Platelet function/reactivity testing and prediction of risk of recurrent vascular events and outcomes after TIA or ischaemic stroke: systematic review and meta-analysis

Exploring the relationship of platelet aggregation function with efficacy and safety outcomes following the administration of prasugrel and clopidogrel in patients with thrombotic stroke: a post hoc analysis of PRASTRO pooled studies

The P2Y12 receptor inhibitor prasugrel was approved for thrombotic stroke in Japan following the phase 3 clinical trials PRASTRO-I, -II, and -III. However, correlations between elevated platelet reaction unit (PRU) and ischemic event risk remain unclear. This post hoc integrated analysis of PRASTRO-I, -II, and -III assessed the relationships of PRU with efficacy and safety outcomes, and risk factors for high PRU (HPR). Patients from PRASTRO-I, -II, and -III receiving prasugrel or clopidogrel and with PRU values at 4 and 24 weeks after treatment initiation were included. The primary endpoint was PRU at 4 weeks; secondary endpoints included cumulative incidence of ischemic and bleeding events from study drug initiation to 48 weeks. Exploratory univariate and multivariate analyses were conducted to identify HPR risk factors. Of 2688 patients analyzed, 2595 and 2434 had PRU values available at 4 and 24 weeks, respectively. Mean PRU was numerically lower with prasugrel than clopidogrel at 4 weeks (151.3 vs. 195.4) and 24 weeks (143.8 vs. 188.0). CYP2C19 polymorphisms affected PRU at 4 and 24 weeks with clopidogrel but not with prasugrel. PRU at 4 weeks did not predict ischemic and bleeding event incidence up to 48 weeks. The CYP2C19 poor metabolizer phenotype was the strongest HPR risk factor. PRU values at 4 and 24 weeks were numerically lower with prasugrel and unaffected by CYP2C19 genetic polymorphisms. Further research is needed to clarify the relationship of PRU with ischemic and bleeding events.

Cost-effectiveness of platelet function testing in dual antiplatelet therapy decision-making after intracranial aneurysm treatment with flow diversion

Dual antiplatelet therapy (DAPT) use is the standard of practice after flow diversion (FD) for intracranial aneurysms (IAs). Yet, no consensus exists in the literature regarding the optimal regimen. Certain institutions utilize various platelet function testing (PFT) to assess patient responsiveness to DAPT. Clopidogrel is the most commonly prescribed drug during DAPT; however, up to 52% of patients can be non-responders, justifying PFT use. Additionally, prices vary significantly among antiplatelet drugs, often further complicated by insurance restrictions. We aimed to determine the most cost-effective strategy for deciding DAPT regimens for patients after IA treatment. A decision tree with Monte Carlo simulations was performed to simulate patients undergoing various three-month postoperative DAPT regimens. Patients were either universally administered aspirin alongside clopidogrel, ticagrelor, or prasugrel without PFT, or administered one of the former thienopyridine medications based on platelet reactivity unit (PRU) results after clopidogrel. Input data for the model were extracted from the current literature, and the willingness-to-pay threshold (WTP) was defined as $100,000 per QALY as per standard practice in the US. The baseline comparison was with universal clopidogrel DAPT without any PFT. Probabilistic and deterministic sensitivity analyses were performed to evaluate the robustness of the model. Utilizing PFT and switching clopidogrel to prasugrel if resistance is documented was the most cost-effective regimen compared to universal clopidogrel, with a base-case incremental cost-effectiveness ratio (ICER) of $-35,255 (cost $2,336.67, effectiveness 0.85). Performing PFT and switching clopidogrel to ticagrelor (ICER $-4,671; cost $2,995.06, effectiveness 0.84), universal prasugrel (ICER $5,553; cost $3,097.30, effectiveness 0.84), or universal ticagrelor (ICER $75,969; cost $3,801.36, effectiveness 0.84) were all more cost-effective than treating patients with universal clopidogrel (cost $3,041.77, effectiveness 0.83). These conclusions remain robust in probabilistic and deterministic sensitivity analyses. The most cost-effective strategy guiding DAPT after FD for IAs is to perform PFTs and switch clopidogrel to prasugrel if resistance is documented, alongside aspirin. The cost of PFT is strongly justified and recommended when deciding patient-specific DAPT regimens.

