Variability of Platelet Reactivity on Antiplatelet Therapy in Neurointervention Procedure

Antiplatelet Agents Inhibit Platelet Adhesion and Aggregation on Glass Surface Under Physiological Flow Conditions: Toward a Microfluidic Platelet Functional Assay Without Additional Adhesion Protein Modification

ABSTRACT

As the pathogenesis of arterial thrombosis often includes platelet adhesion and aggregation, antiplatelet agents are commonly used to prevent thromboembolic events. Here, a new microfluidic method without additional adhesion protein modification was developed to quantify the inhibitory effect of antiplatelet drugs on the adhesion and aggregation behavior of platelets on glass surfaces under physiological flow conditions. Polydimethylsiloxane-glass microfluidic chips were fabricated by soft photolithography. Blood samples from healthy volunteers or patients before and after taking antiplatelet drugs flowed through the microchannels at wall shear rates of 300 and 1500 second -1 , respectively. The time to reach 2.5% platelet aggregation surface coverage (Ti), surface coverage (A 150s ), and mean fluorescence intensity (F 150s ) were used as quantitative indicators. Aspirin (80 μM) prolonged Ti and reduced F 150s . Alprostadil, ticagrelor, eptifibatide, and tirofiban prolonged Ti and reduced A 150s and F 150s in a concentration-dependent manner, whereas high concentrations of alprostadil did not completely inhibit platelet aggregation. Aspirin combined with ticagrelor synergistically inhibited platelet adhesion and aggregation; GPIb-IX-von Willebrand factor inhibitors partially inhibited platelet aggregation, and the inhibition was more pronounced at 1500 than at 300 second -1 . Patient administration of aspirin or (and) clopidogrel inhibited platelet adhesion and aggregation on the glass surface under flow conditions. This technology is capable of distinguishing the pharmacological effects of various antiplatelet drugs on inhibition of platelet adhesion aggregation on glass surface under physiological flow conditions, which providing a new way to develop microfluidic platelet function detection method without additional adhesive protein modification for determining the inhibitory effects of antiplatelet drugs in the clinical setting.

Tailored antiplatelet therapy in stent assisted coiling for unruptured aneurysms: a nationwide registry study

BACKGROUND

Antiplatelet therapy, where regimens are tailored based on platelet function testing, has been introduced into neurointerventional surgery. This nationwide registry study evaluated the effect and safety of tailored antiplatelet therapy in stent assisted coiling for unruptured aneurysms compared with conventional therapy using a standard regimen.

METHODS

This study enrolled 1686 patients in 44 participating centers who received stent assisted coiling for unruptured aneurysms between January 1, 2019 and December 31, 2019. The standard regimen (aspirin and clopidogrel) was used for all patients in the conventional group (924, 19 centers). The regimen was selected based on platelet function testing (standard regimen for clopidogrel responders; adding cilostazol or replacing clopidogrel with other thienopyridines (ticlopidine, prasugrel, or ticagrelor) for clopidogrel non-responders) in the tailored group (762, 25 centers). The primary outcome was thromboembolic events. Secondary outcomes were bleeding and poor outcomes (increase in modified Rankin Scale score). Outcomes within 30 days after coiling were compared using logistic regression analysis.

RESULTS

The thromboembolic event rate was lower in the tailored group than in the conventional group (30/762 (3.9%) vs 63/924 (6.8%), adjusted OR 0.560, 95% CI 0.359 to 0.875, P=0.001). The bleeding event rate was not different between the study groups (62/762 (8.1%) vs 73/924 (7.9%), adjusted OR 0.790, 95% CI 0.469 to 1.331, P=0.376). Poor outcomes were less frequent in the tailored group (12/762 (1.6%) vs 34 (3.7%), adjusted OR 0.252, 95% CI 0.112 to 0.568, P=0.001).

CONCLUSION

Tailored antiplatelet therapy in stent assisted coiling for unruptured aneurysms reduced thromboembolic events and poor outcomes without increasing bleeding.

