Thromboembolic complications with Pipeline Embolization Device placement: impact of procedure time, number of stents and pre-procedure P2Y12 reaction unit (PRU) value

Intraluminal Flow Diverter Design Primer for Neurointerventionalists

The clinical use of flow diverters for the treatment of intracranial aneurysms has rapidly grown. Consequently, the market and technology for these devices has also grown. Clinical performance characteristics of the flow diverter are well-known to the clinician. However, the engineering design principles behind how these devices achieve ideal clinical performance are less understood. This primer will summarize flow diverter design parameters for neurointerventionalists with the aim of promoting collaboration between clinicians and engineers.

Impact of hemodialysis on efficacies of the antiplatelet agents in coronary artery disease patients complicated with end-stage renal disease

It is controversial whether hemodialysis affects the efficacy of the antiplatelet agents. We aimed to investigate the impact of hemodialysis on efficacies of the antiplatelet agents in coronary artery disease (CAD) patients complicated with end-stage renal disease (ESRD). 86 CAD patients complicated with ESRD requiring hemodialysis were consecutively enrolled. After 5-day treatment with aspirin and clopidogrel or ticagrelor, the platelet aggregations induced by arachidonic acid (PLAA) or adenosine diphosphate (PLADP), and the P2Y12 reaction unit (PRU) were measured before and after hemodialysis. The propensity matching score method was adopted to generate a control group with normal renal function from 2439 CAD patients. In patients taking aspirin, the PLAA remained unchanged after hemodialysis. In patients taking clopidogrel, the PLADP (37.26 ± 17.04 vs. 31.77 ± 16.09, p = 0.029) and corresponding clopidogrel resistance (CR) rate (23 [48.9%] vs. 14 [29.8%], p = 0.022) significantly decreased after hemodialysis, though PRU remained unchanged. Subgroup analysis indicated that PLADP significantly decreased while using polysulfone membrane (36.8 ± 17.9 vs. 31.1 ± 14.5, p = 0.024). In patients taking ticagrelor, PLADP, and PRU remained unchanged after hemodialysis. ESRD patients had higher incidences of aspirin resistance (AR) and CR compared to those with normal renal function (AR: 16.1% vs. 0%, p = 0.001; CR: 48.4% vs. 24.8%, p = 0.024). Hemodialysis does not have negative effect on the efficacies of aspirin, clopidogrel and ticagrelor in ESRD patients with CAD. ESRD patients have higher incidences of AR and CR compared with those with normal renal function.Trial registration ClinicalTrials.gov Identifier: NCT03330223, first registered January 4, 2018.

Diffusion-weighted imaging lesions after intracranial aneurysm treatment with Pipeline Flex and Pipeline Flex with Shield technology: a retrospective cohort analysis

BACKGROUND

The Pipeline Flex embolization device with Shield technology (PED Shield) is the first flow diverter for brain aneurysm treatment approved in the United States using surface-modified technology. The effect of PED Shield on decreasing perioperative diffusion-weighted imaging positive (DWI+) hits, as a marker for in-human decrease thrombogenicity, is unclear.

OBJECTIVE

To determine if the number of periprocedural DWI+ lesions differs between patients with an aneurysm treated with PED Flex and PED Shield.

METHODS

This retrospective study compares the outcomes of consecutive patients with an aneurysm treated with PED Flex and PED Shield. The primary outcome of interest was the occurrence of DWI+ lesions. We also assessed potential predictors of DWI+ lesions and compared the outcomes between on-label and off-label treatment indications.

RESULTS

89 patients were included, 48 (54%) treated with PED Flex and 41 (46%) with PED Shield. After matching, the incidence of DWI+ lesions was 61% and 62% for the PED Flex and PED Shield groups, respectively. Results were consistent across each model with no significant differences in DWI+ lesions between treatment groups, and effect sizes ranging from OR=1.08 (95% CI 0.41 to 2.89) after propensity score matching to OR=1.84 (95% CI 0.65 to 5.47) after multivariable regression. Multivariable models demonstrated reduced DWI+ lesions with balloon-assisted therapies and posterior circulation treatment, while a significant linear relationship was encountered with fluoroscopy time.

CONCLUSION

There was no significant difference in the incidence of perioperative DWI+ lesions between patients with an aneurysm treated with PED Flex and PED Shield. Larger cohorts are likely needed to demonstrate differences between the devices.

Aneurysm Treatment With the Pipeline Vantage Embolization Device in Retrospective Evaluation: Periprocedural Results from the Pipe-VADER Study

OBJECTIVE

The Pipeline Vantage Embolization Device is a fourth-generation flow diverter with an antithrombotic coating and a reduced profile compared to previous Pipeline versions. The objective of this study was to evaluate the procedural feasibility, safety, and efficacy of this device.

METHODS

The Pipe-VADER study was designed as a retrospective, observational study of consecutive patients treated with the Vantage at 3 neurovascular centers. Patient and aneurysm characteristics, procedural parameters, early complications, and extent of postinterventional contrast retention were analyzed on an intention-to-treat basis.

RESULTS

Twenty-eight patients with 31 aneurysms (median size: 5.0 mm, posterior circulation: 4 [12.9%], ruptured: 5 [16.1%]) were included. The technical success rate was 100%, with multiple stents used in 4/30 (13.3%) procedures. Of the 30 procedures, adjunctive coiling was performed in 3 (10.0%) and balloon angioplasty in 2 (6.7%). Median procedure time was 62 minutes. Procedural ischemic stroke occured in 4 (13.3%) cases, whereof 2 were major strokes (6.6%). There were no hemorrhagic complications. Initial contrast retention was observed in 29/31 (93.5%) aneurysms. All 27 overstented side vessels were patent at the end of the procedure. Short-term follow-up (median: 5 months) showed complete and favorable occlusion rates of 70% (14/20) and 80% (16/20), respectively.

CONCLUSIONS

The new Pipeline Vantage appears to be safe and feasible for the treatment of intracranial aneurysms and warrants further evaluation.

Efficacy and Safety of Dual Antiplatelet Therapy with the Routine Use of Prasugrel for Flow Diversion of Cerebral Unruptured Aneurysms

PURPOSE

Prasugrel is not approved for patients treated with flow diverters, which have a high metal coverage ratio. However, robust antiplatelet therapy with prasugrel may prevent thromboembolic complications. We administered prasugrel and aspirin to all patients treated with flow diverters and reported the safety of the antiplatelet therapy regimen.

METHODS

This retrospective, single-center study evaluated the angiographic and clinical data of consecutive patients treated with flow diverters for cerebral unruptured aneurysms between June 2020 and May 2022. All patients received dual antiplatelet therapy, including prasugrel and aspirin. The administration of prasugrel ended 3 or 6 months after the procedure, whereas aspirin use continued for at least 12 months. Periprocedural complications (< 30 days post-procedure) and delayed complications (> 30 days post-procedure) were recorded.

RESULTS

During the study period, 120 unruptured aneurysms were treated with flow diverters in 110 patients. All patients, except one, survived longer than 12 months after the procedure. The rate of thromboembolic complications was 6.4%, and more than half of the patients had transient symptoms; one (0.9%) had a major ischemic stroke. One patient (0.9%) each had an asymptomatic, small subarachnoid hemorrhage and significant hemorrhagic complications with melena. The rate of permanent neurological deficits was 1.8%, and the mortality rate was 0.9%.

CONCLUSIONS

Dual antiplatelet therapy comprising routine use of prasugrel and aspirin for flow diverter-implanted patients possibly contributed to a low rate of thromboembolic complications and low risk of hemorrhagic complications.

Immune Thrombocytopenic Purpura and Intracranial Stenting

Patients with immune thrombocytopenic purpura (ITP) presenting with indications for dual antiplatelet therapy (DAPT) can be difficult to manage due to the precarious balance of managing the need for increased platelet counts as well as inhibition of platelet activity. This case represents a 65 year old woman with ITP who presented with a bilateral subarachnoid hemorrhage secondary to a left ophthalmic aneurysm that required placement of a pipeline embolization device (PED) necessitating DAPT. After treatment of her ITP with pulse dexamethasone for four days, she was safely discharged on one month of DAPT with aspirin and ticagrelor then switched to aspirin monotherapy without any immediate complications. During her period of DAPT, she did not receive additional medical treatment for her ITP. This case successfully presents a high-risk ITP patient requiring DAPT for a neurosurgical procedure and illustrates that these patients can be safely and successfully treated with DAPT once their ITP is stabilized.

A Novel Braided Stent With Customized Simulation Software for Treatment of Intracranial Aneurysms: Multicenter Prospective Trial Before Unrestricted Clinical Application

BACKGROUND AND OBJECTIVES

Planning/guidance software became important tools for physicians' presurgical optimal decision-making. However, there are no intracranial stent products with specifically associated simulation software. We report the "premarket" clinical trial of a new braided stent with a customized simulation software.

METHODS

A stent system with 3 mesh density types (16, 24, and 32 wire mesh) was designed based on computational flow dynamics technology, and a simulation software (virtual stent planner [VSP]) was developed for the optimal stent deployment planning. Stents were selected after simulation on preoperative 3D-processed angioimages, and accuracy of the VSP was evaluated.

RESULTS

Thirty-three unruptured intracranial aneurysms were successfully treated with VSP guidance. Twenty aneurysms (61%) were anterior circulation aneurysms, and 13 (39%) were posterior circulation aneurysms. The average aneurysm size was 7.1 mm, and the mean follow-up period was 19.2 months (11-39.0). There was no major recurrence or retreatment during follow-up, 2 morbidity cases, and no mortality. VSP planning presented slightly smaller stent dimensions compared with postdeployment: 24.2 vs 25.5 mm average, error -1.3 mm, and difference rate-5.46%.

