Increased platelet count and reticulated platelets in recently symptomatic versus asymptomatic carotid artery stenosis and in cerebral microembolic signal-negative patient subgroups: results from the HaEmostasis In carotid STenosis (HEIST) study

Safety of early antiplatelet therapy for non-cardioembolic mild stroke patients with thrombocytopenia

OBJECTIVES

To investigate the safety of early antiplatelet therapy for non-cardioembolic mild stroke patients with thrombocytopenia.

METHODS

Data of acute ischemic stroke patients with baseline National Institutes of Health Stroke Scale (NIHSS) score ≤3 and a platelet count <100×109/L were obtained from a multicenter register. Those who required anticoagulation or had other contraindications to antiplatelet therapy were excluded. Short-term safety outcomes were in-hospital bleeding events, while the long-term safety outcome was a 1-year all-cause death. The short-term neurological outcomes were evaluated by modified Rankin scale (mRS) score at discharge.

RESULTS

A total of 1868 non-cardioembolic mild stroke patients with thrombocytopenia were enrolled. Multivariate regression analyses showed that mono-antiplatelet therapy significantly increased the proportion of mRS score of 0-1 at discharge (OR=1.657, 95%CI: 1.253-2.192, P<0.01) and did not increase the risk of intracranial hemorrhage (OR=2.359, 95%CI: 0.301-18.503, P>0.05), compared with those without antiplatelet therapy. However, dual-antiplatelet therapy did not bring more neurological benefits (OR=0.923, 95%CI: 0.690-1.234, P>0.05), but increased the risk of gastrointestinal bleeding (OR=2.837, 95%CI: 1.311-6.136, P<0.01) compared with those with mono-antiplatelet therapy. For patients with platelet counts ≤75×109/L and >90×109/L, antiplatelet therapy significantly improved neurological functional outcomes (both P<0.05). For those with platelet counts (>75-90)×109/L, antiplatelet therapy resulted in a significant improvement of 1-year survival (P<0.05). For patients even with concurrent coagulation abnormalities, mono-antiplatelet therapy did not increase the risk of various types of bleeding (all P>0.05) but improved neurological functional outcomes (all P<0.01). There was no significant difference in the occurrence of bleeding events, 1-year all-cause mortality risk, and neurological functional outcomes between aspirin and clopidogrel (all P>0.05).

CONCLUSIONS

For non-cardioembolic mild stroke patients with thrombocytopenia, antiplatelet therapy remains a reasonable choice. Mono-antiplatelet therapy has the same efficiency as dual-antiplatelet therapy in neurological outcome improvement with lower risk of gastrointestinal bleeding.

Molecular Pathways of Vulnerable Carotid Plaques at Risk of Ischemic Stroke: A Narrative Review

The concept of vulnerable carotid plaques is pivotal in understanding the pathophysiology of ischemic stroke secondary to large-artery atherosclerosis. In macroscopic evaluation, vulnerable plaques are characterized by one or more of the following features: microcalcification; neovascularization; lipid-rich necrotic cores (LRNCs); intraplaque hemorrhage (IPH); thin fibrous caps; plaque surface ulceration; huge dimensions, suggesting stenosis; and plaque rupture. Recognizing these macroscopic characteristics is crucial for estimating the risk of cerebrovascular events, also in the case of non-significant (less than 50%) stenosis. Inflammatory biomarkers, such as cytokines and adhesion molecules, lipid-related markers like oxidized low-density lipoprotein (LDL), and proteolytic enzymes capable of degrading extracellular matrix components are among the key molecules that are scrutinized for their associative roles in plaque instability. Through their quantification and evaluation, these biomarkers reveal intricate molecular cross-talk governing plaque inflammation, rupture potential, and thrombogenicity. The current evidence demonstrates that plaque vulnerability phenotypes are multiple and heterogeneous and are associated with many highly complex molecular pathways that determine the activation of an immune-mediated cascade that culminates in thromboinflammation. This narrative review provides a comprehensive analysis of the current knowledge on molecular biomarkers expressed by symptomatic carotid plaques. It explores the association of these biomarkers with the structural and compositional attributes that characterize vulnerable plaques.

Towards a greater understanding of reduced response to aspirin in children with congenital heart disease post-cardiac surgery using immature platelet fraction

OBJECTIVE

A high platelet turnover rate may produce a population of platelets that confers an inadequate response to aspirin. We aimed to investigate the relationship between residual platelet aggregation and platelet turnover in paediatric cardiology patients on aspirin monotherapy by evaluating the fraction of immature platelets as a marker for turnover and secondly to test the predictive value of the immature platelet fraction (IPF) to classify patients as responsive or non-responsive to aspirin.