Relationship between platelet aggregation and stroke risk after percutaneous coronary intervention: a PENDULUM analysis

In patients undergoing percutaneous coronary intervention (PCI) with a stent, high on-treatment platelet reactivity may be associated with an increased risk of stroke. This post hoc analysis of the PENDULUM registry compared the risk of post-PCI stroke according to on-treatment P2Y₁₂ reaction unit (PRU) values. Patients aged ≥ 20 years who underwent PCI were stratified by baseline PRU (at 12 and 48 h post-PCI) as either high (HPR, > 208), optimal (OPR, > 85 to ≤ 208), or low on-treatment platelet reactivity (LPR, ≤ 85). The incidences of non-fatal ischemic and non-ischemic stroke through to 12 months post-PCI were recorded. Almost all enrolled patients (6102/6267 [97.4%]) had a risk factor for ischemic stroke, and most were receiving dual antiplatelet therapy. Of the 5906 patients with PRU data (HPR, n = 2227; OPR, n = 3002; LPR, n = 677), 47 had a non-fatal stroke post-PCI (cumulative incidence: 0.68%, ischemic; 0.18%, non-ischemic stroke). Patients with a non-fatal ischemic stroke event had statistically significantly higher post-PCI PRU values versus those without an event (P = 0.037). The incidence of non-fatal non-ischemic stroke was not related to PRU value. When the patients were stratified by PRU ≤ 153 versus > 153 at 12–48 h post-PCI, a significant difference was observed in the cumulative incidence of non-fatal stroke at 12 months (P = 0.044). We found that patients with ischemic stroke tended to have higher PRU values at 12–48 h after PCI versus those without ischemic stroke.

Clinical trial registration: UMIN000020332.

Clopidogrel Versus Ticagrelor for Antiplatelet Therapy in Transcarotid Artery Revascularization (TCAR) in the Society for Vascular Surgery Vascular Quality Initiative

OBJECTIVE

Transcarotid artery revascularization (TCAR) with dynamic flow reversal is a hybrid technique for operative management of carotid artery stenosis. Dual antiplatelet therapy is recommended for patients undergoing TCAR; however, nonresponders to these medications may be predisposed to perioperative thromboembolic complications. Prevalent in up to 44-66% of patients taking clopidogrel, high on-treatment platelet reactivity (HTPR) may thus be responsible for a portion of adverse cerebrovascular events in TCAR. A previous single-institution study has demonstrated the use of ticagrelor as a viable alternative to clopidogrel for antiplatelet therapy in patients undergoing TCAR; however, large-scale comparisons between clopidogrel and ticagrelor are needed to confirm the safety of ticagrelor outside of highly selected patients and providers.

METHODS

Data from patients enrolled in the Society for Vascular Surgery Vascular Quality Initiative undergoing TCAR with a perioperative antiplatelet therapy regimen including either clopidogrel or ticagrelor from January 2015 to March 2021 were analyzed and compared. Multivariable logistic regression and propensity score matching were used to evaluate the primary 30-day outcomes of stroke, major bleeding event, and combined stroke/myocardial infarction (MI)/death rate while adjusting for baseline characteristics of the patients.

RESULTS

A total of 11973 patients underwent TCAR with a dual antiplatelet therapy regimen that included clopidogrel versus 426 patients with ticagrelor. Compared to clopidogrel, patients on ticagrelor were significantly more likely to have coronary artery disease (51% vs 66% [P = <.001]), particularly unstable angina or MI within 6 months (3% vs 9% [P = <.001]), and more likely to have insulin-dependent diabetes mellitus (14% vs 19% [P = <.001]). The unadjusted 30-day rates of stroke, major bleeding, and combined stroke/MI/death were not statistically significant among both groups (1.3% vs 0.5% [P = .14], 2.4% vs 1.4% [P = .18], and 1.9% vs 1.6% [P = .71], respectively). After multivariable adjustment and propensity matching, these remained statistically insignificant.

CONCLUSIONS

Despite a substantially higher medical risk in patients undergoing TCAR with ticagrelor, 30-day rates of stroke, major bleeding events, and combined stroke/MI/death were similar between patients on ticagrelor and clopidogrel as part of adjunctive antiplatelet therapy. Randomized prospective trials, and studies with larger sample sizes and longer follow-up will be needed to better examine the outcome differences in TCAR between these two medications.

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.

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.

Preliminary Experience of Neuroform Atlas Stenting as a Rescue Treatment after Failure of Mechanical Thrombectomy Caused by Residual Intracranial Atherosclerotic Stenosis

Objective

The low-profile Neuroform Atlas stent can be deployed directly without an exchange maneuver by navigating into the Gateway balloon. This retrospective study assessed the safety and efficacy of Neuroform Atlas stenting as a rescue treatment after failure of mechanical thrombetomy (MT) for large artery occlusion.