CONCLUSION

Based on this result, the new stents and software guidance system were approved by the Ministry of Health and Welfare as a combined medical device. VSP provided precise deployment with minimal error compared with actual stent and can contribute to better stent deployment even for less experienced physicians.

Assessing the efficacy of VerifyNow platelet-function testing in predicting postoperative thromboembolic complications of neuroendovascular surgery: A systematic review and meta-analysis (part 1)

BACKGROUND

Despite the heavily debated use of routine platelet-function testing, the VerifyNow Platelet Reactivity Unit (PRU) assay has been increasingly adopted as standard of care for assessing risk of postoperative thromboembolic complications of neuroendovascular surgery.

OBJECTIVE

We conducted a systematic review and meta-analysis to examine the relationship between platelet response and risk of ischemic events from neuroendovascular surgery, assess the efficacy of point-of-care platelet-function testing in predicting thromboembolic outcomes, and assess whether a clinically useful threshold for platelet response can be defined in order to standardize guidelines.

METHODS

PubMed, Embase, and Scopus were searched. Following deduplication, articles were first screened for relevance by title and abstract, followed by full text.

RESULTS

Of 735 resultant articles, 22 studies consisting of 3266 patients undergoing neuroendovascular intervention were included. Diagnoses included both intracranial and extracranial pathologies, of which 45.8% were treated with flow diversion, 16.4% with stent-assisted coil embolization, 15.8% with intracranial stenting, 12.0% with simple coil embolization, 3.4% with balloon-assisted coil embolization, 3.6% with extracranial stenting, and 3.0% with an alternate method. 54.5% (12/22) of studies determined platelet hyporesponse to be an independent predictor of postoperative thromboembolic complications, with 27.3% (6/22) of studies reporting a similar, but non-statistically significant trend. 18.2% (4/22) of studies found no relationship between platelet response and postoperative thromboembolic complications. The estimated clinical threshold for PRU to prevent thromboembolic complications varied greatly across studies (Range: > 144-295 PRU). Meta-analysis found platelet hyporesponse to have a 2.23-fold increased risk of thromboembolic complications compared to normoresponders (RR = 2.23, P = 0.03).

CONCLUSION

While PRU demonstrates a significant predictive value for postoperative thromboembolic complications of neuroendovascular surgery, the target therapeutic threshold for minimizing ischemic events remains unclear. Further studies, such as large multicenter cohorts of the existing data, are needed to standardize guidelines.

Assessing the efficacy of VerifyNow platelet-function testing in predicting postoperative hemorrhagic complications of neuroendovascular surgery: A systematic review and meta-analysis (part 2)

BACKGROUND

Dual antiplatelet therapy is used to reduce the risk of thromboembolic complications in neuroendovascular surgery. However, the predictive utility of preoperative platelet-sensitivity testing for decreasing bleed risk in patients undergoing endovascular neurointervention remains unclear.

OBJECTIVE

We conducted a systematic review and meta-analysis to illustrate the association between platelet response and risk of hemorrhagic complications from neuroendovascular surgery, examine the efficacy of the VerifyNow platelet reactivity unit (PRU) assay in predicting hemorrhagic outcomes, and assess whether a clinically useful threshold for platelet response can be defined to standardize guidelines.

METHODS

PubMed, Embase, and Scopus were searched. Articles were screened for relevance by title and abstract, followed by full text.

RESULTS

Of 735 resultant articles, 17 studies of 2084 patients undergoing neuroendovascular intervention were included. Diagnoses included both intracranial and extracranial pathologies, of which 37.8% were treated with flow diversion, 22.4% with stent-assisted coil embolization, 14.3% with intracranial stenting, 12.8% with simple coil embolization, 5.8% with balloon-assisted coil embolization, 2.0% with extracranial stenting, and 4.8% with an alternate method. Precisely, 52.9% (9 out of 17) of studies determined platelet hyperresponse to be an independent predictor of postoperative hemorrhagic complications, with 11.8% (2 out of 17) of studies reporting a similar but non-statistically significant trend. 35.3% (6 out of 17) of studies found no relationship between platelet response and postoperative hemorrhagic complications. The estimated clinical threshold for PRU to prevent hemorrhagic complications varied considerably across studies (range: <46-118 PRU). Meta-analysis found platelet hyperresponse to have more than a 3-fold increased risk of hemorrhagic complications compared to normoresponders (relative risk = 3.2, p = 0.001).

CONCLUSION

Although this meta-analysis shows the predictive utility of the P2Y12 assay for postoperative hemorrhagic complications in neuroendovascular surgery, the optimal therapeutic threshold for minimizing bleeding risk is still uncertain. To better understand the utility of the P2Y12 assay in the perioperative period, further prospective research is needed.

Safety and efficacy analysis of the off-label use of pipeline embolization devices for intracranial aneurysms: a propensity score matching study

Background and objective

The safety and efficacy of on-label use of pipeline embolization devices (PEDs) are well established; however, there is much controversy over their off-label use. This study aimed to investigate the safety and efficacy of the off-label use of PEDs for treating intracranial aneurysms.

Methods

This single-center study retrospectively included patients with digital subtraction angiography, computed tomographic angiography, or magnetic resonance angiography confirmed intracranial aneurysms treated with PEDs who were admitted to our institution between 1 January 2018 and 1 July 2022. Patients were divided into on- and off-label groups according to the Food and Drug Administration criteria published in 2021. Propensity score matching (PSM) was used to balance disparities in baseline information between the two groups. Safety outcomes included postoperative mortality and complication rates, whereas effectiveness outcomes included aneurysm occlusion rate (O'Kelly-Marotta grading system C + D grades), retreatment rate within 12 months, and postoperative functional score [modified Rankin scale (mRS) score]. The study was approved by the Ethics Committee of Scientific Research and Clinical Trial of the First Affiliated Hospital of Zhengzhou University (Ethics number: KY 2018-098-02). All patients provided informed consent.

Results

A total of 242 patients with 261 aneurysms (160 on-label and 101 off-label aneurysms) were included in this study. PSM yielded 81 pairs of patients matched for baseline information. Postoperative hemorrhagic, ischemic, and procedure-related complication rates did not reach statistical significance. In addition, no statistically significant differences in the aneurysm occlusion rate, retreatment rate within 12 months, postoperative functional score (mRS score), or mRS score deterioration rate were observed between the two groups. A higher incidence of in-stent stenosis was observed in the off-label (4.9% vs. 21%, p = 0.002) group than in the on-label group; however, all patients were asymptomatic.

Conclusion

Compared with on-label use, off-label use of PEDs for treating intracranial aneurysms did not increase the risk of complications, and the occlusion rates were comparable. Therefore, decisions regarding clinical management should not rely solely on on- or off-label indications.

Discordance in tests used to detect inhibition of the P2Y12 receptor in patients undergoing interventional neuroradiology procedures

BACKGROUND

Clopidogrel is an inhibitor of the P2Y12 platelet receptor but testing to demonstrate a drug effect is controversial since there are often discordant results between different tests methods.

METHODS

Samples from patients taking clopidogrel prior to intracranial flow-diversion procedures were tested using light transmission aggregometry (LTA), whole blood impedance aggregometry (WBIA) and the VerifyNow device (VND). Samples were classified as concordant if all test results were either responsive (inhibition) or resistant. Discordant results were separated using the VND into those with a responsive versus a resistant test result.

RESULTS

Samples from 96 patients were studied. Concordance for all three tests was seen in 53/96 (55%) of samples, of which 41 (43%) were responsive and 12 (12%) were resistant. Discordance was observed in 43 samples (45%), 37 (28%) of which were caused by responsive VND and either a resistant WBIA or LTA and 6 (7%) of which were caused by a resistant VND but a responsive test result using either WBIA or LTA. These two discordant groups differed in both platelet count and hematocrit, but no such difference was present between the two concordant groups.

CONCLUSION

Discordance in P2Y12 inhibition testing may be partly explained by sample platelet count and hematocrit.

DWI-Detected Ischemic Lesions after Endovascular Treatment for Cerebral Aneurysms: An Updated Systematic Review and Meta-analysis

BACKGROUND AND PURPOSE

DWI-detected ischemic lesions are potential complications of endovascular procedures that are performed to treat intracranial aneurysms. We completed a systematic review and meta-analysis to identify the occurrence of DWI-detected ischemic lesions after endovascular treatment for intracranial aneurysms.

MATERIALS AND METHODS

A systematic literature search of PubMed, the Web of Science, EMBASE, and Scopus between January 2000 and June 2022 of post-endovascular procedures for intracranial aneurysm studies was conducted using the Nested Knowledge AutoLit software. The main outcome was DWI-detected ischemic lesions within 5 days of the procedures. Information regarding associated risk factors such as the type of procedure, patient demographics, and aneurysm characteristics was also collected.

RESULTS

Twenty-nine studies with 2686 patients were included. The overall incidence of DWI ischemic lesions was 47.0% (95% CI, 39.6%-55.8%). The highest rate of lesions was seen with flow diversion at 62.4% (95% CI, 48.4%-80.5%), followed by complex procedures at 49.3% (95% CI, 29.5%-82.1%), stent-assisted coiling at 47.5% (95% CI, 34.6%-65.3%), simple coiling at 47.1% (95% CI, 35.7%-62.3%), and balloon-assisted coiling at 37.0% (95% CI, 28.3%-48.4%). The differences among different techniques were not statistically significant; however, there was significant heterogeneity and a significant risk of publication bias among included studies.

CONCLUSIONS

Many patients who undergo endovascular procedures for intracranial aneurysms present with new postprocedural DWI-detected ischemic lesions, regardless of the endovascular procedure used. Future studies and meta-analyses are needed to investigate early and long-term outcomes of such small infarcts.

Coiling embolization strategy for medium-to-giant-sized intracranial aneurysms treated with pipeline embolization device: a propensity score-weighted study

OBJECTIVES

We aim to investigate associations between different coil strategies and outcomes in the aneurysms treated by a pipeline embolization device (PED).

