Methods for the measurement of platelet function

Optimization of Platelet-Rich Plasma Preparation for Regenerative Medicine: Comparison of Different Anticoagulants and Resuspension Media

Platelet-rich plasma (PRP) has emerged as a promising therapy in regenerative medicine. However, the lack of standardization in PRP preparation protocols presents a challenge in achieving reproducible and accurate results. This study aimed to optimize the PRP preparation protocol by investigating the impact of two different anticoagulants, sodium citrate (SC) and ethylenediaminetetraacetic acid (EDTA), and resuspension media, plasma versus sodium chloride (NaCl). Platelet recovery rates were calculated and compared between groups, in addition to platelet activity and vascular endothelial growth factor (VEGF) released into plasma after PRP activation. The platelet recovery rate was higher with EDTA in comparison to SC (51.04% vs. 29.85%, p = 0.005). Platelet activity was also higher, with a higher expression of two platelet antibodies, platelet surface P-Selectin (CD62p) and PAC-1, in the EDTA group. The concentration of VEGF was higher with SC in comparison to EDTA (628.73 vs. 265.44 pg/mL, p = 0.013). Platelet recovery rates and VEGF levels were higher in PRP resuspended in plasma when compared to NaCl (61.60% vs. 48.61%, p = 0.011 and 363.32 vs. 159.83 pg/mL, p = 0.005, respectively). Our study reinforces the superiority of EDTA (as anticoagulant) and plasma (for resuspension) in obtaining a higher platelet recovery and preserving platelet functionality during PRP preparation.

On-treatment platelet reactivity through the thromboxane A2 or P2Y12 platelet receptor pathways is not affected by pelacarsen

BACKGROUND

Pelacarsen decreases plasma levels of lipoprotein(a) [Lp(a)] and oxidized phospholipids (OxPL). It was previously reported that pelacarsen does not affect the platelet count. We now report the effect of pelacarsen on on-treatment platelet reactivity.

METHODS

Subjects with established cardiovascular disease and screening Lp(a) levels ≥60 mg per deciliter (~ ≥150 nmol/L) were randomized to receive pelacarsen (20, 40, or 60 mg every 4 weeks; 20 mg every 2 weeks; or 20 mg every week), or placebo for 6-12 months. Aspirin Reaction Units (ARU) and P2Y12 Reaction Units (PRU) were measured at baseline and the primary analysis timepoint (PAT) at 6 months.

RESULTS

Of the 286 subjects randomized, 275 had either an ARU or PRU test, 159 (57.8%) were on aspirin alone and 94 (34.2%) subjects were on dual anti-platelet therapy. As expected, the baseline ARU and PRU were suppressed in subjects on aspirin or on dual anti-platelet therapy, respectively. There were no significant differences in baseline ARU in the aspirin groups or in PRU in the dual anti-platelet groups. At the PAT there were no statistically significant differences in ARU in subjects on aspirin or PRU in subjects on dual anti-platelet therapy among any of the pelacarsen groups compared to the pooled placebo group (p > 0.05 for all comparisons).

CONCLUSION

Pelacarsen does not modify on-treatment platelet reactivity through the thromboxane A₂ or P2Y12 platelet receptor pathways.

DNA methylation profile in the whole blood of acute coronary syndrome patients with aspirin resistance

BACKGROUND

Aspirin resistance (AR) results in major adverse cardiovascular events, and DNA methylation might participate in the regulation of this pathological process.

METHODS

In present study, a sum of 35 patients with AR and 35 non-AR (NAR) controls were enrolled. Samples from 5 AR and 5 NAR were evaluated in an 850 BeadChip DNA methylation assay, and another 30 AR versus 30 NAR were evaluated to validate the differentially methylated CpG loci (DML). Then, qRT-PCR was used to investigate the target mRNA expression of genes at CpG loci. Finally, Gene Ontology (GO) as well as Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to reveal the enriched pathways.

RESULTS

The AR and NAR groups displayed significant differences in DNA methylation at 7707 positions, with 270 hypermethylated sites (e.g., cg09555818 located in APOC2) and 7437 sites hypomethylated sites (e.g., cg26828689 located in SLC12A5). Six DML were validated by pyrosequencing, and it was confirmed that DNA methylation (cg16391727, cg21008208, cg21293749, and cg13945576) was related to the increasing risk of AR. The relative mRNA expression of the ROR1 gene was also associated with AR (p = 0.007), suggesting that the change of cg21293749 in DNA methylation might lead to differential ROR1 mRNA expression, ultimately resulting in AR. Furthermore, the identified differentially methylated sites were associated with the molecular pathways such as circadian rhythms and insulin secretion.

CONCLUSION

Hence, the distinct DNA methylation might play a vital role in the biological regulation of AR through the pathways such as circadian rhythms.

Flow cytometry for evaluating platelet immunophenotyping and function in patients with thrombocytopenia

Platelets play an essential role in primary hemostasis through bleeding and thromboembolism. Thus, the diagnosis or evaluation of impaired hereditary, acquired, and drug-related platelet dysfunction has become imperative. The assessment of the platelet function is too complex for routine platelet function study. The major methods involved in platelet function study include platelet function analyzer testing, thromboelastography, thromboelastometry, light transmission aggregometry, and flow cytometry. The current review article focuses on the methods with flow cytometry for immunophenotyping of platelet and evaluating platelet function for platelet disorders, especially in patients with thrombocytopenia. According to the consensus published by the International Society on Thrombosis and Haemostasis, for inherited and acquired platelet disorders, the two major measures by which flow cytometry determines platelet function are glycoprotein IIb/IIIa/P-selectin (CD62p) expression and percentage of leukocyte-platelet aggregates. Using flow cytometry to determine platelet function has several advantages, including good sensitivity to low platelet counts, small blood volume required, and the nonnecessity of centrifugation. However, flow cytometry has still many limitations and challenges, with standardization for routine laboratory testing also proving difficult. Although flow cytometry is available for multipurpose and sensitive study of platelet functions at the same time, the challenging analysis gradually increases and needs to be addressed before reality.

Mean platelet volume and glycaemic control in patients with new-onset Type 2 diabetes mellitus

Introduction:

Type 2 diabetes mellitus (T2DM) is a metabolic disorder associated with vascular complications that are attributable to dysregulated platelet reactivity as measured by mean platelet volume (MPV). This study aimed at determining a relationship between MPV and glycaemic control in new-onset T2DM.

Materials and methods:

This was a prospective study conducted on 236 new-onset T2DM patients divided in two groups as group A, glycosylated haemoglobin A1c (HbA1c < 7.9%; n = 70) and group B, HbA1c ⩾ 8% ( n = 107) who were followed up for 6 months for change in platelet and glycaemic parameters.