METHODS

Sixty patients divided into two age categories (≤90 days, >90 days of age) were included in this prospective observational study. Patients were then stratified into tertiles using their IPF level. Platelet studies included thromboelastography with platelet mapping (TEGPM).

RESULTS

The overall incidence of 'inadequate response to aspirin' was 38 % in our patient cohort recently post-cardiac surgery a consequence that warrants further study. The frequency of inadequate response to aspirin was higher in the upper tertile of IPF when compared to the lower tertile, (88 %) versus (4 %) respectively (p < 0.05). The 'cut off' for IPF was determined to be 3.9 % with a sensitivity of 95.7 %, and a specificity of 92.9 % (area under the curve of 0.955 [CI 0.896-1.014, p < 0.05]).

CONCLUSION

This study demonstrates that inadequate response to aspirin occurs in approximately 38 % of patients undergoing specific high-risk congenital cardiac procedures using the dosing practice of a national centre. This study supports the hypothesis that an elevated platelet turnover may result in aspirin being less effective in patients who are recently post cardiac surgery. These data are of direct translational relevance.

Probability of Cardioembolic vs. Atherothrombotic Pathogenesis of Cryptogenic Strokes in Older Patients

Some clinical, laboratory, ECG, and echocardiographic parameters could provide useful indications to assess the probability of cardioembolism or atherothrombosis in cryptogenic strokes. We retrospectively examined 290 patients with ischemic stroke aged ≥60 years, divided into 3 groups: strokes originating from large artery atherothrombosis (n = 92), cardioembolic strokes caused by paroxysmal atrial fibrillation (n = 88) and cryptogenic strokes (n = 110). In addition to echocardiographic and routine clinical-laboratory variables, neutrophil:lymphocyte ratio, red blood cell distribution width, mean platelet volume, P wave and PR interval duration and biphasic inferior P waves, both on admission and after 7 to 10 days, were also considered. By multiple logistic regression, cardioembolic strokes were compared with large artery atherothrombosis strokes, and beta coefficients were rounded to produce a scoring system. Late PR interval ≥188 ms, left atrium ≥4 cm, left ventricular end-diastolic volume <65 ml, and posterior circulation syndrome were associated with paroxysmal atrial fibrillation (positive scores). In contrast, male gender, hypercholesterolemia, and initial platelet count ≥290 × 10⁹/L were associated with atherothrombosis of large arteries (negative scores). The algebraic sum of these scores produced values indicative of cardioembolism if >0 (positive predictive value 89.1%), or of atherothrombosis, if ≤0 (positive predictive value 72.5%). The area under the receiver operating characteristic curve was 0.85. Among cryptogenic strokes, 41.5% had a score >0 (probable atrial fibrillation) and 58.5% had a score ≤0 (possible atherothrombosis). In conclusion, a scoring system based on electrocardiogram, laboratory, clinical and echocardiographic parameters can provide useful guidance for further investigations and secondary prevention in older patients with cryptogenic stroke.

Immature Platelet Fraction Predicts Adverse Events in Patients With Acute Coronary Syndrome: the ISAR-REACT 5 Reticulated Platelet Substudy

BACKGROUND

Immature or reticulated platelets are associated with impaired efficacy of antiplatelet drugs and adverse events in cardiovascular patients. Their role as a predictive biomarker in patients with acute coronary syndrome treated with potent P2Y₁₂ receptor inhibitors is not fully understood. We aimed to prospectively evaluate reticulated platelets as a predictor of the primary end point of the ISAR-REACT 5 trial consisting of death, myocardial infarction, or stroke at 1 year in patients with acute coronary syndrome randomized to prasugrel or ticagrelor.

METHODS

Immature platelet fraction (IPF) was assessed within 48 hours after randomization. Patients were divided based on the IPF median values: the IPF^high group included patients with IPF>median and the IPF^low group included patients with IPF≤median. Platelet aggregation was assessed using the Multiplate Analyzer and was correlated to IPF.

RESULTS

Five hundred seventy-seven patients were included in the study. IPF values in % (median [interquartile range]) within the first 48 hours did not differ between the two study groups: 3.6 (2.5-5.2)% in the prasugrel group and 3.6 (2.5-5.4)% in the ticagrelor group (P=0.882). The incidence of the primary end point was significantly higher in the IPF^high (IPF>3.6%) group compared with the IPF^low (IPF≤3.6%) group: 13.0% versus 7.2% (HR_adj, 1.74 [1.02-3.00]; P=0.044), independently from the assigned drug (P_int=0.159). No significant association between IPF and BARC 3 to 5 bleeding was observed. ADP-induced platelet aggregation correlated significantly with IPF in patients treated with prasugrel (r=0.22; P=0.005) while no correlation was detected in patients treated with ticagrelor (r=0.09; P=0.257).

