Preinterventional clopidogrel response variability for coil embolization of intracranial aneurysms: clinical implications

Dual Antiplatelet Non-Responder: Resistance to Clopidogrel and Ticagrelor

Background

Dual antiplatelet therapy is often required for neurointerventional procedures, especially when a stent or flow diverter is placed in the cervical and intracranial vessels. Patients are usually started on aspirin and clopidogrel given the simplicity of the once daily regimen with reasonable cost. Unfortunately, about a third of patients do not show the desired antiplatelet response to clopidogrel and another agent needs to be introduced. Ticagrelor is a potent antiplatelet medication that has a favorable pharmacological profile and has emerged as a reliable alternative to clopidogrel in recent years. Despite ticagrelor non-responders being rare, they do exist, and identification of these patients is important.

Results

A 74-year-old female was incidentally found to harbor a right posterior communicating aneurysm which was successfully treated electively with stent-assisted coiling. Platelet inhibition testing revealed non-responsiveness to Clopidogrel. Ticagrelor was initiated but the patient's platelet reactivity unit remained in the normal range. Management algorithms to maximize a patient's ticagrelor response by facilitating enteral absorption were applied but no platelet inhibition was achieved. The patient was eventually identified as a true ticagrelor non-responder.

Conclusion

Resistance to antiplatelet medication can result in devastating complications with permanent neurological deficits. Ticagrelor non-responders are rare but do exist. Platelet inhibition testing should be part of the preprocedural workup for neurointerventions.

Racial differences in P2Y12 inhibitor responsiveness in patients undergoing neuro-endovascular procedures: A cohort from the Middle East

BACKGROUND

Data on P2Y12 inhibitors responsiveness from the middle east is scarce. We sought to investigate patient responsiveness to P2Y12 inhibitors within a cohort of major races that characterize the UAE population. The secondary objective was to assess risk factors for hyper and hypo-responsiveness in this population.

METHODS

We conducted a cross-sectional study on adults who received either clopidogrel or ticagrelor treatments and had platelet responsiveness testing before undergoing neuro-endovascular interventions at our quaternary care hospital between March 2015 and April 2019.

RESULTS

During the study period, 249 subjects met the inclusion criteria. Overall, 17.3 % were hyper-responsive and 25.7 % were hypo-responsive to P2Y12 inhibitors. When comparing between the P2Y12 inhibitors, rates of hyper-responsiveness were significantly higher to ticagrelor when compared to clopidogrel (11 versus 6 %, p = 0.02 respectively). Contrarily, hypo-responsiveness rates were significantly higher in clopidogrel treated patients compared to their ticagrelor treated counterparts (23 versus 2 %, p < .001 respectively). Patients of Middle-Eastern origin showed a significantly higher rate of hypo-responsiveness to both clopidogrel and ticagrelor when compared to other races (41.1 % and 26.7 %, P < 0.001 respectively). Asians showed the highest rates of hyper-responsiveness for both agents. Multivariate logistic regression analysis showed that proton pump inhibitors and statin combination, (OR: 6.39, 95 %CI [1.60, 25.392]), and Middle East vs. Indian subcontinent patients (OR: 4.67, 95 %CI [1.79-12.14]) were independent predictors of hypo-responsiveness to both P2Y12 inhibitors.

CONCLUSION

This study demonstrated a high rate of hypo-responsiveness to P2Y12 inhibitors in a UAE cohort of patients undergoing neuro-endovascular procedures. In addition, therapeutic responsiveness to P2Y12 inhibitors varied markedly based on the racial background. Future larger studies are needed to evaluate genetic variations that may contribute to this rate of hypo-responsiveness in our population.

Clopidogrel versus newer P2Y12 inhibitors in the dual antiplatelet therapy for stent-assisted coil embolization of intracranial aneurysms: A meta-analysis

INTRODUCTION

Stent-assisted coil embolization (SACE) for cerebral aneurysms requires dual antiplatelet therapy (DAPT), commonly clopidogrel plus aspirin is preferable to ticagrelor or prasugrel plus aspirin. However, there are few studies assessing the safety of the association of ticagrelor or prasugrel plus aspirin.

OBJECTIVES

Compare the safety of newer P2Y12 inhibitors with clopidogrel in patients that underwent a SACE for cerebral aneurysms.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we searched PubMed and Embase for studies comparing newer P2Y12 inhibitors with clopidogrel in patients undergoing DAPT for SACE. Outcomes were total number of complications, number of hemorrhagic complications, and number of thromboembolic complications both intraoperative and follow-up. A random effects model was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

We included 1026 patients from six studies. Newer P2Y12 inhibitors were used in 562 (54,77%) patients. There were no significant differences between groups in total number of complications (OR 0.80; 95% CI 0.32, 1.99; p < 0.01; I2 = 78%), in intraoperative hemorrhagic complications (OR 0.66; 95% CI 0.09, 4.71; p = 0.68; I2 = 0%), follow-up hemorrhagic complications (OR 1.23; 95% CI 0.70, 2.15; p = 0.49; I2 = 0%), intraoperative thromboembolic complications (OR 0.43; 95% CI 0.14, 1.35; p = 0.25; I2 = 24%), and in follow-up thromboembolic complications (OR 0.89; 95% CI 0.33, 2.39; p = 0.03; I2 = 59%).

CONCLUSION

In patients who underwent a SACE, newer P2Y12 inhibitors showed no differences in intraoperative and follow-up complications compared with clopidogrel.

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.

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.

Roles of light transmission aggregometry and CYP2C19 genotype in predicting ischaemic complications during interventional therapy for intracranial aneurysms

BACKGROUND AND PURPOSE

Light transmission aggregometry (LTA) and CYP2C19 genotype analysis are commonly used to evaluate the antiplatelet effects of clopidogrel during the interventional treatment of intracranial aneurysms. The aim of this study was to determine which test can predict ischaemic events during these treatments.

METHODS

Patient demographic information, imaging data, laboratory data and ischaemic complications were recorded. LTA and CYP2C19 genotype results were compared, and multiple linear regression was performed to examine factors related to platelet reactivity. Multivariate regression analysis was performed to determine whether LTA and CYP2C19 could predict ischaemic complications and to identify other clinical risk factors. Receiver operating characteristic curve analysis was conducted to calculate the cut-off value for predicting ischaemic complications. A subgroup analysis was also performed for different CYP2C19 genotype metabolisers, as well as for patients with flow diverters and traditional stents.

RESULTS

A total of 379 patients were included, of which 22 developed ischaemic events. Maximum platelet aggregation induced by ADP (ADP-MPA) could predict ischaemic events (p<0.001; area under the curve, 0.752 (95% CI 0.663 to 0.842)), and its cut-off value was 41.5%. ADP-MPA (p=0.001) and hypertension duration >10 years (p=0.022) were independent risk factors for ischaemic events, while the CYP2C19 genotype was not associated with ischaemic events. In the subgroup analysis, ADP-MPA could predict ischaemic events in fast metabolisers (p=0.004) and intermediate metabolisers (p=0.003). The cut-off value for ischaemic events was lower in patients with flow diverters (ADP-MPA=36.4%) than in patients with traditional stents (ADP-MPA=42.9%).

