Antiplatelet resistance and thromboembolic complications in neurointerventional procedures

Antiplatelet Resistance in Coronary Artery Bypass Grafting: A Systematic Review

Background

This systematic review examines the occurrence and implications of resistance to primary antiplatelet agents, aspirin and clopidogrel, often utilised in patients undergoing coronary artery bypass grafting (CABG), alongside the methodologies for assessment of such resistance.

Methods

An extensive literature search across various databases such as PubMed, MEDLINE via Ovid, Embase, and Cochrane CENTRAL until May 2024 was conducted to identify studies evaluating antiplatelet resistance in on-pump and off-pump CABG patients. Following quality assessment, only high-quality studies were incorporated into this review.

Results

This review included 19 studies with 3,915 patients, four of which were randomised controlled trials and 15 were observational studies. Aspirin resistance incidence ranged from 11.0% to 51.5%, while clopidogrel resistance was 22%. Antiplatelet resistance, assessed through a wide variety of methods, was associated with a 13 times increase in the risk of vein graft occlusion and increased rates of mortality, myocardial infarction, and target vessel revascularisation in the case of clopidogrel resistance. The effect of cardiopulmonary bypass on antiplatelet resistance remains ambiguous.

Conclusion

The academic literature lacks a standardised definition for antiplatelet resistance. Assessment methodologies greatly vary, leading to noninterchangeable outcomes. While aspirin resistance has a conflicting overall significant impact on adverse outcomes, clopidogrel resistance correlates with poorer clinical outcomes.

Thromboelastographic and Gene Polymorphism Bimodality Detection for Dual Antiplatelet Aggregation Therapy in Individuals with Clopidogrel-resistant Symptomatic Intracranial Artery Stenosis

BACKGROUND

Recent research indicates that clopidogrel resistance is connected with a patient's future ischemia risk, hence increasing the likelihood of recurrent ischemic cerebrovascular disease. Thromboelastographic and clopidogrel gene polymorphism testing can be used to see how a person responds to antiplatelet therapy and change the treatment plan accordingly. This may be a good way to make antiplatelet aggregation therapy more effective and safer.

OBJECTIVE

The objective of this study was to investigate the efficacy of dual antiplatelet aggregation therapy in patients with symptomatic intracranial large artery stenosis being resistant to clopidogrel tablets. The thromboelastographic and gene polymorphism bimodality detection techniques were used to analyze the clopidogrel resistance influencing factors.

METHODS

89 patients with symptomatic intracranial large arterial stenosis who were admitted to our hospital from February 2021 to February 2022 were selected, classified as large artery atherosclerotic type by TOAST, and confirmed as having severe intracranial large arterial stenosis (70 % to 99 %) by magnetic resonance angiography (MRA), computed tomographic angiography (CTA), and digital subtraction angiography (DSA). All patients were treated with dual antiplatelet therapy with aspirin and clopidogrel, and thromboelastography and clopidogrel gene polymorphism were monitored 1 week later.

RESULTS

44 of 89 patients were clopidogrel-resistant. Among 44 patients, 20 were ticagrelorresistant and 24 were cilostazol-resistant. Clopidogrel had a resistance rate of 49.4%. The recurrence of ischemic cerebrovascular disease in the three groups was statistically significant (P<0.05) after 3 months of follow-up treatment, but bleeding (intracranial, gastrointestinal, respiratory, urinary, and mucocutaneous) and dyspnea were not. The clopidogrel-resistant group had a higher number of females, as well as higher levels of hypertension, diabetes, and platelet count than the sensitive group (P<0.05), but there was no significant difference in age, smoking, alcohol consumption, previous stroke, glycosylated haemoglobin, creatinine, or low-density cholesterol.

CONCLUSION

Using thromboelastographic and gene polymorphism bimodality detection, we found switching to ticagrelor antiplatelet aggregation therapy as better than switching to cilostazol in patients with symptomatic intracranial large artery stenosis being resistant to clopidogrel tablets. The results may be biased due to the study being a single-centre study and having a limited sample size.

Predictors of thromboembolic complications after stent-assisted coiling of acutely ruptured intracranial aneurysms: A retrospective multicenter study

Background

Stent-assisted coiling (SAC) has been reported to safely and effectively treat wide-necked unruptured intracranial aneurysms. However, SAC of acutely ruptured aneurysms is controversial because of perioperative thromboembolic complications. We aimed to investigate the predictors of the thromboembolic complications after SAC of acutely ruptured aneurysms.