CONCLUSIONS

Independently from drug treatment, IPF was associated with the primary end point and therefore is a promising biomarker for the prediction of adverse cardiovascular events in patients with acute coronary syndrome treated with prasugrel or ticagrelor.

REGISTRATION

https://www.

CLINICALTRIALS

gov; Unique identifier: NCT01944800.

Long-Term Safety and Efficacy of Antiplatelet Therapy in Patients With Cerebral Infarction With Thrombocytopenia

This study aimed to investigate the long-term safety and benefits of antiplatelet therapy in patients with cerebral infarction with thrombocytopenia, as evidence regarding this was limited. This cohort trial assessed patients with acute cerebral infarction with thrombocytopenia treated in the Neurology Department of Shanghai Tenth People’s Hospital from January 2016 to December 2018, and enrolled patients were followed up for 9 months. The patients were divided into non-antiplatelet and antiplatelet groups based on the actual intake of antiplatelet drugs. Primary endpoints included hemorrhagic events, recurrence of cerebral infarction, and activity of daily living (ADL) score changes. To balance baseline clinical data, propensity score matching was applied, and there were finally 65 matched patients, including 30 and 35 in the antiplatelet and non-antiplatelet groups, respectively. There were no differences in hemorrhagic and cerebral infarction recurrence rates between the 2 groups. ADL score change was higher in the antiplatelet group than in the non-antiplatelet group (10 vs 5, p = 0.039). In multivariate regression analysis, antiplatelet therapy significantly predicted a positive change in ADL scores [B = 8.381, 95% confidence interval (0.56-16.19)]. In patients with acute cerebral infarction with thrombocytopenia, antiplatelet therapy could the improve the quality of life in the chronic stage.

Profile of reticulated platelets in the early, subacute and late phases after transient ischemic attack or ischemic stroke

Information regarding the profile of reticulated platelets (RP) in ischemic cerebrovascular disease (CVD) patients is limited. Data from two prospective, observational, case-control studies were combined to compare the %RP using whole blood flow cytometry in patients ≤ 4 weeks of TIA/stroke onset (baseline, N = 210), and 14 ±7 days (14d, N = 182) and ≥ 90 days (90d, N = 145) after starting or changing antiplatelet therapy with healthy controls (N = 34). There were no differences in median %RP between the overall CVD patient population at baseline or 14d vs. controls (P ≥ 0.2). However, the median %RP was significantly higher in CVD patients overall at 90d (P = .036), and in the subgroup of patients with "lacunar" TIA/ischemic stroke at baseline (P = .04) and at 90d (P = .01), but not at 14d (P = .06) vs. controls. There were no significant differences in the median %RP between other TIA/stroke subgroups and controls (P ≥ 0.05). Elevated circulating reticulated platelets, as a marker of increased platelet production/turnover, may occur following an ischemic event in a well-phenotyped TIA/ischemic stroke population overall, but may precede symptom onset at least in the subgroup with small vessel occlusion. These data improve our understanding of the profile of reticulated platelets in CVD patients.

Simultaneous assessment of plaque morphology, cerebral micro-embolic signal status and platelet biomarkers in patients with recently symptomatic and asymptomatic carotid stenosis

The relationship between plaque morphology, cerebral micro-embolic signals (MES) and platelet biomarkers in carotid stenosis patients warrants investigation.We combined data from two prospective, observational studies to assess carotid plaque morphology and relationship with cerebral MES and platelet biomarkers in patients with recently symptomatic (≤4 weeks of transient ischaemic attack (TIA)/ischaemic stroke) versus asymptomatic carotid stenosis. Plaque morphology on ultrasound was graded with Grey-Scale Median (GSM) and Gray-Weale (GW) scoring. Bilateral transcranial Doppler ultrasound classified patients as 'MES+ve' or 'MES-ve'. Full blood counts were analysed and flow cytometry quantified CD62P and CD63 expression, leucocyte-platelet complexes and reticulated platelets.Data from 42 recently symptomatic carotid stenosis patients were compared with those from 36 asymptomatic patients. There were no differences in median GSM scores between symptomatic and asymptomatic patients (25 vs. 30; P = 0.31) or between MES+ve vs. MES-ve symptomatic patients (36 vs. 25; P = 0.09). Symptomatic patients with GSM-echodense plaques (GSM ≥25) had higher platelet counts (228 vs. 191 × 10⁹/L), neutrophil-platelet (3.3 vs. 2.7%), monocyte-platelet (6.3 vs. 4.55%) and lymphocyte-platelet complexes (2.91 vs. 2.53%) than 'asymptomatic patients with GSM-echodense plaques' (P ≤ 0.03).Recently, symptomatic carotid stenosis patients with 'GSM-echodense plaques' have enhanced platelet production/secretion/activation compared with their asymptomatic counterparts. Simultaneous assessment with neurovascular imaging and platelet biomarkers may aid risk-stratification in carotid stenosis.