Molecular genomic and epigenomic characteristics related to aspirin and clopidogrel resistance

BACKGROUND

Mediators, genomic and epigenomic characteristics involving in metabolism of arachidonic acid by cyclooxygenase (COX) and lipoxygenase (ALOX) and hepatic activation of clopidogrel have been individually suggested as factors associated with resistance against aspirin and clopidogrel. The present multi-center prospective cohort study evaluated whether the mediators, genomic and epigenomic characteristics participating in arachidonic acid metabolism and clopidogrel activation could be factors that improve the prediction of the aspirin and clopidogrel resistance in addition to cardiovascular risks.

METHODS

We enrolled 988 patients with transient ischemic attack and ischemic stroke who were evaluated for a recurrence of ischemic stroke to confirm clinical resistance, and measured aspirin (ARU) and P2Y12 reaction units (PRU) using VerifyNow to assess laboratory resistance 12 weeks after aspirin and clopidogrel administration. We investigated whether mediators, genotypes, and promoter methylation of genes involved in COX and ALOX metabolisms and clopidogrel activation could synergistically improve the prediction of ischemic stroke recurrence and the ARU and PRU levels by integrating to the established cardiovascular risk factors.

RESULTS

The logistic model to predict the recurrence used thromboxane A synthase 1 (TXAS1, rs41708) A/A genotype and ALOX12 promoter methylation as independent variables, and, improved sensitivity of recurrence prediction from 3.4% before to 13.8% after adding the mediators, genomic and epigenomic variables to the cardiovascular risks. The linear model we used to predict the ARU level included leukotriene B4, COX2 (rs20417) C/G and thromboxane A2 receptor (rs1131882) A/A genotypes with the addition of COX1 and ALOX15 promoter methylations as variables. The linear PRU prediction model included G/A and prostaglandin I receptor (rs4987262) G/A genotypes, COX2 and TXAS1 promoter methylation, as well as cytochrome P450 2C19*2 (rs4244285) A/A, G/A, and *3 (rs4986893) A/A genotypes as variables. The linear models for predicting ARU (r = 0.291, R2 = 0.033, p < 0.01) and PRU (r = 0.503, R2 = 0.210, p < 0.001) levels had improved prediction performance after adding the genomic and epigenomic variables to the cardiovascular risks.

CONCLUSIONS

This study demonstrates that different mediators, genomic and epigenomic characteristics of arachidonic acid metabolism and clopidogrel activation synergistically improved the prediction of the aspirin and clopidogrel resistance together with the cardiovascular risk factors.

TRIAL REGISTRATION

URL: https://www.

CLINICALTRIALS

gov ; Unique identifier: NCT03823274.

Potential Protein Signatures for Recurrence Prediction of Ischemic Stroke

BACKGROUND

Acute ischemic stroke is a major cause of mortality and disability worldwide, with approximately 7.4% to 7.7% recurrence within the first 3 months. This study aimed to identify potential biomarkers for predicting stroke recurrence.

METHODS AND RESULTS

We conducted a nested case-control study using a hospital-based cohort from the Third China National Stroke Registry selecting 214 age- and sex-matched patients with ischemic stroke with hypertension and no history of diabetes or heart disease. Using data-independent acquisition for discovery and multiple reaction monitoring for quantitative validation, we identified 26 differentially expressed proteins in large-artery atherosclerosis (Causative Classification of Ischemic Stroke [CCS]1), 16 in small-artery occlusion (CCS3), and 25 in undetermined causes (CCS5) among patients with recurrent stroke. In the CCS1 and CCS3 subgroups, differentially expressed proteins were associated with platelet aggregation, neuronal death/cerebroprotection, and immune response, whereas differentially expressed proteins in the CCS5 subgroup were linked to altered metabolic functions. Validated recurrence predictors included proteins associated with neutrophil activity and vascular inflammation (TAGLN2 [transgelin 2], ITGAM [integrin subunit α M]/TAGLN2 ratio, ITGAM/MYL9 [myosin light chain 9] ratio, TAGLN2/RSU1 [Ras suppressor protein 1] ratio) in the CCS3 subgroup and proteins associated with endothelial plasticity and blood-brain barrier integrity (ITGAM/MYL9 ratio and COL1A2 [collagen type I α 2 chain]/MYL9 ratio) in the CCS3 and CCS5 subgroups, respectively.