Results:

At 6-month follow-up, there was a significant decrease in HbA1c and MPV (group A (HbA1c: 7.40 ± 0.40 vs 7.03 ± 0.23%, p < 0.03; MPV: 9.65 fl ± 0.74 vs 9.46 fl ± 0.71, p < 0.001) and group B (HbA1c: 10.59 ± 1.89% vs 9.29 ± 1.50%, p < 0.001; MPV: 10.89 fL ± 1.29 vs. 10.23 fL ± 1.40, p< 0.001)). The percentage decline in HbA1c was more in group B (11.81 ± 5.87 vs 4.76 ± 4.58, p < 0.01). There was a positive correlation between ΔMPV and ΔHbA1c in group B; however, we did not observe significant correlation for group A.

Conclusion:

We interpret that in people with diabetes with baseline HbA1c ⩾ 8%, with improvement in glycaemic control, there is a significant decrease in MPV. We propose that a routine MPV testing can be used as a potential marker for glycaemic control in T2DM.

Ilaprazole and Clopidogrel Resistance in Acute Stroke Patients

Clopidogrel, an antiplatelet agent used for secondary prevention of cerebrovascular diseases, is often taken with proton pump inhibitors (PPIs). Generally, the combined use of clopidogrel and PPIs causes adverse drug–drug interactions. VerifyNow is a quick and convenient method to confirm clopidogrel resistance (CR), which compromises adequate antithrombotic effects. We aimed to confirm CR, identify its factors, and determine the influence of the combination of ilaprazole and clopidogrel on clopidogrel using VerifyNow. In this retrospective study, we examined patients who were receiving clopidogrel after three months, starting within one week from the onset of cerebral infarction symptoms. Clinical records, imaging records, and diagnostic laboratory results, including P2Y12 reaction units (PRU), were compared and analyzed to check for CR. Additionally, the groups treated with either both ilaprazole and clopidogrel or with medications other than ilaprazole were comparatively analyzed. CR was defined as a PRU ≥240 after clopidogrel for three months. Among factors influencing CR by affecting clopidogrel metabolism, positive statistical correlations with age and alcohol consumption were confirmed. The diagnostic tests revealed a lower glomerular filtration rate and platelet count of the CR-positive group. This finding proved that the combination therapy of ilaprazole and clopidogrel is safe, as it does not interfere with the metabolism of clopidogrel.

Association between central non-dipping pattern and platelet morphology in adults with type 1 diabetes without cardiovascular disease: a cross-sectional study

The non-dipping pattern is nighttime systolic blood pressure (SBP) fall of less than 10%. Several studies showed that the non-dipping pattern, increased mean platelet volume (MPV), and platelet distribution width (PDW) are associated with elevated cardiovascular risk. Hypertensives with the non-dipping pattern have higher MPV than the dippers but this relationship was never investigated among people with type 1 diabetes mellitus (T1DM). This study aimed to investigate the association between the central dipping pattern and platelet morphology in T1DM subjects. We measured the central and brachial blood pressure with a validated non-invasive brachial oscillometric device—Arteriograph 24—during twenty-four-hour analysis in T1DM subjects without diagnosed hypertension. The group was divided based on the central dipping pattern for the dippers and the non-dippers. From a total of 62 subjects (32 males) aged 30.1 (25.7–37) years with T1DM duration 15.0 (9.0–20) years, 36 were non-dippers. The non-dipper group had significantly higher MPV (MPV (10.8 [10.3–11.5] vs 10.4 [10.0–10.7] fl; p = 0.041) and PDW (13.2 [11.7–14.9] vs 12.3 [11.7–12.8] fl; p = 0.029) than dipper group. Multivariable logistic regression revealed that MPV (OR 3.74; 95% CI 1.48–9.45; p = 0.005) and PDW (OR 1.91; 95% CI 1.22–3.00; p = 0.005) were positively associated with central non-dipping pattern adjusting for age, sex, smoking status, daily insulin intake, and height. MPV and PDW are positively associated with the central non-dipping pattern among people with T1DM.

Platelet function assays for the diagnosis of aspirin resistance

Aspirin, an antiplatelet drug, is commonly used at low doses for numerous indications, including prophylaxis of cardiovascular, neurovascular, and venous thromboembolic events. Due to review articles suggesting that aspirin resistance may result in poorer outcomes, interest in assessing platelet function is increasing. Despite this, platelet function tests are rarely used as part of routine clinical practice and therefore, a basic understanding of these tests may be lacking. Although aspirin resistance can be categorized as clinical or laboratory resistance, determining laboratory resistance is the only way to determine resistance before treatment failure occurs. Therefore, knowledge of platelet assays to determine aspirin resistance is of importance. The following review aims to provide a framework for clinicians to understand the main principles of platelet function tests. This includes comparison of the most frequently used platelet assays to diagnose aspirin resistance, including the basic mechanism, methodology, reference ranges, inter-assay comparison, and their respective clinical considerations when using.

Pharmacokinetic/pharmacodynamic modeling of drug interactions at the P2Y12 receptor between selatogrel and oral P2Y12 antagonists

Selatogrel is a potent and reversible P2Y₁₂ receptor antagonist developed for subcutaneous self‐administration by patients with suspected acute myocardial infarction. After single‐dose emergency treatment with selatogrel, patients are switched to long‐term treatment with oral P2Y₁₂ receptor antagonists. Selatogrel shows rapid onset and offset of inhibition of platelet aggregation (IPA) to overcome the critical initial time after acute myocardial infarction. Long‐term benefit is provided by oral P2Y₁₂ receptor antagonists such as clopidogrel, prasugrel, and ticagrelor. A population pharmacokinetic (PK)/pharmacodynamic (PD) model based on data from 545 subjects in 4 phase I and 2 phase II studies well described the effect of selatogrel on IPA alone and in combination with clopidogrel, prasugrel, and ticagrelor. The PK of selatogrel were described by a three‐compartment model. The PD model included a receptor‐pool compartment to which all drugs can bind concurrently, reversibly or irreversibly, depending on their mode of action. Furthermore, ticagrelor and its active metabolite can bind to the selatogrel‐receptor complex allosterically, releasing selatogrel from the binding site. The model provided a framework for predicting the effect on IPA of selatogrel followed by reversibly and irreversibly binding oral P2Y₁₂ receptor antagonists for sustained effects. Determining the timepoint for switching from emergency to maintenance treatment is critical to achieve sufficient IPA at all times. Simulations based on the interaction model showed that loading doses of clopidogrel and prasugrel administered 15 h and 4.5 h after selatogrel, respectively, provide sustained IPA with clinically negligible drug interaction.

