Platelet Inhibition and Bleeding in Patients Undergoing Non-Cardiac Surgery—The BIANCA Observational Study

2018 ◽  
Vol 118 (05) ◽  
pp. 864-872 ◽  
Author(s):  
Elisabeth Mahla ◽  
Helfried Metzler ◽  
Helmar Bornemann-Cimenti ◽  
Florian Prueller ◽  
Reinhard Raggam ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Observational Study ◽  
Platelet Function ◽  
Platelet Reactivity ◽  
Objective Assessment ◽  
Timing Of Surgery ◽  
Light Transmittance ◽  
Reactivity Index ◽  
Multivariable Logistic Regression Analysis ◽  
Induced Aggregation

AbstractNearly 20% of patients will need non-cardiac surgery within 1 year of coronary stenting and their management is complicated by concomitant antiplatelet therapy. Platelet function testing may optimize the timing of surgery in these patients. In this prospective observational study, we explored the association between platelet reactivity and bleeding in patients undergoing non-cardiac surgery treated with clopidogrel with or without aspirin within 7 days before surgery. The timing of surgery was at the surgeon's discretion. Blood was drawn at induction of anaesthesia and platelet reactivity assessed by light transmittance aggregometry (LTA), vasodilator stimulated phosphoprotein (VASP) assay, Multiplate Analyzer and Innovance PFA-200. The primary endpoint was surgery-related thrombolysis in myocardial infarction (TIMI) bleeding. Among 197 patients enrolled, 72 and 12% underwent surgery within 24 and 48 hours of the last dose of clopidogrel, respectively. The median (interquartile range [IQR]) for pre-operative maximal adenosine diphosphate (ADP)-induced aggregation was 33.0% (21.0–57.5%), for VASP-platelet reactivity index was 61.5% (40.1–75.4%), for Multiplate was 22.0 (14.5–36.0) U*min and for Innovance PFA-200 was 224 (101.0–300.0) seconds. TIMI bleeding, observed in 25% of patients, decreased with increasing tertiles of platelet reactivity to ADP assessed by LTA (p = 0.031). Additionally, in a multivariable logistic regression analysis, platelet reactivity to ADP assessed by LTA was significantly associated with TIMI bleeding, as were age and urgency of surgery. These results demonstrate that in clopidogrel-treated patients, pre-operative platelet reactivity to ADP is associated with surgical bleeding risk. An objective assessment of pre-operative platelet function may optimize the timing of non-cardiac surgery in these patients.

Effect of adjunctive dipyridamole to DAPT on platelet function profiles in stented patients with high platelet reactivity

2014 ◽  
Vol 112 (12) ◽  
pp. 1198-1208 ◽  
Author(s):  
Yongwhi Park ◽  
Udaya Tantry ◽  
Jong-Hwa Ahn ◽  
Kye Hwan Kim ◽  
Jin-Sin Koh ◽  
...  
Keyword(s):  
Platelet Function ◽  
Platelet Reactivity ◽  
Pde5 Inhibitor ◽  
Light Transmittance ◽  
Reactivity Index ◽  
Double Dose ◽  
High Platelet Reactivity ◽  
Number Of Patients ◽  
The Impact

SummaryAdjunctive use of phosphodiesterase (PDE) inhibitor can enhance antiplatelet and vasoprotective properties in patients with cardiovascular disease. The aim of this study was to evaluate the impact of PDE5 inhibitor dipyridamole on platelet function in stented patients with high platelet reactivity (HPR) during dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. Patients with HPR after 600-mg clopidogrel loading were randomly assigned to adjunctive dipyridamole 75 mg twice daily to standard DAPT (DIP group; n = 45) or double-dose clopidogrel of 150 mg daily (DOUBLE group; n = 46) for 30 days. Platelet function was assessed at baseline and 30-day follow-up with platelet reactivity index (PRI) by vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P) assay and platelet aggregation (PA) by light transmittance aggregometry (LTA). Primary endpoint was PRI at 30-day follow-up. HPR was defined as PRI > 50%. Baseline platelet function did not differ between the groups. Following 30-day therapy, platelet function was significantly reduced in the DIP and DOUBLE groups (all p-values ≤ 0.004 and ≤ 0.068, respectively). PRI values were not significantly different between the two groups (mean difference: 3.1%; 95% confidence interval: –2.8% to 9.0%: p = 0.295). PA values and prevalence of HPR were similar between the groups. However, a significant number of patients still exhibited HPR in the DIP (75.6%) and DOUBLE (67.4%) groups. In conclusion, among stented HPR patients, adding dipyridamole to DAPT does not reduce platelet reactivity and prevalence of HPR compared with double-dose clopidogrel therapy, and therefore both strategies are inadequate to overcome HPR.

