Intracerebral hemorrhage after pipeline embolization: Management of antiplatelet agents and the case for point-of-care testing—Case reports and review of literature

The Pipeline Embolization Device: a decade of lessons learned in the treatment of posterior circulation aneurysms in a multicenter cohort

OBJECTIVE

The Pipeline Embolization Device (PED) has prompted a paradigm shift in the approach to posterior circulation aneurysms. The year 2021 marks a decade since FDA approval of this flow diverter, and during this time operators have adapted to its off-label uses. The authors examined whether case selection, practice trends, and patient outcomes have changed over this 10-year period.

METHODS

This study is a retrospective review of consecutive posterior circulation aneurysms managed with the PED at four academic institutions in the US between January 1, 2011, and January 1, 2021. Factors related to case selection, rates of aneurysm occlusion, or complications were identified and evaluated. Angiographic outcomes as well as thromboembolic and hemorrhagic complications were investigated.

RESULTS

This study included 117 patients (median age 60 years). At a median follow-up of 12 months, adequate occlusion (> 90%) was attained in 73.2% of aneurysms. Aneurysm occlusion rates were similar over the study interval. Thromboembolic and hemorrhagic complications were reported in 12.0% and 6.0% of the procedures, respectively. There was a nonsignificant trend toward a decline in the rate of thromboembolic (14.1% in 2011-2015 vs 9.4% in 2016-2021, p = 0.443) and hemorrhagic (9.4% in 2011-2015 vs 1.9% in 2016-2021, p = 0.089) complications.

CONCLUSIONS

The authors observed a trend toward a decline in the rate of thromboembolic and hemorrhagic complications with improved operator experience in using the PED for posterior circulation aneurysms. The use of single-device PED flow diversion significantly increased, as did the tendency to treat smaller aneurysms and observe large unruptured fusiform/dolichoectatic lesions. These findings reflect changes attributable to evolving judgment with maturing experience in PED use.

Treatment of Traumatic Internal Carotid Artery Aneurysm by Flow-Diverter: A Single-Center Experience

AIM

Traumatic intracranial aneurysm (TICA) is a rare vascular lesion with various etiologies and a high mortality rate when diagnosed late. In this study, we present our cases of TICA, which we treated with flow-diverter stents due to different etiological factors.

METHODS

Clinical data were recorded for 8 patients: age, gender, etiological factors, aneurysm location, aneurysm type, rupture, main artery status, and postoperative complications.

RESULTS

75% (n:6) of the patients were male and 25% (n:2) female. Etiologically, there was intracranial tumor surgery in 3 cases (37.5%), fall from height in 2 (25%), road accident in 2 (25%), and blunt trauma in 1 (12.5%). Reconstruction used a flow-diverting stent in all cases. One patient experienced intraoperative iatrogenic rupture of the distal arterioles due to a microwire. Mean angiographic follow-up was 17.8 months (range, 6-32 months). During follow-up, none of the patients required renewed endovascular treatment.

CONCLUSION

Traumatic aneurysm is a vascular lesion with high mortality when diagnosed late. In case of suspected vascular injury after trauma or intracranial surgery, further evaluation should be performed without delay. TICA can be safely treated with flow-diverter stents, conserving the main artery.

The Combination of Stent and Antiplatelet Therapy May Be Responsible of Parenchymal Magnetic Susceptibility Artifacts after Endovascular Procedure

The aim was to assess the occurrence of magnetic susceptibility artifacts (MSA) following endovascular treatment of intracranial aneurysm by stent using susceptibility weighted imaging (SWI). Imaging and clinical data of 46 patients who underwent stent placement in the case of intracranial aneurysm endovascular treatment (S-Group) were retrospectively analyzed and compared to a control group (C-Group) in which 46 patients had coiling alone. The mean number of MSA was higher in the S-group than in the C-group on postprocedural SWI sequence (8.76, 95%CI [5.76; 11.76] vs. 0.78 [0.32; 1.25], respectively, p < 0.001) with a higher frequency of the appearance of MSA also in the S-group (78.26% vs. 21.74% in the C-group, p < 0.001). In the S-group, in the vascular territory of the treated artery, there was a higher number of MSA than in other vascular territories (mean of 5.18 [3.43; 6.92] vs. 3.08 [1.79; 4.36], p = 0.001). An odds ratio (OR) of 20.98 [5.24; 83.95] suggested a higher proportion of onset of MSA in the S-group than in the C-group (p < 0.001). The appearance of MSA after a treatment by stenting for intracranial aneurysm in patients under antiplatelet therapy was common, particularly in the treated artery territory.