CONCLUSIONS

These findings provide a foundation for developing a blood-based biomarker panel, using causative classifications, which may be used in routine clinical practice to predict stroke recurrence.

Personalized Dual Antiplatelet Therapy in Acute Coronary Syndromes: Striking a Balance Between Bleeding and Thrombosis

PURPOSE OF REVIEW

Dual antiplatelet therapy (DAPT)-aspirin in conjunction with a P2Y12 inhibitor-is the cornerstone of managing patients with acute coronary syndromes post-revascularization, but the clinical response is highly variable, with potentially devastating consequences. Herein, we review the mechanisms underpinning said variability and explore emerging approaches to normalizing therapeutic benefit.

RECENT FINDINGS

The potent P2Y12 inhibitors, prasugrel and ticagrelor, exhibit minimal inter-individual variability, replacing clopidogrel in DAPT and achieving greater rates of therapeutic response. However, these benefits decline in later phases when bleeding risk begins to supersede that of ischemia. Guided de-escalation of P2Y12 inhibition as well as shortening DAPT duration have emerged as strategies that retain antithrombotic efficacy while reducing bleeding risk. Aspirin is the other component of DAPT but is also used in isolation for secondary prevention of thrombotic disease. In contrast to the P2Y12 inhibitors, genetic influences on aspirin non-response appear to be outweighed by a triad of clinical factors: non-adherence, enteric aspirin use, and inappropriate dosing according to bodyweight and BMI. Multiple de-escalation strategies for DAPT have been shown to mitigate bleeding risk, but it remains unclear which approach is ideal, necessitating head-to-head investigations to determine which exhibits the most favorable cost-to-benefit ratio. However, there is likely a role for more than one approach in clinical practice, depending on patient risk profile. Our approach to aspirin use is also in need of reassessment: strategies to improve adherence, avoidance of enteric aspirin in cardiac patients, and dose adjustment according to bodyweight and/or BMI are all likely to improve rates of therapeutic response. Moreover, platelet function testing may have a role in identifying patients expected to benefit from primary prophylactic aspirin.

Advances in Neurological Diseases and Stroke

Neurological diseases are a major cause of death and disability worldwide [...].

High on-treatment platelet reactivity is associated with poor outcomes after ischemic stroke: A meta-analysis

OBJECTIVES

High on-treatment platelet reactivity (HTPR) determined by platelet function assays is present in certain patients with ischemic stroke or transient ischemic attack (TIA). However, it is unclear whether HTPR is associated with poor clinical outcomes. Our study aimed to investigate the relationship of HTPR with recurrent vascular events in ischemic stroke or TIA.

METHODS

Pubmed (MEDLINE), EMBASE, and Cochrane Library were searched for eligible studies from inception to January 1, 2022. Stata 17.0 software was used to calculate the risk ratio (RR). Subgroup and sensitivity analyses were conducted to assess the source of heterogeneity. A random-effects model was used when heterogeneity was present. Primary endpoint of the meta-analysis was the risk ratio of recurrent vascular events in HTPR Patients. While stroke and TIA, all-cause death, early neurological deterioration, early new ischemic lesions, and stroke severity measured by National Institute of Health Stroke Scale (NIHSS) scores at admission were also pooled.

RESULTS

Thirty articles (7995 patients) were eligible including 28 cohort studies and 2 prospective case-control studies. The prevalence of HTPR varied from 5.9% to 60%. HTPR was associated with an increased risk of recurrent vascular events (RR = 2.94, 95% CI 2.04-4.23), stroke recurrence (RR = 2.05; 95% CI 1.43-2.95), and all-cause mortality (RR = 2.43; 95% CI 1.83-3.22). Subgroup analysis showed that HTPR determined by optical aggregometry, Verify-Now system and 11dh TXB2 is related to a higher risk of recurrent vascular events (RR = 3.53, 95% CI 1.51-9.40; RR = 2.16, 95% CI 1.02-4.56; RR = 3.76, 95% CI 1.51-9.40, respectively). Moreover, patients with HTPR had an increased incidence of early neurological deterioration (RR = 2.75; 95% CI 1.76-4.30) and higher NIHSS scores at admission (Mean difference 0.19, 95% CI 0.01-0.36).

