising 30% of all intracranial aneurysms and accounting for 40% of all SAH presentations.6,10,16-20 In this article, we present occlusion outcomes, complication rates, recurrence rates, and predictors of recurrence in a large AcoA aneurysm cohort treated primarily with endosaccular embolization. The primary observation was that although close to 80% were ruptured aneurysms, adequate aneurysm occlusion at 6 months was achieved in 90.4%, a stable figure compared with immediate occlusion. One in every 5 patients developed a complication, or a recurrence, or required retreatment. It is essential to note that although the rate of recurrence was high, the need for retreatment did not affect the rate of morbidity or mortality. Of the entire cohort, 16.2% of the patients required a total of 2 treatment sessions, 3.8% required a total of 3 treatment sessions, 0.9% required a total of 4 treatments, and 1 patient (0.2%) required a total of 5 treatment sessions. In the retreatment cohort, there were a total of 98 patients who underwent 128 retreatment procedures. For every 10 patients requiring retreatment, 7 received clipping, and this includes patients who underwent coiling as the initial modality of retreatment. The rate of retreatment was 0% in the clipped cohort (62), while the rate was 42.4% in patients who underwent coiling as a retreatment approach (P < .0001). Increasing aneurysm size and the presence of hypertension were independent predictors of aneurysm recurrence. Increasing age, unruptured status, and the use of a balloon-assisted treatment were protective against aneurysm recurrence.
Interpretation
ISAT reported the angiographic outcomes for ruptured aneurysms treated endovascularly. At the first follow-up, complete aneurysm occlusion was achieved in 66% and neck remnant or subtotal occlusion in 26%. AcoA aneurysms constituted 45.4% of the entire ISAT cohort.21 In addition, Raymond et al22 reported early and long-term angiographic outcomes for a large series of aneurysms treated endovascularly with coils. Complete and adequate occlusions at early and late follow-ups were 44.6% and 85.7% and 38.3% and 83.8%, respectively. It is crucial to note that their series represents early experience with coils covering a period between 1992 and 2002, meaning 2 decades ago. However, such metrics are an important reference point to compare our outcomes with, considering the accrual of experience and improvement in tools in treating aneurysms over the past 2 decades. Fang et al10 completed a meta-analysis compiling 1552 AcoA aneurysms treated endovascularly. Adequate aneurysm occlusion immediately was 88% (95% CI: 81%-93%) and at 6 months was 85% (95% CI = 78%-90%). Such figures, including our series, highlight that 2 of every 10 patients treated endovascularly will not have an adequate aneurysm occlusion, and 4 of every 10 patients will not have complete aneurysm occlusion at follow-up. More importantly, even after 2 decades after the introduction of the detachable coils and the aggregate of experience and product development, minimal improvement in complete occlusion rates has been attained.4-11
It is of paramount importance to achieve superior outcomes, especially that AcoA aneurysms are the most common intracranial aneurysms.12-15 There are 3 variables that play a critical role in achieving superior outcomes—some are general and others are particular to the AcoA location. First, the treatment objective differs in treating ruptured and unruptured aneurysms. In the acute setting, the primary goal is to protect the aneurysm dome at least to prevent rebleeding, have a close follow-up, and stage the treatment to achieve complete occlusion, especially if the patient presented with a high-grade H&H. Second, the location and the peculiar anatomy of the AcoA complex pose a distinctive set of challenges compared with other locations for both surgery and endovascular treatment.19,21,23-25 Such challenges are attributed to the significant proportion of small aneurysm size (<3 mm), which is challenging to embolize using coils, complex anatomy (35% of cases) of the AcoA complex,11,26 complex regional flow dynamics, critical perforators, and finally the challenging angles needed to be traversed to access the aneurysm.11,26 Third, the applicability of adjunctive techniques to achieve higher occlusion rates is limited due to the presence of a ruptured aneurysm where the operator would avoid using a stent-assisted technique in a ruptured situation.27-29 Despite that, the past 2 decades have witnessed a spur in the development of coils, microwires, microcatheters, and stents, thereby allowing enhanced tractability, conformability, and improved deployment accuracy.27-30 In addition, the ability to place a 3- to 4.5-mm diameter stent using an 0.017-in catheter allowed interventionalists to push the envelope and have the upper hand in distal and cross-circulation approaches.30 In our series, adjunctive techniques as the initial modality of treatment were used only in 13.3% of the entire cohort (10.9% balloon-assisted and 2.4% stent-assisted).