MiR-126 Is an Independent Predictor of Long-Term All-Cause Mortality in Patients with Type 2 Diabetes Mellitus

MicroRNAs are endogenous non-coding RNAs that are involved in numerous biological processes through regulation of gene expression. The aim of our study was to determine the ability of several miRNAs to predict mortality and response to antiplatelet treatment among T2DM patients. Two hundred fifty-two patients with diabetes were enrolled in the study. Among the patients included, 26 (10.3%) patients died within a median observation time of 5.9 years. The patients were receiving either acetylsalicylic acid (ASA) 75 mg (65%), ASA 150 mg (15%) or clopidogrel (19%). Plasma miR-126, miR-223, miR-125a-3p and Let-7e expressions were assessed by quantitative real time PCR and compared between the patients who survived and those who died. Adjusted Cox-regression analysis was used for prediction of mortality. Differential miRNA expression due to different antiplatelet treatment was analyzed. After including all miRNAs into one multivariate Cox regression model, only miR-126 was predictive of future occurrence of long-term all-cause death (HR = 5.82, 95% CI: 1.3–24.9; p = 0.024). Furthermore, miR-126, Let-7e and miR-223 expressions in the clopidogrel group were significantly higher than in the ASA group (p = 0.014; p = 0.013; p = 0.028, respectively). To conclude, miR-126 expression is a strong and independent predictor of long-term all-cause mortality among patients with T2DM. Moreover, miR-223, miR-126 and Let-7e present significant interactions with antiplatelet treatment regimens and clinical outcomes.

Platelet bound complement split product (PC4d) is a marker of platelet activation and arterial vascular events in Systemic Lupus Erythematosus

Platelet-bound complement activation products (PC4d) are associated with thrombosis in Systemic Lupus Erythematosus (SLE). This study investigated the effect of PC4d on platelet function, as a mechanistic link to arterial thrombosis. In a cohort of 150 SLE patients, 13 events had occurred within five years of enrollment. Patients with arterial events had higher PC4d levels (13.6 [4.4-24.0] vs. 4.0 [2.5-8.3] net MFI), with PC4d 10 being the optimal cutoff for event detection. The association of arterial events with PC4d remained significant after adjusting for antiphospholipid status, smoking, and prednisone use (p = 0.045). PC4d levels correlated with lower platelet counts (r = -0.26, p = 0.002), larger platelet volumes (r = 0.22, p = 0.009) and increased platelet aggregation: the adenosine diphosphate (ADP) concentration to achieve 50% maximal aggregation (EC₅₀) was lower in patients with PC4d 10 compared with PC4d < 10 (1.6 vs. 3.7, p = 0.038, respectively). These results suggest that PC4d may be a mechanistic marker for vascular disease in SLE.

Numerical and experimental analysis of a high-throughput blood plasma separator for point-of-care applications

Blood plasma separation from undiluted blood is an essential step in many diagnostic procedures. This study focuses on the numerical optimization of the microfluidic blood plasma separator (BPS) and experimental validation of the results to achieve portable blood plasma separation with high purity and reasonable yield. The proposed design has two parts: a microchannel for blood processing and a tank below the aforementioned main channel for plasma collection. The study uses 3D computational fluid dynamic analysis to investigate the optimal ratio of heights between the top microchannel and the tank and their geometry at various flow rates. Thereafter, the results are compared with the experimental findings of the fabricated devices. These results are contrasted with some recent reported works to verify the proposed device's contribution to the improvement in the quality and quantity of the extracted plasma. The optimized design is capable of achieving a 19% yield with purity of 77.1%, depending on the requirement of the point-of-care (POC) application. These amounts could be tuned, for instance to 100% pure plasma, but the yield would decrease to 9%. In this study, the candidate application is hemostasis; therefore, the BPS is integrated to a biomimetic surface for hemostasis evaluation near the patients.

Platelet Phenotyping and Function Testing in Thrombocytopenia

Patients who suffer from inherited or acquired thrombocytopenia can be also affected by platelet function defects, which potentially increase the risk of severe and life-threatening bleeding complications. A plethora of tests and assays for platelet phenotyping and function analysis are available, which are, in part, feasible in clinical practice due to adequate point-of-care qualities. However, most of them are time-consuming, require experienced and skilled personnel for platelet handling and processing, and are therefore well-established only in specialized laboratories. This review summarizes major indications, methods/assays for platelet phenotyping, and in vitro function testing in blood samples with reduced platelet count in relation to their clinical practicability. In addition, the diagnostic significance, difficulties, and challenges of selected tests to evaluate the hemostatic capacity and specific defects of platelets with reduced number are addressed.

Use of the VerifyNow point of care assay to assess the pharmacodynamic effects of loading and maintenance dose regimens of prasugrel and ticagrelor

Prasugrel and ticagrelor are potent oral platelet P2Y₁₂ inhibitors and are recommended over clopidogrel in patients with acute coronary syndrome (ACS). Oral platelet P2Y₁₂ inhibitors are characterized by varying degrees of pharmacodynamic response profiles as assessed by a variety of commercially available assays. Because of its ease of use, rapid turnaround times and ability to provide results specific to P2Y₁₂ inhibitory effects, VerifyNow has emerged as one of the most commonly utilized platelet function assays. However, reference ranges with VerifyNow have been reported mainly for clopidogrel and there has not yet been any study specifically conducted to provide the expected on treatment reference ranges following administration of prasugrel and ticagrelor. This was a prospective single center investigation conducted in 120 patients with ACS who were treated with prasugrel or ticagrelor as per standard of care. Patients who underwent percutaneous coronary interventions (PCI) were treated with a loading dose of prasugrel (60 mg) or ticagrelor (180 mg), and patients who were on maintenance therapy were taking prasugrel (10 mg qd or 5 mg qd) or ticagrelor (90 mg bid). Platelet function testing was performed using the VerifyNow™ PRUTest™. The overall range of PRUTest values was lower than that observed in studies of patients treated with clopidogrel. The use of a maintenance dose regimen had a wider range of PRUTest values compared to the use of a loading dose for both prasugrel (1–179 vs. 2–128) and ticagrelor (1–196 vs. 1–177). The average PRUTest values in patients on prasugrel and ticagrelor maintenance dosing were 20% and 9% higher those observed in patients treated with a loading dose. PRUTest results following loading dose administration were very similar between drugs, but were 20% higher with prasugrel compared with ticagrelor during maintenance dosing. This study establishes expected PRUTest ranges for patients taking loading and maintenance doses of prasugrel and ticagrelor.

Clinical Trial Registrationhttp://www.clinicaltrials.gov Unique Identifier: NCT04492423, registered July 2020 retrospectively registered.

Platelet electrical resistance for measuring platelet activation and adhesion in human health and disease

BACKGROUND

The ability to measure changes in platelet reactivity is important to identify novel aspects of platelet biology and develop targeted therapeutics to prevent bleeding or thrombosis. Current platelet function testing allows for single agonist analysis at a time. The ability to phenotype platelets in a single assay with multiple agonists and adhesion substrates could yield more insights into altered pathways than are feasible with current approaches. We hypothesized platelet electrical resistance (PER) could be used for more comprehensive phenotyping of platelets.