CONCLUSIONS

This meta-analysis demonstrates HTPR is associated with higher risk of recurrent vascular events, early neurological deterioration and increased severity in patients with ischemic stroke and TIA. HTPR measured by platelet function assays may guide the use of antiplatelet agents in ischemic stroke and TIA.

Comparison of Different Laboratory Tests to Identify “Aspirin Resistance” and Risk of Vascular Events among Ischaemic Stroke Patients: A Double-Blind Study

“Aspirin resistance” (AR) is associated with increased risk of vascular events. We aimed to compare different platelet function tests used in identifying AR and assess their implications on clinical outcome. We performed platelet aggregation studies on non-cardioembolic ischaemic stroke patients taking aspirin 100 mg/day and 30 non-stroke controls. Data were collected on demographics, vascular risk factors, and concomitant medications. Cut-offs for AR were (1) light transmission aggregometry (LTA) of ≥20% using arachidonic acid (AA), ≥70% using ADP, or ≥60% using collagen; and (2) VerifyNow® assay ≥ 550 ARU. Telephone follow-ups were conducted by study staff blinded to AR status to ascertain the occurrence of vascular outcomes (stroke, myocardial infarction, amputation, death). A total of 113 patients were recruited, mean age 65 ± 8 years, 47% women, 45 ± 15 days from index stroke. 50 (44.3%, 95% CI 34.9–53.9) had AR on at least 1 test. Frequency of AR varied from 0% to 39% depending on method used and first vs. recurrent stroke. There were strong correlations between LTA AA, VerifyNow® and Multiplate® ASPItest (r = 0.7457–0.8893), but fair to poor correlation between LTA collagen and Multiplate® COLtest (r = 0.5887) and between LTA ADP and Multiplate® ADPtest (r = 0.0899). Of 103 patients with a mean follow up of 801 ± 249 days, 10 (9.7%) had vascular outcomes, of which six had AR by LTA-ADP. AR by LTA-ADP is associated with increased risk of vascular outcome (p = 0.034). Identification of AR is not consistent across different platelet function tests. LTA of ≥70% using 10 µM ADP in post-stroke patients taking aspirin is associated with increased risk of vascular outcome.

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.

Feasibility of platelet marker analysis in ischemic stroke patients and their association with one-year outcome. A pilot project within a subsample of the Stroke Induced Cardiac Failure in Mice and Men (SICFAIL) cohort study

Patients with ischemic stroke (IS) are at increased risk of mortality and recurrent cerebro- or cardiovascular events. Determining prognosis after IS remains challenging but blood-based biomarkers might provide additional prognostic information. As platelets are crucially involved in the pathophysiology of vascular diseases, platelet surface proteins (PSP) are promising candidates as prognostic markers in the hyperacute stage. In this pilot study, feasibility of PSP analysis by flow cytometry (HMGB1, CD84, CXCR4, CXCR7, CD62p with and without ADP-stimulation, CD41, CD61, CD40, GPVI) was investigated in 99 (median 66 years, 67.5% male) acute IS patients admitted to Stroke Unit within a substudy of the Stroke-Induced Cardiac FAILure in mice and men (SICFAIL) cohort study. Association between PSP expression and unfavorable one-year outcome (cerebro- or cardiovascular event, all-cause mortality and care dependency defined as Barthel Index <60) was explored. PSP measurements were feasible. Several process- (e.g. temperatures, processing times) and patient-related factors (e.g. prestroke ischemic events, surgery, blood pressure, antiplatelet therapy) were identified to be potentially associated with PSP expression. Elevated CD40 levels above study population's median were associated with unfavorable outcome. Standardized conditions during blood draw and processing within the hyperacute stroke unit setting are required and patient-related characteristics must be considered for valid measurements of PSP.Trial registration: German Clinical Trials Register (DRKS00011615).