CONCLUSIONS

ADP-MPA can predict ischaemic complications during endovascular treatment of intracranial aneurysms. Patients with flow diverters require stronger antiplatelet medication than patients with traditional stents.

Variability of response on prophylactic prasugrel for endovascular treatment of intracranial aneurysms: Clinical implications

BACKGROUND AND PURPOSE

Prophylactic prasugrel for endovascular treatment of intracranial aneurysms has been introduced and increased, but HTPR (high on-treatment platelet reactivity) or LTPR (low on-treatment platelet reactivity) of prasugrel is not uncommon in clinical circumstances. To investigate the predisposing factors of HTPR and LTPR on prasugrel premedication in the neurointerventional field and to determine its clinical implications.

MATERIALS AND METHODS

Between February 2016 and December 2020, 191 patients treated with coil embolization using prophylactic prasugrel in 234 intracranial aneurysms were the final candidates for this study. Patient and aneurysm characteristics, clinical status, and laboratory study values were carefully reviewed retrospectively. We performed risk factor analyses for HTPR and LTPR on prasugrel.

RESULTS

Ultimately, 20 patients (10.5%) had HTPR, and 74 patients (38.7%) were categorized as having LTPR. In multivariable analyses, the factors related to HTPR were BMI (adjusted OR 1.21, 95% CI 1.04-1.41, p = 0.01), history of antithrombotics (adjusted OR 3.79, 95% CI 1.39-10.34, p = 0.01), and hematocrit (adjusted OR 0.91, 95% CI 0.84-0.99, p = 0.03). Low BMI was the only risk factor for LTPR (adjusted OR 0.84, 95% CI 0.76-0.94, p = 0.001).

CONCLUSION

In the neurointerventional field, high BMI and prior use of antithrombotic agents were related to HTPR, and low BMI was associated with LTPR on prophylactic prasugrel. High hematocrit levels decreased the risk of HTPR. When preparing endovascular treatment for intracranial aneurysms, attention to patients with these clinical features is required to address the possibility of ischemic or bleeding complications.

Safety and Efficacy of Low-dose Prasugrel in the Endovascular Treatment of Unruptured Aneurysms in the Elders (≥ 75 Years)

PURPOSE

The effectiveness and safety of low-dose prasugrel (PSG) premedication for endovascular treatment of unruptured intracranial aneurysms (UIAs) have been widely reported. In this study, we evaluated the clinical outcomes of elders patients (≥ 75 years) treated with PSG.

METHODS

A total of 200 patients with 209 UIAs who were administered PSG as premedication (20 mg loading and 5 mg maintenance with 100 mg aspirin) between March 2018 and December 2021 were retrospectively enrolled. Among them, 39 patients were aged 75 years or over (elders group), and 161 patients were aged under 75 years (control group). Patients' clinical data were collected, and outcomes were compared between the two groups.

RESULTS

Of the 200 patients with PSG, 9 cases (4.5%) had overall complications (7 ischemic, 2 hemorrhagic). In the comparison between the elders group and the control group, no significant differences were observed in the overall complication rates (elders group vs. control group; 2.6% vs. 5.0%, P = 1.00). Moreover, the rates of poor clinical outcome were comparable (2.6% vs. 1.2%, P = 0.48). The subgroup analysis of patients with stent-assisted procedures revealed no significant differences in complication rates (0% vs. 1.6%, P = 1.00) or poor clinical outcomes (0% vs. 0%, P = 1.00) during maintenance with aspirin 100 mg or PSG 5 mg.

CONCLUSION

The complication rates in the elders treated with low-dose PSG premedication were similar to those in the control. Low-dose PSG premedication could be prescribed without any additional risk for the endovascular treatment of UIAs in elders patients.

Thromboelastography 6s for assessment of platelet function during coil embolization of unruptured intracranial aneurysms

OBJECTIVES

Methods for assessing platelet function in patients with neurovascular disease remain controversial and poorly studied. This study aimed to assess associations between thromboelastography 6s (TEG6s) measurements and postoperative ischemic complications in patients with unruptured intracranial aneurysms (UIAs) treated by coil embolization.

METHODS

Eighty-four patients with UIAs taking a combined aspirin and clopidogrel protocol were retrospectively reviewed from January 2021 to May 2022. Blood samples were obtained for TEG6s to assess platelet function on the day of coil embolization. To identify acute ischemic complications, diffusion-weighted imaging (DWI) was performed within 24 h after coil embolization. Multivariate logistic regression analysis was conducted to identify potential risk factors for postoperative positive DWI (DWI (+)) lesions.

RESULTS

Forty-three of the 84 patients (51%) with DWI (+) lesions were identified. Compared with patients without DWI (+) lesions, Adenosine diphosphate (ADP)-induced platelet-fibrin clot strength (MA_ADP) was significantly higher (53.6 mm [Interquartile range (IQR): 48.3-58.3 mm] vs 46.7 mm [IQR: 36.8-52.2 mm]; p=0.001) and ADP inhibition rate (ADP%) was significantly lower (19% [IQR: 11-31%] vs 31% [IQR: 21-44%]; p=0.001) in DWI (+) patients. Multivariate analysis identified MA_ADP, ADP%, and procedure time as significant independent predictors of subsequent DWI (+) lesions (odds ratios: 1.07, 0.96, and 1.02, respectively). Based on receiver operating characteristic curve analysis, MA_ADP >50.9 mm and ADP% <28.8% were associated with postoperative DWI (+) lesions in patients undergoing coil embolization for UIAs.

CONCLUSIONS

MA_ADP and ADP% as assessed by TEG6s can offer reliable parameters to predict postoperative ischemic complications after coil embolization of UIAs. Lower MA_ADP values and higher ADP% may decrease the risk of postoperative ischemic complications.

Clopidogrel Bolus is Inferior to Sustained Clopidogrel Pretreatment in Patients Undergoing Carotid Artery Stent Placement

BACKGROUND

Clopidogrel bolus is an option used before carotid artery stent (CAS) placement when sustained clopidogrel pretreatment is not used.

OBJECTIVE

To compare the effect of clopidogrel bolus (450 mg administered ≥4 hours) with sustained clopidogrel pretreatment (48 hours or greater) before CAS among patients recruited in the Carotid Revascularization Endarterectomy versus Stenting Trial.

METHODS

We compared the rates of primary end point (either any stroke, myocardial infarction, or death during the periprocedural period or any ipsilateral stroke within 4 years) between patients who received clopidogrel bolus and those who received sustained clopidogrel pretreatment using Cox proportional hazards analysis after adjusting for age, sex, symptomatic status, and initial severity of stenosis (≥70% vs <70%) over 4 years.

RESULTS

The rate of periprocedural stroke (7.3% vs 3.4%, P = .03) and primary end point (11.3% vs 5.9%, P = .02) was significantly higher among patients who received clopidogrel bolus. The risk of primary end point was significantly higher in patients who received clopidogrel bolus (hazards ratio 1.9, 95% CI 1.1-3.4, P = .02) after adjusting for potential confounders. The overall mean (±standard deviation) primary end point-free survival based on Kaplan-Meier analysis was 7.0 ± 0.2 years for patients who received clopidogrel bolus and 8.9 ± 0.1 years for those who received sustained clopidogrel pretreatment (log-rank test P = .011).

