Publications by authors named "Ferenc Sarkady"

12 Publications

  • Page 1 of 1

Decreased clot burden is associated with factor XIII Val34Leu polymorphism and better functional outcomes in acute ischemic stroke patients treated with intravenous thrombolysis.

PLoS One 2021 7;16(7):e0254253. Epub 2021 Jul 7.

Division of Clinical Laboratory Sciences, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.

Background: Intravenous thrombolysis using recombinant tissue plasminogen activator remains the mainstay treatment of acute ischemic stroke (AIS), although endovascular treatment is becoming standard of care in case of large vessel occlusions (LVO). To quantify the thrombus burden in LVO, a semiquantitative CT angiography (CTA) grading system, the clot burden score (CBS) can be used. Here we aimed to study the association between CBS and various hemostasis parameters, and to evaluate which parameters are major determinants of thrombolysis outcome.

Methods: In this single-centered prospective observational case-control study, 200 anterior circulation AIS patients receiving intravenous thrombolysis treatment without thrombectomy were enrolled: 100 AIS patients with LVO (CBS 0-9) and 100 age- and sex-matched AIS patients without LVO (CBS 10). Fibrinogen, α2-plasmin inhibitor, plasminogen, factor XIII and D-dimer were assessed from blood samples taken before and 24 h after thrombolysis, and FXIII-A Val34Leu was genotyped. CBS was calculated using admission CTA. Short-term outcomes were defined based on the change in NIHSS by day 7, long-term outcomes were assessed according to the modified Rankin scale at 3 months post-event.

Results: Poor outcomes were significantly more frequent in the CBS 0-9 group. Plasminogen activity on admission was significantly higher in the CBS 0-9 group. In a univariate analysis, significant protective effect of the Leu34 allele against developing larger clots (CBS 0-9) could be demonstrated (OR:0.519; 95%CI:0.298-0.922, p = 0.0227). Multivariate regression analysis revealed that CBS is an independent predictor of short- and long-term functional outcomes, while such effect of the studied hemostasis parameters could not be demonstrated.

Conclusions: CBS was found to be a significant independent predictor of thrombolysis outcomes. FXIII-A Leu34 carrier status was associated with smaller thrombus burden, which is consistent with the in vitro described whole blood clot mass reducing effects of the allele, but the polymorphism had no effect on thrombolysis outcomes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0254253PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8263307PMC
July 2021

A modified in vitro clot lysis assay predicts outcomes and safety in acute ischemic stroke patients undergoing intravenous thrombolysis.

Sci Rep 2021 Jun 16;11(1):12713. Epub 2021 Jun 16.

Division of Clinical Laboratory Sciences, Department of Laboratory Medicine, Faculty of Medicine, Kálmán Laki Doctoral School, University of Debrecen, 98 Nagyerdei krt., Debrecen, 4032, Hungary.

The outcome of intravenous thrombolysis using recombinant tissue plasminogen activator (rt-PA) is only favorable in ≈ 40% of acute ischemic stroke (AIS) patients. Moreover, in ≈ 6-8% of cases, intracerebral hemorrhage (ICH) develops. We tested whether a modification of clot lysis assay (CLA), might predict therapy outcomes and safety. In this prospective observational study, blood samples of 231 AIS patients, all receiving intravenous rt-PA, were taken before thrombolysis. Cell-free DNA (cfDNA), CLA and CLA supplemented with cfDNA and histones (mCLA) were determined from the blood samples. Stroke severity was determined by NIHSS on admission. ICH was classified according to ECASSII. Short- and long-term outcomes were defined at 7 and 90 days post-event according to ΔNIHSS and by the modified Rankin Scale, respectively. Stroke severity demonstrated a step-wise positive association with cfDNA levels, while a negative association was found with the time to reach 50% lysis (50%CLT) parameter of CLA and mCLA. ROC analysis showed improved diagnostic performance of the mCLA. Logistic regression analysis proved that 50%CLT is a predictor of short-term therapy failure, while the AUC parameter predicts ICH occurrence. A modified CLA, supplemented with cfDNA and histones, might be a promising tool to predict short-term AIS outcomes and post-lysis ICH.
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http://dx.doi.org/10.1038/s41598-021-92041-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8208992PMC
June 2021

A Modified Clot Lysis Assay Predicts Outcomes in Non-traumatic Intracerebral Hemorrhage Stroke Patients-The IRONHEART Study.