Abstract 5603: Oral Dosing of PRT060128, a Novel Direct-acting, Reversible P2Y 12 Antagonist Overcomes High Platelet Reactivity in Patients Non-responsive to Clopidogrel Therapy

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Paul A Gurbel ◽  
Pamela B Conley ◽  
Patrick Andre ◽  
Gillian Stephens ◽  
Daniel D Gretler ◽  
...  
Keyword(s):  
Oral Dose ◽  
Single Oral Dose ◽  
Platelet Function ◽  
Large Scale ◽  
Platelet Reactivity ◽  
Light Transmittance ◽  
High Platelet Reactivity ◽  
Clopidogrel Therapy ◽  
Direct Acting ◽  
Induced Aggregation

Introduction: The ADP receptor P2Y 12 plays a central role in platelet function. Clopidogrel therapy is associated with various limitations including irreversible inhibition, a delayed antiplatelet effect, wide response variability, and non-responsiveness that has been linked to adverse ischemic event occurrence. We report the first pharmacodynamic study of a single oral dose of PRT060128 (PRT128), a novel, direct-acting reversible P2Y 12 inhibitor in patients with high platelet reactivity while on maintenance dose clopidogrel therapy(75mg/d) and aspirin. Methods: Previously stented patients (n=27) on maintenance aspirin and clopidogrel therapy were screened for high platelet reactivity (HPR) defined as upper tertile 5μ M ADP-induced aggregation (>43%) based on prior studies conducted at our Center; 7/27 had HPR and were treated with a single oral dose (60 mg) of PRT128. Platelet function was assessed at baseline, 4 hours, 6 hours, and 24 hours post-dosing by light transmittance aggregometry (LTA) stimulated by 5μ M, 20 μ M ADP, and 4μ g/ml collagen; Thrombelastography PlateletMapping (MA ADP ), Accumetrics P2Y12 assay (PRU), platelet reactivity ratio (%) by vasodilator stimulated phosphoprotein phosphorylation (VASP), and Perfusion Chamber Assay (PCA). Results: Results shown in the Table represent means ± standard deviation for the 7 patients at each time point. Conclusion: Based on results using multiple pharmacodynamic assays, PRT060128 is a potent rapid-acting inhibitor of P2Y 12 that overcomes high platelet reactivity in patients non-responsive to clopidogrel therapy. The pharmacodynamic properties of this novel P2Y 12 antagonist warrant future large scale investigations to determine clinical efficacy.

Impact of adjunctive cilostazol therapy on platelet function profiles in patients with and without diabetes mellitus on aspirin and clopidogrel therapy

2011 ◽  
Vol 106 (08) ◽  
pp. 253-262 ◽  
Author(s):  
Dominick J. Angiolillo ◽  
Piera Capranzano ◽  
Jose Luis Ferreiro ◽  
Masafumi Ueno ◽  
Davide Capodanno ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Platelet Function ◽  
Thrombin Generation ◽  
Platelet Reactivity ◽  
Flow Cytometric Analysis ◽  
Light Transmittance ◽  
Reactivity Index ◽  
Pharmacodynamic Effects ◽  
Increased Risk ◽  
Clopidogrel Therapy