CONCLUSION

Clopidogrel bolus was associated with higher rates of adverse outcomes compared with sustained clopidogrel pretreatment in patients who underwent CAS. Therefore, clopidogrel bolus may not be equivalent to sustained clopidogrel pretreatment.

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.

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.

Risk Factors for Recanalization after Coil Embolization

The aim of our study was to identify risk factors for recanalization 6 months after coil embolization using clinical data followed by computational fluid dynamics (CFD) analysis. Methods: Firstly, clinical data of 184 patients treated with coil embolization were analyzed retrospectively. Secondly, aneurysm models for high/low recanalization risk were generated based on ROC curves and their cut-off points. Afterward, CFD was utilized to validate the results. Results: In multivariable analysis, aneurysm filling during the first embolization was an independent risk factor whilst packing density was a protective factor of recanalization after 6 months in patients with aSAH. For patients with unruptured aneurysms, packing density was found to be a protective factor whilst the aneurysm neck size was an independent risk factor. Complex flow pattern and multiple vortices were associated with aneurysm shape and were characteristic of the high recanalization risk group. Conclusions: Statistical analysis suggested that there are various factors influencing recanalization risk. Once certain values of morphometric parameters are exceeded, a complex flow with numerous vortices occurs. This phenomenon was revealed due to CFD investigations that validated our statistical research. Thus, the complex flow pattern itself can be treated as a relevant recanalization predictor.

Ticagrelor resistance: a case series and algorithm for management of non-responders

The placement of cervical and intracranial stents requires the administration of antiplatelet drugs to prevent thromboembolic complications. Ticagrelor has emerged as the most widely used alternative in clopidogrel non-responders owing to its potent antiplatelet effects. Because ticagrelor does not require hepatic activation, many neurointerventionalists choose to forgo laboratory testing of platelet inhibition. In rare instances, patients may not achieve adequate platelet inhibition following ticagrelor administration. In this paper we review the mechanism of action of ticagrelor and its use in cerebrovascular procedures. We present two cases of ticagrelor non-responsiveness from two high-volume cerebrovascular centers, discuss their management, and propose an algorithm for managing ticagrelor non-responsiveness.

P2Y12 inhibitors for the neurointerventionalist

The use of antiplatelets is widespread in clinical practice. However, for neurointerventional procedures, protocols for antiplatelet use are scarce and practice varies between individuals and institutions. This is further complicated by the quantity of antiplatelet agents which differ in route of administration, dosage, onset of action, efficacy and ischemic and hemorrhagic complications. Clarifying the individual characteristics for each antiplatelet agent, and their associated risks, will increasingly become relevant as the practice of mechanical thrombectomy, stenting, coiling and flow diversion procedures grows. The aim of this review is to summarize the existing literature for the use of P2Y12 inhibitors in neurointerventional procedures, examine the quality of the evidence, and highlight areas in need of further research.

Clopidogrel response predicts thromboembolic events associated with coil embolization of unruptured intracranial aneurysms: A prospective cohort study

Objective

Periprocedural thromboembolic events are a serious complication associated with coil embolization of unruptured intracranial aneurysms. However, no established clinical rule for predicting thromboembolic events exists. This study aimed to clarify the significance of adding preoperative clopidogrel response value to clinical factors when predicting the occurrence of thromboembolic events during/after coil embolization and to develop a nomogram for thromboembolic event prediction.

Methods

In this prospective, single-center, cohort study, we included 345 patients undergoing elective coil embolization for unruptured intracranial aneurysm. Thromboembolic event was defined as the occurrence of intra-procedural thrombus formation and postprocedural symptomatic cerebral infarction within 7 days. We evaluated preoperative clopidogrel response and patients’ clinical information. We developed a patient-clinical-information model for thromboembolic event using multivariate analysis and compared its efficiency with that of patient-clinical-information plus preoperative clopidogrel response model. The predictive performances of the two models were assessed using area under the receiver-operating characteristic curve (AUC-ROC) with bootstrap method and compared using net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

Results

Twenty-eight patients experienced thromboembolic events. The clinical model included age, aneurysm location, aneurysm dome and neck size, and treatment technique. AUC-ROC for the clinical model improved from 0.707 to 0.779 after adding the clopidogrel response value. Significant intergroup differences were noted in NRI (0.617, 95% CI: 0.247–0.987, p < .001) and IDI (0.068, 95% CI: 0.021–0.116, p = .005).

Conclusions

Evaluation of preoperative clopidogrel response in addition to clinical variables improves the prediction accuracy of thromboembolic event occurrence during/after coil embolization of unruptured intracranial aneurysm.

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.

Antiplatelet Loading Effects Prior to Endovascular Treatment: Carotid Artery Stenosis versus Unruptured Cerebral Aneurysms

Objective

Carotid artery stenosis and cerebral aneurism may have different platelet functions and antiplatelet responses because these diseases have different etiologies. In this study, we compared the antiplatelet loading effects prior to endovascular treatment between carotid artery stenosis and unruptured cerebral aneurysm (UCA) patients.

Methods

Nine patients with asymptomatic carotid artery stenosis (ACS), 14 with symptomatic carotid artery stenosis (SCS), and 20 with unruptured cerebral aneurysms were enrolled in this study. Antiplatelet (aspirin + clopidogrel) loading effects prior to endovascular treatment were evaluated using light transmission aggregometry and platelet aggregate detection methods.

Results

Although there are differences in the prevalence of atherosclerosis risk factors, maximum aggregation rates in light transmission aggregometry and platelet aggregation-prone properties were not different in the three disease groups.

Conclusion

Preoperative dual antiplatelet therapy with aspirin and clopidogrel may be appropriate for both carotid artery stenosis and cerebral aneurism patients even though their conditions and background factors differ.

Tailored antiplatelet agent medication in clopidogrel hyporesponsive patients before stent-assisted coiling: single-center experience

PURPOSE

In patients requiring stent procedures, resistance or hyperresponsiveness to antiplatelet medications is often observed. This study aims to evaluate the efficacy and safety of tailoring medications in these patients.

METHODS

This retrospective study included 223 patients who underwent endovascular treatment for intracranial aneurysm between October 2018 and October 2019. Patients were categorized as hyporesponsive, hyperresponsive, and normoresponsive groups according to the initial PRU response. For the hypo- or hyperresponders, we tailored medication by modifying the dose or changing the drug. PRUs before and after tailoring were compared in each group. PRU reponses in patients who underwent Cytochrome P450 2C19 (CYP2C19) genotyping were also determined.

RESULTS

Of the 73 clopidogrel-resistant patients, the mean PRU values after tailoring showed a greater decrease in the group that switched to prasugrel (n = 56), from 223 to 131, than in the clopidogrel reloading group (n = 17), from 238 to 209. In 31 hyperresponders, PRU increased from 49 to 94 after the dose adjustment. CYP2C19 genotyping showed that PRU tended to increase as the number of mutated alleles increased. There were five (2.3%) ischemic events (three transient ischemic attacks and two minor strokes) in a mean follow-up of 8 months, but no hemorrhage.

CONCLUSIONS

The stent-assisted coiling was successfully performed with acceptable range of ischemic events and without hemorrhage in all patients, including those who applied tailored medication. Low-dose prasugrel was effective for obtaining appropriate PRU values for initial medication as well as for clopidogrel-resistant patients. The genetic test did not provide reliable results in determining clopidogrel resistance.