Front Neurol 2021 20;12:613441. Epub 2021 Apr 20.

Division of Clinical Laboratory Sciences, Department of Laboratory Medicine, Faculty of Medicine, Kálmán Laki Doctoral School University of Debrecen, Debrecen, Hungary.

Non-traumatic intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes and results in a higher rate of mortality as compared to ischemic strokes. In the IRONHEART study, we aimed to find out whether a modified clot lysis assay method, that includes the effect of neutrophil extracellular traps (NETs) might predict ICH outcomes. In this prospective, observational study, 89 consecutive non-traumatic ICH patients were enrolled. Exclusion criteria included aneurysm rupture, cancer, liver- or kidney failure or hemorrhagic diathesis. On admission, detailed clinical and laboratory investigations were performed. ICH volume was estimated based on CT performed on admission, day 14 and 90. A conventional clot lysis assay (CLA) and a modified CLA (mCLA) including cell-free-DNA and histones were performed from stored platelet-free plasma taken on admission. Clot formation and lysis in case of both assays were defined using the following variables calculated from the turbidimetric curves: maximum absorbance, time to maximum absorbance, clot lysis times (CLT) and area under the curve (CLA AUC). Long-term ICH outcomes were defined 90 days post-event by the modified Rankin Scale (mRS). All patients or relatives provided written informed consent. Patients with more severe stroke (NIHSS>10) presented significantly shorter clot lysis times of the mCLA in the presence of DNA and histone as compared to patients with milder stroke [10%CLT: NIHSS 0-10: median 31.5 (IQR: 21.0-40.0) min vs. NIHSS>10: 24 (18-31.0) min, = 0.032]. Shorter clot lysis times of the mCLA showed significant association with non-survival by day 14 and with unfavorable long-term outcomes [mRS 0-1: 36.0 (22.5.0-51.0) min; mRS 2-5: 23.5 (18.0-36.0) min and mRS 6: 22.5 (18.0-30.5) min, = 0.027]. Estimated ICH volume showed significant negative correlation with mCLA parameters, including 10%CLT ( = -0.3050, = 0.009). ROC analysis proved good diagnostic performance of mCLA for predicting poor long-term outcomes [AUC: 0.73 (0.57-0.89)]. In a Kaplan-Meier survival analysis, those patients who presented with an mCLA 10%CLT result of >38.5 min on admission showed significantly better survival as compared to those with shorter clot lysis results (=0.010). Parameters of mCLA correlate with ICH bleeding volume and might be useful to predict ICH outcomes.
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http://dx.doi.org/10.3389/fneur.2021.613441DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8093390PMC
April 2021

Prognostic Value of Various Hemostasis Parameters and Neurophysiological Examinations in Spontaneous Intracerebral Hemorrhage: The IRONHEART Study Protocol.

Front Neurol 2021 17;12:615177. Epub 2021 Mar 17.

Department of Neurology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.

Stroke is one of the leading causes of death in all developed countries. In Hungary, more than 10,000 patients die annually due to cerebrovascular diseases according to the WHO Mortality Database. Of these patients, 10-15 % suffer non-traumatic intracerebral hemorrhage (ICH). ICH results in a higher rate of mortality as compared to ischemic stroke and outcomes are difficult to predict. In the IRONHEART study, we aim to test various hemostasis parameters and clinical neurophysiological examinations in evaluating outcome in ICH. In this prospective, observational study, we plan to enroll consecutive patients with non-traumatic spontaneous ICH admitted to a single Stroke Center (Department of Neurology, University of Debrecen, Hungary). The protocol of the IRONHEART study includes the investigation of detailed clinical, laboratory investigations, and various neurophysiological examinations. Stroke severity is quantified based on the National Institutes of Health Stroke Scale (NIHSS) on admission and day 7, 14, and 90 after the onset of stroke. Cranial CT is performed on admission, day 14, and 90 to estimate the ICH volume. Modified Rankin Scale (mRS) is used for evaluating the long-term outcome (90 days post-event). Blood is drawn immediately on admission for specific hemostasis tests. Digital and quantitative EEG techniques and motor evoked potential (MEP) are performed to evaluate the prognosis of cerebral hemorrhage on admission (within 24-48 h), immediately before discharge (~10-14 days later), and 3 months after the event. The following outcomes are investigated: primary outcomes: mortality by day 14 and day 90, secondary long-term outcome at 90 days post-event where mRS 0-2 is defined as favorable long-term outcome. If associations between outcomes and the investigated parameters (hemostasis and neurophysiological examinations) are confirmed, results might aid prognosis assessment in this subtype of stroke with particularly high mortality. Improving clinical grading systems on ICH severity and outcomes by including the investigated parameters could help to better guide the management of these patients in the future.
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http://dx.doi.org/10.3389/fneur.2021.615177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8010310PMC
March 2021

Incorporation of α2-Plasmin Inhibitor into Fibrin Clots and Its Association with the Clinical Outcome of Acute Ischemic Stroke Patients.