SummaryCilostazol is a platelet inhibitor which when added to aspirin and clopidogrel has shown to reduce the risk of recurrent ischaemic events without an increase in bleeding. These clinical benefits have shown to be more pronounced in patients with diabetes mellitus (DM). However, it remains unknown whether cilostazol exerts different pharmacodynamic effects in patients with and without DM. This was a randomised, double-blind, placebo-controlled, cross-over pharmacodynamic study comparing platelet function in patients with and without DM on aspirin and clopidogrel therapy. Patients (n=111) were randomly assigned to either cilostazol 100 mg or placebo twice daily for 14 days and afterwards crossed-over treatment for another 14 days. Platelet function was performed at baseline, 14 days post-randomisation, and 14 days post-cross-over. Functional testing to assess P2Y12 signalling included flow cytometric analysis of phosphorylation status of vasodilatorstimulated phosphoprotein measured by P2Y12 reactivity index (PRI), light transmittance aggregometry and VerifyNow. Thrombin generation processes were also studied using thrombelastography. Significantly lower PRI values were observed following treatment with cilostazol compared with placebo both in DM and non-DM groups (p < 0.0001). The absolute between-treatment differences of PRI between groups was a 35.1% lower in patients with DM (p=0.039). Similar results were obtained using all other functional measures assessing P2Y12 signalling. Thrombin generation was not affected by cilostazol. Cilostazol reduces platelet reactivity both in patients with and without DM, although these pharmacodynamic effects are enhanced in patients with DM. Despite the marked platelet inhibition, cilostazol does not alter thrombin-mediated haemostatic processes, which may explain its ischaemic benefit without the increased risk of bleeding.

Enhanced platelet aggregation and activation under conditions of hypothermia

2007 ◽  
Vol 98 (12) ◽  
pp. 1266-1275 ◽  
Author(s):  
Ruben Xavier ◽  
Ann White ◽  
Susan Fox ◽  
Robert Wilcox ◽  
Stan Heptinstall
Keyword(s):  
Cardiac Surgery ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Baseline Levels ◽  
Spontaneous Aggregation ◽  
High Concentrations ◽  
Induced Aggregation ◽  
P2y12 Antagonist

SummaryThe effects on platelet function of temperatures attained during hypothermia used in cardiac surgery are controversial. Here we have performed studies on platelet aggregation in whole blood and platelet-rich plasma after stimulation with a range of concentrations of ADP, TRAP, U46619 and PAF at both 28°C and 37°C. Spontaneous aggregation was also measured after addition of saline alone. In citrated blood, spontaneous aggregation was markedly enhanced at 28°C compared with 37°C. Aggregation induced by ADP was also enhanced. Similar results were obtained in hirudinised blood. There was no spontaneous aggregation in PRP but ADP-induced aggregation was enhanced at 28°C. The P2Y12 antagonist AR-C69931 inhibited all spontaneous aggregation at 28°C and reduced all ADP-induced aggregation responses to small, reversible responses. Aspirin had no effect. Aggregation was also enhanced at 28°C compared with 37°C with low but not high concentrations of TRAP and U46619. PAF-induced aggregation was maximal at all concentrations when measured at 28°C, but reversal of aggregation was seen at 37°C. Baseline levels of platelet CD62P and CD63 were significantly enhanced at 28°C compared with 37°C. Expression was significantly increased at 28°C after stimulation with ADP, PAF and TRAP but not after stimulation with U46619. Overall, our results demonstrate an enhancement of platelet function at 28°C compared with 37°C, particularly in the presence of ADP.

scholarly journals 2529

2017 ◽  
Vol 1 (S1) ◽  
pp. 67-67
Author(s):  
Dagmar Fredy Hernandez Suarez ◽  
Kyle Melin ◽  
Angel Lopez-Candales ◽  
Jorge Duconge
Keyword(s):  
Platelet Function ◽  
Clinical Characteristics ◽  
Platelet Reactivity ◽  
Artery Aneurysm ◽  
Multivariable Logistic Regression Analysis ◽  
Cross Sectional ◽  
Group I ◽  
Clopidogrel Therapy ◽  
Study Population ◽  
Artery Disease