An episode of SAH puts a patient at 22-fold higher risk of rebleeding compared with the general population.31 In addition, the Cerebral Aneurysm Rerupture After Treatment (CARAT) study has not only shown that the degree of aneurysm occlusion after initial coiling is a strong predictor of the risk of subsequent rupture, with a 2.9% risk in cases with 91% to 99% aneurysm occlusion, but there is also a higher risk of rupture when aneurysm occlusion is <90% (5.9%-17.6%).32 In our series, only 4 of every 10 patients (59.6%) had complete immediate occlusion, and 2 of every 10 had recurrence requiring retreatment (19.8%). Therefore, a significant proportion of treated patients were at risk of developing a rebleed whether because of aneurysm recurrence or incomplete initial occlusion. The rate of aneurysm recurrence in our series is in concordance with reported figures in the literature.2,6,7,9,19,20,33 Raymond and Roy2 reported a major recurrence rate of 20.7% and a 39.8% for ruptured aneurysms. Moreover, studies that included AcoA reported a recurrence rate ranging from 14.6% to 37.5%.6,7,9,19,20,33 In a meta-analysis about AcoA aneurysms, the rate of retreatment was 7% (95% CI = 5%-12%), and unexpectedly, no difference between ruptured and nonruptured aneurysms was observed.10 It is essential to identify the features that increase the risk of aneurysm recurrence, and as such, it may be best to tailor the follow-up for those patients to intervene early when necessary and decrease the risk of rebleeding. In our series and previous studies,19,34,35 the presence of hypertension, younger age, rupture status, large aneurysm size, and the use of simple coiling were independent predictors of aneurysm recurrence. Surprisingly, our study did not show an association between aneurysm orientation and rate of recurrence.10
It has been firmly established by ISAT that the endovascular approach is superior compared with microsurgery for ruptured aneurysms for functional dependence and mortality at the 1-year follow-up.21 However, this evidence cannot be extrapolated to unruptured or recurrent aneurysms, and we still lack high-level evidence to guide management in those cases. Moreover, the issues of cost-effectiveness in the short term and long term were overlooked by ISAT. Coiling achieves inferior occlusion rates compared with microsurgical clipping, leading to higher retreatment rates (ISAT hazard ratio 6.9 in coiling compared with clipping—early-stage retreatment: 8.8% endovascular vs 2.9% microsurgical and late-stage retreatment: 8.6% endovascular vs 0.9% microsurgical).14,21 Moreover, the 5-year follow-up data from the ISAT showed that functional dependence was no longer significantly different between both groups. There is a higher rebleeding frequency in patients treated endovascularly than those treated surgically (3.3% vs 1.2%).14 The Cooperative Study of Intracranial Aneurysms and Subarachnoid Hemorrhage reported a rebleeding rate at 1.4% per year.36,37
Generalizability
In this study, the recurrence rate was 21.8%, and the retreatment rate was 21.1%. Among the retreatment cohort, there was a significantly higher subsequent retreatment rate in the endovascular group (0% in the clipping group vs 42.4% in the endovascular group, P < .0001). Such figures substantiate that the ISAT conclusions cannot and should not be generalized to nonruptured or recurrent aneurysms. Tailored treatment plans that exhaust all options should be used in every patient to achieve the best outcome. In the acute setting, balloon-assisted or simple coiling is optimal to achieve effective and safe outcomes. However, for recurrent aneurysms, microsurgical reconstruction was found to achieve better outcomes when compared with the endovascular approach although it poses challenges of its own.38 It is critical to note that we grouped simple coiling with adjunctive coiling, which was 11 cases in total, and 1 patient had a failed attempt, and one had a recurrence. This is of paramount importance because it is well-established that adjunctive coiling achieves superior outcomes compared with simple coiling.15
Limitations
We acknowledge that this study has several limitations, one of which is its retrospective nature. Another limitation is operator bias in choosing clipping or other modalities of retreatment in cases of recurrence. Lastly, follow-up duration was midterm and long-term follow-up might be necessary to further assess outcomes.