Methods

We performed a retrospective multicenter analysis of 110 consecutive patients with ruptured intracranial aneurysms treated with SAC within 72 h of the onset of subarachnoid hemorrhage. Thromboembolic complications were defined as any angiographic filling defects at the aneurysms base or the distal artery during the stent treatment and the new onset of symptomatic ischemia and a new hypo-density in a vascular distribution confirmed by CT scan within 24 h of treatment. These patients were grouped into patients with thromboembolic complications and those without thromboembolic complications. A multivariate logistic regression analysis was performed to identify predictors of thromboembolic complications.

Results

One hundred and one patients with 101 ruptured aneurysms were included in this study. 9 (8.9%) patients experienced thromboembolic complications. Patients with thromboembolic complications had a higher rate of unfavorable outcomes at discharge (P < 0.001) and at the last follow-up (p = 0.017). Of these patients, four patients presented with intraprocedural thrombus formation, and 5 experienced postprocedural ischemia. There was a trend toward thromboembolic complications in patients with a higher Fisher grade (p = 0.076) and those treated with intravenous tirofiban (p = 0.052). Patients with thromboembolic complications more often presented with poor grade clinical conditions (p = 0.005) and aneurysms with a large dome to neck ratio (p = 0.031). In the multivariate analysis, a worse World Federation World Federation of Neurological Societies (WFNS) grade (OR = 8.241; 95% CI 1.686–40.292; P = 0.009) and a larger dome to neck ratio (OR = 5.385; 95% CI 1.023–28.337; P = 0.047) were independent predictors of thromboembolic complications.

Conclusion

Patients with thromboembolic complications are more likely to have an unfavorable outcome. A worse clinical condition before the treatment and a larger dome to neck ratio were independent predictors of thromboembolic complications after SAC of acutely ruptured intracranial aneurysms.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The safety and efficacy of the LVIS stent for the treatment of ruptured intracranial aneurysms within 24 hours: A multicenter retrospective study

OBJECTIVE

Stent-assisted coiling is increasingly used in the treatment of acutely ruptured intracranial aneurysms. However, the optimal timing of the stent-assisted coiling remains unknown. We aimed to investigate the safety and efficacy of the Low Profile Visualized Intraluminal Support (LVIS) stent for ruptured aneurysms treatment within 24 h comparing to the treatment between 25 and 72 h of symptom onset.

PATIENTS AND METHODS

We conducted a multicenter retrospective study on 110 consecutive patients with ruptured intracranial aneurysms. These patients were treated with LVIS stent within 72 h in four tertiary hospitals between January 2017 and December 2017. The timing of treatment was grouped into the treatment within 24 h and the treatment between 25 and 72 h. Baseline characteristics, periprocedural complications, angiographic results, and clinical outcomes were compared between the two groups.

RESULTS

A total of 101 patients were included. 49 (48.5 %) patients were treated within 24 h and 52 (51.5 %) within between 25 and 72 h. Periprocedural complications occurred in 2 (4.1 %) patients treated within 24 h compared with those in 10 (19.2 %) treated between 25-72 h (P = 0.032). No early rebleeding occurred in both groups. 45 (91.8 %) of 49 aneurysms had complete occlusion on immediate angiography compared with 46 (88.5 %) of 52 aneurysms had complete occlusion. 2 (2.0 %) aneurysms were retreated. The clinical outcomes and angiographic results did not differ between the two groups.

CONCLUSIONS

The LVIS stent-assisted coiling may be safe and effective in the treatment of selected patients with ruptured aneurysms within 24 h of symptom onset.

Utility of platelet function testing in stent-assisted coiling of cerebral aneurysms

BACKGROUND

Thromboembolic complications are the primary risks of stent-coiling of cerebral aneurysms. The utility of platelet function testing in stent-assisted aneurysm coiling remains controversial. This study aimed to assess a pharmacy-mediated antiplatelet management protocol for stent-assisted coiling.

METHODS

Stent-coiled aneurysms at an academic institution in the United States between 2015 and 2018 were retrospectively reviewed. All patients were managed using a pharmacy-mediated antiplatelet protocol, which required repeated platelet function testing and subsequent dose adjustments. Medication dosage, number of adjustments, aspirin reaction units (ARU) and P2Y12 reaction units (PRU), as well as complication rates, angiographic and functional outcome were analyzed.