OBJECTIVES/SPECIFIC AIMS: To determine the association between clinical characteristics and platelet reactivity in Hispanic patients on clopidogrel therapy. METHODS/STUDY POPULATION: A cross-sectional pilot study was performed in 58 Puerto Rican patients diagnosed with any type of vascular disease and actively receiving a maintenance dose of clopidogrel for at least 7 days. The study population was divided into 2 groups: Group I with non-high on-treatment platelet reactivity (TPR); Group II with high TPR. To determine the platelet function, P2Y12 reaction units (PRU) were obtained by VerifyNow® P2Y12 assay (Accumetrics, USA). RESULTS/ANTICIPATED RESULTS: We studied a heterogeneous cohort of patients with coronary artery disease (57%), peripheral artery disease (30%), carotid artery stenosis (7%), cerebral artery aneurysm (3%), and stroke (3%) on clopidogrel therapy for secondary prevention of thromboembolic events. The mean TPR was 205±49 PRU (range: 61–304), with a prevalence of 28% patients with high TPR (PRU≥230). No significant clinical differences were found between the non-high TPR and high-TPR groups (p>0.05). However, multivariable logistic regression analysis showed that both diabetes mellitus (OR=7.5; CI: 1.01–51.9) and proton-pump inhibitors (OR=13.6; CI: 1.3–142.0) were independently correlated with high TPR (p<0.05) after adjusting for other clinical variables. DISCUSSION/SIGNIFICANCE OF IMPACT: These results provide new insight into the importance of clinical characteristics on platelet reactivity in this Caribbean population. Further studies are warranted to determine whether important clopidogrel pharmacogenes are related with platelet function in Hispanics, as well as the role of TPR in guiding antiplatelet therapy and predicting future adverse cardiovascular events in this population.

The impact of renal function on platelet reactivity and clinical outcome in patients undergoing percutaneous coronary intervention with stenting

2014 ◽  
Vol 112 (12) ◽  
pp. 1174-1181 ◽  
Author(s):  
Nicoline Breet ◽  
Corine de Jong ◽  
Willem Jan Bos ◽  
Jochem van Werkum ◽  
Heleen Bouman ◽  
...  
Keyword(s):  
Renal Function ◽  
Antiplatelet Therapy ◽  
Platelet Function ◽  
Platelet Reactivity ◽  
Light Transmittance ◽  
Clinical Trial Registration ◽  
Platelet Function Test ◽  
Increased Risk ◽  
Function Test ◽  
The Impact

SummaryPatients with chronic kidney disease (CKD) have an increased risk of cardiovascular disease. Previous studies have suggested that patients with CKD have less therapeutic benefit of antiplatelet therapy. However, the relation between renal function and platelet reactivity is still under debate. On-treatment platelet reactivity was determined in parallel by ADP- and AA-induced light transmittance aggregometry (LTA) and the VerifyNow® System (P2Y12 and Aspirin) in 988 patients on dual antiplatelet therapy, undergoing elective coronary stenting. Patients were divided into two groups according to the presence or absence of moderate/severe CKD (GFR<60 ml/min/1.73 m2). Furthermore, the incidence of all-cause death, non-fatal acute myocardial infarction, stent thrombosis and stroke at one-year was evaluated. Patients with CKD (n=180) had significantly higher platelet reactivity, regardless of the platelet function test used. Patients with CKD more frequently had high on-clopidogrel platelet reactivity (HCPR) and high on-aspirin platelet reactivity (HAPR) regardless of the platelet function test used. After adjustment for potential confounders, this was no longer significant. The event-rate was the highest in patients with both high on-treatment platelet reactivity (HPR) and CKD compared to those with neither high on-treatment platelet reactivity nor CKD. In conclusion, the magnitude of platelet reactivity as well as the incidence of HPR was higher in patients with CKD. However, since the incidence of HPR was similar after adjustment, a higher rate of co-morbidities in patients with CKD might be the major cause for this observation rather than CKD itself. CKD-patients with HCPR were at the highest risk of long-term cardiovascular events.Clinical Trial Registration: www.clinicaltrials.gov: NCT00352014.

