Publications by authors named "Elisabeth Mahla"

37 Publications

Procalcitonin measurement by Diazyme™ immunturbidimetric and Elecsys BRAHMS™ PCT assay on a Roche COBAS modular analyzer.

Clin Chem Lab Med 2021 Mar 12. Epub 2021 Mar 12.

Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria.

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http://dx.doi.org/10.1515/cclm-2020-1541DOI Listing
March 2021

Supplemental Fibrinogen Restores Platelet Inhibitor-Induced Reduction in Thrombus Formation without Altering Platelet Function: An In Vitro Study.

Thromb Haemost 2020 Nov 9;120(11):1548-1556. Epub 2020 Aug 9.

Otto Loewi Research Center, Division of Pharmacology Medical University of Graz, Graz, Austria.

Background:  For patients treated with dual antiplatelet therapy, standardized drug-specific 3-to-7 day cessation is recommended prior to major surgery to reach sufficient platelet function recovery. Here we investigated the hypothesis that supplemental fibrinogen might mitigate the inhibitory effects of antiplatelet therapy.

Methods And Results:  To this end blood from healthy donors was treated in vitro with platelet inhibitors, and in vitro thrombus formation and platelet activation were assessed. Ticagrelor, acetylsalicylic acid, the combination of both, and tirofiban all markedly attenuated the formation of adherent thrombi, when whole blood was perfused through collagen-coated microchannels at physiological shear rates. Addition of fibrinogen restored in vitro thrombus formation in the presence of antiplatelet drugs and heparin. However, platelet activation, as investigated in assays of P-selectin expression and calcium flux, was not altered by fibrinogen supplementation. Most importantly, fibrinogen was able to restore in vitro thrombogenesis in patients on maintenance dual antiplatelet therapy after percutaneous coronary intervention.

Conclusion:  Thus, our in vitro data support the notion that supplementation of fibrinogen influences the perioperative hemostasis in patients undergoing surgery during antiplatelet therapy by promoting thrombogenesis without significantly interfering with platelet activation.
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http://dx.doi.org/10.1055/s-0040-1715445DOI Listing
November 2020

How Do Type of Preoperative P2Y Receptor Inhibitor and Withdrawal Time Affect Bleeding?

Ann Thorac Surg 2021 01 18;111(1):77-84. Epub 2020 Jun 18.

Division of Anesthesiology for Cardiovascular Surgery and Intensive Care Medicine, Medical University of Graz, Graz, Austria.

Background: Despite recommendations for standardized preoperative waiting of at least 3, 5, and 7 days for ticagrelor, clopidogrel, and prasugrel, respectively, there is still substantial interinstitutional variation in preoperative discontinuation of dual antiplatelet therapy in patients needing coronary artery bypass grafting (CABG).

Methods: In 299 patients undergoing CABG with or without valve intervention less than 7 days after last P2Y receptor inhibition, this study evaluated calculated red blood cell loss and Bleeding Academic Research Consortium type 4 (BARC-4) bleeding.

Results: A total of 83% of patients underwent CABG less than 48 hours after last drug intake. Calculated blood loss was lower in patients taking clopidogrel as compared with prasugrel or ticagrelor (1063 mL [690 to 1394 mL] vs 1351 mL [876 to 1829 mL] vs 1330 mL [994 to 1691 mL]; P < .001). Overall, 135 (45%) patients sustained BARC-4 bleeding; the incidence differed among the groups (P = .015) and was significantly higher in prasugrel-treated patients, as compared with clopidogrel-treated patients. In multivariable linear regression analysis, European System for Cardiac Operative Risk Evaluation II (EuroSCORE II), aspirin dose, cardiopulmonary bypass time, drug withdrawal time, and type of P2Y receptor inhibitor were significantly associated with red blood cell loss. Compared with 0 to 24 hours, a period of more than 48 hours of preoperative discontinuation substantially reduced calculated blood loss by 37% to 48% and BARC-4 bleeding by 58% to 71%, depending on the P2Y receptor inhibitor.

Conclusions: Exposure to prasugrel and ticagrelor 24 hours or less before CABG increases both calculated blood loss and BARC-4 bleeding as compared with clopidogrel. Although discontinuation for longer than 48 hours substantially reduced calculated blood loss and BARC-4 bleeding across all P2Y receptor inhibitors, our single-center data further support strict adherence to the 2017 guidelines whenever justified by stable hemodynamics and nonjeopardized myocardium.
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http://dx.doi.org/10.1016/j.athoracsur.2020.04.126DOI Listing
January 2021

Is There a Role for Preoperative Platelet Function Testing in Patients Undergoing Cardiac Surgery During Antiplatelet Therapy?

Circulation 2018 11;138(19):2145-2159

Inova Center for Thrombosis Research and Drug Development, Inova Heart and Vascular Institute, Falls Church, VA (U.S.T., P.A.G.).