RESULTS

A total of 56 aneurysms (median size 5 mm, range 2.6-14.0 mm) in 54 patients (median age 58.5 years) were treated with stent-assisted coil embolization. Most aneurysms were located at the basilar tip (28.6%). Median pre-procedure ARU and PRU were 442.5 (range 363-594) and 123.5 (range 1-252), respectively. Approximately two-thirds of all procedures required at least one aspirin dose adjustment and 88.5% of procedures required at least one clopidogrel dose adjustment. There were two (3.6%) thromboembolic complications. One of the thromboembolic complications occurred in a patient where the pharmacy-mediated protocol was violated. There were no hemorrhagic complications. Last imaging follow-up demonstrated complete aneurysm occlusion in 83.9%.

CONCLUSION

In patients where the pharmacy-mediated antiplatelet protocol was followed, the thromboembolic complication rate was 1.8%. This complication rate compares favorably to those reported in large contemporary series. Nevertheless, the pharmacy-mediated protocol places a significant burden on both the patient and healthcare system.

Platelet Function Testing in Neurovascular Procedures: Tool or Gimmick?

Background

Platelet inhibitors are used to prevent thromboembolic complications related to neurovascular stenting (NVS) procedures. Despite substantial inter-individual variability of functional platelet inhibition, the value of platelet function tests (PFT) to assess inhibition remains controversial.

Objective

This study was conducted to compare differences in thromboembolic complication rates associated with NVS in platelet-inhibited patients with and without PFT. Clinical neurological outcomes were assessed by differences in the modified Rankin Scale (mRS).

Materials and Methods

One hundred seventeen consecutive patients underwent elective NVS procedures within a 7-year period. All patients received aspirin and clopidogrel 8 days before the procedure. Fifty-two patients were treated without assessment of platelet inhibition, and 65 patients were tested for clopidogrel resistance. When clopidogrel resistance was revealed, corresponding patients were converted to ticagrelor. Changes in mRS and thromboembolic event rates were compared between the 2 cohorts.

Results

Thirty-five percent of patients from the cohort subjected to PFT tests showed inadequate platelet inhi-bition under clopidogrel and were converted to ticagrelor. Compared to the non-PFT test -cohort, neurological deficits were significantly reduced (12 vs. 0%; p = 0.009) and a lower number of thromboembolic events was found (12 vs. 3%; p > 0.05) within the test cohort.

Conclusion

PFT appears to identify patients with clopidogrel resistance prior to NVS procedures. When non-responders are converted to alternative platelet inhibitors, neurological outcomes and thromboembolic complication rates may improve. Consequently, this study provides preliminary evidence that PFT may be a useful clinical tool to enhance procedural safety and improve clinical outcomes in NVS procedures.

Postoperative Anticoagulation After Neurologic Surgery

Management of anticoagulation and antiplatelet medications after neurosurgery can be complex, especially given that these patients have multiple medical comorbidities. In turn, neurosurgical patients are at high risk for the development of venous thromboembolism after surgery, so neurosurgeons must consider the use of pharmacologic prophylaxis. Developments in endovascular neurosurgery have produced therapies that require close management of antiplatelet medications to prevent postoperative complications. Any of these patient populations may need intrathecal access. This article highlights current strategies for managing these issues in the neurosurgical patient population.

Update on flow diverters for the endovascular management of cerebral aneurysms

Flow diversion has become a well-accepted option for the treatment of cerebral aneurysms. Given the significant treatment effect of flow diverters, numerous options have emerged since the initial Pipeline embolization device studies. In this review, the authors describe the available flow diverters, both endoluminal and intrasaccular, addressing nuances of device design and function and presenting data on complications and outcomes, where available. They also discuss possible future directions of flow diversion.

Clopidogrel Response Variability in Unruptured Intracranial Aneurysm Patients Treated with Stent-Assisted Endovascular Coil Embolization : Is Follow-Up Clopidogrel Response Test Necessary?

Objective

The purpose of this study was to analyze the variability of clopidogrel responses according to duration of a clopidogrel drug regimen after stent-assisted coil embolization (SAC), and to determine the correlation between the variability of clopidogrel responses and thromboembolic or hemorrhagic complications.