Platelet reactivity in patients with aortic stenosis depends on LV-AO angle

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
P Mourikis ◽  
S Zako ◽  
L Dannenberg ◽  
R M'Pembele ◽  
T Hohlfeld ◽  
...  
Keyword(s):  
Aortic Stenosis ◽  
Platelet Activation ◽  
Platelet Function ◽  
Cox Regression ◽  
Light Transmission ◽  
Platelet Reactivity ◽  
Funding Source ◽  
Local Inflammation ◽  
German Research Foundation ◽  
Induced Aggregation

Abstract Background The pathogenesis of aortic stenosis (AS) is not fully understood. However, local inflammation of the valve appears to be a main player. Except haemostasis, platelets contribute to inflammatory processes in various ways. Furthermore, platelet function is altered in patients with AS. Moreover, a steep angle between the left ventricle and the aorta (LV-AO-angle) leads to turbulent blood flow. However, it is not known if platelet reactivity is associated with steep LV_AO angle in patients with AS. Methods We included 289 patients with severe AS and performed cardiac computertomography to assess the LV-AO-angle. Platelet function was evaluated by light transmission aggregometry by using collagen and adenosine-diphosphate to induce platelet activation Results ADP- and collagen induced aggregation showed a significant negative correlation with LV-AO-angle (ADP: r=−0.19, p=0.0009, R2=0.022; collagen: r=−0.21, p=0.0004, R2=0.027). ADP-induced MoA was significant higher in patients with a LV-AO-angle &lt;160° in comparison to patients with an angle ≥160° (&lt;160°: 66.99±20.72% vs. ≥160°: 60.66±19.85%, p=0.009). Collagen-induced platelet reactivity was significant higher in patients with a LV-AO-angle &lt;160° in comparison to patients with an angle ≥160° (&lt;160°: 78.67±13.19% vs. ≥160°: 73.85±14.44%, p=0.003). Multivariate cox-regression revealed that LV-AO angle &lt;160 was a robust predictor of ADP- and collagen-induced platelet aggregation Conclusion A steep LV-AO-angle is associated with enhanced platelet reactivity in patients with AS. Platelet activation is known to lead to local inflammation. Therefore, enhanced platelet reactivity could play crucial in the progression of AS. The clinical significance of a steep LV-AO-angle needs be evaluated in further trials. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): German Research Foundation

The Assessment of High Post-Clopidogrel Platelet Reactivity Using the Vasodilator-Stimulated Phosphoprotein Phosphorylation Index – Comparison with Light Transmittance Aggregometry.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1093-1093
Author(s):  
In-Suk Kim ◽  
Young-Hoon Jeong ◽  
Arum Kim ◽  
Gyeong-Won Lee
Keyword(s):  
Roc Curve ◽  
Platelet Reactivity ◽  
Flow Cytometric Analysis ◽  
Curve Analysis ◽  
Light Transmittance ◽  
Reactivity Index ◽  
Roc Curve Analysis ◽  
Flow Cytometric ◽  
Light Transmittance Aggregometry ◽  
P Index