Up to 11% of patients presenting with acute coronary syndromes undergo coronary artery bypass grafting. Guidelines largely recommend a one-size-fits-all preoperative discontinuation period for P2Y receptor blockers to avoid bleeding. These recommendations do not account for highly variable pharmacodynamic responsiveness and for variable recovery of platelet reactivity following discontinuation of P2Y receptor blockers. Several observational studies have demonstrated that an objective measurement of platelet function among these patients may reduce the waiting period while mitigating the risk of bleeding. Based on these findings, 2 recent guidelines included a Class IIa and IIb recommendation for platelet function testing in patients undergoing cardiac surgery. The following review article describes the rationale for discontinuation of dual antiplatelet therapy before cardiac surgery and the limitations with this approach, available platelet function assays to assess pharmacodynamic effects, and the association between platelet inhibition and other clinical factors with surgery-related bleeding. The information will assist the reader in determining which patients undergoing cardiac surgery might benefit from preoperative platelet function monitoring.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.118.035160DOI Listing
November 2018

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

Thromb Haemost 2018 05 6;118(5):864-872. Epub 2018 Apr 6.

Inova Center for Thrombosis Research and Drug Development, Inova Heart and Vascular Institute, Falls Church, Virginia, United States.

Nearly 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 ( = 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.
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http://dx.doi.org/10.1055/s-0038-1641153DOI Listing
May 2018

Pneumatic tube system transport does not alter platelet function in optical and whole blood aggregometry, prothrombin time, activated partial thromboplastin time, platelet count and fibrinogen in patients on anti-platelet drug therapy.

Biochem Med (Zagreb) 2017 Feb;27(1):217-224

Clinical Institute of Medical and Laboratory Diagnostics, Medical University Graz, Graz, Austria; Research Unit "Perioperative Platelet Function", Medical University of Graz, Graz, Austria.

Introduction: The aim of this study was to assess pneumatic tube system (PTS) alteration on platelet function by the light transmission aggregometry (LTA) and whole blood aggregometry (WBA) method, and on the results of platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen.

Materials And Methods: Venous blood was collected into six 4.5 mL VACUETTE® 9NC coagulation sodium citrate 3.8% tubes (Greiner Bio-One International GmbH, Kremsmünster, Austria) from 49 intensive care unit (ICU) patients on dual anti-platelet therapy and immediately hand carried to the central laboratory. Blood samples were divided into 2 Groups: Group 1 samples (N = 49) underwent PTS (4 m/s) transport from the central laboratory to the distant laboratory and back to the central laboratory, whereas Group 2 samples (N = 49) were excluded from PTS forces. In both groups, LTA and WBA stimulated with collagen, adenosine-5'-diphosphate (ADP), arachidonic acid (AA) and thrombin-receptor-activated-peptide 6 (TRAP-6) as well as platelet count, PT, APTT, and fibrinogen were performed.

Results: No statistically significant differences were observed between blood samples with (Group 1) and without (Group 2) PTS transport (P values from 0.064 - 0.968). The AA-induced LTA (bias: 68.57%) exceeded the bias acceptance limit of ≤ 25%.

Conclusions: Blood sample transportation with computer controlled PTS in our hospital had no statistically significant effects on platelet aggregation determined in patients with anti-platelet therapy. Although AA induced LTA showed a significant bias, the diagnostic accuracy was not influenced.
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http://dx.doi.org/10.11613/BM.2017.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5382865PMC
February 2017

To stop or continue aspirin before aortocoronary bypass operations-do we have enough evidence to adequately guide us?

J Thorac Dis 2016 Jul;8(7):E578-80

Inova Center for Thrombosis Research and Drug Development, Inova Heart and Vascular Institute, Falls Church, VA, USA.

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http://dx.doi.org/10.21037/jtd.2016.05.19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4958850PMC
July 2016

Does Platelet Reactivity Predict Bleeding in Patients Needing Urgent Coronary Artery Bypass Grafting During Dual Antiplatelet Therapy?

Ann Thorac Surg 2016 Dec 1;102(6):2010-2017. Epub 2016 Jul 1.

Inova Center for Thrombosis Research and Drug Development, Inova Heart and Vascular Institute, Falls Church, Virginia. Electronic address:

Background: Up to 15% of patients require coronary artery bypass grafting (CABG) during dual antiplatelet therapy. Available evidence suggests an association between platelet reactivity and CABG-related bleeding. However, platelet reactivity cutoffs for bleeding remain elusive. We sought to explore the association between platelet reactivity and bleeding.

Methods: Patients on aspirin and a P2Y receptor inhibitor within 48 hours before isolated CABG (n = 149) were enrolled in this prospective study. Blood was drawn 2 to 4 hours preoperatively and platelet reactivity assessed by light transmittance aggregometry (LTA), vasodilator-stimulated phosphoprotein (VASP) assay, Multiplate analyzer and Innovance PFA2Y. The primary endpoint was calculated red blood cell loss computed as follows: (blood volume × preoperative hematocrit × 0.91) - (blood volume × hematocrit × 0.91 on postoperative day 5) + (mL of transfused red blood cells × 0.59).