Intravenous cangrelor and oral ticagrelor as an alternative to clopidogrel in acute intervention

BACKGROUND

Dual antiplatelet therapy (DAP) is necessary to prevent thromboembolic events during carotid stenting, stent-assisted coil embolization, and implant of flow diverters (FD). However, DAP in the acute phase may be challenging. An intravenous alternative, cangrelor, has rapid onset, short plasma half-life, and more reliable antiplatelet action for acute interventions. The study objective was to evaluate feasibility and safety of IV cangrelor during acute neuroendovascular surgery procedures.

METHODS

We performed a retrospective analysis of our database of patients treated with stent-assisted coil embolization, FD placement for aneurysmal subarachnoid hemorrhage (aSAH), or stenting for acute internal carotid artery (ICA) occlusion where IV cangrelor was used. Morbidity, mortality, incidence of thromboembolic events, hemorrhages, and 90-day outcomes were reported.

RESULTS

Ten patients were found in our database from June 2018 through January 2019. Four patients had aSAH, four had middle cerebral artery strokes with tandem lesions, one had an ICA occlusion, and one had a vertebral artery aneurysm. One of the ten patients experienced a thrombotic event. One patient developed new post-procedural bleeding and two had worsening intracranial hemorrhage. Five patients were discharged home in stable condition, two to acute rehabilitation, one to a nursing facility, and two others expired (likely the result of the severe and evolving strokes). Of the eight who were discharged, six (75%) had a good 90-day functional outcome (modified Rankin Scale 0-2).

CONCLUSION

Acute administration of IV cangrelor with or without oral ticagrelor is a feasible antiplatelet treatment option for acute neuroendovascular procedures.

The Effect of Ticagrelor on Platelet Reactivity in Patients with Clopidogrel Resistance Undergoing Neuroendovascular Procedures

BACKGROUND AND PURPOSE

Suboptimal platelet inhibition by clopidogrel (clopidogrel resistance) may be associated with high rates of stent thrombosis and ischemic events. Our objective was to determine if ticagrelor, a P2Y₁₂ receptor inhibitor, can result in platelet inhibition in patients with clopidogrel resistance.

METHODS

A thromboelastography-platelet mapping assay was used in all patients undergoing neuroendovascular procedures requiring oral clopidogrel. In patients with suboptimal platelet inhibition (<60%) on clopidogrel, ticagrelor was imitated after an oral bolus of 180 mg followed by 90 mg twice daily and the platelet mapping assay was repeated. The primary endpoint was hemorrhagic complications classified as major (hemoglobin decrease >5 g/dL or intracranial hemorrhage with deficits), minor (hemoglobin decrease 3-5 g/dL or intracranial hemorrhage without residual deficits), or insignificant.

RESULTS

Suboptimal platelet inhibition on clopidogrel was seen in 70 of 106 patients undergoing neuroendovascular procedures. There was a significantly higher magnitude of platelet inhibition with ticagrelor compared with clopidogrel in patients with clopidogrel resistance (mean ± SD: 85.90 ± 10.74% vs. 29.26 ± 17.71%; P < .001); 50 of 70 patients showed optimal inhibition. Two patients had major (fatal) hemorrhagic events (both received either intravenous thrombolytics and/or eptifibatide infusion). Three patients had minor hemorrhagic events, and two patients had insignificant hemorrhagic events. Four of seven hemorrhagic events occurred in patients with optimal response to clopidogrel, two occurred in patients with suboptimal response to ticagrelor, and one occurred in a patient with optimal response to ticagrelor.

CONCLUSIONS

Oral ticagrelor can augment platelet inhibition in patients who have clopidogrel resistance.

Radiological and clinical outcomes of endovascular coiling of proximal A1 aneurysms

Aneurysms of the proximal anterior cerebral artery (A1) are rare. Of these A1 aneurysms, proximal A1 aneurysms are among the most challenging for endovascular coiling. This study aimed to evaluate the angiographic features and radiological and clinical outcomes of endovascular coiling of proximal A1 aneurysms. We recruited 38 patients with 38 proximal A1 aneurysms treated with endovascular coiling between September 2005 and April 2016. Baseline patient characteristics, aneurysm morphology, endovascular treatment techniques, immediate post-procedural radiological outcome, and follow-up clinical and radiological outcomes were evaluated, as were risk factors for recurrence. Sixteen proximal A1 aneurysms ruptured (42.1%). Six procedural complications (15.8%), including 5 thromboembolisms and 1 coil migration, were noted. There was no procedural morbidity or mortality. Immediate post-procedural radiological outcomes showed complete occlusion in 23, residual necks in 12, and residual sacs in 3 lesions. Follow-up angiographic outcomes were possible for 28 lesions (73.7%). Follow-up angiography showed sac recurrence in 3 (10.7%) and neck recurrence in 3 (10.7%) lesions. Retreatment was performed in 4 lesions (14.3%); all were treated by endovascular coiling. The presence of aneurysmal ruptures was only significant regarding recurrence in univariate logistic regression analysis. In our study, endovascular coiling of proximal A1 aneurysms was associated with a relatively high rate of procedural complications but not with procedural morbidity and mortality. The recurrence and retreatment rates of endovascular coiling of proximal A1 aneurysms were relatively high, and presence of rupture was significant for recurrence.

The Efficacy of P2Y12 Reactive Unit to Predict the Periprocedural Thromboembolic and Hemorrhagic Complications According to Clopidogrel Responsiveness and Safety of Modification of Dual Antiplatelet Therapy : A Meta-Analysis

The efficacy of P2Y12 reaction unit (PRU) of VerifyNow still remains as a controversial issue in neurointervention. So we investigated the usefulness of PRU of VerifyNow to predict the peri-procedural thromboembolic events (TE) and hemorrhagic events (HE). And we evaluated the safety of modified dual antiplatelet therapy (DAPT) or triple antiplatelet therapy (TAPT) for clopidogrel hyporesponders. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science and Scopus on August 19 2018. Data was collected the 1) incidence of TE between clopidogrel responder and clopidogrel hypo-responder, 2) incidence of HE between clopidogrel hyper-responder and clopidogrel responder and hypo-responder, and 3) incidence of TE and HE between modified DAPT or TAPT and standard DAPT in clopidogrel hypo-responder. High cut-off value of PRU was defined as PRU >40% or <220. Fifteen studies were enrolled. Clopidogrel responder showed lower incidence of TE than hypo-responder (risk ratio [RR], 0.32; 95% confidence interval [CI], 0.17-0.61; p<0.001). With the high cut-off value of PRU, clopidogrel responder showed more lower incidence of TE than hypo-responder (RR, 0.11; 95% CI, 0.02-0.45; p=0.002). The incidence of periprocedural HE have higher on clopidogrel hyper-responder than clopidogrel responder and hypo-responder (RR, 4.26; 95% CI, 1.10-16.44; p=0.04; I2=66%). The incidence of periprocedural TE after changing regimen of DAPT for clopidogrel hypo-responder have a tendency to reduce, but there was no significant difference between modified DAPT or TAPT group and standard DAPT group (p>0.05). The incidence of periprocedural HE after changing regimen of DAPT for clopidogrel hypo-responder was no significant difference between modified DAPT or TAPT group and standard DAPT group (p>0.05). PRU is a useful tool as a predictor of peri-procedural TE or HE on neurointervention. PRU has a threshold effect of cut-off value to predict the peri-procedural TE. Modified DAPT or TAPT to prevent TE in clopidogrel hypo-responders could not reduce the incidence of TE. We should investigate the further research about modification of regiment on neurointervention.