Methods

A total of 47 patients who underwent SAC procedures to treat unruptured intracranial aneurysms were enrolled in the study. Preoperatively, patients received more than seven days of aspirin (100 mg) and clopidogrel (75 mg), daily. P2Y12 reaction unit (PRU) was checked with the VerifyNow test one day before the procedure (pre-PRU) and one month after the procedure (post-PRU). PRU variability was calculated as the difference between the initial response and the follow-up response. Patients were sorted into two groups based on their response to treatment : responsive and hypo-responsive.

Results

PRU variability was significantly greater in the hypo-responsive group when compared to the responsive group (p=0.019). Pre-PRU and serum platelets counts were significantly correlated with PRU variation (p=0.005 and p=0.004, respectively). Although thromboembolic complication had no significant correlated factors, hemorrhagic complication was correlated with pre-PRU (p=0.033).

Conclusion

In conclusion, variability of clopidogrel responses during clopidogrel medication was correlated to serum platelet counts and the initial clopidogrel response. Thromboembolic and hemorrhagic complications did not show correlation with the variability of clopidogrel response, or the clopidogrel response after one month of medication; however, hemorrhagic complication was associated with initial clopidogrel response. Therefore, it is recommended to test patients for an initial clopidogrel response only, as further tests would be insignificant.

Antiplatelet drug resistance did not increase the thromboembolic events after stent-assisted coiling of unruptured intracranial aneurysm: a single center experience of 99 cases

We aimed to evaluate the correlation between aspirin or clopidogrel resistance and the risk of thromboembolic events (TEs). Between June 2011 and April 2015, we reviewed clinical and angiographic characteristics, and TEs in the patients undergoing stent-assisted coil embolization (SAC) of unruptured intracranial aneurysms (UIA) at our institution. We did not modify antiplatelet medication in patients with resistance. The relationships between antiplatelet resistance and the occurrence of acute symptomatic TEs, any diffusion-positive lesions, multiple diffusion-positive lesions, or delayed TEs were investigated. Ninety-nine endovascular treatments with stent-assisted technique were performed on 99 patients. The prevalence of aspirin resistance was 12% and clopidogrel resistance was 62.6%. Acute symptomatic TEs were demonstrated in 4 patients (4%). Diffusion-positive lesions were found in 82 patients [82.1%; 36 patients were group I (≤5) and 46 patients were group II (>5)]. Delayed TEs were demonstrated in 10 patients (10.1%). Neither aspirin resistance nor clopidogrel resistance was relevant to the development of acute symptomatic TEs, any diffusion-positive lesions, multiple diffusion-positive lesions, and delayed TEs (P _logistic = not available, 0.448, 0.362, and 0.829 for aspirin resistance and P _logistic = 0.607, 0.367, 0.278, and 0.245 for clopidogrel resistance). Without modification of antiplatelet medication, we demonstrated 4% of acute symptomatic TEs and 10% of delayed TEs. Aspirin or clopidogrel resistance did not show significant relationships with acute and delayed TEs in the SAC of UIA.

Contribution of whole platelet aggregometry to the endovascular management of unruptured aneurysms: an institutional experience

BACKGROUND

Stent-assisted coiling of intracranial aneurysms is an efficient alternative treatment to surgical clipping but requires prolonged antiplatelet therapy. Some patients are non-responsive to aspirin and/or clopidogrel.

OBJECTIVE

To analyze the implications of this assessment using the 'whole blood aggregometry (WBA) by impedance' technique.

MATERIALS AND METHODS

The Southwestern Tertiary Aneurysm Registry was reviewed between 2002 and 2012 for patients with unruptured aneurysms treated with stent-assisted coiling. The study population was divided into patients who were tested preoperatively for platelet responsiveness to aspirin and clopidogrel ('tested' patients) and those who were not ('non-tested'). Where necessary, tested patients received additional doses of antiplatelet drugs to achieve adequate platelet inhibition. Endpoints included the incidence of non-responsiveness, the rates of thrombotic and hemorrhagic complications, and the rates of permanent morbidity and mortality.

RESULTS

A total of 266 patients fulfilled our selection criteria: 114 non-tested patients who underwent 121 procedures, and 152 tested patients who underwent 171 procedures. The two groups did not vary significantly in patient age, gender, and aneurysms location. Aspirin non-responsiveness was detected in 3 patients (1.75%) and clopidogrel non-responsiveness in 21 patients (12.3%). Non-tested patients had an 11.6% rate of thrombotic complications with a 4.1% permanent morbidity or mortality rate versus 2.3% and 0.6% in tested patients (p=0.0013). The incidence of hemorrhagic complications was similar between the two groups.