METHODS

Patients with medium-to-giant-sized aneurysms treated by PED were included. The total cohort was divided into PED-alone and PED-coiling groups, and the PED-coiling group was further divided into loose and dense packing subgroups. Multivariate logistic analyses and stabilized inverse probability of treatment weighting (sIPTW) were performed to investigate the relationships between coiling strategies and outcomes. Restricted cubic spline (RCS) curves were used to describe the coiling degree and angiographic outcome relationship.

RESULTS

A total of 398 patients with 410 aneurysms were included. Aneurysms treated with PED coiling had a lower incomplete occlusion rate (15.3% vs. 30.3%, p = 0.002), higher total perioperative complication rate (14.2% vs. 3.5%, p = 0.001), longer production time (142.14 min vs. 101.26 min, p < 0.001), and higher total cost ($45,158.63 vs. $34,680.91, p < 0.001) than those treated with PED alone. There were no differences in outcomes between the loose and dense packing subgroups. However, the total cost was higher in the dense packing group ($43,787.46 vs. $47,288.32, p = 0.001) than in the loose packing group. The result was still robust in the multivariate and sIPTW analyses. The RCS curves showed "L-shape" relationships between the coil degree and angiographic outcomes.

CONCLUSION

Compared with PED alone, PED coiling could improve aneurysm occlusion. However, it could also increase the total complication risk, prolong procedure time, and increase the total cost. Compared with loose packing, dense packing did not enhance the treatment effectiveness but increased the treatment cost.

CLINICAL RELEVANCE STATEMENT

The additional treatment effect from coiling embolization declines sharply after a certain point. Specifically, the aneurysm occlusion rate is roughly stable when the coil number is greater than 3 or the total coil length is longer than 150 cm.

KEY POINTS

• Compared with pipeline embolization device (PED) alone, PED combined with coiling can improve aneurysm occlusion. • Compared with PED alone, PED combined with coiling increases the total complication risk, cost, and prolongs procedure time. • Compared with loose packing, dense packing did not increase the treatment effectiveness but increased the cost.

First clinical experience with the Derivo 2heal embolization device for the treatment of intracranial aneurysms

OBJECTIVE

The development of new flow-diverting devices with antithrombotic coatings may result in an improved safety profile, particularly a reduction in ischaemic stroke rates. The aim of this study was to evaluate our initial experience with the recently introduced coated Derivo® 2heal® Embolization Device (Acandis, Pforzheim, Germany).

METHODS

This is a retrospective, single-centre analysis of patients with intracranial aneurysms undergoing Derivo® 2heal® Embolization Device treatment. Patient and aneurysm characteristics, procedural parameters, complications, and degree of initial and short-term aneurysm occlusion were evaluated on an intention-to-treat basis.

RESULTS

A total of 16 unruptured aneurysms in 9 patients were treated with the Derivo® 2heal® Embolization Device in 10 treatment sessions. In one case the Derivo® 2heal® Embolization Device could not be deployed due to severe friction in the microcatheter. In all successful cases, one Derivo® 2heal® Embolization Device was sufficient to treat the target aneurysm and no additional coiling was performed. In-stent balloon angioplasty was performed in one procedure (10%) to improve vessel wall apposition. Twelve arterial side branches were covered in 9 procedures and all were patent at the end of the procedure. There were no clinical complications and no thromboembolic events during treatment. At the end of the procedure, contrast retention was observed in 13/16 (81%) aneurysms and at short-term follow-up, 6/9 (67%) were completely occluded.

CONCLUSIONS

The preliminary results of the new Derivo® 2heal® Embolization Device appear promising and warrant further evaluation by multicentre studies with long-term follow-up.

Treatment of cerebral aneurysms with flow diversion or stent assisted coiling in patients on concurrent oral anticoagulation

BACKGROUND

Flow diversion and stent assisted coiling are increasingly utilized strategies in the endovascular treatment of cerebral aneurysms. Ischemic and hemorrhagic complications play an important role in the outcome following such embolizations. Little is published regarding patients on concurrent oral anticoagulation and undergoing such embolizations and the rates of complications and patient outcomes.

MATERIALS AND METHODS

Retrospective data for consecutive patients on concurrent oral anticoagulation undergoing flow diversion or stent assisted coiling for cerebral aneurysms was accessed from databases at the participating sites. Patient demographics, comorbidities, antiplatelet regimens, aneurysm characteristics, complications, and radiographic results were recorded and descriptive statistics reported.

RESULTS

Eleven patients were identified undergoing embolization in the setting of preoperative anticoagulant use and included seven patients undergoing flow diversion and four patients undergoing stent assisted coiling. There was a wide range of antiplatelet and anticoagulant management strategies. There were four major complications in three patients (27.2%) to include two serious bleeding events in addition to ischemic strokes. Both serious bleeding events occurred in patients continued on oral anticoagulation with the addition of antiplatelets. At a mean follow-up of 9.6 months, three aneurysms had continued filling for a good radiographic outcome of 72.7%.

CONCLUSIONS

Anticoagulant and antiplatelet use in the setting of flow diversion or stent assisted coiling may carry increased risks as compared to historical norms and, for flow diversion, offer decreased efficacy.

Active drug-coated flow diverter in a preclinical model of intracranial stenting

BACKGROUND

Flow diverters carry the risk of thromboembolic complications (TEC). We tested a coating with covalently bound heparin that activates antithrombin to address TEC by locally downregulating the coagulation cascade. We hypothesized that the neuroimaging evidence of TEC would be reduced by the coating.

METHODS

16 dogs were implanted with overlapping flow diverters in the basilar artery, separated into two groups: heparin-coated (n=9) and uncoated (n=7). Following implantation, high-frequency optical coherence tomography (HF-OCT) was acquired to quantify acute thrombus (AT) formation on the flow diverters. MRI was performed postoperatively and repeated at 1, 2, 3, 4, and 8 weeks, consisting of T1-weighted imaging, time-0f-flight (ToF), diffusion weighted imaging (DWI), susceptibility weighted imaging (SWI), and fluid attenuated inversion recovery (FLAIR) sequences. Neurological examinations were performed throughout the 8-week duration of the study.

RESULTS

The mean AT volume on coated devices was lower than uncoated (0.014 vs 0.018 mm³); however, this was not significant (P=0.3). The mean number of foci of magnetic susceptibility artifacts (MSAs) on SWI was significantly different between the uncoated and coated groups at the 1-week follow-up (P<0.02), and remained statistically different throughout the duration of the study. The AT volume showed a direct linear correlation with the MSA count and 80% of the variance in the MSA could be explained by the AT volume (P<0.001). Pathological analysis showed evidence of ischemic injury at locations of MSA.

CONCLUSIONS

Heparin-coated flow diverters significantly reduced the number of new MSAs after 1 week follow-up, showing the potential to reduce TEC.

Flow diversion for posterior circulation aneurysms: a multicenter retrospective study

Background

The prevalence of intracranial aneurysms is approximately 3% worldwide. Posterior circulation (PC) aneurysms have a higher risk of treatment complications than anterior circulation aneurysms. Improving the survival rate and quality of life of patients with PC aneurysms remains one of the most important issues in the field.

Objectives

Flow diverter (FD) treatment of PC aneurysms remains controversial. We aimed to investigate the effects of FD treatment and analyze differences among different application methods or aneurysm types in PC aneurysms.

Design

This is a multicenter retrospective study.

Methods

Patients with PC aneurysms treated with the pipeline embolization device (PED) or Tubridge embolization device (TED) between 2015 and 2020 in five neurovascular centers were retrospectively enrolled. The primary outcomes were major perioperative complication, clinical outcome, and aneurysm occlusion rates. Univariable and multivariable logistic regression analyses were used to determine the risk factors of each outcome.

Results

In total, 252 aneurysms were included. Major perioperative complication, favorable clinical outcome, and complete occlusion rates were 7.5%, 91.0%, and 79.1%, respectively. Compared with other types of aneurysms, dissecting aneurysms had the best clinical outcome and highest occlusion rate. Both clinical and angiographic outcomes were independently associated with the aneurysm location at the basilar artery. Aneurysm size was not associated with any outcome. TED had similar clinical and angiographic outcomes compared with PED but more perioperative major complications. Tandem treatment and coiling assistance may have poorer clinical outcomes but similar occlusion rates. Single- and multiple-stent treatments had similar outcomes.

Conclusion

FD treatment of PC aneurysms achieved favorable clinical outcomes and long-term aneurysm occlusion rates with acceptable perioperative complication rates, especially in dissecting and non-basilar artery aneurysms. There was no additional improvement in outcomes with coiling assistance, multi-stent application, or tandem treatment. Therefore, the use of PC aneurysms should be carefully considered.

Antiplatelet therapy adjustment improved the radiomic characteristics of acute silent cerebral infarction after stent-assisted coiling in patients with high on-treatment platelet reactivity: A prospective study

Background

We aimed to investigate the effects of high on-treatment platelet reactivity (HPR) and antiplatelet therapy adjustment on high-risk radiomic features in patients with antiplatelet therapy adjustment on acute silent cerebral infarction (ASCI) who had unruptured intracranial aneurysms (UIA) after stent placement.

Methods

This single-institution study prospectively included 230 UIA patients who had ACSI after stent placement in our hospital between January 2015 and July 2020. All patients underwent magnetic resonance imaging with diffusion-weighted imaging (MRI-DWI) after stent placement and 1,485 radiomic features were extracted from each patient. The least absolute shrinkage and selection operator regression methods were used for selection of high-risk radiomic features associated with clinical symptoms. In addition, 199 patients with ASCI were classified into three groups: controls without HPR (n = 113), HPR patients with standard antiplatelet therapy (n = 63) and HPR patients with antiplatelet therapy adjustment (n = 23). We compared high-risk radiomic features between three groups.