Different Clopidogrel Response Elicited by Lansoprazole or Esomeprazole in Patients Undergoing Neurointervention with Dual Antiplatelet Therapy

BACKGROUND

Aspirin-clopidogrel dual antiplatelet therapy and a proton-pump inhibitor are used worldwide to prevent thromboembolism and peptic ulceration in patients undergoing neurointervention. We performed VerifyNow assays (Accumetrics, San Diego, CA, USA) to retrospectively examine the relationship between the effectiveness of antiplatelet agents and different proton-pump inhibitor types.

METHODS

Sixty-four patients with unruptured intracranial aneurysm scheduled for neurointervention received aspirin-clopidogrel dual antiplatelet therapy plus the proton-pump inhibitor lansoprazole (n = 34) or esomeprazole (n = 30). A low response to aspirin and clopidogrel was defined in terms of aspirin reaction units > 550 and P2Y12 reaction units ≥ 230, respectively, by VerifyNow assay. The characteristics, response to antiplatelet therapy, and clinical outcomes were compared in patients treated with lansoprazole or esomeprazole.

RESULTS

The preoperative mean VerifyNow aspirin reaction units and P2Y12 reaction units were 466.0 ± 67.3 and 205.0 ± 67.6, respectively. The mean aspirin reaction unit value was 482.0 ± 64.1 in the lansoprazole group, and 461.5 ± 70.9 in the esomeprazole group (p = 0.77). The mean P2Y12 reaction unit was 220.0 ± 64.4 in the lansoprazole group, and 174.5 ± 65.0 in the esomeprazole group; there was a significant difference in the clopidogrel response of patient treated with lansoprazole or esomeprazole (p = 0.005).

CONCLUSIONS

Our VerifyNow assay results suggest that when on lansoprazole fewer patients achieved the therapeutic goal and required extra therapy before neurointervention.

Association of Thrombelastographic Parameters with Complications in Patients with Intracranial Aneurysm After Stent Placement

OBJECTIVE

A prospective trial was conducted to investigate the platelet function and association between thrombelastographic (TEG) parameters and embolic or hemorrhagic complications in patients with intracranial aneurysm undergoing stent treatment.

METHODS

Between September 2013 and June 2016, we prospectively recruited patients with intracranial aneurysm who were treated with stent-assisted coiling. TEG parameters were used to assess the platelet function before stenting procedures. The primary study end point was the onset of ischemic stroke, transient ischemic attack, or silent ischemic events in the territory of the stented artery within 6 months after the procedure. The secondary end point was assessed by bleeding events.

RESULTS

Four hundred and thirty-one patients with 453 intracranial aneurysms were enrolled. A total of 519 neurovascular stents were implanted. During the follow-up, a total of 70 primary end points (16.2%) and 59 secondary end points (13.7%) were detected. Thromboembolic complications such as symptomatic and slient ischemic complications were more frequently observed in patients with large aneurysms (>10 mm, P = 0.01), lower adenosine diphosphate (ADP) inhibition rate (P < 0.0001), and higher ADP-induced platelet-fibrin clot strength (maximum amplitude of adenosine diphosphate [MA-ADP]) (P < 0.0001). Besides, based on multivariate analysis, a higher ADP inhibition ratio was identified as a significant independent predictor of subsequent bleeding events (P < 0.0001). According to the receiver operating characteristic curve analysis, the safe range of the ADP inhibition ratio and MA-ADP of the TEG analysis were identified as 29.45%-55.4% and <46.15, respectively.

CONCLUSIONS

The ADP inhibition ratio and MA-ADP of TEG analysis were associated with subsequent cerebral ischemic events and intracranial or extracranial bleeding events in patients with intracranial aneurysm after stent treatment.

Advantages and disadvantages of the ENVOY 6F distal access guiding catheter in endovascular coiling for anterior circulation aneurysms

OBJECTIVE

Selecting an appropriate guiding catheter to provide both sufficient supportability for working devices and sufficient distal navigability is essential for ensuring the success of a procedure. This study aimed to evaluate the advantages and disadvantages of using the ENVOY 6F distal access (DA) guiding catheter in coil embolization of anterior circulation cerebral aneurysms.

METHODS

We included 98 patients (72 [73.5%] women, median age: 63 [range: 25-84] years) who underwent endovascular coiling with the ENVOY 6F DA guiding catheter from May to November 2016. We analyzed data on patient demographics and the number of co-axial techniques to position the guiding catheter, initial and final location of the catheter, and complications related to the catheter.

RESULTS

The co-axial technique was used to position the ENVOY 6F DA guiding catheter in the internal carotid artery (ICA) in 20 cases (20.41%). The initial position of the ENVOY 6F DA guiding catheter involved the cervical ICA (79.6%), horizontal petrous ICA (17.3%), and vertical petrous ICA (3.1%). Final control angiograms after endovascular coiling showed proximal change in the final, compared to the initial, position of the ENVOY 6F DA guiding catheter in 25 cases (25.51%). Procedure-related complications were observed in nine patients (9.18%), involving vasospasm in all cases; however, there was no symptomatic case.

CONCLUSION

The ENVOY 6F DA guiding catheter had relatively sufficient distal navigability without symptomatic procedural complications. However, the change in the catheter position after endovascular coiling denoted insufficient supportability.

Variability of Platelet Reactivity on Antiplatelet Therapy in Neurointervention Procedure

As more intracranial aneurysms and other cerebrovascular pathologies are treated with neurointervention procedure, thromboembolic events that frequently lead to serious neurological deficit or fatal outcomes are increasing. In order to prevent the thromboembolic events, antiplatelet therapy is used in most procedures including coil embolization, stenting, and flow diversion. However, because of variable individual pharmacodynamics responses to antiplatelet drugs, especially clopidogrel, it is difficult for clinicians to select the adequate antiplatelet regimen and its optimal dose. This article reviews the neurointervention literature related to antiplatelet therapy and suggests a strategy for tailoring antiplatelet therapy in individual patients undergoing neurointervention based on the results of platelet function testing.

Selective compromise of hypoplastic posterior communicating artery variants with aneurysms treatable by coil embolization: clinical and radiologic outcomes

Background

Posterior communicating artery (PcoA) compromise may serve as adjunctive treatment in patients with hypoplastic variants of PcoA who undergo coil embolization of PcoA aneurysms. However, procedural safety and the propensity for later recanalization are still unclear.

Objective

To evaluate clinical and radiologic outcomes of coil embolization in this setting, focusing on compromise of PcoA.

Methods

As a retrospective review, we examined 250 patients harboring 291 aneurysms of hypoplastic PcoAs, all consecutively treated by coil embolization between January 2004 and June 2016. PcoA compromise was undertaken in conjunction with 81 of the treated aneurysms (27.8%; incomplete 53; complete 28). Medical records and radiologic data were assessed during extended monitoring.