CONCLUSIONS

Preoperative platelet inhibition testing using WBA can be useful to assess and correct antiaggregant non-responsiveness, and may reduce postoperative mortality and permanent morbidity.

Association between Postprocedural Infarction and Antiplatelet Drug Resistance after Coiling for Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE

Procedure-related thromboembolism is a major limitation of coil embolization, but the relationship between thromboembolic infarction and antiplatelet resistance is poorly understood. The purpose of this study was to verify the association between immediate postprocedural thromboembolic infarction and antiplatelet drug resistance after endovascular coil embolization for unruptured intracranial aneurysm.

MATERIALS AND METHODS

This study included 338 aneurysms between October 2012 and March 2015. All patients underwent postprocedural MR imaging within 48 hours after endovascular coil embolization. Antiplatelet drug resistance was checked a day before the procedure by using the VerifyNow system. Abnormal antiplatelet response was defined as >550 aspirin response units and >240 P2Y12 receptor reaction units. In addition, we explored the optimal cutoff values of aspirin response units and P2Y12 receptor reaction units. The primary outcome was radiologic infarction based on postprocedural MR imaging.

RESULTS

Among 338 unruptured intracranial aneurysms, 134 (39.6%) showed diffusion-positive lesions on postprocedural MR imaging, and 32 (9.5%) and 105 (31.1%) had abnormal aspirin response unit and P2Y12 receptor reaction unit values, respectively. Radiologic infarction was associated with advanced age (65 years and older, P = .024) only with defined abnormal antiplatelet response (aspirin response units ≥ 550, P2Y12 receptor reaction units ≥ 240). P2Y12 receptor reaction unit values in the top 10th percentile (>294) were associated with radiologic infarction (P = .003). With this cutoff value, age (adjusted odds ratio, 2.29; 95% confidence interval, 1.28-4.08), P2Y12 receptor reaction units (>294; OR, 3.43; 95% CI, 1.53-7.71), and hyperlipidemia (OR, 2.05; 95% CI, 1.04-4.02) were associated with radiologic infarction in multivariate analysis.

CONCLUSIONS

Radiologic infarction after coiling for unruptured aneurysm was closely associated with age. Only very high P2Y12 receptor reaction unit values (>294) predicted postprocedural infarction. Further controlled studies are needed to determine the precise cutoff values, which could provide information regarding the optimal antiplatelet regimen for aneurysm coiling.

Predicting intraprocedural rupture and thrombus formation during coiling of ruptured anterior communicating artery aneurysms

Background

Intraprocedural rupture and thrombus formation are serious complications during coiling of ruptured intracranial aneurysms, and they more often occur in patients with anterior communicating artery (ACoA) aneurysms.

Objective

To identify independent predictors of intraprocedural rupture and thrombus formation during coiling of ruptured ACoA aneurysms.

Methods

Between January 2008 and February 2015, 254 consecutive patients with 255 ACoA aneurysms were treated with coiling. We retrospectively reviewed intraoperative angiograms and medical records to identify intraprocedural rupture and thrombus formation, and re-measured aneurysm morphologies using CT angiography images. Multivariate logistic regression models were used to determine independent predictors of intraprocedural rupture and thrombus formation.

Results

Of the 231 patients included, intraprocedural rupture occurred in 10 (4.3%) patients, and thrombus formation occurred in 15 (6.5%) patients. Patients with smaller aneurysms more often experienced intraprocedural rupture than those with larger aneurysms (3.5±1.3 mm vs 5.7±2.3 mm). Multivariate analysis showed that smaller ruptured aneurysms (p=0.003) were independently associated with intraprocedural rupture. The threshold of aneurysm size separating rupture and non-rupture groups was 3.5 mm. Multivariate analysis showed that a history of hypertension (p=0.033), aneurysm neck size (p=0.004), and parent vessel angle (p=0.023) were independent predictors of thrombus formation. The threshold of parent vessel angle separating thrombus and non-thrombus groups was 60.0°.

Conclusions

Ruptured aneurysms <3.5 mm were associated with an increased risk of intraprocedural rupture, and parent vessel angle <60.0°, wider-neck aneurysms, and a history of hypertension were associated with increased risk of thrombus formation during coiling of ruptured ACoA aneurysms.