METHODS

Platelets were isolated from male and female healthy donors (age 39.6 ± 6.9) and septic patients (age 44.0 ± 13.5). PER 96-well plates were coated with various substrates, including fibrinogen and collagen. Platelets were added to the coated plates in the presence or absence of thrombin or convulxin. Platelet activation and spreading was monitored by measuring changes in electrical impedance.

RESULTS

Platelets adhesion to fibrinogen and collagen increased impedance. In addition, impedance increased in response to thrombin or convulxin. No changes in impedance were observed in the absence of platelets or when wells were uncoated, indicating changes in impedance were directly due to platelet adhesion and activation. Inhibiting integrin αIIbβ3 decreased impedance when fibrinogen was used as a substrate, consistent with platelet-dependent effects. Platelets from septic patients caused increased impedance compared to healthy donors, demonstrating this assay can be used to assess platelet hyperreactivity.

CONCLUSION

PER can be applied as a high throughput tool to measure platelet reactivity in health and disease, where platelet activation is increased.

Platelet Dysfunction after Traumatic Brain Injury: A Review

Coagulopathy is a known sequela of traumatic brain injury (TBI) and can lead to increased morbidity and mortality. Platelet dysfunction has been identified as one of several etiologies of coagulopathy following TBI and has been associated with poor outcomes. Regardless of whether the platelet dysfunction occurs as a direct consequence of the injury or because of pre-existing medical comorbidities or medication use, accurate detection and monitoring of response to therapy is key to optimal patient care. Platelet transfusion has been proposed as a potential therapeutic intervention to treat platelet dysfunction, with several studies using platelet function assays to monitor response. The development of increasingly precise diagnostic testing is providing enhanced understanding of the specific derangement in the hemostatic process, allowing clinicians to provide patient-specific treatment plans. There is wide variability in the currently available literature on the incidence and clinical significance of platelet dysfunction following TBI, which creates challenges with developing evidence-based management guidelines. The relatively high prevalence of platelet inhibitor therapy serves as an additional confounding factor. In addition, the data are largely retrospective in nature. We performed a literature review to provide clarity on this clinical issue. We reviewed 348 abstracts, and included 97 manuscripts in our final literature review. Based on the currently available research, platelet dysfunction has been consistently demonstrated in patients with moderate-severe TBI. We recommend the use of platelet functional assays to evaluate patients with TBI. Platelet transfusion directed at platelet dysfunction may lead to improved clinical outcome. A randomized trial guided by implementation science could improve the applicability of these practices.

Assessment of Shear-Dependent Kinetics of Primary Haemostasis With a Microfluidic Acoustic Biosensor

Primary haemostasis is a complex dynamic process, which involves in-flow interactions between platelets and sub-endothelial matrix at the area of the damaged vessel wall. It results in a first haemostatic plug, which stops bleeding, before coagulation ensues and consolidates it. The diagnosis of primary haemostasis defect would benefit from evaluation of the whole sequence of mechanisms involved in platelet plug formation in flow. This work proposes a new approach that is based on characterization of the shear-dependent kinetics that enables the evaluation of the early stages of primary haemostasis. We used a label-free method with a quartz crystal microbalance (QCM) biosensor to measure the platelet deposits over time onto covalently immobilized type I fibrillar collagen. We defined three metrics: total frequency shift, lag time, and growth rate. The measurement was completed at four predefined shear rates prevailing in small vessels (500, 770, 1000 and 1500 s^-1) during five minutes of perfusion with anticoagulated normal whole blood. The rate of the frequency shift over the first five minutes was strongly influenced by shear rate conditions, presenting a maximum around 770 s^-1, and varying by a factor larger than three in the studied shear rate range. To validate the biosensor signal, the total frequency shift was compared to results obtained by atomic force microscopy (AFM) on final platelet deposits. The results show that shear-dependent kinetic assays are promising as an advanced method for screening of primary haemostasis.

Point-of-Care Platelet Function Monitoring: Implications for Patients With Platelet Inhibitors in Cardiac Surgery

Although most physicians are comfortable managing the limited anticoagulant effect of aspirin, the recent administration of potent P2Y₁₂ receptor inhibitors in patients undergoing cardiac surgery remains a dilemma. Guidelines recommend discontinuation of potent P2Y₁₂ inhibitors 5- to- 7 days before surgery to reduce the risk of postoperative hemorrhage. Such a strategy might not be feasible before urgent surgery, due to ongoing myocardial ischemia or in patients at high risk for thromboembolic events. Recently, different point-of-care devices to assess functional platelet quality have become available for clinical use. The aim of this narrative review was to evaluate the implications and potential benefits of platelet function monitoring in guiding perioperative management and therapeutic options in patients treated with antiplatelets, including aspirin or P2Y₁₂ receptor inhibitors, undergoing cardiac surgery. No objective superiority of one point-of-care device over another was found in a large meta-analysis. Their accuracy and reliability are generally limited in the perioperative period. In particular, preoperative platelet function testing has been used to assess platelet contribution to bleeding after cardiac surgery. However, predictive values for postoperative hemorrhage and transfusion requirements are low, and there is a significant variability between and within these tests. Further, platelet function monitoring has been used to optimize the preoperative waiting period after cessation of dual antiplatelet therapy before urgent cardiac surgery. Furthermore, studies assessing their value in therapeutic decisions in bleeding patients after cardiac surgery are scarce. A general and liberal use of perioperative platelet function testing is not yet recommended.

Management of a decompensated acute-on-chronic intracranial venous sinus thrombosis

A 34-year-old female patient presented during the 10th week of her second gravidity with headache, nausea and vomiting 2 weeks before admission. Her medical history was remarkable for a heterozygous factor V Leiden mutation, elevated lipoprotein A, and a cerebral venous thrombosis (CVT) after oral contraceptive intake 15 years before. Magnetic resonance imaging (MRI) suggested acute and massive intracranial sinus thrombosis. Despite full-dose anticoagulation, the patient deteriorated clinically and eventually became comatose. Now, MRI/magnetic resonance angiography revealed vasogenic edema of both thalami, of the left frontal lobe, and of the head of the caudate nucleus, with venous stasis and frontal petechial hemorrhage. She was referred for endovascular treatment. Diagnostic angiography confirmed a complete superficial and deep venous sinus occlusion. Endovascular access to the straight and superior sagittal sinus was possible, but neither rheolysis nor balloon angioplasty resulted in recanalization of the venous sinuses. Monitored heparinization was continued and antiaggregation was initiated. The patient remained comatose for another 5 days and MRI showed progress of the cytotoxic edema. On day 6, infusion of eptifibatide at body-weight-adapted dosage was started. The following day, the patient improved and slowly regained consciousness. MRI confirmed regression of the edema. The eptifibatide infusion was continued for a total of 14 days. Thereafter two doses of 180 mg ticagrelor per os (PO) daily were started. The patient remained on acetylsalicylic acid (ASA), ticagrelor, and enoxaparin on an unchanged dosage regimen. She was discharged home 26 days after the endovascular treatment without serious neurological deficit, with the pregnancy intact. At the 30th week of pregnancy the dosage of ASA was reduced to 300 mg once PO daily. Cesarian delivery was carried out at the 38th week of pregnancy. The newborn was completely healthy. Ultima ratio therapeutic options for severe intracranial venous sinus thrombosis refractory to anticoagulation are discussed, with an emphasis on platelet-function inhibition.