Results

Of the patients who had acute infarction after MRI-DWI, 31 (13.5%) exhibited clinical symptoms. Eight risk radiomic features associated with clinical symptoms were selected, and the radiomics signature exhibited good performance. In ASCI patients, compared with controls, the radiomic characteristics of ischemic lesion in HPR patients were consistent with the following high-risk radiomic features associated with clinical symptoms: higher gray-level values, greater variance in intensity values, and greater homogeneity. However, the adjustment of antiplatelet therapy in HPR patients modified the high-risk radiomic features, which showed lower gray-level values, less variance in intensity values, and more heterogeneous texture. The radiomic shape feature of elongation showed no notable difference between three groups.

Conclusion

Adjustment of antiplatelet therapy might reduce the high-risk radiomic features of UIA patients with HPR after stent placement.

Effects of different stent size selection on pipeline embolization device treatment of intracranial aneurysms

Background

Pipeline embolization device (PED) is becoming increasingly common in therapeutic practice. In idealized model studies, treatment effectiveness may vary with different stent sizes in the same vasculature. The true effect of stent size selection in the clinical setting remains unknown, however.

Objective

To determine the true effect of stent size selection in the clinical setting.

Design

It is a retrospective review.

Methods

A retrospective review was conducted on consecutive patients with aneurysms treated with a PED at our institution. The primary exposures were the difference between the diameter of the stent and the parent artery (DD) and the difference between the length of the stent and the aneurysm neck (DL). The outcomes were the clinical and angiographic results, perioperative complications, balloon application, and in-stent stenosis. The results were generated using univariable and multivariable logistic regression and restricted cubic spline (RCS) curves.

Results

A larger DD was significantly associated with incomplete occlusion [odds ratio (OR) = 2.37; 95% confidence interval (CI) = 1.43-3.98; p < 0.001], while a larger DL was significantly associated with balloon application (OR = 1.12; 95% CI = 1.02-1.23; p = 0.021) and in-stent stenosis (>25%) (OR = 1.07; 95% CI = 1.01-1.16; p = 0.042). The RCS curve indicated that the risk of incomplete occlusion increased as the DD became larger, the possibility of balloon application increased as the DL increased when the DL was >5.7 mm, and the risk of in-stent stenosis (>25%) increased as the DL increased.

Conclusion

In the clinical setting, stent selection was associated with treatment effectiveness and may add to the treatment burden. These occurrences should be considered for aneurysms treated with PED.

Ticagrelor versus Clopidogrel in the Dual Antiplatelet Regimen for Unruptured Intracranial Aneurysm Treated with Stent-Assisted Coil Embolization: A Single-Center Cohort Study

BACKGROUND

Dual antiplatelet therapy (DAPT) of aspirin plus clopidogrel is commonly used in patients with unruptured intracranial aneurysms treated with stent-assisted coil (SAC) embolization. However, the unpredictable clopidogrel efficacy of the 5%-55% nonresponders limits its use. Ticagrelor, as a potential alternative of clopidogrel, is an antiplatelet agent with low resistance rates but uncertain efficacy and safety in these patients.

METHODS

A single-center cohort study was performed to compare the efficacy and safety of ticagrelor with clopidogrel in the DAPT regimen in patients with unruptured intracranial aneurysms and treated with SAC. The patients with clopidogrel resistance identified as inadequate adenosine diphosphate inhibition rate determined by thromboelastography were treated with ticagrelor instead, and both drugs achieved adequate suppression of platelet aggregation when stents were implanted. The occurrence of major adverse cardiovascular and cerebrovascular events (MACCE) and bleeding events was recorded through 6 months follow-up.

RESULTS

Data from 86 patients with 99 unruptured intracranial aneurysms and treated by SAC with clopidogrel were compared with those from 108 patients with 111 aneurysms and treated with ticagrelor. Neither the baseline characteristics nor the incidence of the MACCE or bleeding events differed between the groups. Ticagrelor exerted significantly higher adenosine diphosphate inhibition rate than that of the clopidogrel. Multivariable logistic regression analysis showed that the incidence of MACCE was related to hematocrit and fibrinogen levels.

CONCLUSIONS

Ticagrelor seemed to be as effective and safe as clopidogrel for SAC in unruptured intracranial aneurysms. Hematocrit and fibrinogen levels were independent risk factors for the incidence of MACCE.

Diffusion-weighted imaging lesions after endovascular treatment of cerebral aneurysms: A network meta-analysis

Background

Thromboembolism is one of the common complications in endovascular treatments including coiling alone, stent-assisted coiling (SAC), balloon-assisted coiling (BAC), and flow-diverting (FD) stents. Such treatments are widely used in intracranial aneurysms (IAs), which usually present as positive lesions in diffusion-weighted imaging (DWI). Whether these adjunctive techniques increase postprocedural DWI-positive lesions after endovascular treatment remains unclear.

Methods

A thorough electronic search for the literature published in English between January 2000 and October 2022 was conducted on PubMed, Medline, and EMBASE. Eighteen studies (3 cohort studies and 15 case-control studies) involving 1,843 patients with unruptured IAs (UIAs) were included. We performed a frequentist framework network meta-analysis (NMA) to compare the rank risks of cerebral thromboembolism of the above four endovascular treatments. The incoherence test was used to analyze the statistical disagreement between direct and indirect evidence. Funnel plots were used to analyze publication bias.

Results

The incidences of DWI lesions in patients who received FD stents, SAC, BAC, and coiling alone were 66.1% (109/165), 37.6% (299/795), 31.1% (236/759), and 25.6% (236/921). The incidence of DWI lesions in patients who received FD stents was higher than that in patients who received SAC [OR: 2.40; 95% CI (1.15, 5.00), P < 0.05], BAC [OR: 2.62; 95% CI (1.19, 5.77), P < 0.05], or coiling alone [OR: 2.77; 95% CI (1.26, 6.07), P < 0.05]. The incoherence test showed preferable consistency in this NMA. No obvious publication bias was found in the funnel plot.

Conclusion

FD stent placement brings more ischemic lesions identified by DWI than any other procedures for patients with UIA. The characteristics of FD stents may result in a high incidence of DWI lesions.

Ticagrelor versus clopidogrel dual antiplatelet therapy for unruptured intracranial aneurysms treated with flowdiverter

BACKGROUND AND PURPOSE

Antiplatelet therapy (APT) is a key element limiting the risk of thromboembolic events (TEE) in neuroendovascular procedures, including aneurysm treatment with flowdiverter. Clopidogrel combined with aspirin is the mostly reported dual APT (DAPT). However, resistance phenomenon and intraindividual efficacy fluctuation are identified limitations. In recent years, ticagrelor has been increasingly used in this indication. We compared these two DAPT regimens for intracranial aneurysm treated with flowdiverter.

METHODS

We conducted a multicentric retrospective study from prospectively maintained databases in two high volume centers extracting consecutive patients presenting unruptured intracranial aneurysm treated with flowdiverter and receiving DAPT (May 2015 to December 2019).  Two groups were compared according to their DAPT regimen: "ticagrelor+aspirin" and "clopidogrel+aspirin". Clopidogrel group was systematically checked with platelet test inhibition before endovascular procedure. The primary endpoint was composite, defined as any thrombo-embolic event (TEE) or major hemorrhagic event occurring the first 6 months during and after embolization RESULTS: 260 patients met our inclusion criteria. Baseline patients and aneurysms characteristics were comparable between groups, except for aneurysm location, median size and pre-treatment modified Rankin scale. No significant difference was observed regarding the primary composite outcome: 11.5% (12/104) in the ticagrelor group versus 10.9% (17/156) in the clopidogrel group (p = 1.000). There was also no significant difference in secondary outcomes including TEE (10.5 vs 9.0%; p = 0.673), major hemorrhage (0.9 vs 1.2%; p = 0.651) and clinical outcome (at least 1-point mRS worsening during follow up: 6.7% vs 8.3%; p = 0.813).

CONCLUSION

First-line DAPT with ticagrelor+aspirin seems as safe and effective as clopidogrel+aspirin regimen.

Flow diversion treatment for giant intracranial serpentine aneurysms

Background

Giant serpentine aneurysms (GSAs) are among the most complex and challenging type of intracranial aneurysms. Surgical clipping, bypass, or endovascular parent artery occlusion has been the main treatment of GSAs in the past. However, studies on flow diversion (FD) are limited. Therefore, we reported our experience with patients with GSAs treated with FD.

Methods

Patients with GSAs treated with FD from 2012 to 2020 in our single center were retrospectively reviewed. Angiographic outcomes were graded according to the O’Kelly–Marotta scale as complete occlusion (D), trace filling (C), entry remnant (B), or aneurysm filling (A). Clinical outcomes were assessed using the modified Rankin scale (mRS) score. We also collected the patients’ treatment details and perioperative complications.

Results

Thirteen patients with 14 aneurysms were included, including three in the anterior circulation and 11 in the posterior circulation. Grades B–D were found in 72.7% (8/11) of the GSAs. Good prognosis (mRS score, 0–2) was found in 66.7% (8/12) and 50.0% (6/12) of the patients at the 6-month and latest follow-up, respectively. Parent artery occlusion was found in three cases of GSAs. Five postoperative complications were observed, including two minor complications and three major complications.

Conclusion

Although reconstructive treatment with FD could be considered as one of the treatment strategies for patients with both anterior and posterior circulation GSAs, however, the risk of complications and parent artery occlusion should be considered.

Thromboembolic Events Detected by Diffusion-Weighted Magnetic Resonance Imaging after Flow Diverter Treatment: The Impact of Procedure Time

BACKGROUND

Periprocedural thromboembolism is a serious complication of endovascular treatment for intracranial aneurysms. In addition to symptomatic ischemia, asymptomatic postprocedural diffusion-weighted image-positive lesions (DPLs) are considered important. However, few studies have reported significant risk factors associated with DPLs and symptomatic ischemic stroke after flow diverter (FD) treatment. This study aimed to investigate the frequency and risk factors associated with DPLs after FD treatment.