Utility of quantitative magnetic resonance angiography and non-invasive optimal vessel analysis for identification of complications and long-term hemodynamic changes in post-pipeline embolization patients

INTRODUCTION

Quantitative magnetic resonance angiography and non-invasive optimal vessel analysis serve as powerful tools to collect and analyze hemodynamic data from pipeline embolization patients. At our institution, patients receive post-embolization quantitative magnetic resonance angiography within 24 h of treatment and within 6 months for follow-up to evaluate pipeline patency. Here, we aim to elucidate the long-term hemodynamic changes following pipeline embolization device placement and report two cases in which in-stent stenosis was detected.

METHODS

Medical records of patients who underwent pipeline embolization device placement for an internal carotid artery aneurysm between 2017 and 2019 were reviewed. Patients who received post-procedure NOVA and follow-up NOVA were included in the study (n = 32). Location and size of aneurysm, number of pipeline embolization device deployed, and complications were collected along with the non-invasive optimal vessel analysis report (flow volume rate (ml/min), mean, systolic, and diastolic flow velocities (cm/s), and vessel diameter (mm)). Internal carotid artery vessel flow rate was measured proximal to the pipeline embolization device. Derivations of hemodynamic parameters (pulsatility index, Lindegaard ratio, and wall shear stress) were calculated.

RESULTS

The middle cerebral artery mean and diastolic flow velocities were significantly lower on the follow-up NOVA compared to the post-procedure NOVA. Moreover, follow-up NOVA demonstrated lower middle cerebral artery wall shear stress on the side with flow diversion compared to the post-procedure NOVA. In-stent stenosis, requiring intervention, was detected in two patients on follow-up NOVA. One patient had a successful balloon angioplasty of the stented internal carotid artery that resolved her stenosis. However, the second patient developed progressive stenosis and expired despite intervention.

CONCLUSION

Long-term hemodynamic adaptations post-pipeline embolization device demonstrate decreased wall shear stress and decreased mean and diastolic flow velocities in the distal middle cerebral artery, which suggest decreasing velocity of blood flow with endothelialization of the device. Furthermore, follow-up NOVA is a useful tool for detecting potential flow-related complications such as in-stent stenosis.

Endovascular treatment of vertebral and basilar artery aneurysms with low-profile visualized intraluminal support device

Background

The Low-profile Visualized Intraluminal Support (LVIS) device is a self-expanding, nitinol, single-braid, closed-cell device that was recently developed for endovascular embolization of intracranial aneurysms. However, current knowledge regarding the use of LVIS devices to treat vertebral and basilar artery aneurysms is limited. We aimed to evaluate the feasibility, efficacy, and safety of the LVIS device for treating vertebral and basilar artery aneurysms.

Methods

Between January 2015 and December 2017, patients with vertebral and basilar artery aneurysms treated using LVIS stents were enrolled in this study. We analyzed patients’ demographic, clinical and aneurysmal characteristics, procedural details, complications, and angiographic and clinical follow-up results.

Results

We identified 63 patients with 64 vertebral and basilar artery aneurysms who underwent treatment with (n = 59) or without (n = 5) LVIS stenting, including 10 patients with ruptured aneurysms. Forty-one aneurysms were located at the vertebral artery, and 23 at the basilar artery. Intraprocedural-related complications developed in three (4.8%) patients, while none of these patients developed morbidities or died during follow-up. Three patients developed post-procedural complications (4.8%). Two patients experienced ischemic events immediately post-procedure. A minor permanent morbidity developed in one of the two patients (1.6%). The mortality rate was 1.6%, for that the patient died of brainstem hemorrhage after 1 month of follow-up. At a mean follow-up of 12.5 months, 39/43 (90.7%) patients had stable or improved aneurysms, and four (9.3%) had recanalized.

Conclusions

LVIS device of vertebral and basilar artery aneurysms may be an acceptable safety profile and may represent a reasonable treatment option in the short-term. Long-term and larger cohort studies are necessary to validate our results.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02180-1.

Risk Factor Analysis of Delayed Intracerebral Hemorrhage After Coil Embolization of Unruptured Cerebral Aneurysms

Background: We sought to analyze diffusion-weighted imaging (DWI) and dual antiplatelet therapy (DAPT) for risk factors of delayed intracerebral hemorrhage (d-ICH) after coil embolization for an unruptured intracranial aneurysm (UIA).

Methods: A total of 539 aneurysms were analyzed in this study. Ruptured and flow diverter cases were excluded. All aneurysms enrolled in this study were treated with stent-assisted or simple coiling techniques. Before the procedure, all patients administered (DAPT). After the procedure, patients who underwent stent-assisted coil embolization were given DAPT, and patients who underwent simple coiling were given single antiplatelet therapy (SAPT) only during their admission. The response of the antiplatelet agent was assessed the day before the procedure with The VerifyNow assay. DWI MRI and CT were obtained routinely the next day after the procedure. d-ICH was defined as an intracerebral hemorrhagic lesion identified in follow up CT at least 48 h after the procedure.