The Effect of Mean Platelet Volume/Platelet Count Ratio on Dipper and Non-Dipper Blood Pressure Status

Background and Objectives: The mean platelet volume (MPV) represents a possible marker of platelet activation. There is an association between the platelet count (PC) and inflammation and platelet reactivity. We assessed the association between the MPV/PC ratio and circadian alterations in blood pressure (BP). Material and Methods: One hundred and twenty subjects in total, 80 hypertensive subjects and 40 healthy subjects (controls), were enrolled in the study group. Twenty four hour ambulatory BP monitoring (ABPM) was applied to all subjects. According to ABPM results, the hypertensive subjects were separated into two groups, such as dippers (n = 40) and non-dippers (n = 40). In all subjects, the collection of venous peripheral blood samples was performed on admission for PC and MPV measurements. Results: The two groups exhibited similar clinical baseline characteristics. A significantly higher MPV/PC ratio was determined in non-dippers compared to that in dippers and normotensives. The higher MPV/PC ratio was observed in non-dippers in comparison with that in dippers and normotensives (0.046 ± 0.007 to 0.032 ± 0.004 fL/[10⁹/L]; 0.046 ± 0.007 to 0.026 ± 0.004 fL/[10⁹/L], p < 0.001, respectively). A receiver operating characteristic (ROC) curve analysis showed that the optimum cut-off value of the MPV/PC ratio for predicting non-dipping patterns in hypertensive patients was 0.036 (area under the curve [AUC]: 0.98, p < 0.001). According to the cut-off value, sensitivity and specificity were found to be 95% and 95%, respectively. Conclusions: The higher MPV/PC ratio was determined in non-dipper hypertensive subjects in comparison with that in dipper hypertensive subjects. An elevation of platelet activity and an increase in thrombus burden are reflected by an increase in the MPV/PC ratio. The MPV/PC ratio may underlie the increase in cardiovascular risk in non-dippers compared to that in dippers.

Hemostasis-On-a-Chip: Impedance Spectroscopy Meets Microfluidics for Hemostasis Evaluation

In the case of vascular injury, a complex process (of clotting) starts, involving mainly platelets and coagulation factors. This process in healthy humans is known as hemostasis, but when it is deregulated (thrombosis), it can be the cause of important cardiovascular diseases. Nowadays, the aging of the population and unhealthy lifestyles increase the impact of thrombosis, and therefore there is a need for tools to provide a better understanding of the hemostasis mechanisms, as well as more cost-effective diagnosis and control devices. This study proposes a novel microflow chamber, with interchangeable biomimetic surfaces to evaluate global hemostasis, using reduced amounts of blood sample and reagents, and also a minimized time required to do the test. To validate the performance of this novel device, a study on the new oral anticoagulant Apixaban (APIX) has been performed and compared to previous conventional techniques. The test shows an excellent agreement, while the amount of the required sample has been reduced (only 100 µL is used), and the amount of reagent as well. An imprinted electrode embedded in the chamber in order to measure the impedance during the coagulation process. This approach distinguishes the impedance behavior of plasma poor in platelets (PPP) and plasma rich in platelets (PRP) for the first time.

Bad blood: A coagulopathy associated with trauma and massive transfusion review

Coagulopathy in trauma patients is a known contributor to death due to hemorrhage. In fact, it seen as frequently as 35% of the time. The complexity of the coagulopathy pathway requires a deliberate and planned approach. The methods used to assess and detect if a patient is coagulopathic remain challenging, but tools have been developed to assist the practitioner to effectively manage and even quickly reverse the coagulopathy. The purpose of this review is to educate trauma and emergency medicine staff on the currently available diagnostic tools to assess coagulopathy, to provide an overview of the coagulopathy pathway, as well as provide examples of how to intervene and treat coagulopathy, including the use of crew resource management during mass transfusion protocol activations.

The relationship between mean platelet volume and albuminuria in patients with type 2 diabetes mellitus

BACKGROUND&AIM

Mean platelet volume (MPV) is suggested as a marker of platelet reactivity and tendency for thrombosis and microvascular complications like albuminuria in patients with type 2 DM. We aimed to measure the MPV in patients with type 2 DM and its correlation with albuminuria, body mass index (BMI), duration of DM, hypertension (HTN), stroke, ischemic heart disease (IHD), and HbA1c level.

METHODS

A cross sectional study included 100 patients with type 2 DM ≥ 18 y of both genders who were randomly selected from the medical units of Baghdad Teaching Hospital. After taking verbal consents; MPV was measured&correlated with aimed variables. Diabetics with HbA1c ≤ 7% were considered as having adequate control while those with (HbA1c) > 7% as having poor control. Albumin creatinine ratio (ACR) in urine was measured and classified into normal, moderately and severely increased. Odds ratios with 95% CI were calculated and P ≤ 0.05 was considered as statistically significant.

RESULTS

The mean MPV was 7.7 fl ± 1.2. Regarding ACR, 42% had normal level, 37% with moderately increased and 21% had severely increased level. Regarding HbA1c, 68% were having poorly controlled DM. Mean platelets' count and MPV were higher in the uncontrolled group with a statistically significant association. There was a statistically significant positive correlation between MPV and albuminuria, duration of DM, HTN, IHD, Stroke, BMI, HbA1c, and platelets count.

CONCLUSIONS

The mean MPV was statistically significantly higher in the uncontrolled DM group and there was a statistically significant positive correlation between MPV and albuminuria.

Newly Identified HNP-F from Human Neutrophil Peptide-1 Promotes Hemostasis

Active hemostatic agents can play a crucial role in saving patients' lives during surgery. Active hemostats have several advantages including utilization of natural blood coagulation and biocompatibility. Among them, although human neutrophil peptide-1 (HNP-1) has been previously reported with the hemostatic mechanism, which part of HNP-1 facilitates the hemostatic activity is not known. Here, a partial peptide (HNP-F) promoting hemostasis, originating from HNP-1, has been newly identified by the blood coagulation ability test. HNP-F shows the best hemostatic effect between the anterior half and posterior half of peptides. Moreover, microscopic images show platelet aggregation and an increase in the concentration of platelet factor 4, and the scanning electron microscope image of platelets support platelet activation by HNP-F. Thromboelastography indicates decreased clotting time and increased physical properties of blood clotting. Mouse liver experiments demonstrate improved hemostatic effect by treatment of peptide solution. Cell viability and hemolysis assays confirm the HNP-F's biosafety. It is hypothesized that the surface charge and structure of HNP-F could be favorable to interact with fibrinogen or thrombospondin-1. Collectively, because HNP-F as an active peptide hemostat has many advantages, it could be expected to become a potent hemostatic biomaterial, additive or pharmaceutical candidate for various hemostatic applications.