Biomolecules 2021 02 25;11(3). Epub 2021 Feb 25.

Division of Clinical Laboratory Science, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary.

Cross-linking of α2-plasmin inhibitor (α2-PI) to fibrin by activated factor XIII (FXIIIa) is essential for the inhibition of fibrinolysis. Little is known about the factors modifying α2-PI incorporation into the fibrin clot and whether the extent of incorporation has clinical consequences. Herein we calculated the extent of α2-PI incorporation by measuring α2-PI antigen levels from plasma and serum obtained after clotting the plasma by thrombin and Ca. The modifying effect of FXIII was studied by spiking of FXIII-A-deficient plasma with purified plasma FXIII. Fibrinogen, FXIII, α2-PI incorporation, in vitro clot-lysis, soluble fibroblast activation protein and α2-PI p.Arg6Trp polymorphism were measured from samples of 57 acute ischemic stroke patients obtained before thrombolysis and of 26 healthy controls. Increasing FXIII levels even at levels above the upper limit of normal increased α2-PI incorporation into the fibrin clot. α2-PI incorporation of controls and patients with good outcomes did not differ significantly (49.4 ± 4.6% vs. 47.4 ± 6.7%, = 1.000), however it was significantly lower in patients suffering post-lysis intracranial hemorrhage (37.3 ± 14.0%, = 0.004). In conclusion, increased FXIII levels resulted in elevated incorporation of α2-PI into fibrin clots. In stroke patients undergoing intravenous thrombolysis treatment, α2-PI incorporation shows an association with the outcome of therapy, particularly with thrombolysis-associated intracranial hemorrhage.
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http://dx.doi.org/10.3390/biom11030347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996613PMC
February 2021

Uninterrupted Dabigatran Administration Provides Greater Inhibition against Intracardiac Activation of Hemostasis as Compared to Vitamin K Antagonists during Cryoballoon Catheter Ablation of Atrial Fibrillation.

J Clin Med 2020 Sep 22;9(9). Epub 2020 Sep 22.

Department of Cardiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary.

Background: Cerebral thromboembolism is a rare but feared complication of transcatheter ablation in patients with atrial fibrillation (AF). Here, we aimed to test which pre-procedural anticoagulation strategy results in less intracardiac activation of hemostasis during ablation.

Patients And Methods: In this observational study, 54 paroxysmal/persistent AF patients undergoing cryoballoon ablation were grouped according to their periprocedural anticoagulation strategy: no anticoagulation (oral anticoagulation (OAC) free; = 24), uninterrupted vitamin K antagonists (VKA) ( = 11), uninterrupted dabigatran ( = 17). Blood was drawn from the left atrium before and immediately after the ablation procedure. Cryoablations were performed according to standard protocols, during which heparin was administered. Heparin-insensitive markers of hemostasis and endothelial damage were tested from intracardiac samples: D-dimer, quantitative fibrin monomer (FM), plasmin-antiplasmin complex (PAP), von Willebrand factor (VWF) antigen, chromogenic factor VIII (FVIII) activity.

Results: D-dimer increased significantly in all groups post-ablation, with lowest levels in the dabigatran group (median [interquartile range]: 0.27 [0.36] vs. 1.09 [1.30] and 0.74 [0.26] mg/L in OAC free and uninterrupted VKA groups, respectively, < 0.001). PAP levels were parallel to this observation. Post-ablation FM levels were elevated in OAC free (26.34 [30.04] mg/L) and VKA groups (10.12 [16.01] mg/L), but remained below cut-off in all patients on dabigatran (3.98 [2.0] mg/L; < 0.001). VWF antigen and FVIII activity increased similarly post-ablation in all groups, suggesting comparable procedure-related endothelial damage.