Results: A larger positive lesion on day 1 DWI MRI (p = 0.001), the value of PRU (p = 0.002), and the inhibition rate (p = 0.025) were considered meaningful risk factors for d-ICH in univariate analysis. Accordingly, larger DWI positivity (OR = 83.73, 95% CI = 11.132–712.886, P = 0.001) and PRU (OR = 0.98, 95% CI = 0.972–0.999, P = 0.033) reached statistical significance in multivariate analysis.

Conclusions: Thromboembolic infarction may work as an initiating factor, and antiplatelet medication may work as an aggravating factor. We might suggest that a tailored reduction in antiplatelet agents could help reduce d-ICH when a larger volume of post-procedural thromboembolic infarction is seen on 1-day follow-up DWI MRI.

The Pipeline Embolization Device: Changes in Practice and Reduction of Complications in the Treatment of Anterior Circulation Aneurysms in a Multicenter Cohort

BACKGROUND

The Pipeline Embolization Device (PED; Medtronic, Dublin, Ireland) has become an important tool for the treatment of cerebral aneurysms. Since FDA approval, there are ongoing efforts to increase aneurysm occlusion rates and reduce the incidence of complications.

OBJECTIVE

To assess aneurysm occlusion and complication rates over time.

METHODS

Retrospective analysis of consecutive anterior circulation aneurysms treated with a single PED between 2011 and 2016 at 3 academic institutions in the US was performed. Factors contributing to changes in aneurysm occlusion and complication rates over time were identified and evaluated.

RESULTS

A total of 284 procedures were performed on 321 anterior circulation aneurysms in 284 patients. At a median follow-up of 13 mo (mean 18 mo), complete or near complete occlusion (>90%) was achieved in 85.9% of aneurysms. There was no significant change in aneurysm occlusion rate or procedure length over time. Thromboembolic complication occurred in 8.1% of procedures, and there was a trend toward decreased incidence from 16.3% in 2011/2012 to 3.3% in 2016 (P = .14). Hemorrhagic complications significantly decreased from 8.2% in 2011/2012 to 0 to 1.0% in 2014-2016 (P = .1).

CONCLUSION

We report a notable drop in the rate of hemorrhagic and to a lesser extent thromboembolic complications with increased experience with PED in a multicenter cohort. Multiple factors are believed to contribute to this drop, including the evolved interpretation of platelet function testing, the switching of clopidogrel nonresponders to ticagrelor, and the reduced use of adjunctive coiling.

Predictors of Complications, Functional Outcome, and Morbidity in a Large Cohort Treated With Flow Diversion

BACKGROUND

A dramatic improvement in obliteration rates of large, wide-necked aneurysms has been observed after the FDA approved the Pipeline Embolization Device (PED) in 2011.

OBJECTIVE

To assess the predictors of complications, morbidity, and unfavorable outcomes in a large cohort of patients with aneurysms treated with PED.

METHODS

A retrospective chart review of a prospectively maintained database for subjects treated with flow diversion from 2010 to 2019.

RESULTS

A total of 598 aneurysms were treated during a period extending from 2010 to 2019 (84.28% females, mean age 55.5 yr, average aneurysm size 8.49 mm). Morbidity occurred at a rate of 5.8% and mortality at a rate of 2.2%. Ischemic stroke occurred at a rate of 3%, delayed aneurysmal rupture (DAR) at 1.2%, and distal intraparenchymal hemorrhage (DIPH) at 1.5%. On multivariate analysis, the predictor of stroke was aneurysm size &gt;15 mm. Predictors of DAR were previous subarachnoid hemorrhage (SAH), increasing aneurysm size, and posterior circulation aneurysm. Predictors of DIPH were using more than 1 PED and baseline P2Y12 value. Predictors of in-stent stenosis were the increasing year of treatment and balloon angioplasty, whereas increasing age and previous treatment were negatively associated with in-stent stenosis. Predictors of morbidity were posterior circulation aneurysms, increasing aneurysm size, and hypertension, and incidental aneurysm diagnosis was protective for morbidity.

CONCLUSION

Flow diversion is a safe and effective treatment option for aneurysms. A better understanding of predictive factors of complications, morbidity, and functional outcomes is of high importance for a more accurate risk assessment.

Microhemorrhagic transformation of ischemic lesions on T2*-weighted magnetic resonance imaging after Pipeline embolization device treatment

OBJECTIVE

The authors sought to demonstrate that hemorrhagic transformation of ischemic lesions is the main cause of delayed intracerebral hemorrhage (ICH) after Pipeline embolization device (PED) treatment and to estimate the rate of hemorrhagic transformation of new postprocedure ischemic lesions.