Management of antiplatelet therapy in patients undergoing neuroendovascular procedures

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

The association between aspirin resistance and extent and severity of coronary atherosclerosis

OBJECTIVE:

Uncontrolled inflammatory responses could contribute to the pathogenesis of many leading causes of human morbidity and mortality. Aspirin is an anti-inflammatory and antithrombotic drug that is used in the primary and secondary protection in atherothrombotic diseases and complications. The aim of the present study was to analyze the effect of aspirin resistance on the extent and severity of atherosclerosis.

METHODS:

One hundred patients who underwent coronary angiography with suspected or known coronary artery disease and were using aspirin were enrolled in the study.

RESULTS:

Of these 100 patients, 30 (8 female and 22 male) formed the aspirin-resistant group (ARG), and 70 (22 female and 48 male) formed the control group. Gensini scoring system (GSS) was significantly higher in the ARG than in the control group (80.5 (36–166) vs. 45 (2–209); p<0.001). The number of percutaneous coronary intervention (PCI) patients was significantly higher in the ARG (13 of 30 (43.3%) ARG vs. 13 of 70 (18.6%) control group; p=0.01). Furthermore, when we evaluate the 16 reintervention patients, stent restenosis was significantly higher in the ARG (11 of 16 (68.75%) ARG vs. 5 of 16 (31.25%) control group; p=0.016). Multivariate logistic regression analysis revealed that GSS (p=0.038; 95% CI: 1.001–1.026) and PCI history (p=0.017; 95% CI: 1.182–89.804) were independent risk factors for aspirin resistance.

CONCLUSION:

In conclusion, atherosclerotic burden as calculated by the GSS is significantly higher in aspirin-resistant patients. According to this result, we suggest that aspirin treatment can be prescribed in higher doses in aspirin resistance patients with coronary events. Furthermore, GSS and PCI history could be independent predictors of aspirin resistance.

Relation of Platelet Indexes to Platelet Reactivity and Periprocedural Myocardial Infarction in Patients Who Underwent Percutaneous Coronary Angioplasty

No comprehensive data are available on the role of platelet indexes (PI) in the periprocedural risk stratification of patients who underwent percutaneous coronary intervention (PCI). The aim of this study was to investigate the relation of PI to platelet reactivity (PR) and periprocedural myocardial infarction (PMI) in patients receiving PCI. A total of 502 PCI patients had preprocedural measurement of PI and PR, the latter assessed by VerifyNow P2Y12 assay. Study end points were incidence of PMI and high platelet reactivity (HPR) according to tertiles of PI and evaluation of PI in HPR patients. Incidence of PMI in the overall population was 6.6%. Rates of PMI were not different in PI tertiles: platelet count (I: 6.0%, II: 7.1%, III: 6.5%; p = 0.74), mean platelet volume (MPV, I: 6.6%, II: 7.3%, III: 5.8%;p = 0.86), platelet distribution width (I: 7.2%, II: 7.2%, III: 5.8%;p = 0.74), and MPV/P ratio (I: 6.6%, II: 6.0%, III: 7.1%; p = 0.91). The occurrence of PMI was significantly different in PR tertiles (I: 3%, II: 5.4%, III: 11.4%; p = 0.006). Platelet count and MPV/P ratio were significantly different in patients with and without HPR (221.8 ± 58.6 × 103/µL vs207 ± 59.4 × 103/µL, p = 0.008; 51.73 ± 15.17 vs 56.7 ± 18.3, p = 0.002).In conclusion, this study showed no relation between PI and PMI in PCI patients but confirms the association of HPR with increased incidence of PMI; thus, PI seem to be not able to identify patients at higher periprocedural risk, but monitoring PR by a bedside assay remains a useful tool for risk stratification.

Risk factors for platelet transfusion in glioblastoma surgery

The objectives of this study are to identify risk factors for and to evaluate clinical outcomes of platelet transfusion in glioblastoma surgery. The medical records of adult patients who underwent craniotomy for glioblastoma resection at a single academic medical center were retrospectively reviewed. We stratified patients into 2 groups: those who were transfused at least 1 unit of platelets intraoperatively or postoperatively (no more than 7 days after surgery), and those who were not transfused with platelets. Through the use of a 1:3 matched cohort analysis, we compared complications, length of stay, discharge disposition, and mortality, across groups. One hundred and five consecutive adult patients were included in this study. Thirteen patients (12.38%) received platelet transfusions. Prior antiplatelet therapy (odds ratio [OR] 8.21, 95% confidence interval [CI]: 2.36-28.58), preoperative platelet count less than 200,000 cells/µL (OR 8.46, 95% CI: 2.16-33.22), and longer operative times (OR 1.73, 95% CI: 1.10-2.72) were significant risk factors for platelet transfusion. There were no significant differences in the outcomes of interest in the matched cohort analysis.

Association between multimorbidity and mean platelet volume in diabetic patients with acute myocardial infarction

AIMS

Diabetes mellitus (DM) is one of the most frequently detected conditions in multimorbid disease clusters. Platelet activation is one of the key mechanisms underlying atherothrombosis in acute myocardial infarction. Available data link mean platelet volume (MPV) to poor prognosis not only in cardiovascular and non-cardiovascular disease. Given the lack of research data on the association between disease clusters and MPV, we have set out to investigate the link between multimorbidity and MPV in diabetic patients with acute myocardial infarction.

METHODS

A total of 277 patients with DM and STEMI undergoing primary percutaneous coronary intervention were enrolled. Based on the number of comorbidities the study population was divided into two groups: group 1 (N = 58) with ≤ 1 comorbidity and group 2 (N = 219) with ≥ 2 comorbidities. A subanalysis was performed within the multimorbidity group: group 2A with two or three comorbidities (N = 156) and group 2B with at least four comorbidities (N = 63).

RESULTS

In the study population, 15.9% of patients had one comorbidity, and 22.0, 34.3, and 22.7% of patients had two, three, or at least four comorbid conditions, respectively. Both MPV and PDW were elevated in multimorbid patients (9.3 vs 10.8 fl and 9.5 vs 10.3 fl, respectively). The highest platelet volume indices were observed in patients with at least four comorbid conditions. There was a moderate positive correlation between MPV and the total number of comorbidities, the number of CVD comorbidities, and the number of non-CVD comorbidities.

CONCLUSIONS

These findings indicate that multimorbidity is associated with an increase in platelet volume indices. MPV values increased with the increasing number of comorbid conditions. Importantly, MPV values were elevated in some, but not all CVD and non-CVD conditions.