CONCLUSION
In the setting of recurrence, microsurgical reconstruction leads to improved outcomes regarding durable occlusion, thus avoiding the potential for multiple interventions in the future. Patients presenting with young age, presence of hypertension, ruptured aneurysms, large aneurysm size, or treatment through simple coiling are at high risk of aneurysm recurrence.
Footnotes
Supplemental digital content is available for this article at neurosurgery-online.com.
Ahmad Sweid and Kareem El Naamani contributed equally to this work.
Funding
This study did not receive funding or financial support. Dr Starke is supported by the NREF, Joe Niekro Foundation, Brain Aneurysm Foundation, Bee Foundation, and by the National Institute of Health (UL1TR002736, KL2TR002737) through the Miami Clinical and Translational Science Institute from the National Center for Advancing Translational Sciences and the National Institute on Minority Health and Health Disparities. Its contents are solely the authors' responsibility and do not necessarily represent the official views of the NIH.
Disclosures
Dr Jabbour is a consultant for Medtronic, MicroVention, Cerus Endovascular, and Balt. Dr Tjoumakaris is a consultant for Medtronic and MicroVention. Dr Gooch is a consultant for Stryker. Dr Starke has consulting and teaching agreements with Penumbra, Abbott, Medtronic, InNeuroCo, and Cerenovus. The other authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.
Supplemental Digital Content
Supplemental Digital Content. Methods and limitation section.
COMMENTS
Of the 463 anterior communicating artery aneurysms treated primarily with endovascular coiling at the authors' institution, recurrence was observed in 101 (21.8%) cases, and of those, 98 (22.4%) underwent retreatment. The combined frequency of retreatment for the coiling group (simple coiling, stent-assisted coiling, and balloon-assisted coiling) was 42.4%, which was significantly higher compared to the zero incident of retreatment in the clipping group (P < .0001, OR: infinity). On multivariate analysis, hypertension and increasing aneurysm size were independent predictors of aneurysm recurrence. On the other hand, unruptured aneurysm status, balloon-assisted coiling as a primary treatment, and increasing age were independent predictors of protection against aneurysm recurrence.
The salient conclusion from this manuscript is that microsurgical expertise remains valuable in order to provide the best possible care to patients who suffer from anterior communicating artery aneurysms, the most common location for both unruptured and ruptured aneurysms. Although such technical expertise may no longer be as widespread in the neurosurgical armamentarium as endovascular expertise has become widely disseminated, concentrated training of neurosurgeons with advanced microsurgical skills remains essential. The inherent variability of aneurysms with respect to morphology and natural history demands a varied skillset to optimize patient outcome.
Shahab Sattari
Judy Huang
Baltimore, Maryland, USA
The authors present a single-center retrospective series of 463 patients with primarily endovascularly treated (EVT) unruptured and ruptured ACoA aneurysms with a median angiographic follow-up of only 7 months. Aneurysm recurrence was observed in 101 out of 463 patients (22%), and of these, 98 patients underwent retreatment (clipping as the final modality in 71% and EVT in 29%). They conclude that retreatment by clipping may reduce the need for multiple EVT. This is an interesting study, but why so many of the aneurysms recurred and so quickly, and why were almost half of the cases initially reoperated on and not by re-EVT which may be easier? At our department, the retreatment rate after EVT for unruptured ACoA aneurysm is only 4% (median follow-up 5 years, unpublished data), and the cross-over rate from EVT to clipping is nowadays almost nonexisting.
The goal should be total exclusion of the aneurysm, but small remnants seem to behave differently in ruptured and unruptured aneurysms and depend also on the primary treatment method, location, and external risk factors. Typically, in unruptured cases, a remnant may be only followed up as these tend to remain stable, or if needed, effectively retreated by EVT. In ruptured aneurysms, even incomplete EVT seems to protect from rerupture probably due to thrombosis, aneurysm wall, and flow characteristics. Clipping of previously EVT-treated aneurysms may be a true challenge due to scarring and decreasing surgical experience and should carefully be weighed against the somewhat undefined natural history of remnants.
Rahul Raj
Ville Nurminen
Mika Niemelä
Helsinki, Finland
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Supplemental Digital Content. Methods and limitation section.