von Willebrand Factor Antigen, von Willebrand Factor Propeptide, and ADAMTS13 in Carotid Stenosis and Their Relationship with Cerebral Microemboli

BACKGROUND

 The relationship between von Willebrand factor antigen (VWF:Ag), VWF propeptide (VWFpp), VWFpp/VWF:Ag ratio, ADAMTS13 activity, and microembolic signal (MES) status in carotid stenosis is unknown.

METHODS

 This prospective, multicenter study simultaneously assessed plasma VWF:Ag levels, VWFpp levels and ADAMTS13 activity, and their relationship with MES in asymptomatic versus symptomatic moderate-to-severe (≥50-99%) carotid stenosis patients. One-hour transcranial Doppler ultrasound of the middle cerebral arteries classified patients as MES+ve or MES-ve.

RESULTS

 Data from 34 asymptomatic patients were compared with 43 symptomatic patients in the "early phase" (≤4 weeks) and 37 patients in the "late phase" (≥3 months) after transient ischemic attack (TIA)/ischemic stroke. VWF:Ag levels were higher (p = 0.049) and VWFpp/VWF:Ag ratios lower (p = 0.006) in early symptomatic than in asymptomatic patients overall, and in early symptomatic versus asymptomatic MES-ve subgroups (p ≤0.02). There were no intergroup differences in VWFpp expression or ADAMTS13 activity (p ≥0.05). VWF:Ag levels and ADAMTS13 activity decreased (p ≤ 0.048) and VWFpp/VWF:Ag ratios increased (p = 0.03) in symptomatic patients followed up from the early to late phases after TIA/stroke. Although there were no differences in the proportions of symptomatic and asymptomatic patients with blood group O, a combined analysis of early symptomatic and asymptomatic patients revealed lower median VWF:Ag levels in patients with blood group O versus those without blood group O (9.59 vs. 12.32 µg/mL, p = 0.035).

DISCUSSION

 VWF:Ag expression, a marker of endothelial ± platelet activation, is enhanced in recently symptomatic versus asymptomatic carotid stenosis patients, including in MES-ve patients, and decreases with ADAMTS13 activity over time following atherosclerotic TIA/ischemic stroke.

Reticulated platelets – clinical application and future perspectives

Reticulated platelets are immature platelets freshly released from the bone marrow into the circulation and contain vestigial amounts of ribonucleic acid. Thus, they can serve as an indicator for the activity of thrombopoiesis. Despite the current lack of a standardized reference method, two types of hematology analyzers have incorporated a fully automated measurement of reticulated platelets. The “immature platelet fraction” (IPF; Sysmex XE-/XN-series) has some clinical utility in the differential diagnosis of thrombocytopenia. This is less clear for “reticulated platelets” (retPLT; Abbott CELL-DYN Sapphire/Alinity HQ). The usefulness of these parameters in the prediction of platelet recovery after chemotherapy or stem cell transplantation and as a decision aid for platelet transfusions has not been unequivocally confirmed. Recent findings have shown an association of reticulated platelets with an adverse risk in patients with coronary artery disease and stroke as well as resistance to anti-platelet therapy. Furthermore, a role of reticulated platelets for the prediction of sepsis was indicated. However, validation in larger prospective trials is necessary to establish the clinical benefit of reticulated platelets in these conditions. This review gives an overview of the available analytical methods and summarizes the current knowledge regarding the clinical application of reticulated platelets.