METHODS

Patients who underwent PED placement (PED group) from November 2015 to March 2017 or stent-mediated embolization (EN group) from December 2010 to October 2015 were retrospectively analyzed. Pre- and postprocedural MR images and 6-month follow-up MR images for each patient were scored for the presence of postprocedural bland ischemic and hemorrhagic lesions using diffusion-weighted MRI (DWI) and T2*-weighted MRI (T2*WI), respectively.

RESULTS

The PED group comprised 28 patients with 30 intracranial aneurysms, and the EN group comprised 24 patients with 27 intracranial aneurysms. The mean number of ischemic lesions on DWI 1 day postprocedure was higher in the PED group than in the EN group (5.2 vs 2.7, p = 0.0010). The mean number of microbleeds detected on T2*WI 6 months postprocedure was higher in the PED group than in the EN group (0.6 vs 0.15, p = 0.028). A total of 36.7% of PED-treated patients exhibited new microbleeds on T2*WI at 6 months postprocedure, with at least 77.8% of these lesions representing hemorrhagic transformations of the new ischemic lesions observed on day 1 postprocedure. The rate of adjunctive coil embolization (27.3% vs 0.0%, p = 0.016) and the mean number of ischemic lesions observed 1 day postprocedure (6.6 vs 4.3, p = 0.020) were predictors of subsequent microbleeds in the PED group.

CONCLUSIONS

New microbleeds detected using T2*WI at 6 months postprocedure were more common after PED treatment than after stent-mediated embolization. Approximately three-quarters of these lesions were hemorrhagic transformations of new ischemic lesions observed on day 1 postprocedure. Prevention of intraprocedural or postprocedural infarcts is necessary to reduce the risk of hemorrhagic complications following PED placement.

Use of Pipeline™ embolization device for the treatment of traumatic intracranial pseudoaneurysms: Case series and review of cases from literature

OBJECTIVE

Intracranial traumatic pseudoaneurysms (PSA) are a rare but dangerous subtype of cerebral aneurysm. Reports documenting use of flow-diverting stents to treat traumatic intracranial PSAs are few and lack long-term follow-up. To our knowledge, this is the largest case-series to date demonstrating use of Pipeline Endovascular Device (PED) for traumatic intracranial PSAs.

PATIENTS AND METHODS

Retrospective review of 8 intracranial traumatic PSAs in 7 patients treated using only PED placement. Patients were followed clinically and angiographically for at least 6 months.

RESULTS

Seven patients with a mean age of 37 years were treated for 8 intracranial pseudo-aneurysms between 2011-2015. Six aneurysms were the result of blunt trauma; 2 were from iatrogenic injury during transsphenoidal surgery. Mean clinical and angiographic follow-up in surviving patients was 15.2 months. In patients with angiographic follow-up, complete occlusion was achieved in all but one patient, who demonstrated near-complete occlusion. No ischemic events or stent-related stenosis were observed. One patient developed a carotid-cavernous fistula after PED, which was successfully retreated with placement of a second PED. There were two mortalities. One was due to suspected microwire perforation remote from the target aneurysm resulting in SAH/IPH. The other was due to a traumatic SDH and brainstem hemorrhage from an unrelated fall during follow-up interval.

CONCLUSIONS

Use of PED for treatment of intracerebral PSAs following trauma or iatrogenic injury showed good persistent occlusion, and acceptable complication rate for this high-risk pathology. Risks of this procedure and necessary antiplatelet therapy require appropriate patient selection. Larger prospective studies are warranted.

Patterns, Predictors, and Outcomes of Postprocedure Delayed Hemorrhage Following Flow Diversion for Intracranial Aneurysm Treatment

OBJECTIVE

To evaluate patterns, predictors, and outcomes of postprocedure delayed hemorrhage (PPDH) following flow diversion therapy for intracranial aneurysm treatment.

METHODS

From 2012 to 2016, 50 patients with 52 aneurysms were treated with the Pipeline embolization device. Device placement was performed as a standalone therapy or with adjunctive coil embolization. Patients underwent dual antiplatelet therapy for 6 months after treatment. Medical comorbidities; aneurysm traits; and treatment factors, including platelet function testing, were studied. Statistical analysis was performed using cross-tabulation.