Influencing factors in quantitative measurement using activated platelet levels and platelet-activating capacity for the assessment of thrombosis in pre-metabolic syndrome and type 2 diabetes mellitus

Activated platelet levels and platelet-activating capacity are well recognized as useful index parameters for the physiological and pharmacological prediction of thrombotic events. Recently, quantitative measurements for platelet functions using a flow cytometer have been increasing gradually. However, the relation of physiological factors, such as sex, aging, and laboratory tests, to platelet functions has not been well documented. We conducted a blood analysis of people with normal/pre-metabolic syndrome and patients with type 2 diabetes mellitus to clarify the pathological factors. The levels of basal (non-stimulated)-activated, platelet-expressed P-selectin and activated platelet stimulated by agonists were measured by a flow cytometer, and ratios of platelet-activating capacity were also calculated. Statistical analyses indicated significantly high basal-activated platelet in pre-metabolic syndrome, and basal-activated platelet was positively associated with hyperlipidemia and hepatic damage. Platelet-activating capacity was significantly low in aging and hyperlipidemia, but high in hyperglycemia, and was negatively associated with hyperlipidemia and hepatic damage. Aging and high nutrient condition impaired platelet functions. Quantitative measurements of basal-activated platelet and platelet-activating capacity are precise parameters for the prediction of thrombotic events.

Haemostatic profiles assessed by thromboelastography in patients with end-stage renal disease

Patients with end-stage renal disease (ESRD) have abnormalities in the cellular and plasmatic systems regulating blood homeostasis, which may contribute to their risk for thrombotic and bleeding complications. However, their relative contributions in this population are poorly understood. The aim of this study was to evaluate the distribution of enzymatic and cellular abnormalities in ESRD patients on haemodialysis as assessed by thromboelastography (TEG®). Whole blood samples were analysed by TEG in ESRD patients (n=70) and in a control group (n=70) of subjects with coronary artery disease. Profiles were constructed considering the maximum amplitude (MA), a marker of platelet function, and reaction time (R), a marker of thrombin generation, values. R values were higher in ESRD patients compared with the control group (8.2 ± 2.8 vs. 5.7 ± 1.9 minutes [min], p <0.0001), while there were no differences in MA (66.7 ± 8.1 vs. 66.2 ± 6.6 mm, p=0.562). Nor mal manufacturer defined coagulation (2–8 min) and aggregation (51–69 mm) parameters were present in 31% of ESRD patients compared with 56% of controls (p=0.006). A hypocoagulable status was observed in 42.9% of ESRD patients compared with 8.9% in the control group (p<0.0001). There were no differences in platelet function, which showed a hyperaggregable status in 41.4% versus 35.7% of cases (p=0.603). Abnormalities in both parameters were observed in 15.7% of ESRD patients versus 1.4% in the control group (p = 0.004), which were more common among older patients (p= 0.005). In conclusion, patients with ESRD have an elevated prevalence of abnormal haemostatic profiles, which may contribute to their elevated risk of bleeding and thrombotic complications.

Impact of pharmacokinetic-pharmacodynamic modelling in early clinical drug development

Early clinical pharmacology studies in healthy subjects are often dissociated from patient studies. In this review we encourage the use of modelling and simulation techniques to generate valuable information at an early stage of clinical development. We illustrate these principles by presenting 5 different case studies from a spectrum of therapeutic drug classes. Their application leads to a better understanding of drug characteristics early on, thereby facilitating the design of dose-finding studies in the target patient population and saving resources.

Use of Aspirin and P2Y12 Response Assays in Detecting Reversal of Platelet Inhibition With Platelet Transfusion in Patients With Traumatic Brain Injury on Antiplatelet Therapy

BACKGROUND

At present, guidelines are lacking on platelet transfusion in patients with a traumatic intracranial bleed and history of antiplatelet therapy. The aspirin and P2Y 12 response unit (ARU and PRU, respectively) assays detect the effect of aspirin and P2Y 12 inhibitors in the cardiac population.

OBJECTIVE

To describe the reversal of platelet inhibition after platelet transfusion using the ARU and PRU assays in patients with traumatic brain injury.

METHODS

Between 2010 and 2015, we conducted a prospective comparative cohort study of patients presenting with a positive head computed tomography and a history of antiplatelet therapy. ARU and PRU assays were performed on admission and 6 hours after transfusion, with a primary end point of detection of disinhibition after platelet transfusion.

RESULTS

One hundred seven patients were available for analysis. Seven percent of patients taking aspirin and 27% of patients taking clopidogrel were not therapeutic on admission per the ARU and PRU, respectively. After platelet transfusion, 51% of patients on any aspirin and 67% of patients on any clopidogrel failed to be reversed. ARU increased by 71 ± 76 per unit of apheresis platelets for patients taking any aspirin, and PRU increased by 48 ± 46 per unit of apheresis platelets for patients taking any clopidogrel.

CONCLUSION

A significant percentage of patients taking aspirin or clopidogrel were not therapeutic and thus would be unlikely to benefit from a platelet transfusion. In patients with measured platelet inhibition, a single platelet transfusion was not sufficient to reverse platelet inhibition in almost half.

Utility of the Aspirin and P2Y12 Response Assays to Determine the Effect of Antiplatelet Agents on Platelet Reactivity in Traumatic Brain Injury

BACKGROUND

Premorbid antithrombotic medication may worsen intracranial injury and outcome after traumatic brain injury (TBI). Routine laboratory tests are insufficient to evaluate platelet activity.

OBJECTIVE

To profile the spectrum of platelet inhibition, as measured by aspirin and P2Y12 response unit assays, in a TBI population on antiplatelet therapy.

METHODS

This single-center, prospective cohort study included patients presenting to our institution between November 2010 and January 2015 with a clinical history of TBI. Serum platelet reactivity levels were determined immediately on admission and analyzed using the aspirin and P2Y12 response unit assays; test results were reported as aspirin response units and P2Y12 response units. We report congruence between assay results and clinical history as well as differences in assay results between types of antiplatelet therapy.

RESULTS

A sample of 317 patients was available for analysis, of which 87% had experienced mild TBI, 7% moderate, and 6% severe; the mean age was 71.5 years. The mean aspirin response units in patients with a history of any aspirin use was 456 ± 67 (range, 350-659), with 88% demonstrating therapeutic platelet inhibition. For clopidogrel, the mean P2Y12 response unit was 191 ± 70 (range, 51-351); 77% showed therapeutic response.

CONCLUSION

Rapid measurement of antiplatelet function using the aspirin and P2Y12 response assays indicated as many as one fourth of patients on antiplatelet therapy do not have platelet dysfunction. Further research is required to develop guidelines for the use of these assays to guide platelet transfusion in the setting of TBI.