Methods

Between June 2018 and December 2019, a total of 31 patients underwent Neuroform Atlas stenting with prior Gateway balloon angioplasty after failure of conventional MT caused by residual intracranial atherosclerotic stenosis (ICAS). Primary outcomes were successful recanalization and patency of the vessel 24 hours after intervention. Secondary outcomes were vessel patency after 14 days and 3-month modified Rankin Scale. Peri-procedural complications, intracerebral hemorrhage (ICH), and 3-month mortality were reviewed.

Results

With a 100% of successful recanalization, median value of stenosis was reduced from 79.0% to 23.5%. Twenty-eight patients (90.3%) showed tolerable vessel patency after 14 days. New infarctions occurred in three patients (9.7%) over a period of 14 days; two patient (6.5%) underwent stent occlusion at 24 hours, and the other patient (3.2%) with delayed stent occlusion had a non-symptomatic dot infarct. There were no peri-procedural complications. Two patients (6.5%) developed an ICH immediately after the procedure with one of them is symptomatic.

Conclusion

Neuroform Atlas stenting seems to be an effective and safe rescue treatment modality for failed MT with residual ICAS, by its high successful recanalization rate with tolerable patency, and low peri-procedural complication rate. Further multicenter and randomized controlled trials are needed to confirm our findings.

Outcomes and strategy of tailored antiplatelet therapy with ticagrelor in patients undergoing transcarotid artery revascularization

OBJECTIVE

Antiplatelet drug resistance is associated with periprocedural ischemic complications in patients undergoing intravascular stent implantation. Nonresponders are subject to increased risk of stent thrombosis and in-stent stenosis, and high on-treatment platelet reactivity (HTPR) is present in up to 44% of patients taking clopidogrel, a widely used component of dual antiplatelet therapy (DAPT). Evidence points to ticagrelor as a viable alternative to overcome HTPR on clopidogrel. Studies have shown fewer thromboembolic events with ticagrelor therapy; however, results on bleeding risk are mixed, and its safety and efficacy in hybrid operative techniques have yet to be established. Transcarotid artery revascularization (TCAR) is a hybrid procedure to treat severe carotid stenosis. The objective of this study was to establish the safety and efficacy of ticagrelor as part of DAPT in patients undergoing TCAR and to develop a protocol to ensure adequate antithrombotic protection throughout the operative course.

METHODS

Data were collected retrospectively for patients undergoing TCAR on DAPT of aspirin and ticagrelor for symptomatic (≥50%) or asymptomatic (≥80%) carotid stenosis. Preoperative platelet reactivity was determined using Thromboelastography with Platelet Mapping (Haemonetics Corporation, Braintree, Mass), with adequate platelet reactivity defined as maximal amplitude produced by adenosine diphosphate <50 mm. The primary safety end point was 30-day major bleeding event rate. Primary efficacy end points were 30-day incidence of ipsilateral cerebrovascular ischemic event (stroke or transient ischemic attack), myocardial infarction, and death. Secondary end points were postoperative length of hospital stay, procedure time, and clamp/flow reversal time.

RESULTS

Sixty-seven TCAR procedures with patients receiving periprocedural DAPT of ticagrelor and aspirin were performed during the study period. Patients had an average age of 79 years, and 28 (42%) were symptomatic. The mean procedure time was 45.8 ± 9.2 minutes, with a mean clamp/flow reversal time of 4.8 ± 1.5 minutes, and mean postoperative length of hospital stay of 3.1 ± 2.2 days for inpatients and 1.3 ± 0.8 days for outpatients. Technical success was achieved in all cases, with no 30-day major bleeding events and no occurrence of ipsilateral cerebrovascular ischemic event, myocardial infarction, or death.

CONCLUSIONS

Initial experience with ticagrelor as part of DAPT in patients undergoing TCAR demonstrated its safety and efficacy in both symptomatic and asymptomatic disease. No bleeding events or thromboembolic complications occurred. Furthermore, a protocol to administer ticagrelor to assay for HTPR on ticagrelor and consequent medication and patient management is proposed. Ticagrelor may represent a safe and effective alternative to overcome clopidogrel nonresponsiveness in DAPT regimens for TCAR.