RESULTS

Six PPDHs (12%) occurred 2-16 days (mean 6.8 days) after Pipeline placement, manifesting as 1 of 2 distinct patterns: convexity subarachnoid hemorrhage (cSAH) (n = 4) or lobar intraparenchymal hemorrhage (IPH) (n = 2). All PPDHs occurred ipsilateral to the device; 1 IPH occurred ipsilateral but in a different arterial territory. PPDH occurred in both treated anterior communicating artery aneurysms. Cases of PPDH demonstrated on average lower P2Y12 reaction unit values at the time of treatment. Platelet function testing at the time of hemorrhage was consistently hypertherapeutic. Patients with cSAH had only minimal worsening of modified Rankin Scale score at the time of discharge, whereas the 2 patients with IPH experienced significant deterioration.

CONCLUSIONS

PPDH is a poorly understood complication following flow diversion therapy that can result in significant morbidity. In our experience, nonaneurysmal cSAH does not result in poor clinical outcomes, whereas IPH leads to long-term deficits or death. As previously suggested, there appears to be a correlation between low P2Y12 reaction unit values and PPDH.

Middle cerebral artery pressure changes following Pipeline flow diversion

Objective Pipeline embolization devices (PED) are commonly used for endovascular treatment of cerebral aneurysms but changes in intracranial hemodynamics after PED deployment are poorly understood. Here, we assess middle cerebral artery (MCA) and systemic blood pressure before and after PED treatment. Methods Records of patients with cerebral aneurysms proximal to the internal carotid artery terminus treated with PED at our institution between 2015 and 2017 were retrospectively reviewed. Patients were included if ipsilateral MCA pressure measurements were available. Ipsilateral MCA pressure was transduced via the microcatheter before and after PED deployment. Systemic arterial blood pressure was also simultaneously recorded. MCA, systemic blood pressure, and ratios of MCA to systemic blood pressure values were compared before and after treatment among the study cohort using the two-sample paired Student t test. Results Fourteen patients were included. Mean age was 54 years. Among the entire cohort, the ratio of MCA to systemic systolic and mean blood pressure were significantly higher after treatment (respectively 0.76 vs. 0.69, p = 0.01, and 0.94 vs. 0.89, p = 0.03), and the ratio of MCA to systemic diastolic pressures showed an increasing trend (1.08 vs. 1.03, p = 0.09). The percentage of ratio increase was independent of aneurysm size ( r = -0.24, p = 0.42 for systolic ratio; r = -0.09, p = 0.74 for diastolic ratio; r = -0.09; p = 0.76 for mean ratio, respectively). Conclusions Following PED deployment, the ratio of ipsilateral MCA to systemic systolic and mean blood pressure increased. These pressure changes should be further evaluated in a larger sample size.

Intracranial contrast transit times on digital subtraction angiography decrease more in patients with delayed intraparenchymal hemorrhage after Pipeline

Background Pipeline embolization devices (PEDs) are used for endovascular treatment of cerebral aneurysms but can be associated with delayed ipsilateral intraparenchymal hemorrhage (DIPH). Changes in intracranial hemodynamics after PED are poorly understood. Objective Here, we assess hemodynamic changes after PED in patients and compare these changes in patients with and without DIPH (DIPH+ and DIPH-). Methods Records of patients with distal internal carotid artery (ICA) aneurysms treated with PED at our institution between 2012 and 2017 were retrospectively reviewed. Regions of interest were selected proximally to PED over the cavernous ICA and distally over the middle cerebral artery (MCA), and then transit times were determined using syngo iFlow software (Siemens). Ratio of MCA to ICA transit time was compared before, after treatment, and at follow-up. Ratios were also compared between DIPH+ and DIPH- subgroups. Correlations between aneurysm size, age, and ratios were investigated. Results Fifty-three patients were included. The ratio of MCA to ICA transit time decreased significantly after PED deployment (1.13 vs. 1.22, p < 0.01). The ratio in the DIPH + subgroup ( n = 4) was significantly lower (1.00 vs. 1.14, p = 0.01) and decreased significantly more (21% vs. 4.4%, p = 0.02) compared to the DIPH- subgroup ( n = 49). The ratio tended to be higher in larger aneurysms at baseline ( r = 0.25, p = 0.07) but not after PED treatment ( r = 0.11, p = 0.15). Age did not correlate with ratio. Conclusion The ratio of MCA to ICA transit time decreases following PED treatment and decreases more in patients with DIPH. These contrast transit time changes can be detected in real time immediately after PED deployment.

Clinical and angiographic outcomes in patients with intracranial aneurysms treated with the pipeline embolization device: intra-procedural technical difficulties, major morbidity, and neurological mortality decrease significantly with increased operator experience in device deployment and patient management

PURPOSE

Flow diversion constitutes a pivotal advancement in endovascular intracranial aneurysm treatment, but requires development of a new skill set. The aim of this study is to determine whether outcomes after treatment with the Pipeline Embolization Device improve with experience.