Relationship Between Plasma Pentraxin 3 Concentration and Platelet Indices in Patients With Stable Coronary Artery Disease

Few reports have analyzed the effect of pentraxin 3 (PTX3) on platelets and their activation. We explored the association between plasma PTX3 and platelet indices. Forty-nine patients with stable coronary artery disease (CAD) were enrolled. Based on median PTX3, the study population was divided into group 1 (n = 25; PTX3 ≤ 0.98 ng/mL) and group 2 (n = 24; PTX3 > 0.98 ng/mL). Platelet indices investigated included mean platelet volume (MPV), platelet distribution width (PDW), platelets and large cell ratio (P-LCR), MPV to platelet count ratio (MPV/PC), platelet to lymphocyte ratio (PLR), and MPV to lymphocyte ratio (MPVLR). Patients with lower PTX3 had a higher lymphocyte count. Platelet count was similar in both groups. Notwithstanding, patients with higher PTX3 concentrations had elevated MPV (8.3 vs 10.0 fL; P < .001) and PDW (9.4 vs 12.4 fL; P < .001). However, the MPV/PC ratio was similar in both groups. Thromboinflammatory biomarkers (PLR, MPVLR) were also elevated in group 2. Pentraxin 3showed a strong, positive correlation with MPV ( r = .75, P < .01) and PDW ( r = .80, P < .01), and weak to moderate correlation with MPVLR. In conclusion, PTX3 is associated with larger platelet size as assessed by platelet volume indices. There is a strong correlation between plasma PTX3 level and MPV and PDW.

Proteinuria Predicts Resistance to Antiplatelet Therapy in Ischemic Stroke

The occurrence of a stroke while on antiplatelet agents presents a therapeutic dilemma. One of the main causes for recurrent strokes is antiplatelet resistance more commonly known as high on treatment platelet reactivity (HTPR). Prior studies have established that proteinuria is associated with HTPR following myocardial infarction. Here, we investigated whether dipstick proteinuria correlates with HTPR in patients presenting with stroke. We performed a retrospective cohort analysis of 102 patients admitted for a recurrent ischemic stroke that had either a VerifyNow aspirin or VerifyNow clopidogrel laboratory test performed to assess platelet reactivity. Dipstick proteinuria was defined as > 30 mg/dl (2+ or more). HTPR was defined as an aspirin resistance unit > 550 for aspirin and a P2Y12 reactivity unit > 208 for clopidogrel. Patients with proteinuria on dipstick were significantly more likely to have HTPR to either aspirin (p value 0.017) or clopidogrel (p value 0.017). After controlling for age, smoking, diabetes, hypertension, CAD and GFR, proteinuria was an independent predictor of HTPR for patient taking aspirin (p = 0.025). Platelet resistance is an entity that undermines the activity of antiplatelet agents in reducing stroke risk. Here, we demonstrate an association with increased platelet reactivity and proteinuria. This highlights a potential new therapeutic target in reducing future stroke risk.

Usefulness of Mean Platelet Volume-to-Lymphocyte Ratio for Predicting Angiographic No-Reflow and Short-Term Prognosis After Primary Percutaneous Coronary Intervention in Patients With ST-Segment Elevation Myocardial Infarction

Primary percutaneous coronary intervention (pPCI) is associated with improved prognosis in patients with ST-segment elevation myocardial infarction (STEMI). However, no-reflow phenomenon limits the benefit of revascularization and predicts adverse outcomes. The specific mechanism for its occurrence is still not entirely clear, and it is believed at present that platelet activation and inflammation play a pivotal role in developing no-reflow. Both increased mean platelet volume (MPV), which is a platelet activation marker, and lymphopenia, which is an inflammation marker, have been linked to adverse events and poor prognosis after STEMI. Recently, MPV-to-lymphocyte ratio (MPVLR) has emerged as a novel marker of poor short- and long-term prognosis in diabetic patients with STEMI who underwent pPCI. In this study, we aimed to investigate whether MPVLR predicts angiographic no-reflow and in-hospital mortality in all STEMI patients. From January 2014 to January 2017, a total of 1,206 patients who underwent pPCI, admitted within 12 hours from symptom onset, were enrolled and divided into 2 groups based on the final thrombolysis in myocardial infarction (TIMI) flow grading. No-reflow was defined as post-pPCI TIMI grade 0, 1, and 2 flows and normal-reflow was defined as TIMI 3 flow. The incidence of no-reflow was 16.1% (n = 198). The MPVLR values were higher in no-reflow group than in normal-reflow group (p <0.001). In multivariate analysis, MPVLR was an independent predictor of angiographic no-reflow. Furthermore, in multivariable Cox regression models adjusted for potential confounders, MPVLR was independently and positively associated with the hazard of 30-day all-cause mortality. In conclusion, the MPVLR was a strong independent predictor for angiographic no-reflow and short-term mortality in patients with STEMI who underwent pPCI.

How I use laboratory monitoring of antiplatelet therapy

Antiplatelet therapy is of proven benefit in coronary artery disease and a number of other clinical settings. This article reviews platelet function, molecular targets of antiplatelet agents, and clinical indications for antiplatelet therapy before focusing on a frequent question to hematologists about the 2 most commonly used antiplatelet therapies: Could the patient be aspirin “resistant” or clopidogrel “resistant”? If so, should results of a platelet function test be used to guide the dose or type of antiplatelet therapy? Whether such guided therapy is of clinical benefit to patients has been a source of controversy. The present article reviews this subject in the context of 2 prototypical clinical cases. Available evidence does not support the use of laboratory tests to guide the dose of aspirin or clopidogrel in patients with so-called aspirin or clopidogrel “resistance.”

Application of whole-exome sequencing to direct the specific functional testing and diagnosis of rare inherited bleeding disorders in patients from the Öresund Region, Scandinavia

Rare inherited bleeding disorders (IBD) are a common cause of bleeding tendency. To ensure a correct diagnosis, specialized laboratory analyses are necessary. This study reports the results of an upfront diagnostic strategy using targeted whole exome sequencing. In total, 156 patients with a significant bleeding assessment tool score participated in the study, of which a third had thrombocytopenia. Eighty‐seven genes specifically associated with genetic predisposition to bleeding were analysed by whole exome sequencing. Variants were classified according to the five‐tier scheme. We identified 353 germline variants. Eight patients (5%) harboured a known pathogenic variant. Of the 345 previously unknown variants, computational analyses predicted 99 to be significant. Further filtration according to the Mendelian inheritance pattern, resulted in 59 variants being predicted to be clinically significant. Moreover, 34% (20/59) were assigned as novel class 4 or 5 variants upon targeted functional testing. A class 4 or 5 variant was identified in 30% of patients with thrombocytopenia (14/47) versus 11% of patients with a normal platelet count (12/109) (P < 0·01). An IBD diagnosis has a major clinical impact. The genetic investigations detailed here extricated our patients from a diagnostic conundrum, thus demonstrating that continuous optimization of the diagnostic work‐up of IBD is of great benefit.