Conclusion: Dabigatran provides greater inhibition against intracardiac activation of hemostasis as compared to VKAs during cryoballoon catheter ablation.
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http://dx.doi.org/10.3390/jcm9093050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7563747PMC
September 2020

Intracardiac Fibrinolysis and Endothelium Activation Related to Atrial Fibrillation Ablation with Different Techniques.

Cardiol Res Pract 2020 12;2020:1570483. Epub 2020 Feb 12.

Institute of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.

Objective: The effect of pulmonary vein isolation (PVI) on fibrinolytic and endothelial activation with currently applied periprocedural anticoagulation has not been explored. We measured markers of fibrinolysis and endothelium activation before and after PVI with the second-generation cryoballoon (Cryo), pulmonary vein ablation catheter (PVAC-Gold), and irrigated radiofrequency (IRF).

Methods: Markers of fibrinolysis and endothelium activation in left atrial (LA) blood samples were measured in 31 patients before and after PVI (Cryo:10, PVAC-Gold: 7, IRF: 14). Periprocedural anticoagulation included uninterrupted vitamin K antagonist and iv heparin (ACT≥300 sec) during LA dwelling.

Results: Levels of (median; interquartile range, mgFEU/L) increased with all techniques (PVAC: 0.34; 0.24-0.50 versus 0.70; 0.61-1.31; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; (ng/ml) increased after Cryo (247.3, 199.9-331.6 versus 270.9, 227.9-346.7; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; (%) decreased with the PVAC (1.931; 0.508-3.859 versus 0.735, 0.240-2.707; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; and increased after PVI with all the 3 techniques. The levels of (ng/ml) did not change after PVAC procedures, but increased after Cryo (542, 6; 428.5-753.1 versus 619.2; 499.8-799.0; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93; =0.0313, Cryo: 0.33; 0.28-0.49 versus 0.79; 0.65-0.93.

Conclusion: PVI with contemporary ablation techniques and periprocedural antithrombotic treatment induces coagulation and endothelium activation of similar magnitude with different ablation methods.
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http://dx.doi.org/10.1155/2020/1570483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037955PMC
February 2020

PAI-1 5G/5G genotype is an independent risk of intracranial hemorrhage in post-lysis stroke patients.

Ann Clin Transl Neurol 2019 11 21;6(11):2240-2250. Epub 2019 Oct 21.

Faculty of Medicine, Department of Laboratory Medicine, Division of Clinical Laboratory Sciences, University of Debrecen, 98 Nagyerdei krt., Debrecen, 4032, Hungary.

Objective: Thrombolysis by recombinant tissue plasminogen activator (rt-PA) is the main pharmacological therapy in acute ischemic stroke (IS); however, it is only effective in a subset of patients. Here we aimed to investigate the role of plasminogen activator inhibitor-1 (PAI-1), an effective inhibitor of t-PA, and its major polymorphism (PAI-1 4G/5G) in therapy outcome.

Methods: Study population included 131 consecutive IS patients who all underwent thrombolysis. Blood samples were taken on admission, 1 and 24 h after rt-PA infusion. PAI-1 activity and antigen levels were measured from all blood samples and the PAI-1 4G/5G polymorphism was determined. Clinical data including NIHSS were registered on admission and day 1. ASPECTS was assessed using CT images taken before and 24 h after thrombolysis. Intracranial hemorrhage (ICH) was classified according to ECASS II. Long-term outcome was defined 90 days post-event by the modified Rankin Scale (mRS).

Results: PAI-1 activity levels dropped transiently after thrombolysis, while PAI-1 antigen levels remained unchanged. PAI-1 4G/5G polymorphism had no effect on PAI-1 levels and did not influence stroke severity. PAI-1 activity/antigen levels as measured on admission were significantly elevated in patients with worse 24 h ASPECTS (<7). Logistic regression analysis including age, sex, NIHSS on admission, BMI, history of arterial hypertension, and hyperlipidemia conferred a significant, independent risk for developing ICH in the presence of 5G/5G genotype (OR:4.75, 95%CI:1.18-19.06). PAI-1 levels and PAI-1 4G/5G polymorphism had no influence on long-term outcomes.

Interpretation: PAI-1 5G/5G genotype is associated with a significant risk for developing ICH in post-lysis stroke patients.
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http://dx.doi.org/10.1002/acn3.50923DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856768PMC
November 2019

Elevated Factor VIII and von Willebrand Factor Levels Predict Unfavorable Outcome in Stroke Patients Treated with Intravenous Thrombolysis.