METHODS

We retrospectively reviewed all patients with intracranial aneurysms treated with Pipeline at two centers over a 4.5-year period. Baseline patient and aneurysm characteristics, complications, and angiographic outcomes were analyzed.

RESULTS

One hundred forty patients underwent 150 Pipeline procedures to treat 167 intracranial aneurysms during the study period, 109 women, mean age 55.4 years. One hundred twenty-six aneurysms were ICA, mean size 10.2 mm and mean neck 6.4 mm. Intra-procedural technical difficulties were higher during the first 75 procedures compared with the subsequent 75 (13.3 vs 2.7%; p = 0.03), as combined major morbidity and neurological mortality (14.7 vs 4%; p = 0.046). In multivariate regression analysis, increased operator experience with Pipeline remained an independent predictor of intra-procedural technical difficulties (p = 0.02, odds ratio (OR) 0.015, 95% CI 0.0004-0.55) and combined major morbidity and neurological mortality (p = 0.03, OR 0.16, 95% CI 0.03-0.84). At last follow-up, 123 aneurysms were completely occluded (81.5%, mean 24 months). In our cohort, age ≤ 53 years was an independent predictor of complete aneurysm occlusion at last follow-up (p = 0.001, OR 0.92, 95% CI 0.88-0.97). Five aneurysms were retreated (3.3%).

CONCLUSION

The Pipeline embolization device is an effective treatment for intracranial aneurysms. The risk of intra-procedural technical difficulties and combined major morbidity and neurological mortality decreases significantly with increased operator experience in Pipeline deployment and patient management.

Flow diversion with the pipeline embolization device for patients with intracranial aneurysms and antiplatelet therapy: A systematic literature review

Flow diversion with the Pipeline Embolization Device (PED) is reported as a safe and efficient treatment for patients with intracranial aneurysms; however, literature discussing the antiplatelet (APT) regimen used before and after the PED is limited. Our aim was to systematically review and summarize available data regarding the APT regimen and the platelet function test (PFT) that was used. We also sought to provide an overview of the aneurysm morphologies and adverse event rates associated with the PED use. This systematic review was conducted according to the PRISMA statement and eligible studies were identified through search of the PubMed and Cochrane databases. We reviewed 28 studies, involving 1556 patients that underwent aneurysm treatment with the PED. The preprocedural aspirin (ASA) 300- 325mg (2-14days) combined with clopidogrel 75mg (3 to >10days) were used as a treatment strategy in 61.7% of patients and ASA 81mg with clopidogrel 75mg for 5-10days for 27%. Patients who received low versus high dose pre-PED ASA, were at less risk for a hemorrhagic event (0.7% versus 3.3%, p=0.053); however no statistical significance was reached. There was also lack of relationship between patients that received low versus high preprocedural ASA in terms of thromboembolic events. Regarding postprocedural APT, ASA (>6months) and clopidogrel (3- 12 months) was the regimen of choice for 93% of patients. Most studies conducted at least one PFT, most common being the VerifyNow. The most frequently reported target P2Y12 Reaction unit (PRU) and Aspirin Reaction Unit (ARU) values were <230 and <550 respectively. There was no statistically demonstrable difference in regards to thrombotic events between centers that conducted at least one PFT and centers that did not test their patients with a PFT. The overall rates of symptomatic thrombotic episodes were 6.6% and hemorrhagic were 3%. The pre- and post-PED APT dose and duration varies across different institutions. More prospective studies are needed to compare the efficacy of different APT agents and reach conclusions regarding use of PFT and platelet reaction values in order to decrease hemorrhagic and thromboembolic complications associated with the PED.

Middle cerebral artery flow velocity increases more in patients with delayed intraparenchymal hemorrhage after Pipeline

Objective

Pipeline Embolization Devices (PED) are commonly used for endovascular treatment of cerebral aneurysms but can be associated with delayed ipsilateral intraparenchymal hemorrhage (DIPH). The role that altered intracranial hemodynamics may play in the pathophysiology of DIPH is poorly understood. We assess middle cerebral artery (MCA) flow velocity changes after PED deployment.

Materials and methods

Patients with aneurysms located proximal to the internal carotid artery terminus treated with PED at our institution between 2015 and 2016 were retrospectively reviewed. Patients were included if MCA flow velocities were measured using transcranial Doppler. Bilateral MCA flow velocities, ratio of ipsilateral to contralateral MCA flow velocity, and bilateral MCA pulsatility index before and after PED deployment were assessed.