METHODS

Between November 2015 and December 2021, 84 patients harboring 85 untreated, unruptured intracranial aneurysms treated with FD were enrolled.

RESULTS

DPLs after FD treatment were confirmed in 74 patients (87.1%), among whom 69 (93.2%) were clinically asymptomatic. In the univariate analyses, age >55 years (P = 0.040), smoking (P = 0.023), preprocedural P2Y12 reaction unit value of >185 (P = 0.030), larger dome size of >9.3 mm (P = 0.013), and prolonged procedure time >80 minutes (P < 0.001) were significantly associated with postprocedural DPLs. In the multiple logistic regression model, only prolonged procedure time >80 minutes (odds ratio, 10.72; 95% confidence interval, 1.346-233.899; P = 0.023) was statistically significant. The mediator effect showed that the association between procedure time and the occurrence of DPLs was not significantly modified by any other factors, although only adjunctive coiling showed a tendency (P-value for interaction = 0.070).

CONCLUSIONS

Prolonged procedure time >80 minutes was the only identifiable factor related to postprocedural DPLs. Adjunctive coiling tended to mediate the effects of a prolonged procedure time on the occurrence of DPLs after FD treatment.

Use of a p64 MW Flow Diverter with Hydrophilic Polymer Coating (HPC) and Prasugrel Single Antiplatelet Therapy for the Treatment of Unruptured Anterior Circulation Aneurysms: Safety Data and Short-term Occlusion Rates

Purpose

To assess the safety and short-term occlusion rates in procedures using the p64 MW hydrophilic polymer-coated (HPC) flow diverter (FD) with prasugrel single antiplatelet therapy (SAPT) for the treatment of anterior circulation saccular aneurysms.

Methods

We retrospectively identified patients who underwent treatment of one or more intracranial anterior circulation saccular aneurysms between March 2020 and December 2021 with a p64 MW HPC FD and prasugrel SAPT with verified P2Y12 platelet receptor inhibition. Patients diagnosed with fusiform, dissecting, or recently ruptured aneurysms were excluded. Periprocedural and postprocedural complications, clinical outcomes, and angiographic follow-up results were evaluated.

Results

One hundred and two patients with 132 intracranial aneurysms met the inclusion criteria. Previous or concomitant treatments (e.g., coil occlusion) had been performed on 18 of these aneurysms. The technical success rate (i.e., implantation of the intended FD) was 100% with an average of 1.1 devices implanted per patient. Periprocedural and postprocedural complications occurred in 13.6% and 6.8% of these patients, respectively. No mortality or permanent clinical deterioration (i.e., modified Rankin scale score ≥ 3) were reported. Early follow-up digital subtraction angiography revealed aneurysmal occlusion rates of 72.6% and 83.8% at four and nine months, respectively.

Conclusions

The implantation of a p64 MW HPC FD with prasugrel SAPT is safe and results in rapid, reliable and effective aneurysmal occlusion.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-022-03153-8.

Imaging Intracranial Aneurysms in the Endovascular Era: Surveillance and Posttreatment Follow-up

While most intracranial aneurysms (IAs) remain asymptomatic over a patient's lifetime, those that rupture can cause devastating outcomes. The increased usage and quality of neuroimaging has increased detection of unruptured IAs and driven an increase in surveillance and treatment of these lesions. Standard practice is to treat incidentally discovered unruptured IAs that confer high rupture risk as well as ruptured IAs to prevent rehemorrhage. IAs are increasingly treated with coil embolization instead of microsurgical clipping; more recently, flow diversion and intrasaccular flow disruption have further expanded the versatility and utility of endovascular IA treatment. Imaging is increasingly used for posttreatment IA follow-up in the endovascular era. While cerebral angiography remains the standard for IA characterization and treatment planning, advances in CT and CT angiography and MR angiography have improved the diagnostic accuracy of noninvasive imaging for initial diagnosis and surveillance. IA features including size, dome-to-neck ratio, location, and orientation allow rupture risk stratification and determination of optimal treatment strategy and timing. The radiologist should be familiar with the imaging appearance of common IA treatment devices and the expected imaging findings following treatment. In distinction to clipping and coil embolization, flow diversion and intrasaccular flow disruption induce progressive aneurysm obliteration over months to years. Careful assessment of the device; the treated IA; adjacent brain, bone, meninges; and involved extracranial and intracranial vasculature is crucial at posttreatment follow-up imaging to confirm aneurysm obliteration and identify short-term and long-term posttreatment complications. An invited commentary by Chatterjee is available online. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ^©RSNA, 2022.

Critical Angiographic and Sonographic Analysis of Intra Aneurysmal and Downstream Hemodynamic Changes After Flow Diversion

Introduction

Successful treatment of intracranial aneurysms after flow diversion (FD) is dependent on the flow modulating effect of the device. We aimed to investigate the intra-aneurysmal and parent vessel hemodynamic changes, as well as the incidence of silent emboli following treatment with various FD devices.

Methods

We evaluated the appearance of the eclipse sign in nine distinct phases of cerebral angiography before and immediately after FD placement in correlation with aneurysm occlusion. Angiographic and clinical data of consecutive procedures were analyzed retrospectively. Patients who had successful FD procedure without adjunctive coiling, visible eclipse sign on post embolization angiography, and reliable follow-up angiographic data were included in the analysis. Detailed analysis of hemodynamic data from transcranial doppler after FD was performed in selected patients, such as monitoring for silent emboli.

Results

Among all patients (N = 65) who met inclusion criteria, complete aneurysm occlusion at 12 months was achieved in 89% (58/65). Eclipse sign prior to FD was observed in 42% (27/65) with unchanged appearance in 4.6% (3/65) of the treated patients. None of these three patients achieved complete aneurysm occlusion. Among all analyzed variables, such as aneurysm size, device type used, age, and appearance of the eclipse sign pre- and post-FD, the most reliable predictor of permanent aneurysm occlusion at 12 months was earlier, prolonged, and sustained eclipse sign visibility in more than three angiographic phases in comparison to the baseline (p &lt; 0.001). Elevation in flow velocities within the ipsilateral vascular territory was noted in 70% (9/13), and bilaterally in 54% (7/13) of the treated patients. None of the patients had silent emboli.

Conclusions

Intra-aneurysmal and parent vessel hemodynamic changes after FD can be reliably assessed by the cerebral angiography and transcranial doppler with important implications for the prediction of successful treatment.

Safety and Efficacy of Coils in Conjunction With the Pipeline Flex Embolization Device for the Treatment of Cerebral Aneurysms

Background: Flow diverters (FD) have shown promising results in the treatment of intracranial aneurysms (IAs). However, there is still controversy whether pipeline flex embolization device (PED flex)-assisted coils can facilitate the curing of aneurysms. Our aim was to assess the safety and effectiveness of PED flex adjunctive with coils (PED flex + coil) in the treatment of IAs. Method: Patients who underwent PED flex treatment in combination with coiling between January 2018 and June 2020 were included in this study. The clinical and radiographic characteristics before and after treatments were retrospectively evaluated. The study cohort comprised of 125 patients with 140 IAs, which was subdivided into two subgroups: one group included patients treated only through PED alone, and the other group included patients treated through PED flex adjunctive with coil. Patient baseline characteristics, aneurysm characteristics, treatment-related factors, and outcomes were analyzed to determine the effectiveness of both techniques. Results: Aneurysms in the PED flex + coil group were larger (10.0 ± 5.8 mm, P < 0.001) and wider (7.2 ± 4.6 mm, P = 0.002) compared with those in the PED flex group. There was no statistical difference in the perioperative complication rate between the two groups. The overall complete occlusion rate was 75.7% at 6.2 months, with 71.7% at 6.2 ± 1.7 months in the PED flex group and 85.4% at 6.2 ± 1.8 months in the PED flex + coil group, respectively. A higher percentage of satisfactory angiography results was found in the PED flex + coil group during follow-up (92.7 vs. 78.8%, P = 0.047). Conclusion: PED flex placement with adjunctive coil embolization represents a safe alternative option for the treatment of IAs. In these cases, coil embolization increases the occlusion rate in PED flex-treated patients without increasing the periprocedural complications.

Flow Diverter Devices for the Treatment of Unruptured Vertebral Artery Dissecting Aneurysm

Objective

Vertebral artery dissecting aneurysm (VADA) is a very rare subtype of intracranial aneurysms; when ruptured, it is associated with significantly high rates of morbidity and mortality. Despite several discussions and debates, the optimal treatment for VADA has not yet been established. In the last 10 years, flow diverter devices (FDD) have emerged as a challenging and new treatment method, and various clinical and radiological results have been reported about their safety and effectiveness. The aim of our study was to evaluate the clinical and radiological results with the use of FDD in the treatment of unruptured VADA.

Methods

We retrospectively evaluated the data of all patients with unruptured VADA treated with FDD between January 2018 and February 2021 at our hybrid operating room. Nine patients with unruptured VADA, deemed hemodynamically unstable, were treated with FDD. Among other parameters, the technical feasibility of the procedure, procedure-related complications, angiographic results, and clinical outcomes were evaluated.

Results

Successful FDD deployment was achieved in all cases, and the immediate follow-up angiography showed intra-aneurysmal contrast stasis with parent artery preservation. A temporary episode of facial numbness and palsy was noted in one patient; however, the symptoms had completely disappeared when followed up at the outpatient clinic 2 weeks after the procedure. The 3–6 months follow-up angiography (n=9) demonstrated complete/near-complete obliteration of the aneurysm in seven patients, and partial obliteration and segmental occlusion in one patient each. In the patient who achieved only partial obliteration, there was a sac 13 mm in size, and there was no change in the 1-year follow-up angiography. In the patient with segmental occlusion, the cause could not be determined. The clinical outcome was modified Rankin Scale 0 in all patients.