Results

During the mean follow-up of 33.9±24.6 months (median 36 months), a total of 107 (36.8%) coiled aneurysms showed recanalization (minor 50; major 57). Recanalization rates were as follows: PcoA preservation 40.5% (85/210); incomplete PcoA occlusion 34.0% (18/53); complete PcoA occlusion 14.3% (4/28). Aneurysms >7 mm (HR 3.40; P<0.01), retreatment for recanalization (HR 3.23; P<0.01), and compromise of PcoA (P<0.01) emerged from multivariate analysis as significant risk factors for recanalization. Compared with PcoA preservation, complete PcoA compromise conferred more favorable outcomes (HR 0.160), whereas incomplete compromise of PcoA fell short of statistical significance. Thromboembolic infarction related to PcoA compromise did not occur in any patient.

Conclusion

PcoA compromise in conjunction with coil embolization of PcoA aneurysms appears safe in hypoplastic variants of PcoA, helping to prevent recanalization if complete occlusion is achieved.

Management of antiplatelet therapy in patients undergoing neuroendovascular procedures

Neuroendovascular techniques for treating cerebral aneurysms and other cerebrovascular pathology are increasingly becoming the standard of care. Intraluminal stents, aneurysm coils, and other flow diversion devices typically require concomitant antiplatelet therapy to reduce thromboembolic complications. The variability inherent with the pharmacodynamic response to common antiplatelet agents such as aspirin and clopidogrel complicates optimal selection of antiplatelet agents by clinicians. This review serves to discuss the literature related to antiplatelet use in neuroendovascular procedures and provides recommendations for clinicians on how to approach patients with variable response to antiplatelet agents, particularly clopidogrel.

Low-Dose Prasugrel in Patients with Resistance to Clopidogrel for the Treatment of Cerebral Aneurysms

Thromboembolism is one of the major complications of stent assisted coiling in treatment of cerebral aneurysm. Clopidogrel resistance is so common and prasugrel is more effective in its rapid and potent effect. We investigated changes in the value of P2Y12 resistance unit (PRU) when prasugrel was administered to patients with clopidogrel resistance. One hundred mg of aspirin and 75 mg of clopidogrel were administered for 5 days before the procedure, and PRU were examined. The resistance to clopidogrel was defined as the inhibition of PRU was less than 20%. PRU was re-examined after loading 20 mg of prasugrel. We treated 98 consecutive patients between January 2018 and July 2018, and 24 patients (24.5%) had resistance to clopidogrel. Nineteen patients were female. The mean PRU value at admission was 238.5±36.9 and the percentage inhibition value was 4.8±6.3%. After the use of prasugrel, the mean PRU and percentage inhibition values were measured as 124.9±49.9 and 48.0±19.24, respectively. All patients except one patient had a PRU inhibition value as a responder. There was no hemorrhage or thromboembolic complication during mean 1.5 months follow-up after embolization procedure. In conclusion, in patients resistant to clopidogrel, the low dose prasugrel seems to be effective in keeping the percentage inhibition value of PRU within the normal range in treatment of cerebral aneurysm. Further study will be needed to determine the optimal dose of prasugrel to enhance prevention effect of thromboembolism and to reduce hemorrhagic complications during stent assisted coiling.

Preliminary Study of Tirofiban Infusion in Coil Embolization of Ruptured Intracranial Aneurysms

BACKGROUND

There have been some reports on the use of intra-arterial tirofiban in ruptured intracranial aneurysms, but few studies have reported on the use of 24 h of intravenous tirofiban infusion in patients with subarachnoid hemorrhage.

OBJECTIVE

To present our experience with intravenous tirofiban infusion, in the form of a monotherapy as well as in addition to intra-arterial tirofiban, as a prophylactic, and as a rescue management for thrombus in patients who have undergone embolization with coils for ruptured intracranial aneurysms.

METHODS

Between December 2008 and January 2015, we retrospectively reviewed 249 ruptured intracranial aneurysms that were treated with coiling at our institutions. A total of 28 patients harboring 28 ruptured and 3 unruptured intracranial aneurysms underwent intravenous tirofiban infusion during or after coil embolization of an aneurysm. Intra-arterial infusion of tirofiban via a microcatheter was also performed in 26 patients.

RESULTS

Thromboembolic formation during the procedure was detected in 25 cases. Intra-arterial tirofiban dissolved the thromboembolus under angiographic control after 10 or more minutes in 19 (76%) of 25 patients. Two intracranial hemorrhagic complications (increase in the extent of hematoma) occurred during the follow-up period. Two cases of other complications occurred: hematuria and perioral bleeding.

CONCLUSION

Intravenous tirofiban, as a monotherapy or in addition to intra-arterial tirofiban for thrombotic complications, seems to be useful as a treatment for acute aneurysm. However, alternatives to tirofiban should be considered if an associated hematoma is discovered before a patient receives a tirofiban infusion.

Stent-assisted coil embolization of anterior communicating artery aneurysms: safety, effectiveness, and risk factors for procedural complications or recanalization

INTRODUCTION

Stent-assisted coil (SAC) embolization is an alternative treatment option for anterior communicating artery (AcoA) aneurysms. This study was undertaken to assess the safety and effectiveness of SAC embolization in treating AcoA aneurysms and to determine risk factors for related procedural complications or recanalization.

METHODS

Between August 2008 and December 2016, 184 patients with AcoA aneurysms were treated with SAC embolization. Cumulative medical record and radiologic data were analyzed using binary logistic regression to identify factors predisposing to procedural complications or recanalization.

RESULTS

Contralateral A1 segment hypoplasia was observed in 59 patients (32.1%). Three types of stents (LVIS, Enterprise, and Neuroform) were variably placed by one of two routes: (1) ipsilateral A1 to ipsilateral A2 (75.5%) or (2) ipsilateral A1 to contralateral A2 (24.5%). Procedural complications occurred in 17 patients (thromboembolism 12; procedural leakage 3; both 2), showing a significant relation to subarachnoid hemorrhage at presentation (OR 57.750; P<0.01). Occlusion was documented immediately after embolization in 130 aneurysms (70.6%) and, in 23 (13.1%) of 175 AcoA aneurysms followed by angiography (median 25.9±18.5 months), recanalization developed (minor, 15; major, 8). Stent configuration (ipsilateral A1 to contralateral A2, P=0.024), maximum aneurysm size (>7 mm, P<0.01), and A1 segment hypoplasia (P=0.039) were identified as risk factors for recanalization.

CONCLUSION

SAC embolization is a safe and effective method of treating unruptured AcoA aneurysms, regardless of anatomic or clinical features. However, in the event of rupture, procedural complications are likely. Stent configuration, aneurysm size, and A1 segment hypoplasia were identified as significant risk factors for recanalization.

Follow-Up Outcomes After Re-Embolization for Recanalized Aneurysms After Initial Coiling: Further Recurrence Rates and Related Risk Factors

BACKGROUND

Although it is well known that coiled aneurysms can recanalize over time, long-term outcomes of re-embolization for recurred aneurysms have not been adequately investigated. We studied the retreatment outcomes of re-embolized aneurysms during follow-up monitoring and assessed the risk factors related to further recanalization.

METHODS

A total of 129 patients with 133 aneurysms were retrospectively reviewed. Each aneurysm was subjected to re-embolization because of major recanalization after initial coil embolization and underwent midterm and extended monitoring after retreatment. Cumulative medical records and radiologic data were assessed. Repeat recurrence rates and related risk factors were assessed by binary logistic regression analysis.