Results

10 patients of mean age 52 years were included. Two patients had DIPH within 48 hours after PED deployment. We observed that these two patients had a higher increase in ipsilateral MCA mean flow velocity after treatment compared with patients without DIPH (39.5% vs 5.5%). Additionally, before PED deployment, patients with DIPH had a higher ipsilateral MCA pulsatility index (1.55 vs 0.98) and a higher ratio of ipsilateral to contralateral MCA mean flow velocity (1.35 vs 1.04).

Conclusions

After PED, ipsilateral MCA mean flow velocity increases more in patients with DIPH. These flow velocity changes suggest the possible role of altered distal intracranial hemodynamics in DIPH after PED treatment of cerebral aneurysms. Further data are required to confirm this observation.

Optimal pediatric dosing of anti-platelet agents for pipeline stent embolization -a case report and review of the literature

BACKGROUND

Various strategies are emerging for dosing antiplatelet therapies in preparation for pipeline stent embolization in adults. Hyper-response is associated with hemorrhagic complications. Hypo-response is associated with thromboembolic events. Dosing of antiplatelet agents is highly variable, with little consensus among experts for adults-and even more so for children. To date, pipeline stents have been deployed in 11 pediatric patients, ages 4-15. A variety of clopidogrel and aspirin dosing regimens have been used, with response tested in only three patients, who were all therapeutic. Thrombotic events occurred in two patients, neither of whom were tested.

CASE

We describe here the first case of a hemorrhagic complication in a hyper-responsive pediatric patient undergoing placement of a pipeline stent.

DISCUSSION

As the use of endovascular therapies requiring dual anti-platelet agents becomes more established, there is an increasing need to develop titration protocols that minimizes the risk of thrombotic and hemorrhagic events.

P2Y12 hyporesponse (PRU>200) is not associated with increased thromboembolic complications in anterior circulation Pipeline

Introduction

Recent reports suggest that thromboembolic complications are associated with Pipeline embolization device (PED) placement cluster in P2Y12 hyporesponders.

Objective

To evaluate the role of P2Y12 hyporesponse in PED placement by retrospectively reviewing a single-center series of patients.

Methods

We retrospectively reviewed an institutional review board-approved database of patients with an aneurysm at a single institution and identified all patients with a measured P2Y12 reaction unit (PRU)>200 who had undergone anterior circulation PED placement. Events such as transient ischemic attack, stroke, and hemorrhage were identified as well as demographic and procedural details.

Results

Fifty-two patients with a PRU >200 had undergone anterior circulation PED placement. Four patients had prior subarachnoid hemorrhage (SAH) (8%) and 11 aneurysms (21%) had been previously treated. The average aneurysm size was 7.6 mm (±6.2). PED thrombosis occurred intraprocedurally in three patients, none of whom developed neurological deficits after abciximab administration. Treatment of all patients was successful and 48 procedures (92%) had no complications. One patient had a major stroke (2%) with permanent hemiparesis. There were three minor complications (6%): one minor stroke with a visual field cut, one 10 cc intracranial hemorrhage with transient left lower extremity weakness, and one transient neurological deficit not verified by imaging. No deaths or cases of SAH occurred.

Conclusions

P2Y12 hyporesponse (PRU>200) is not associated with increased periprocedural complications in a contemporary series of patients undergoing anterior circulation PED placement. Titration of antiplatelet medications to P2Y12 >200 remains unindicated and may increase the risk of hemorrhagic complications.

Carotid cavernous fistula after Pipeline placement: a single-center experience and review of the literature

Objective

Carotid cavernous fistula (CCF) development after Pipeline Embolization Device (PED) treatment of cavernous carotid aneurysms (CCA) can be a challenging pathology to treat for the neurointerventionalist.

Methods

A database of all patients whose aneurysms were treated with the PED since its approval by the Food and Drug Administration in 2011 was retrospectively reviewed. Demographic information, aneurysm characteristics, treatment technique, antiplatelet regimen, and follow-up data were collected. A literature review of all papers that describe PED treatment of CCA was then completed.

Results

A total of 44 patients with 45 CCAs were identified (38 women, 6 men). The mean age was 59.9±9.0 years. The mean maximal aneurysm diameter was 15.9±6.9 mm (mean neck 7.1±3.6 mm). A single PED was deployed in 32 patients, with two PEDs deployed in 10 patients and three PEDs in 3 patients. Adjunctive coiling was performed in 3 patients. Mean follow-up duration based on final imaging (MR angiography or digital subtraction angiography) was 14.1±12.2 months. Five patients (11.4%) developed CCFs in the post-procedural period after PED treatment, all within 2 weeks of device placement. These CCFs were treated with a balloon test occlusion followed by parent artery sacrifice. Our literature review yielded only three reports of CCFs after PED placement, with the largest series having a CCF rate of 2.3%.