Conclusion

Our preliminary study using FDD to treat hemodynamically unstable unruptured VADA showed that FDD is safe and effective. Our study has limitations in that the number of cases is small, and it is not a prospective study. However, we believe that the study contributes to evidence regarding the safety and effectiveness of FDD in the treatment of unruptured VADA.

Safety of Oral P2Y12 Inhibitors in Interventional Neuroradiology: Current Status and Perspectives

In the field of interventional neuroradiology, antiplatelet agents are commonly used to prepare patients before the implantation of permanent endovascular materials. Among the available drugs, clopidogrel is the most frequently used one, but resistance phenomena are considered to be relatively common. Prasugrel and ticagrelor were recently added to the pharmacologic arsenal, but the safety of these agents in patients undergoing neurointerventional procedures is still a subject of discussion. The cumulative experience with both drugs is less extensive than that with clopidogrel, and the experience with patients in the neurology field is less extensive than in the cardiology domain. In the present article, we provide a narrative review of studies that investigated safety issues of oral P2Y12 inhibitors in interventional neuroradiology and discuss potential routes for future research.

Repeat Flow Diversion for Cerebral Aneurysms Failing Prior Flow Diversion: Safety and Feasibility From Multicenter Experience

BACKGROUND AND PURPOSE

Aneurysmal persistence after flow diversion (FD) occurs in 5% to 25% of aneurysms, which may necessitate retreatment. There are limited data on safety/efficacy of repeat FD-a frequently utilized strategy in such cases.

METHODS

A series of consecutive patients undergoing FD retreatment from 15 centers were reviewed (2011-2019), with inclusion criteria of repeat FD for the same aneurysm at least 6 months after initial treatment, with minimum of 6 months post-retreatment imaging. The primary outcome was aneurysmal occlusion, and secondary outcome was safety. A multivariable logistic regression model was constructed to identify predictors of incomplete occlusion (90%-99% and <90% occlusion) versus complete occlusion (100%) after retreatment.

RESULTS

Ninety-five patients (median age, 57 years; 81% women) harboring 95 aneurysms underwent 198 treatment procedures. Majority of aneurysms were unruptured (87.4%), saccular (74.7%), and located in the internal carotid artery (79%; median size, 9 mm). Median elapsed time between the first and second treatment was 12.2 months. Last available follow-up was at median 12.8 months after retreatment, and median 30.6 months after the initial treatment, showing complete occlusion in 46.2% and near-complete occlusion (90%-99%) in 20.4% of aneurysms. There was no difference in ischemic complications following initial treatment and retreatment (4.2% versus 4.2%; P>0.99). On multivariable regression, fusiform morphology had higher nonocclusion odds after retreatment (odds ratio [OR], 7.2 [95% CI, 1.97-20.8]). Family history of aneurysms was associated with lower odds of nonocclusion (OR, 0.18 [95% CI, 0.04-0.78]). Likewise, positive smoking history was associated with lower odds of nonocclusion (OR, 0.29 [95% CI, 0.1-0.86]). History of hypertension trended toward incomplete occlusion (OR, 3.10 [95% CI, 0.98-6.3]), similar to incorporated branch into aneurysms (OR, 2.78 [95% CI, 0.98-6.8]).

CONCLUSIONS

Repeat FD for persistent aneurysms carries a reasonable success/safety profile. Satisfactory occlusion (100% and 90%-99% occlusion) was encountered in two-thirds of patients, with similar complications between the initial and subsequent retreatments. Fusiform morphology was the strongest predictor of retreatment failure.

Antiplatelet Therapy and Periprocedural Risk Factor Analysis for Pipeline Embolization Device Treatment of Unruptured Internal Carotid Artery Aneurysms: A Retrospective, Multicenter Analysis

BACKGROUND

Aneurysm treatment using the Pipeline Embolization Device has been established but appropriate maintenance of dual antiplatelet therapy (APT) is essential. This multicenter retrospective study assessed whether APT was properly adjusted for clopidogrel resistance and identified risk factors associated with periprocedural complications.

METHODS

Consecutive cases of use of the Pipeline Embolization Device for internal carotid artery aneurysms (>10 mm) between November 2015 and April 2020 were analyzed. Dual APT (aspirin + clopidogrel) was prescribed before treatment. If preprocedural P2Y12 reaction unit (PRU) values were >240, APT was adjusted. Periprocedural complications were compared between APT nonadjustment and adjustment groups and periprocedural risk factors were also analyzed.

RESULTS

A total of 162 procedures were assessed. The mean maximum aneurysm size was 15.35 mm. APT adjustment was required in 47 cases (29.0%), primarily by switching to prasugrel. There were no significant differences in complication incidence between the 2 groups even after propensity score matching. The risk factor independently associated with ischemic complications was a neck size of 8 mm or larger (odds ratio [OR], 5.25; P = 0.018) and restricting analysis to the APT nonadjustment group showed PRU values of 190 or higher (OR, 5.84; P = 0.047) and neck sizes of 8 mm or larger (OR, 7.05; P = 0.029) as significant factors. The risk factor independently associated with hemorrhagic complications was a neck size of 7 mm or larger (OR, 11.57; P = 0.023).

CONCLUSIONS

APT adjustment for clopidogrel resistance was safe and effective. Neck width was a risk factor for both ischemic and hemorrhagic complications. PRU values of 190 or higher were also associated with ischemic complications.

Pipeline Embolization Device for the Treatment of Ruptured Intracerebral Aneurysms: A Multicenter Retrospective Study

Background and Purpose: The utilization of flow diversion for ruptured intracerebral aneurysms (IAs) is still limited. We aimed to demonstrate our multicenter experience using the pipeline embolization device (PED) for ruptured IAs that were difficult to treat by clipping and coiling.

Methods: Thirty-eight patients with ruptured IAs who underwent PED treatment from 2015 to 2020 were retrospectively reviewed. Factors associated with procedure-related stroke (ischemic and hemorrhagic) and clinical and angiography outcomes were analyzed.

Results: There were 14 (36.8%) saccular IAs, 12 (31.6%) blister-like IAs, and 12 (31.6%) dissecting IAs. Perforator involvement was noted in 10 (26.3%) IAs. Early PED placement ( ≤ 15 days) and adjunctive coiling treatment were performed in 27 (71.1%) and 22 (57.9%) cases, respectively. The overall rate of stroke-related complications was 31.6% (12/38) (including rates of 10.5% for procedure-related hemorrhagic complications and 15.8% for procedure-related infarction). The mortality rate was 13.2% (5/38), and 84.2% of patients (32/38) had favorable outcomes. Thirty-two (84.2%) patients underwent follow-up angiographic evaluations; of these, 84.4% (27 patients) had complete occlusion and 15.6% had incomplete obliteration. Multivariate analysis revealed that early PED placement was not associated with a high risk of procedure-related stroke or an unfavorable outcome. Adjunctive coiling exhibited an association with procedure-related stroke (p = 0.073). Procedure-related hemorrhagic complications were significantly associated with an unfavorable outcome (p = 0.003). Immediate contrast stasis in the venous phase was associated with complete occlusion during follow-up (p = 0.050).

Conclusion: The PED is a feasible and effective treatment to prevent rebleeding and achieve aneurysm occlusion, but it is associated with a substantial risk of periprocedural hemorrhage and ischemic complications in acute ruptured IAs. Therefore, the PED should be used selectively for acutely ruptured IAs. Additionally, adjunctive coiling might increase procedure-related stroke; however, it may reduce aneurysm rebleeding in acutely ruptured IAs. Patients with immediate contrast stasis in the venous phase were more likely to achieve total occlusion. A prospective study with a larger sample size should be performed to verify our results.

The inhibition rate estimated using VerifyNow can help to predict the thromboembolic risk of coil embolization for unruptured intracranial aneurysms

BACKGROUND

The role of the inhibition rate of VerifyNow in assessing the thromboembolic risk of coil embolization for unruptured intracranial aneurysms is unclear.

OBJECTIVE

To carry out a retrospective study to determine whether the inhibition rate could provide additional help in predicting thromboembolic events when it was used for patients with a P2Y12 reaction unit (PRU) level of 220 or lower.

METHODS

Patients who underwent coil embolization for unruptured aneurysms with an appropriate PRU level (PRU 220 or lower) between January 1, 2015 and December 31, 2018 were analyzed. A total of 954 patients with 1020 aneurysms were included in this study. The primary outcome was the thromboembolic events occurring within 30 days after coil embolization. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) were obtained to determine the quantitative predictive ability of the inhibition rate. The optimal cut-off value was derived using the Youden index.

RESULTS

Thromboembolic events developed in 11 patients (1.08% of 1020 procedures). The AUC of the ROC curve was 0.83. The optimal cut-off value of the inhibition rate derived using the maximum Youden index was 22.0%. A sensitivity test using a multiple logistic regression analysis demonstrated that the inhibition rate was a significant variable for predicting thromboembolic events.

CONCLUSIONS

The inhibition rate can be used to determine high thromboembolic risks for patients with PRU levels of 220 or lower. The optimal cut-off value of the inhibition rate was 22.0% when the PRU level was 220 or less.

The utility of platelet inhibition testing in patients undergoing Pipeline embolization of intracranial aneurysms

BACKGROUND

The utility of using the VerifyNow P2Y12 platelet inhibition assay in patients undergoing Pipeline embolization of intracranial aneurysms remains controversial. As we have routinely employed the assay for patients undergoing flow diversion, we elected to explore the relationship between P2Y12 hyporesponse as indicated by a P2Y12 Reaction Units (PRU) value >200 and treatment outcomes, including intraprocedural platelet aggregation and ischemic complications.