RESULTS

A total of 47 aneurysms (35.3%) showed re-recanalization at 6 months after re-embolization, with 17 and 30 instances of minor and major recanalization, respectively. Multivariate analysis indicated that posterior circulation (hazard ratio [HR], 6.129; P = 0.010), large aneurysm (>7 mm) (HR, 13.598; P < 0.001), and incomplete occlusion at the second coiling (HR, 9.975; P = 0.001) were significant factors for repeat recanalization. Of 86 aneurysms showing complete occlusion at the midterm, 76 were further evaluated (≥12 months), showing 18 aneurysms (23.7%) of delayed re-recanalization during a follow-up of 230.1 aneurysm-years. Of 15 aneurysms with minor recanalization at 6 months, 6 (40.0%) progressed to major recanalization during a follow-up of 44.0 aneurysm-years.

CONCLUSIONS

Most re-coiled aneurysms (64.7%) showed complete occlusion at the 6-month follow-up. However, posterior circulation, large aneurysm (>7 mm), and incomplete occlusion at the second coiling were risks for further recanalization. The midterm and delayed re-recanalization rates of the re-embolized aneurysms seem to be higher than those of the initial aneurysms.

Relationship between adverse events and antiplatelet drug resistance in neurovascular intervention: a meta-analysis

Background

This meta-analysis aimed to evaluate the association between antiplatelet resistance and the risk of procedure-related complications in neurovascular interventions.

Methods

We identified relevant articles by searching electronic databases and reviewed the reference lists of selected papers. The risk of adverse events between antiplatelet responders and hyporesponders during neurointervention was compared in eligible clinical studies. Risk ratios (RRs) and 95% CIs were pooled using a random-effects meta-analysis.

Results

Of 2134 potentially relevant studies, our search identified 15 studies enrolling a total of 2365 patients. Pooled RRs showed thromboembolic events (TEE) were more frequent in hyporesponders (RR 2.634, 95% CI 1.465 to 4.734). However, hemorrhagic complications did not differ between the two groups (RR 1.236, 95% CI 0.642 to 2.380). In subgroup analysis, hyporesponders showed a higher prevalence of TEE with standard antiplatelet medication, but there was no obvious difference in TEE between the two arms when using a modified antiplatelet medication (RR 3.645, 95% CI 1.537 to 8.646; and RR 1.877, 95% CI 0.749 to 4.751). Studies using stent placement for aneurysms showed a higher TEE rate in hyporesponders (RR 3.221, 95% CI 1.899 to 5.464).

Conclusion

Antiplatelet resistance was significantly associated with TEE in neurointervention, and this adverse event was associated with individually-intensified antiplatelet medication as well as the type of neurointerventional procedure. Our findings support the use of antiplatelet resistance assays and tailored antiplatelet medications in neurovascular stent placement as a management strategy to reduce thromboembolic risk.

Antiplatelet Premedication for Stent-Assisted Coil Embolization of Intracranial Aneurysms: Low-Dose Prasugrel vs Clopidogrel

BACKGROUND

The use of antiplatelet medications to prevent thrombosis in the treatment of cerebral aneurysms with stents has become widely emphasized.

OBJECTIVE

To compare low-dose prasugrel with clopidogrel in stent-assisted coil embolization of intracranial aneurysms.

METHODS

This is a retrospective review of 311 aneurysms from 297 patients who underwent stent-assisted endovascular coil embolization of unruptured intracranial aneurysm between November 2014 and March 2017. Thromboembolic and hemorrhagic adverse events were compared between 207 patients who received low-dose prasugrel (PSG group) and 90 patients who received clopidogrel (CPG group).

RESULTS

P2Y12 reaction unit (PRU) values were significantly lower in the PSG group (PSG group vs CPG group, 132.3 ± 76.9 vs 238.1 ± 69.1; P &lt; .001); the percentage of inhibition was also statistically higher in the PSG group (54.0 ± 26.0% vs 20.8 ± 18.6%; P &lt; .001). Thromboembolic events occurred less frequently in the PSG group than in the CPG group (0.9% vs 6.4%; P = .01), whereas there was no significant difference in the percentage of hemorrhagic complications (0.5% vs 2.2%; P = .22). In the multivariate analysis, clopidogrel as the antiplatelet medication was the sole significant risk factor for thromboembolism in this series of patients undergoing stent-assisted coil embolization.

CONCLUSION

Use of low-dose PSG as an antiplatelet premedication is quick, effective, and safe for stent-assisted coil embolization of unruptured intracranial aneurysms. Prasugrel premedication significantly lowered the frequency of thromboembolic events without increasing the risk of hemorrhage.

Prevalence of poor biological response to clopidogrel

The existence of poor biological response to clopidogrel has been shown in some patients. Despite the increasing number of studies, this phenomenon remains difficult to quantify. We performed a systematic review to estimate the prevalence of poor biological response to clopidogrel and investigate the factors known to modulate this. An exhaustive search was performed. Altogether 171 publications were identified, providing data for a total of 45,664 subjects. The estimated prevalence of poor biological response to clopidogrel ranged from 15.9% to 49.5% according to the platelet function assay employed. The assays most frequently used were light transmittance aggregometry (LTA), the vasodilator-stimulated phosphoprotein (VASP) assay and the Verify -now® assay. For all these assays, higher cut-off values were associated with a lower prevalence of poor biological response to clopidogrel. However, when choosing a fixed cut-off point for each assay, the prevalence of poor biological response to clopidogrel was highly variable suggesting that other factors could modulate poor biological response to clopidogrel. Finally, none of the studied factors could apparently explain the variability of poor biological response to clopidogrel. This meta-analysis shows that the prevalence of poor biological response depends on the assay employed, the cut-off value and on various unidentified additional factors.

Growth-Related Major Recanalization of Coiled Aneurysms: Incidence and Risk Factors

BACKGROUND

Though endovascular techniques and procedural devices continue to advance, recurrence of embolized aneurysms is still problematic. Enlarging size during follow-up is the presumed basis of recanalization in some lesions, but such growth has not been adequately investigated.

OBJECTIVE

To generate estimates of growth in coiled aneurysms with major recanalization, focusing on incidence and risk factors involved.

METHODS

A cohort of 134 patients harboring 139 aneurysms were retrospectively reviewed, each subjected to re-embolization for major recanalization after initial coil embolization. Cumulative medical records and radiological data were assessed. The aneurysms were grouped by nature of recanalization, either related or unrelated to growth. Growth was defined as &gt;50% increase in aneurysm volume (including coil mass) at the time of re-embolization, compared initial status. Aneurysm volumes were determined by volume of coil mass within full confines of the aneurysm. Univariate and multivariate analyses were performed to identify risk factors predisposing to growth.

RESULTS

Major recanalization was growth related in 74 coiled aneurysms (53.2%) and unrelated to growth (by coil compaction) in 65 (46.8%). Multiple logistic regression analysis indicated that growth of coiled aneurysm was linked to aneurysms initially ruptured at presentation (P = .002) and aneurysm size &lt;7 mm (P &lt; .001). Cumulative growth rates were as follows: 14 (18.9%), 6 mo; 18 (24.3%), 12 mo; 13 (17.6%), 24 mo; 10 (13.5%), 36 mo; and 19 (25.7%), &gt;36 mo.