Conclusions

CCF formation is a known risk of PED treatment of CCA. Although transvenous embolization can be used for treating CCFs, parent artery sacrifice remains a viable option on the basis of these data. Studies support the view that adjunctive coiling may have a protective effect against post-PED CCF formation. None of the coiled aneurysms in our database or in the literature have ruptured. Follow-up data will lead to a better understanding of the safety profile of the PED for CCA.

Risk Factors for Hemorrhagic Complications following Pipeline Embolization Device Treatment of Intracranial Aneurysms: Results from the International Retrospective Study of the Pipeline Embolization Device

BACKGROUND AND PURPOSE

Spontaneous intraparenchymal hemorrhage is a dreaded complication of unknown etiology following flow-diversion treatment. Using the International Retrospective Study of the Pipeline Embolization Device registry, we studied demographic, aneurysm, and procedural characteristics associated with intraparenchymal hemorrhage following Pipeline Embolization Device treatment.

MATERIALS AND METHODS

We identified patients in the International Retrospective Study of the Pipeline Embolization Device registry with intraparenchymal hemorrhage unrelated to index aneurysm rupture post-Pipeline Embolization Device treatment. The rate of intraparenchymal hemorrhage was determined by baseline demographics, comorbidities, aneurysm characteristics, and procedural characteristics (including anticoagulation use, platelet testing, number of devices used, sheaths, catheters, and guidewires). Categoric variables were compared with χ(2) testing, and continuous variables were compared with the Student t test.

RESULTS

Of 793 patients with 906 aneurysms, 20 (2.5%) had intraparenchymal hemorrhage. Fifteen intraparenchymal hemorrhages (75.0%) occurred within 30 days of treatment (median, 5 days; range, 0-150 days). Nine patients with intraparenchymal hemorrhage (45.0%) died, 10 (50.0%) had major neurologic morbidity, and 1 had minor neurologic morbidity (5.0%). Intraparenchymal hemorrhage was ipsilateral to the Pipeline Embolization Device in 16 patients (80%) and contralateral in 3 patients (15.0%). Variables associated with higher odds of intraparenchymal hemorrhage included treatment of ruptured aneurysms (OR, 4.44; 95% CI, 1.65-11.94; P = .005) and the use of ≥ 3 Pipeline Embolization Devices (OR, 4.10; 95% CI, 1.34-12.58; P = .04). The Shuttle sheath was not associated with intraparenchymal hemorrhage (OR, 0.97; 95% CI, 0.38-2.45; P = .95).

CONCLUSIONS

Spontaneous intraparenchymal hemorrhage following Pipeline Embolization Device treatment is a rare-but-devastating complication, with nearly all patients having morbidity or mortality. Variables associated with intraparenchymal hemorrhage included the use of multiple Pipeline Embolization Devices and treatment of ruptured aneurysms. The Shuttle, a device that was previously thought to be associated with intraparenchymal hemorrhage, was not associated with it.

A New Protocol for Anticoagulation With Tirofiban During Flow Diversion

BACKGROUND:

Flow diversion is increasingly used to treat intracranial aneurysms. In previous reports, patients were pretreated with aspirin and clopidogrel before the intervention for the prevention of thromboembolic complications.

OBJECTIVE:

To assess the safety and efficacy of a new protocol for anticoagulation using tirofiban during flow diversion.

METHODS:

All patients received a 0.10–μg.kg−1.min−1 maintenance infusion of tirofiban intraoperatively without a loading dose. All patients were loaded with aspirin (325 mg) and clopidogrel (600 mg) just before the procedure or intraoperatively. No patient was pretreated with aspirin or clopidogrel. Thromboembolic and hemorrhagic complications were recorded.

RESULTS:

A total of 46 patients were treated with this protocol. Six patients (13%) had sustained a subarachnoid hemorrhage and were treated with the Pipeline Embolization Device within 24 hours of aneurysm rupture. The mean number of devices was 1.2 ± 0.66; adjunctive coiling was performed in 3 patients (6.5%). There were 2 complications (4.3%), 1 thromboembolic (2.2%) and 1 hemorrhagic (2.2%; monocular vision loss from occlusion of the central retinal artery in 1 patient and a parenchymal hemorrhage managed conservatively in another patient). No patient developed thrombocytopenia or retroperitoneal, gastrointestinal, or genitourinary bleeding. Of 46 patients, 44 (95.7%) had a modified Rankin Scale score of 0 to 2 at their follow-up visit.

CONCLUSION:

A protocol of anticoagulation with tirofiban during flow diversion has an excellent safety profile. This protocol provides a reasonable alternative to pretreatment with aspirin and clopidogrel and is useful in patients with ruptured aneurysms or when the use of a stent is unexpected.