Abstract Abstract 1093 Background Flow cytometric analysis of platelet reactivity index of vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P) is a suitable test to evaluate the “high post-treatment platelet reactivity (HPPR)”. A reliable cut-off of VASP-P index is needed to identify the HPPR. However, an ideal cut-off identifying HPPR using the VASP-P index remains undetermined. We aimed to show the comparison between light transmittance aggregometry (LTA) and flow cytometric analysis of VASP-P index and assess the cut-offs of identifying HPPR using VASP-P index. Methods We enrolled consecutively patients undergoing percutaneous coronary intervention (PCI) in real clinical practice (n = 516). They all received clopidogrel and aspirin, performed LTA (5 and 20 μmol/l ADP-induced, and 1.6 nmol/l arachidonic acid (AA)-induced PR) and flow cytometric analysis of VASP-P index simultaneously and compared the different platelet measures. Based on previously suggested cut-offs, 5 μmol/l ADP-induced maximal platelet reactivity (PRmax) > 42.9%, 5 μmol/l ADP-induced PRmax > 50%, 20 μmol/l ADP-induced PRmax > 62%, 20 μmol/l ADP-induced PRmax > 64.5%, and 1.6 mmol/l AA-induced PRmax > 20%, the cut-offs of identifying HPPR using flow cytometric analysis of VASP-P were determined by receiver-operating characteristics (ROC) curve analysis. Results Excellent correlations were observed between LTA with ADP-induced PRmax and flow cytometric analysis of VASP-P according to the ROC curve analyses. The ROC curve analyses demonstrated that 5 μmol/l ADP-induced PRmax > 42.9% could distinguish between patients with and without VASP-P index > 54.9% (area under curve [AUC] 0.926, 95% confidence interval (CI) 0.903–0.949, sensitivity 82.8%, and specificity 88.5%, p < 0.001) and 5 μmol/l ADP-induced PRmax > 50% could distinguish between patients with and without VASP-P index > 57.4% (AUC 0.937, 95% CI 0.914–0.961, sensitivity 91.5%, and specificity 85.2%, p < 0.001). ROC curve analysis demonstrated 20 μmol/l ADP-induced PRmax > 62% could distinguish between patients with and without VASP-P index > 55.2% (AUC 0.948, 95% CI 0.927–0.969, sensitivity 95.7%, and specificity 87.3%, p < 0.001) and 20 μmol/l ADP-induced PRmax > 64.5% could distinguish between patients with and without VASP-P index > 55.9% (AUC 0.925, 95% CI 0.900–0.951, sensitivity 88.3%, and specificity 83.0%, p < 0.001), respectively. However, fair correlation was observed between AA-induced PRmax and VASP-P index and 1.6 nmol/l AA-induced PRmax > 20% could distinguish between patients with and without VASP-P index > 52.4% (AUC 0.761, 95% CI 0.719–0.802, sensitivity 68.5%, and specificity 72.7%, p < 0.001). We defined the ideal threshold of VASP-P index > 56%. The VASP-P index > 56% showed a substantial agreement with 5 μmol/l and 20 μmol/l ADP-induced PRmax (Table 1). However, VASP-P index > 56% showed a moderate agreement with 1.6 nmol/l AA)-induced PRmax > 20% (Table 1). Conclusion There are significant correlations between the suggested cut-offs of HPPR. Because VASP-P index > 56 is well matched with 5 μmol/l ADP-induced PRmax > 42.9%, 5 μmol/l ADP-induced PRmax > 50%, 20 μmol/l ADP-induced PRmax > 62%, and 20 μmol/l ADP-induced PRmax > 64.5%., it might suggest that VASP-P index > 56 has a practical implication for stratification of high-risk ischemic events. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Head-to-Head Comparison of Consensus-Recommended Platelet Function Tests to Assess P2Y12 Inhibition—Insights for Multi-Center Trials

2020 ◽  
Vol 9 (2) ◽  
pp. 332
Author(s):  
Jean-Christophe Bélanger ◽  
Fabio Luiz Bandeira Ferreira ◽  
Mélanie Welman ◽  
Rahma Boulahya ◽  
Jean-François Tanguay ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Platelet Reactivity ◽  
Receptor Activation ◽  
P2y12 Receptor ◽  
Reactivity Index ◽  
Specific Method ◽  
Vasp Phosphorylation ◽  
Receptor Inhibitor

The vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation level is a highly specific method to assess P2Y12 receptor inhibition. Traditionally, VASP phosphorylation is analyzed by flow cytometry, which is laborious and restricted to specialized laboratories. Recently, a simple ELISA kit has been commercialized. The primary objective of this study was to compare the performance of VASP assessment by ELISA and flow cytometry in relation to functional platelet aggregation testing by Multiplate® whole-blood aggregometry. Blood from 24 healthy volunteers was incubated with increasing concentration of a P2Y12 receptor inhibitor (AR-C 66096). Platelet function testing was carried out simultaneously by Multiplate® aggregometry and by VASP assessment through ELISA and flow cytometry. As expected, increasing concentrations of the P2Y12 receptor inhibitor induced a proportional inhibition of platelet aggregation and P2Y12 receptor activation across the modalities. Platelet reactivity index values of both ELISA- and flow cytometry-based VASP assessment methods correlated strongly (r = 0.87, p < 0.0001) and showed minimal bias (1.05%). Correlation with Multiplate® was slightly higher for the flow cytometry-based VASP assay (r = 0.79, p < 0.0001) than for the ELISA-based assay (r = 0.69, p < 0.0001). Intraclass correlation (ICC) was moderate for all the assays tested (ICC between 0.62 and 0.84). However, categorization into low, optimal, or high platelet reactivity based on these assays was strongly concordant (κ between 0.86 and 0.92). In conclusion, the consensus-recommended assays with their standardized cut-offs should not be used interchangeably in multi-center clinical studies but, rather, they should be standardized throughout sites.

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