Stent-assisted coiling versus coiling alone of ruptured anterior communicating artery aneurysms: A single-center experience

OBJECTIVE

Endovascular coiling of anterior communicating artery (ACoA) aneurysms has evolved; however, stent-assisted coiling of ruptured aneurysms remains controversial. We aimed to compare periprocedural complications, angiographic and clinical outcomes after stent-assisted coiling with coiling alone of ruptured ACoA aneurysms.

METHODS

We performed a retrospective review of consecutive 222 patients with ruptured ACoA aneurysms treated with endovascular coiling within 7 days after ictus. Patients were grouped into stent-assisted coiling and coiling alone groups. Baseline characteristics, periprocedural complications, clinical outcomes, and angiographic results were compared between the two groups.

RESULTS

63 (28.4%) patients underwent stent-assisted coiling and 159 (71.6%) underwent coiling alone. There were no statistically significant differences in age, sex, clinical grading and Fisher grade. Larger aneurysms (P=0.002) and wider-neck aneurysms (P<0.001) were more often treated with stent-assisted coiling within 72h (P=0.025). Intraprocedural aneurysm rupture occurred in 6 (9.5%) patients treated with stent-assisted coiling compared with in 5 (3.1%) treated with coiling alone (P<0.048). Thrombus formation occurred in 10 (15.9%) patients after stent-assisted coiling compared with 6 (3.8%) after coiling alone (P=0.002). Stent-assisted coiling achieved a lower rate of immediate occlusion than coiling alone (P=0.045). Postoperative complications, clinical outcomes, and follow-up aneurysm occlusion did not significantly differ.

CONCLUSIONS

Stent-assisted coiling of ruptured ACoA aneurysms was associated with a higher rate of intraprocedural complications and associated with a lower immediate occlusion rate. However, Postoperative complications and clinical outcomes did not differ. Long-term angiographic results require further study.

Genetic determinations of variable responsiveness to clopidogrel and implications for neurointerventional procedures

Endovascular intervention is emerging as a substitute for open surgical procedures for the treatment of cerebrovascular disease. However, up to 9% of patients undergoing neurointerventional procedures develop thromboembolic complications. Strategies to reduce periprocedural thromboembolic events are dominated by the use of dual antiplatelet therapy (DAT) which has been validated based on studies of peripheral vascular and coronary intervention. Of note, DAT decreases adverse vascular outcomes by 75-80% in patients undergoing percutaneous coronary intervention (PCI). It follows that similar treatment effects would be observed in neurointerventional populations. However, a growing body of evidence demonstrates that a subgroup of patients respond suboptimally to DAT, and in particular to clopidogrel (termed clopidogrel hyporesponders). These patients may be at an increased risk of thromboembolic complications such as in-stent thrombosis following neurointerventional procedures. Previous studies report 5-30% suboptimal response to clopidogrel in the cardiovascular population, while a higher prevalence is seen in populations undergoing neurointerventional procedures, i.e. as much as 66%. Knowledge of the mechanism leading to clopidogrel hyporesponsiveness is accumulating. A number of genetic polymorphisms, in particular CYP 2C19*2, have been associated with clopidogrel hyporesponsiveness and clinical outcomes. In addition, there are significant differences in the prevalence of CYP 2C19*2 across racial groups. Approximately 50% of Asians and 25% of Caucasians harbor the CYP 2C19*2 allele. While no prospective randomized trials currently exist to demonstrate improved clinical outcomes with genotype-based treatment for carriers of the CYP 2C19*2 polymorphism, a number of studies show that an increased dose of clopidogrel improves platelet inhibition in hyporesponders. The aim of the review is to examine the current understanding of the genetic basis of clopidogrel hyporesponsiveness in patients undergoing neurointerventional procedures and to explore current efforts using genotype and phenotype testing as well as alternative strategies to overcome the clopidogrel hyporesponsiveness.

Dual antiplatelet therapy plus postoperative heparin and dextran is safe and effective for reducing risk of embolic stroke during aneurysm coiling

BACKGROUND

Thromboembolic events represent a clinically significant cause of neurological morbidity during the endovascular management of cerebral aneurysms. We have implemented an anti-thromboembolic regimen consisting of pre- and postoperative dual antiplatelet therapy, as well as postoperative anticoagulation using heparin and dextran. The aims of our study were to examine the effect of this regimen on thromboembolic rates during elective aneurysm coiling, and to elucidate risk factors associated with the development of thromboembolic events in this setting.