CONCLUSION

Our data suggest that aneurysms presenting with hemorrhage and small-sized aneurysms (&lt;7 mm) are predisposed major recanalization by growth after coil embolization, as opposed to coil compaction.

Microguidewire Looping to Traverse Stented Parent Arteries of Intracranial Aneurysms

Objective

Stents are widely used in coil embolization of intracranial aneurysms, but on occasion, a microcatheter must traverse a stented segment of artery (so-called trans-cell technique) to select an aneurysm, or double stenting may necessary. In such situations, microguidewire passage and microcatheter delivery through a tortuous stented parent artery may pose a technical challenge. Described herein is a microguidewire looping technique to facilitate endovascular navigation in these circumstances.

Methods

To apply this technique, the microguidewire tip is looped before entering the stented parent artery and then advanced distally past the stented segment, with the loop intact. Rounding of the tip prevents interference from stent struts during passage. A microcatheter is subsequently passed into the stented artery for positioning near the neck of aneurysm, with microguidewire assistance. The aneurysm is then selected, steering the microcatheter tip (via inner microguidewire) into the dome.

Results

This technique proved successful during coil embolization of nine saccular intracranial aneurysms (internal carotid artery [ICA], 6; middle cerebral artery, 2; basilar tip, 1), performing eight trans-cell deliveries and one additional stenting. Selective endovascular embolization was enabled in all patients, resulting in excellent clinical and radiologic outcomes, with no morbidity or mortality directly attributable to microguidewire looping.

Conclusion

Microguidewire looping is a reasonable alternative if passage through a stented artery is not feasible by traditional means, especially at paraclinoid ICA sites.

Insufficient platelet inhibition and thromboembolic complications in patients with intracranial aneurysms after stent placement

OBJECT

Insufficient platelet inhibition has been associated with an increased incidence of thromboembolic complications in cardiology patients undergoing percutaneous coronary intervention. Data regarding the relationship between insufficient platelet inhibition and thromboembolic complications in patients undergoing neurovascular procedures remain controversial. The purpose of this study was to assess the relationship of insufficient platelet inhibition and thromboembolic complications in patients with intracranial aneurysm undergoing stent treatment.

METHODS

The authors prospectively recruited patients with intracranial aneurysms undergoing stent treatment and maintained the data in a database. MRI with diffusion-weighted sequences was performed within 24 hours of stent insertion to identify acute ischemic lesions. The authors used thromboelastography to assess the degree of platelet inhibition in response to clopidogrel and aspirin. Univariate and multivariate logistic regression analysis was used to identify potential risk factors of thromboembolic complications.

RESULTS

One hundred sixty-eight patients with 193 aneurysms were enrolled in this study. Ninety-one of 168 (54.2%) patients with acute cerebral ischemic lesions were identified by diffusion-weighted MRI. In 9 (5.4%) patients with ischemic lesions, transient ischemic attack or stroke was found at discharge, and these complications were found in 11 (6.5%) patients during the follow-up period. The incidence of periprocedural thromboembolic complications increased with resistance to antiplatelet agents, hypertension, hyperlipidemia, complete occlusion, and aneurysm of the anterior circulation. The multivariate regression analysis demonstrated that the anterior circulation and adenosine diphosphate (ADP) inhibition percentage were independent risk factors of perioperative thromboembolic complications. The maximum amplitude and ADP inhibition percentage were independent risk factors for thromboembolic complications during the follow-up period.

CONCLUSIONS

The ADP inhibition percentage is related to thromboembolic complications after stent placement for intracranial aneurysms. The increase of the ADP inhibition may decrease the risk of thromboembolic complications.

Prophylactic Antiplatelet Medication in Endovascular Treatment of Intracranial Aneurysms: Low-Dose Prasugrel versus Clopidogrel

BACKGROUND AND PURPOSE

Prophylactic antiplatelet medication is beneficial in decreasing thromboembolic complications during endovascular treatment of unruptured intracranial aneurysms. The efficacy may be limited by variability of individual response to antiplatelet medication, especially clopidogrel. We compared the efficacy of 2 antiplatelet medications, low-dose prasugrel and clopidogrel, in patients undergoing endovascular treatment of unruptured aneurysms.

MATERIALS AND METHODS

From November 2014 to July 2015, 194 patients with a total of 222 unruptured aneurysms underwent endovascular treatment at a single institution. Laboratory and clinical data from the prospectively maintained registry were used in this study. Antiplatelet medication was given the day before endovascular treatment (prasugrel 20 mg or 30 mg or clopidogrel 300 mg). Response to the antiplatelet medication was measured by the VerifyNow system. Periprocedural adverse event rates between the 2 groups were compared.

RESULTS

There were no significant differences in the baseline characteristics of patients and aneurysms between the 2 groups. The P2Y12 reaction unit values were lower (clopidogrel group versus prasugrel group, 242.7 ± 69.8 vs 125.7 ± 79.4; P < .0001) and percentage inhibition values were higher (22.1% ± 19.7% vs 60.2 ± 24.7%; P < .0001) in the prasugrel group. There were no thromboembolic events, but there was 1 procedural bleed in each group, without any clinical consequences.

CONCLUSIONS

The prasugrel group showed more effective and consistent platelet inhibition. We may omit the antiplatelet response assay with the low-dose prasugrel premedication before the endovascular treatment of patients with unruptured aneurysms. Further study is required to determine whether there is benefit of this strategy regarding clinical outcome.

Carotid Endarterectomy on Antiplatelet Agents in the Era of Point-of-Care Testing

OBJECTIVE

The safety of carotid endarterectomy in patients with a response to antiplatelet agents (aspirin and clopidogrel) confirmed by point-of-care testing is unknown. Thus, we sought to determine whether using point-of-care assessment of platelet inhibition reveals risk factors for operative complications or predicts clinical outcomes.

METHODS

We reviewed records of carotid endarterectomy patients treated from March 2013 to July 2015 to extract demographics, lesion characteristics, laboratory data, procedural complications, and follow-up. Administration of aspirin, clopidogrel, or therapeutic anticoagulation within 5 days before surgery was recorded.

RESULTS

We analyzed 79 patients with 86 lesions (mean age 70.9 ± 10.0 years). More patients with a P2Y12 reaction unit (PRU) <170 had neck hematomas (4/10, 40.0%) than those with a PRU ≥170 (2/9, 22.2%) (P = 0.63). Estimated blood loss ≥100 mL was more frequent among patients with PRU <170 (9/10, 90.0%) than among those with PRU ≥170 (5/9, 55.6%) (P = 0.09). Clopidogrel use, regardless of response, independently predicted neck hematoma in a logistic regression model, with increased odds of 8.5. Mean postoperative modified Rankin Scale scores did not differ statistically between clopidogrel users and nonusers at a mean follow-up of 108.5 ± 146.3 days (P = 0.27).

CONCLUSIONS

Clopidogrel use within 5 days of carotid endarterectomy independently predicted postoperative neck hematomas, most of which were managed conservatively. Patients with PRU <170 were more likely to have estimated blood loss ≥100 mL during surgery and surgery lasting ≥3 hours.