METHODS

All successful intracranial aneurysm Pipeline treatments performed at our institution from November 2011 to May 2019 were included. The rate of P2Y12 hyporesponse and treatment outcomes were evaluated. Multivariable logistic regression was utilized to determine independent predictors of treatment outcomes.

RESULTS

333 qualifying treatments were performed in 297 patients. Clopidogrel hyporesponse was initially noted in 24%, falling to 17% by day-of-procedure by dose titration. A glycoprotein (GP) IIb/IIIa inhibitor was administered prophylactically in 3% of cases for persistent, profound hyporesponse. 27 (8.1%) patients developed acute platelet aggregation; only 6 demonstrated day-of-procedure P2Y12 hyporesponse. Day-of-procedure hyporesponse was not associated with intraprocedural platelet aggregation or ischemic complications. Greater Pipeline embolization device (PED) diameter was associated with a reduced odds of platelet aggregation (OR 0.38, 95% CI 0.17 to 0.85; p=0.019). Antiplatelet non-compliance (OR 25.20, 95% CI 3.86 to 164.61; p=0.001) and treatment of posterior circulation aneurysms (OR 5.23, 95% CI 1.22 to 22.33; p=0.026) were the only independent predictors of ischemic complications.

CONCLUSIONS

P2Y12 hyporesponse was not associated with acute platelet aggregation or ischemic complications in our patients undergoing Pipeline embolization of intracranial aneurysms, possibly due to aggressive management of the hyporesponse using clopidogrel dose titration and/or GP IIb/IIIa inhibitor administration.

First multicenter experience using the Silk Vista flow diverter in 60 consecutive intracranial aneurysms: technical aspects

Background

The aim of this study was to assess the technical success and procedural safety of the new Silk Vista device (SV) by evaluating the intraprocedural and periprocedural complication rate after its use in several institutions worldwide.

Methods

The study involved a retrospective review of multicenter data regarding a consecutive series of patients with intracranial aneurysms, treated with the SV between September 2020 and January 2021. Clinical, intra/periprocedural and angiographic data, including approach, materials used, aneurysm size and location, device/s, technical details and initial angiographic aneurysm occlusion, were analyzed.

Results

60 aneurysms were treated with SV in 57 procedures. 66 devices were used, 3 removed and 63 implanted. The devices opened instantaneously in 60 out of 66 (91%) cases and complete wall apposition was achieved in 58 out of 63 (92%) devices implanted. In 4 out of 66 (6%) devices a partial opening of the distal end occurred, and in 5 (8%) devices incomplete apposition was reported. There were 3 (5%) intraprocedural thromboembolic events managed successfully with no permanent neurological morbidity, and 4 (7%) postprocedural events. There was no mortality in this study. The initial occlusion rates in the 60 aneurysms were as follows: O’Kelly–Marotta (OKM) A in 34 (57%) cases, OKM B in 15 (25%) cases, OKM C in 6 (10%) cases, and OKM D in 5 (8%) cases.

Conclusions

Our study demonstrated that the use of the new flow diverter Silk Vista for the treatment of intracranial aneurysms is feasible and technically safe.

Multiple pipeline embolization devices improves aneurysm occlusion without increasing morbidity: A single center experience of 140 cases

INTRODUCTION

Rates of aneurysm occlusion with the pipeline embolization device (PED) has varied widely in the literature from 55.7% to 93.3% at 6 months, which may reflect a difference in technique including sizing and number of devices used.

METHODS

140 cases at our institution were retrospectively reviewed, and aneurysms treated with a single PED vs. multiple were compared.

RESULTS

Complete aneurysm occlusion was achieved in 86.9% at 6 months, 91.8% at 1 year, and 97.6% at longest follow-up. Retreatment with an additional device was required in 7 (5.1%). Major and minor complication rate within 30 days was 1.4% and 5.0%, and at greater than 30 days was 0.8% and 3.1%. Patients treated with multiple PEDs had significantly higher rates of aneurysm occlusion at 6 months (92.9% vs. 75.6%, p = 0.017) and 12 months (98.4% vs. 81.1%, p = 0.014), with no difference in complications. The two groups were similar aside from a higher number of ophthalmic and paraophthalmic aneurysms treated with multiple PEDs (23.4% vs. 6.5%, p = 0.004; and 35.1% vs. 17.4%, p = 0.020), and more posterior communicating artery and recurrent aneurysms treated with a single PED (28.3% vs. 3.2%, p = 0.001; 23.9% vs. 8.5%, p = 0.031). The use of multiple PEDs was found to be an independent predictor of aneurysm occlusion in a multivariate analysis (p = 0.015).

CONCLUSIONS

The use of multiple PEDs for intracranial aneurysms leads to significantly higher occlusion rates without added morbidity. This benefit is particularly appropriate for ophthalmic segment aneurysms, while more distal segments with eloquent perforating branches should be managed with caution.

P2Y12 inhibitors in neuroendovascular surgery: An opportunity for precision medicine

INTRODUCTION

Dual antiplatelet therapy (DAPT), primarily the combination of aspirin with a P2Y12 inhibitor, in patients undergoing intravascular stent or flow diverter placement remains the primary strategy to reduce device-related thromboembolic complications. However, selection, timing, and dosing of DAPT is critical and can be challenging given the existing significant inter- and intraindividual response variations to P2Y12 inhibitors.

METHODS

Assessment of indexed, peer-reviewed literature from 2000 to 2020 in interventional cardiology and neuroendovascular therapeutics with critical, peer-reviewed appraisal and extraction of evidence and strategies to utilize DAPT in cardio- and neurovascular patients with endoluminal devices.

RESULTS

Both geno- and phenotyping for DAPT are rapidly and conveniently available as point-of-care testing at a favorable cost-benefit ratio. Furthermore, systematic inclusion of a quantifying clinical risk score combined with an operator-linked, technical risk assessment for potential adverse events allows a more precise and individualized approach to new P2Y12 inhibitor therapy.

CONCLUSIONS

The latest evidence, primarily obtained from cardiovascular intervention trials, supports that combining patient pharmacogenetics with drug response monitoring, as part of an individually tailored, precision medicine approach, is both predictive and cost-effective in achieving and maintaining individual target platelet inhibition levels. Indirect evidence supports that this gain in optimizing drug responses translates to reducing main adverse events and overall treatment costs in patients undergoing DAPT after intracranial stent or flow diverting treatment.

[Treatment of intracranial aneurysms with flow diverters]

CLINICAL ISSUE

The clinical picture of a subarachnoid haemorrhage (SAH) is associated with a high morbidity and mortality, due to the associated complications. Therefore, both unruptured and ruptured aneurysms are to be treated based on an individual and interdisciplinary treatment concept. Several endovascular procedures are already available for the treatment of intracranial aneurysms. A more recent concept is the treatment with vessel-reconstructive stents so-called flow diverters.

PRACTICAL RECOMMENDATIONS

Due to the continuous development and revision of flow diverters, the initial complication rates have been significantly reduced, which now effectively and efficiently justifies their clinical use. After careful patient selection and risk-benefit assessment, the implantation of a flow diverter can also be considered for the treatment of ruptured aneurysms and is often the only therapy option in such situations.

Endovascular treatment of bilateral intracranial vertebral artery aneurysms: an algorithm based on a 10-year neurointerventional experience

BACKGROUND

The management of bilateral intracranial vertebral artery dissecting aneurysms (IVADAs) is controversial, and requires the development of endovascular treatment modalities and principles. We aim to investigate the endovascular treatment strategy and outcomes of bilateral IVADAs.

METHODS

We identified all bilateral IVADAs at a high-volume neurointerventional centre over a 10-year period (from January 2009 to December 2018). Radiographic and clinical data were recorded, and a treatment algorithm was derived.

RESULTS

Twenty-seven patients with bilateral IVADAs (54 IVADAs in total, 51 unruptured, 3 ruptured) were diagnosed. Four patients (14.8%) received single-stage endovascular treatment, 12 patients (44.4%) with staged endovascular treatment and 11 patients (40.8%) with unilateral endovascular treatment of bilateral IVADAs. Thirty-six IVADAs (85.7%) have complete obliteration at the follow-up angiography. Two of three ruptured IVADAs with stent-assisted coiling recanalised, and had further recoiling. Three patients (11.1%) have intraprocedural or postprocedural complications (two in single-stage and one in staged). Twenty-five patients (92.6%) had a favourable clinical outcome, and two patients (7.4%, all in single-stage) showed an unfavourable clinical outcome at follow-up. For the patients with unilateral reconstructive endovascular treatment, the contralateral untreated IVADAs were stable and had no growth or ruptured during follow-up period. None of all IVADAs had rebleeding during the clinical follow-up.

CONCLUSIONS

Endovascular treatment can be performed in bilateral IVADAs with high technical success, high complete obliteration rates and acceptable morbidity/mortality. Contralateral IVADAs had low rates of aneurysm growth and haemorrhage when treated in a staged/delayed fashion.

Cangrelor dose titration using platelet function testing during cerebrovascular stent placement

BACKGROUND

Optimal antiplatelet inhibition is vital during cerebrovascular stenting procedures, yet no standardized recommendation exists for antithrombotic therapy in these scenarios. Cangrelor is an intravenous P2Y12 inhibitor with a favorable pharmacokinetic profile for use during neuroendovascular stenting.

METHODS

A retrospective review of all neuroendovascular patients who underwent stenting between 1 January 2019 and 22 March 2020 and were treated with cangrelor was conducted. Thirty-seven patients met inclusion criteria.

RESULTS

All patients were administered a bolus of 5 mcg/kg of cangrelor followed by a maintenance infusion. Antiplatelet effects of cangrelor were monitored using platelet reactivity units (PRU). Based on the initial PRU, seven patients' doses were adjusted with subsequent PRUs in or near the goal range of 50-150. One patient experienced an acute intraprocedural occlusion likely related to a subtherapeutic PRU which subsequently resolved with cangrelor dose adjustment and intra-arterial tirofiban administration, and one patient experienced a post-procedure stent occlusion which required a thrombectomy and intra-arterial tirofiban administration. No hemorrhagic complications occurred.