METHODS

We conducted a retrospective review of patients who underwent elective intracranial aneurysm coiling between January 2005 and February 2012. The primary outcome of interest was the occurrence of a clinically significant peri-procedural thromboembolic event. Secondary outcomes included the occurrence of a central nervous system (CNS) or systemic hemorrhage.

RESULTS

During the study period, 312 patients underwent elective aneurysm coiling and six (2 %) thromboembolic events occurred; three (1 %) occurred in the group that received the anti-thromboembolic regimen (261 patients) and three (6 %) occurred in the group that did not receive the regimen (51 patients), resulting in a statistically significant difference (P = 0.024). Both the presence of a hypercoagulable state (P = 0.014) and the lack of the anti-thromboembolic regimen (P = 0.043) were significantly associated with the occurrence of a thromboembolic event.

CONCLUSIONS

This study provides evidence that the regimen described here is safe and reduces thromboembolic complications during elective aneurysm coiling. Ours is likely the most aggressive regimen in the published literature and significantly reduced the rate of thromboembolism without any significant increase hemorrhagic complications.

Is eptifibatide a safe and effective rescue therapy in thromboembolic events complicating cerebral aneurysm coil embolization? Single-center experience in 42 cases and review of the literature

INTRODUCTION

Thromboembolic complications are the most frequent perioperative complications of endovascular treatment of intracranial aneurysms. Even if the effectiveness of glycoprotein IIb/IIIa inhibitors has been reported, the outcomes in published clinic data are contradictory. This study aims to assess the effectiveness and the safety of eptifibatide in thromboembolic complications during intracranial aneurysm embolization procedure.

METHODS

Between 2006 and 2012, 650 patients with intracranial aneurysm were treated using endovascular coil embolization, and in 62 cases (9.5 %), an intra-arterial thrombus developed. Glycoprotein IIb/IIIa inhibitor was administrated in 45 of them who required a rescue treatment. These 45 patients were treated with an intra-arterial bolus (0.2 mg/kg) of eptifibatide. We respectively reviewed the angiographic and clinical outcomes, and the periprocedural complications of the rescue treatment.

RESULTS

No intra- or early postoperative (48 h) bleeding was observed after treatment. A total recovery of the entire arterial tree (TICI 3) was established in 28 cases (62.2 %), a partial revascularization in 13 cases (28.8 %) (5 TICI 2A and 8 TICI 2B), and no revascularization or reperfusion (TICI 0 or TICI 1) in 4 cases (9 %). Eptifibatide was more effective on proximal obstructions and in-stent occlusions than on peripheral distal thrombus, which were completely disintegrated one time out of three.

CONCLUSION

Intra-operative intra-arterial use of eptifibatide does not imply an increase of hemorrhagic events. Even if eptifibatide allows for a high rate of arterial recanalization, its effectiveness seems to be less important in cases of distal occlusions.

Clopidogrel resistance is associated with thromboembolic complications in patients undergoing neurovascular stenting

BACKGROUND AND PURPOSE

Antiplatelet drug resistance has been associated with thromboembolic complications in patients after coronary stent placement. It has not been well-studied in patients who have neurovascular stent-placement procedures. This study aimed to analyze the relationship between antiplatelet drug resistance and neurovascular stent-placement complications.

MATERIALS AND METHODS

A prospective data base of all patients treated at our institution was used to identify patients with neurovascular stent-placement procedures. During a 4.5-year period, all patients undergoing neurovascular stent placement were evaluated for aspirin and clopidogrel resistance by using the VerifyNow assay. During an observational phase, all patients received 75 mg of clopidogrel and aspirin (group A). During the intervention phase (group B), patients were given additional clopidogrel on the basis of the clopidogrel resistance assay. We assessed the development of thromboembolic complications within 30 days of the procedure in patients who were resistant-versus-nonresistant to clopidogrel.

RESULTS

Of 96 patients who had neurovascular stent placement, 5.2% were resistant to aspirin and 36.5% were resistant to clopidogrel. Periprocedural thromboembolic complications were seen in 7 patients (7.3%). In a multivariate logistic regression model, clopidogrel resistance, higher diastolic blood pressure, and lack of statin use were significantly associated with periprocedural thromboembolic complication. There was a nonsignificant decrease in thromboembolic complications in patients whose clopidogrel dosage was tailored to the assay.

CONCLUSIONS

In our series, clopidogrel resistance was associated with increased periprocedural thromboembolic complications from neurovascular stent-placement procedures. Targeting the clopidogrel dose to platelet inhibition assays may improve clinical outcomes and requires further study.