Front Neurol 2017 23;8:721. Epub 2018 Jan 23.

Division of Clinical Laboratory Sciences, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.

Introduction: Plasma factor VIII (FVIII) and von Willebrand factor (VWF) levels have been associated with the rate and severity of arterial thrombus formation and have been linked to outcomes following thrombolytic therapy in acute myocardial infarction patients. Here, we aimed to investigate FVIII and VWF levels during the course of thrombolysis in acute ischemic stroke (AIS) patients and to find out whether they predict long-term outcomes.

Materials And Methods: Study population included 131 consecutive AIS patients (median age: 69 years, 60.3% men) who underwent i.v. thrombolysis with recombinant tissue plasminogen activator (rt-PA). Blood samples were taken on admission, 1 and 24 h after rt-PA administration to measure FVIII activity and VWF antigen levels. Neurological deficit of patients was determined according to the National Institutes of Health Stroke Scale (NIHSS). ASPECT scores were assessed using computer tomography images taken before and 24 h after thrombolysis. Intracranial hemorrhage was classified according to the European Cooperative Acute Stroke Study (ECASS) II criteria. Long-term functional outcome was determined at 90 days after the event by the modified Rankin scale (mRS).

Results: VWF levels on admission were significantly elevated in case of more severe AIS [median and IQR values: NIHSS <6:189.6% (151.9-233.2%); NIHSS 6-16: 199.6% (176.4-250.8%); NIHSS >16: 247.8% (199.9-353.8%),  = 0.013]; similar, but non-significant trend was observed for FVIII levels. FVIII and VWF levels correlated well on admission ( = 0.748,  < 0.001) but no significant correlation was found immediately after thrombolysis ( = 0.093,  = 0.299), most probably due to plasmin-mediated FVIII degradation. VWF levels at all investigated occasions and FVIII activity before and 24 h after thrombolysis were associated with worse 24 h post-lysis ASPECT scores. In a binary backward logistic regression analysis including age, gender, high-sensitivity C-reactive protein, active smoking, diabetes, and NIHSS >5 on admission, elevated FVIII and VWF levels after thrombolysis were independently associated with poor functional outcomes (mRS ≥ 3) at 90 days (immediately after thrombolysis: FVIII: OR: 7.10, 95% CI: 1.77-28.38,  = 0.006, VWF: OR: 6.31, 95% CI: 1.83-21.73,  = 0.003; 24 h after thrombolysis: FVIII: OR: 4.67, 95% CI: 1.42-15.38,  = 0.011, VWF: OR: 19.02, 95% CI: 1.94-186.99,  = 0.012).

Conclusion: Elevated FVIII activity and VWF antigen levels immediately after lysis and at 24 h post-therapy were shown to have independent prognostic values regarding poor functional outcomes at 90 days.
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http://dx.doi.org/10.3389/fneur.2017.00721DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5787073PMC
January 2018

Intracardiac Hemostasis and Fibrinolysis Parameters in Patients with Atrial Fibrillation.

Biomed Res Int 2017 21;2017:3678017. Epub 2017 Jun 21.

Division of Clinical Laboratory Sciences, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.

Aims: To identify intracardiac hemostasis or fibrinolysis abnormalities, which are associated with atrial fibrillation (AF) and increase the risk of thromboembolism.

Patients And Methods: Patient group consisted of 24 patients with AF and control group included 14 individuals with other supraventricular tachycardia undergoing transcatheter radiofrequency ablation. Blood samples were drawn from the femoral vein (FV), left atrium (LA), and left atrial appendage (LAA) before the ablation procedure. Fibrinogen, factor VIII (FVIII) and factor XIII activity, von Willebrand factor (VWF) antigen, thrombin-antithrombin (TAT) complex, quantitative fibrin monomer (FM), plasminogen, -plasmin inhibitor, plasmin--antiplasmin (PAP) complex, PAI-1 activity, and D-dimer were measured from all samples.

Results: Levels of FVIII and VWF were significantly elevated in the FV and LA of AF patients as compared to controls. TAT complex, FM, PAP complex, and D-dimer levels were significantly elevated in the LA as compared to FV samples in case of both groups, indicating a temporary thrombotic risk associated with the catheterization procedure.