DISCUSSION

Cangrelor utilization during neuroendovascular stenting with maintenance doses of <2 mcg/kg/min with dose adjustments based on platelet function testing has not been previously described. Cangrelor presents many advantages compared to standard therapy in patients undergoing stent placement related to its pharmacokinetic profile, rapid onset of action, ease of transition to oral P2Y₁₂ antiplatelet agents, and measurability.

CONCLUSION

Cangrelor is a promising alternative to currently available therapies, especially in patients with a high hemorrhagic risk.

Flow diversion of fusiform intracranial aneurysms

Fusiform aneurysms are less common than saccular aneurysms, but have higher associated mortality and rebleeding rates. Recently, flow diversion has emerged as a possible treatment option. The purpose of this study was to determine the safety and efficacy of the Pipeline Embolization Device (PED) for the treatment of ruptured and unruptured fusiform aneurysms. This was a retrospective analysis of patients with fusiform intracranial aneurysms treated with a PED at a quaternary care center between January 2012 and September 2019. Occlusion rates, neurologic morbidity/mortality, and other clinical variables were analyzed. Twenty-nine patients with 30 fusiform aneurysms were treated with a PED. Sixteen aneurysms (53%) were located in the anterior circulation and 14 aneurysms (47%) were in the posterior circulation. The mean maximal diameter of the aneurysms was 10.1 ± 5.6 mm (range 2.3-25 mm). Angiographic and clinical follow-up were available for 28 aneurysms (93%). The median follow-up was 17.4 months (IQR 4.8 to 28 months) and occlusion rates were graded according to the O'Kelly-Marotta (OKM) scale. Of patients with DSA follow-up, 15 aneurysms (60%) were completely occluded (OKM D) and 19 aneurysms (76%) had a favorable occlusion result (OKM C1-3 and D). The overall complication rate was 26.7% with a neurological morbidity rate of 6.7% and neurological mortality rate of 3.4%. Flow diversion can be an effective treatment for both ruptured and unruptured fusiform aneurysms. Nevertheless, complete occlusion rates are lower than for saccular aneurysms. Therefore, flow diversion should be considered only if other more direct treatment options, such as clipping or stent/coiling are not applicable. Flow diversion should be used cautiously in patients presenting with rupture.

Promoting endothelialization of flow-diverting stents: a review

Intracranial flow-diverting (FD) stents have revolutionized the treatment of intracranial aneurysms in recent years, but complications resulting from failed endothelialization can still occur. Approaches to promote endothelialization are understudied, but hold promise in mitigating both short- and long-term complications associated with FD stent insertion. The aim of this review is to highlight the various features of and modifications that have been made to FD stents in order to expedite endothelialization. More specifically, we focus on how endothelialization can be influenced by the stent design, wall apposition, surface modifications, and the inclusion of biological agents.

Safety and efficacy of ticagrelor as single antiplatelet therapy in prevention of thromboembolic complications associated with the Pipeline Embolization Device (PED): multicenter experience

BACKGROUND

Flow diversion (FD) is a common treatment modality for complex intracranial aneurysms. A major concern regarding the use of FD is thromboembolic events (TEE). There is debate surrounding the optimal antiplatelet regimen to prevent TEE. We aim to evaluate the safety and efficacy of ticagrelor as a single antiplatelet therapy (SAPT) for the prevention of TEE following FD for complex aneurysm treatment.

METHODS

A retrospective review of a prospectively maintained neuroendovascular database at three endovascular centers was performed. Patients were included if they had an intracranial aneurysm that was treated with FD between January 2018 and September 2019 and were treated with ticagrelor as SAPT. Primary outcomes included early (within 72 hours post-procedure) and late (within 6 months) ischemic events.

RESULTS

A total of 24 patients (mean age 47.7 years) with 36 aneurysms were eligible for analysis, including 15 (62.5%) females. 14 (58.3%) patients presented with subarachnoid hemorrhage. 35 aneurysms arose from the anterior circulation and 1 from the posterior circulation. 23 aneurysms had a saccular morphology, whereas 7 were fusiform and 6 were blister. For the treatment of all 36 aneurysms, 30 procedures were performed with 32 FD devices. Procedural in-stent thrombosis occurred in 2 cases and was treated with intra-arterial tirofiban without complications. Aneurysm re-bleeding was reported in 1 (4.2%) patient. There were no reported early or late TEE. Three patients discontinued ticagrelor due to systemic side effects.

CONCLUSION

Ticagrelor is a safe and effective SAPT for the prevention of TEE after FD. Large multicenter prospective studies are warranted to validate our findings.

A 70-Year-Old Female with Unexpected Platelet Function Testing Results

A 70-year-old female with a history of hypertension and left A2 segment aneurysm was scheduled for pipeline embolization device (PED) placement. Preinterventional antiplatelet prophylaxis included aspirin and ticagrelor. Unexpectedly, after 13 days of treatment, VerifyNow showed a P2Y12 reaction unit (PRU) value of 216, approximately >5 times the mean PRU of other patients on aspirin and ticagrelor. We confirmed platelet reactivity and ticagrelor resistance with light transmission aggregometry. Antiplatelet therapy was switched to prasugrel, and aspirin was continued. Eight days later, the P2Y12 reaction value (PRU) was 164. PED was placed without complications. Unlike clopidogrel, ticagrelor is a direct P2Y12 inhibitor that does not require metabolism to an active metabolite. Ticagrelor resistance is very rarely reported. To the best of our knowledge, there has been no case of ticagrelor resistance reported in the context of pre-PED placement prophylaxis.

Flow diversion for internal carotid artery aneurysms: Impact of complex aneurysm features and overview of outcome

OBJECTIVE

Flow diversion is a popular technique used to treat ordinary small, as well as complex internal carotid artery (ICA) aneurysms. We describe aneurysm occlusion rates, complications and patient outcomes in patients with ICA aneurysms treated with flow diverter stents.

PATIENTS AND METHODS

We identified all consecutive patients with ICA aneurysms that were treated with flow diverter stents between 2014 and 2019 at our institution. We divided the aneurysms into two anatomic subgroups (cavernous and supraclinoid segments). All the imaging studies and medical records were reviewed for relevant features in relation to aneurysms, complications and patient outcomes.

RESULTS

A total of 62 patients with 76 ICA aneurysms (72 unruptured; 4 ruptured) were treated with 70 flow diversion procedures, including six re-treatments. Complete aneurysm occlusion was achieved in 61 % of patients at 6-month follow-up (cavernous 69 %, supraclinoid 58 %), and in 69 % at the latest follow-up (mean of 18 months). Postprocedural intracranial ischemia or hemorrhage was seen in 24 % of patients, including two aneurysm ruptures after flow diversion, and related major long-term functional decline or mortality was seen in 6% of patients. Preprocedural dysfunction of extraocular muscles or vision disturbance improved moderately at best (40-60 %). At the latest follow-up, 54 patients (87 %) were functionally independent (mRS ≤2).

CONCLUSION

Flow diversion for cavernous and supraclinoid ICA aneurysms demonstrated acceptable results, but complex aneurysm features cause uncertainty in predicting aneurysm occlusion probability. Patients should be informed of the non-negligible rate of complications, and of only moderate improvement rate of cranial nerve dysfunctions.

The Evolution of Flow-Diverting Stents for Cerebral Aneurysms; Historical Review, Modern Application, Complications, and Future Direction

In spite of the developing endovascular era, large (15–25 mm) and giant (>25 mm) wide-neck cerebral aneurysms remained technically challenging. Intracranial flow-diverting stents (FDS) were developed to address these challenges by targeting aneurysm hemodynamics to promote aneurysm occlusion. In 2011, the first FDS approved for use in the United States market. Shortly thereafter, the Pipeline of Uncoilable or Failed Aneurysms (PUFS) study was published demonstrating high efficacy and a similar complication profile to other intracranial stents. The initial FDA instructions for use (IFU) limited its use to patients 22 years old or older with wide-necked large or giant aneurysms of the internal carotid artery (ICA) from the petrous segment to superior hypophyseal artery/ophthalmic segment. Expanded IFU was tested in the Prospective Study on Embolization of Intracranial Aneurysms with PipelineTM Embolization Device (PREMIER) trial. With further post-approval clinical data, the United States FDA expanded the IFU to include patients with small or medium, wide-necked saccular or fusiform aneurysms from the petrous ICA to the ICA terminus. However, IFU is more restrictive in South Korea than in United States. Several systematic reviews and meta-analyses have sought to evaluate the overall efficacy of FDS for the treatment of cerebral aneurysms and consistently identify FDS as an effective technique for the treatment of aneurysms broadly with complication rates similar to other traditional techniques. A growing body of literature has demonstrated high efficacy of FDS for small aneurysms; distal artery aneurysms; non-saccular aneurysms posterior circulation aneurysms and complication rates similar to traditional techniques. In the short interval since the Pipeline Embolization Device was first introduced, FDS has been firmly entrenched as a powerful tool in the endovascular armamentarium. As new FDS are developed, established FDS are refined, and delivery systems are improved the uses for FDS will only expand further. Researchers continue to work to optimize the mechanical characteristics of the FDS themselves, aiming to optimize deploy ability and efficacy. With expanded use for small to medium aneurysms and posterior circulation aneurysms, FDS technology is firmly entrenched as a powerful tool to treat challenging aneurysms, both primarily and as an adjunct to coil embolization. With the aforementioned advances, the ease of FDS deployment will improve and complication rates will be further minimized. This will only further establish FDS deployment as a key strategy in the treatment of cerebral aneurysms.