Platelet Function Tests Predicting the Efficacy and Safety of Aspirin Secondary Prevention

OBJECTIVE

To precisely prevent stroke, we evaluated three platelet function tests and their associations with clinical outcomes in ischemic stroke patients.

METHODS

On-treatment platelet reactivity of acute minor stroke patients taking aspirin plus clopidogrel was tested by light transmittance aggregometry (LTA), thromboelastography (TEG) and platelet function analyzer (PFA). Mann-Whitney U tests and receiver operating characteristic (ROC) curve analysis were used to assess their associations with recurrent events and clinical outcome prediction.

RESULTS

127 acute minor stroke patients were stringently selected and followed for 13 months. Eight patients (6.3%) self-reported the recurrence and 13 (10.2%) patients self-reported bleeding. Recurrent patients displayed significantly higher on-treatment platelet reactivity when measured with LTA (p = 0.030) and PFA (p < 0.001). Further ROC analysis demonstrated that LTA and PFA had modest-to-fair ability to predict stroke recurrence (LTA: area under the curve [AUC], 0.765; 95% CI, 0.584-0.945, PFA: AUC, 0.832; 95% CI, 0.658-1.000). However, TEG (measured by the platelet inhibition rate) could not detect the difference between recurrent patients and non-recurrent patients (p = 0.515) and predict recurrent events (AUC, 0.569; 95% CI, 0.368-0.770). None of the tests were associated with bleeding except for PFA (p < 0.001), with AUC of PFA reaching 0.772 (0.726-0.818).

CONCLUSIONS

Of the three tests assessed, the predictive accuracies of PFA and LTA were satisfying for aspirin secondary prevention, while TEG's performance was poor. Only PFA could provide accurate prognostic information for bleeding.

Antiplatelet Drugs for Neurointerventions: Part 2 Clinical Applications

Endovascular techniques have expanded to include balloon and stent-assistance, flow diversion and individualized endovascular occlusion devices, to widen the treatment spectrum for more complex aneurysm morphologies. While usually well-tolerated by patients, endovascular treatment of intracranial aneurysms carries the risk of complications, with procedure-related ischemic complications being the most common. Several antiplatelet agents have been studied in a neurointerventional setting for both prophylaxis and in the setting of intraprocedural thrombotic complications. Knowledge of these antiplatelet agents, evidence for their use and common dosages is important for the practicing neurointerventionist to ensure the proper application of these agents.Part one of this two-part review focused on basic platelet physiology, pharmacology of common antiplatelet medications and future directions and therapies. Part two focuses on clinical applications and evidence based therapeutic regimens.

The 2020 breakthroughs in early secondary prevention: dual antiplatelet therapy versus single antiplatelet therapy

PURPOSE OF REVIEW

Single antiplatelet therapy represents an established treatment in secondary prevention of ischemic strokes and transient ischemic attacks (TIAs). In contrast with coronary artery disease, the use of dual antiplatelet therapy (DAPT) for secondary prevention in patients with acute cerebral ischemia (ACI) remains under debate. In this narrative review, we present and analyse the most recent findings concerning the potential efficacy and safety of DAPT therapy after ischemic strokes or TIA.

RECENT FINDINGS

Following the publication of the three (CHANCE, POINT and THALES) large, randomized-controlled, clinical trials (RCTs) that showed efficacy of early DAPT for the secondary prevention after minor AIS or TIA, short-term DAPT use is becoming the most prevalent choice of treatment. Notably, DAPT is even more popular after AIS attributed to large artery atherosclerosis given randomized data from small RCTs supporting the use of DAPT in patients with extracranial or intracranial atherosclerosis and microembolization detected by transcranial Doppler. Recent subanalysis of data from the randomized trials aim to identify specific patient subgroups, which are determined by genetic, imaging or clinical characteristics, and for whom DAPT appears to be more beneficial. The potential role of different antiplatelet agents (aspirin, clopidogrel, ticagrelor) is also discussed.

SUMMARY

DAPT has recently proven its efficacy for the early secondary prevention of AIS patients with minor stroke severity and high-risk TIA patients. However, the length of DAPT is still controversial, as well as the individualized selection of AIS or TIA patients with the lower risk of bleeding and with the greater benefit in prevention of ischemic cerebrovascular and cardiovascular events.