Prognostic significance of reticulated platelet levels in diabetic patients with stable coronary artery disease

Levels of reticulated platelets (RP) increase during high platelet turnover conditions, and have been shown to correlate with diabetes mellitus (DM) status. Little is known regarding the prognostic significance of levels of RP among patients with stable coronary artery disease (SCAD). The study consisted of patients with SCAD and DM, who visited our cardiology outpatient clinic between June 2016 and February 2017. RP levels were measured at baseline as immature platelet fraction (IPF)%, using flow cytometry. Outcomes at 2 years consisted of bleeding events and major adverse cardiovascular events (MACE), which included death, myocardial infarction, cerebrovascular accident and urgent revascularization. The study included 104 patients (mean age - 71.2 ± 9.5 years, 76.9% were male, and 83.7% had hypertension). IPF was significantly higher at baseline among patients who had suffered from a MACE (4.57% vs. 2.53%, p < .001), and lower in patients who had suffered from bleeding events, compared with those who had not (1.57% vs. 3.00%, p = .004). There were higher rates of MACE at higher IPF quartiles (p < .001, AUC-0.770), and higher rates of bleeding at the lowest quartiles (p = .007, AUC-0.781). In SCAD patients with DM, levels of RP are associated with a higher risk of MACE, and inversely correlated with the risk of bleeding.

Relationship between 'on-treatment platelet reactivity', shear stress, and micro-embolic signals in asymptomatic and symptomatic carotid stenosis

BACKGROUND

Assessment of 'high on-treatment platelet reactivity (HTPR)' could enhance understanding of the pathophysiology of first or recurrent vascular events in carotid stenosis patients on antiplatelet therapy.

METHODS

This prospective, multi-centre study assessed antiplatelet-HTPR status and its relationship with micro-emboli signals (MES) in asymptomatic vs. symptomatic ≥ 50-99% carotid stenosis. Platelet function/reactivity was assessed under 'moderately high shear stress' with the PFA-100^® and 'low shear stress' with VerifyNow^® and Multiplate^® analysers. Bilateral 1-h transcranial Doppler ultrasound of the middle cerebral arteries classified patients as MES + ve or MES - ve.

RESULTS

Data from 34 asymptomatic patients were compared with 43 symptomatic patients in the 'early phase' (≤ 4 weeks) and 37 patients in the 'late phase' (≥ 3 months) after TIA/ischaemic stroke. Median daily aspirin doses were higher in early symptomatic (225 mg; P < 0.001), but not late symptomatic (75 mg; P = 0.62) vs. asymptomatic patients (75 mg). There was a lower prevalence of aspirin-HTPR in early (28.6%; P = 0.028), but not late symptomatic (38.9%; P = 0.22) compared with asymptomatic patients (56.7%) on the PFA-100^®, but not on the VerifyNow^® or Multiplate^® (P ≤ 0.53). Early symptomatic patients had a higher prevalence of aspirin-HTPR on the PFA-100^® (28.6%) vs. VerifyNow^® (9.5%; P = 0.049), but not Multiplate^® assays (11.9%, P = 0.10). There was no difference in aspirin-HTPR prevalence between any symptomatic vs. asymptomatic MES + ve or MES - ve subgroup.

DISCUSSION

Recently symptomatic moderate-severe carotid stenosis patients had a lower prevalence of aspirin-HTPR than their asymptomatic counterparts on the PFA-100^®, likely related to higher aspirin doses. The prevalence of antiplatelet-HTPR was positively influenced by higher shear stress levels, but not MES status.

Usefulness of plateletcrit in the prediction of major adverse cardiac and cerebrovascular events in patients with carotid artery stenosis

Objectives

Platelets play an important role in the pathogenesis of atherosclerosis and the physiopathology of cardiovascular events. Plateletcrit provides complete information on total platelet mass. The relationship between plateletcrit values and long-term outcomes in patients with carotid stenosis is not known. The purpose of the present study is to evaluate the reliability of plateletcrit for predicting major adverse cardiac and cerebrovascular events (MACCE) in patients with carotid stenosis.

Methods

A total of 230 patients with more than 50% stenosis of the carotid artery were retrospectively included in this study. All cases were divided into two groups according to the calculated threshold value of plateletcrit with receiver operating characteristics curve and baseline parameters and clinical outcomes were compared. Univariate and multivariate analyses were used to evaluate the association between the plateletcrit and MACCE.

Results

The cut-off value for plateletcrit was found to be 0.233 for predicting MACCE, with 56.2% sensitivity and 68.0% specificity. High plateletcrit levels were demonstrated to be statistically higher in patients with MACCE (0.247 in the MACCE (+) group vs. 0.213 in the MACCE (–) group, p < 0.001). In the Kaplan–Meier survival analysis, the long-term mortality rate was higher in the high plateletcrit group ( p = 0.006). Multivariate regression analysis showed that plateletcrit was independently associated with MACCE (OR: 2.196, CI: 1.200–4.018; p = 0.011).

Conclusions

Our data suggest that plateletcrit has an independently predictive value for long-term mortality and MACCE, and it can be used as a marker to predict the long-term adverse outcomes in patients with carotid stenosis.