Conclusions: None of the investigated hemostasis or fibrinolysis parameters showed significant intracardiac alterations in AF patients as compared to non-AF controls. AF patients have elevated FVIII and VWF levels, most likely due to endothelial damage, presenting at both intracardiac and systemic level.
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http://dx.doi.org/10.1155/2017/3678017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5497646PMC
April 2018

How to test the effect of aspirin and clopidogrel in patients on dual antiplatelet therapy?

Platelets 2016 17;27(1):59-65. Epub 2015 Jun 17.

a Division of Clinical Laboratory Sciences, Faculty of Medicine , University of Debrecen , Debrecen , Hungary .

Dual antiplatelet therapy with clopidogrel and aspirin is frequently used for the prevention of recurrent ischemic events. Various laboratory methods are used to detect the effect of these drugs administered in monotherapy, however their value in dual therapy has not been explored. Here, we determined which methods used for testing the effect of clopidogrel or aspirin are influenced by the other antiplatelet agent. One arm of the study included 53 ischemic stroke patients being on clopidogrel monotherapy showing effective inhibition of the P2Y12 ADP receptor. Laboratory tests routinely used for the detection of aspirin resistance (arachidonic acid (AA)-induced platelet aggregation/secretion, AA-induced thromboxane B2 (TXB2) production in platelet-rich plasma and VerifyNow Aspirin assay) were carried out on samples obtained from these patients. The other arm of the study involved 52 patients with coronary artery disease being on aspirin monotherapy. Methods used for testing the effect of clopidogrel (ADP-induced platelet aggregation and secretion, flow cytometric analysis of vasodilator-stimulated phosphoprotein (VASP) phosphorylation and a newly developed P2Y12-specific platelet aggregation (ADP[PGE1] test)) were performed on samples obtained from these patients. Clopidogrel monotherapy significantly inhibited AA-induced platelet aggregation and secretion, moreover, AA-induced TXB2 production was also significantly decreased. VASP phosphorylation and AA-induced platelet aggregation showed fair correlation in patients taking clopidogrel only. Clopidogrel did not inhibit the VerifyNow Aspirin test significantly. Aspirin monotherapy influenced ADP-induced platelet aggregation and secretion, but did not have an effect on VASP phosphorylation and on the ADP[PGE1] platelet aggregation test.
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http://dx.doi.org/10.3109/09537104.2015.1031098DOI Listing
October 2016

Comparison of a new P2Y12 receptor specific platelet aggregation test with other laboratory methods in stroke patients on clopidogrel monotherapy.

PLoS One 2013 2;8(7):e69417. Epub 2013 Jul 2.

Clinical Research Center, University of Debrecen, Medical and Health Science Center, Debrecen, Hungary.

Background: Clinical studies suggest that 10-50% of patients are resistant to clopidogrel therapy. ADP induced platelet aggregation, a widely used test to monitor clopidogrel therapy, is affected by aspirin and is not specific for the P2Y12 receptor inhibited by clopidogrel.

Objectives: To develop a P2Y12-specific platelet aggregation test and to compare it with other methods used for monitoring clopidogrel therapy.

Patients/methods: Study population included 111 patients with the history of ischemic stroke being on clopidogrel monotherapy and 140 controls. The effect of clopidogrel was tested by a newly developed ADP(PGE1) aggregation test in which prostaglandin E1 treated platelets are used. Results of conventional ADP induced platelet aggregation, VerifyNow P2Y12 assay and ADP(PGE1) aggregation were compared to those obtained by flow cytometric analysis of vasodilator stimulated phosphoprotein (VASP) phosphorylation. Reference intervals for all assays were determined according to the guidelines of Clinical Laboratory Standards Institute.

Results: The P2Y12-specificity of ADP(PGE1) test was proven by comparing it with ADP aggregation in the presence of P2Y1 antagonist, adenosine 3', 5'-diphosphate. The method was not influenced by aspirin treatment. Approximately 50% of patients were clopidogrel resistant by conventional ADP aggregation and VerifyNow tests. The ADP(PGE1) method and the VASP phosphorylation assay identified 25.9% and 11.7% of patients as non-responders, respectively. ADP(PGE1) aggregation showed good correlation with VASP phosphorylation and had high diagnostic efficiency.

Conclusion: The new ADP(PGE1) method is a reliable test for monitoring P2Y12 receptor inhibition by platelet aggregation. As a subset of patients are non-responders, monitoring clopidogrel therapy by adequate methods is essential.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0069417PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3699657PMC
February 2014
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