Results: Preoperative platelet reactivity was low [median (interquartile range): LTA: 20 (9-28)%; VASP-PRI: 39 (15-73)%; Multiplate adenosine phosphate test: 16 (12-22) U∗min]. Innovance PFA2Y ≥300 seconds, 72%. Median (IQR) red blood cell loss in patients in first the LTA tertile was 1,449 (1,020 to 1,754) mL compared with 1,107 (858 to 1,512) mL and 1,075 (811 to 1,269) mL in those in the second and third tertiles, respectively (p < 0.004). Bleeding Academic Research Consortium (BARC)-4 bleeding differed between tertiles (62% versus 46% versus 36%; p = 0.037). In a multivariable linear regression model, aspirin dose ≥300 mg, cardiopulmonary bypass time, EuroSCORE, and tertile distribution of platelet reactivity were significantly associated with red blood cell loss.

Conclusions: A gradual decrease in red blood cell loss and BARC-4 bleeding occurs with increasing platelet reactivity in patients on antiplatelet therapy undergoing CABG. Our findings support current guidelines to determine time of surgery based on an objective measurement of platelet function (Platelet Inhibition and Bleeding in Patients Undergoing Emergent Cardiac Surgery; clinicaltrials.gov NCT01468597).
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http://dx.doi.org/10.1016/j.athoracsur.2016.05.003DOI Listing
December 2016

Timing of Coronary Bypass Surgery in Patients Receiving Clopidogrel: The Role of VerifyNow.

Can J Cardiol 2016 06 8;32(6):724-5. Epub 2016 Feb 8.

Medizinische Universitat Graz, Graz, Austria.

We briefly report for the first time the association between a point of care platelet recovery test and the timing of coronary artery bypass grafting after clopidogrel withdrawal. We observe an association between suggested wait days and platelet recovery unit values that might potentially allow for safe shorter wait times before coronary artery bypass grafting without increased bleeding. Our results represent an observation and should prompt further validation.
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http://dx.doi.org/10.1016/j.cjca.2016.01.038DOI Listing
June 2016

Predicting the occurrence of major adverse cardiac events within 30 days of a vascular surgery: an empirical comparison of the minimum p value method and ROC curve approach using individual patient data meta-analysis.

Springerplus 2016 9;5:304. Epub 2016 Mar 9.

Department of Clinical Epidemiology and Biostatistics, McMaster University, Health Sciences Centre, Room 2C7, 1280 Main Street West, Hamilton, ON L8S 4K1 Canada ; Population Health Research Institute, Hamilton Health Sciences, Hamilton, ON Canada ; Biostatistics Unit, St Joseph's Healthcare, Hamilton, ON Canada ; Departments of Paediatrics and Anaesthesia, McMaster University, Hamilton, ON Canada ; Centre for Evaluation of Medicine, St Joseph's Healthcare, Hamilton, ON Canada.

We aimed to compare the minimum p value method and the area under the receiver operating characteristics (ROC) curve approach to categorize continuous biomarkers for the prediction of postoperative 30-day major adverse cardiac events in noncardiac vascular surgery patients. Individual-patient data from six cohorts reporting B-type natriuretic peptide (BNP) or N-terminal pro-B-type natriuretic peptide (NTproBNP) were obtained. These biomarkers were dichotomized using the minimum p value method and compared with previously reported ROC curve-derived thresholds using logistic regression analysis. A final prediction model was developed, internally validated, and assessed for its sensitivity to clustering effects. Finally, a preoperative risk score system was proposed. Thresholds identified by the minimum p value method and ROC curve approach were 115.57 pg/ml (p < 0.001) and 116 pg/ml for BNP, and 241.7 pg/ml (p = 0.001) and 277.5 pg/ml for NTproBNP, respectively. The minimum p value thresholds were slightly stronger predictors based on our logistic regression analysis. The final model included a composite predictor of the minimum p value method's BNP and NTproBNP thresholds [odds ratio (OR) = 8.5, p < 0.001], surgery type (OR = 2.5, p = 0.002), and diabetes (OR = 2.1, p = 0.015). Preoperative risks using the scoring system ranged from 2 to 49 %. The minimum p value method and ROC curve approach identify similar optimal thresholds. We propose to replace the revised cardiac risk index with our risk score system for individual-specific preoperative risk stratification after noncardiac nonvascular surgery.
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http://dx.doi.org/10.1186/s40064-016-1936-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4783313PMC
April 2016

Autologous Platelet-Rich Plasma Preparations: Influence of Nonsteroidal Anti-inflammatory Drugs on Platelet Function.

Orthop J Sports Med 2015 Jun 23;3(6):2325967115588896. Epub 2015 Jun 23.

Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria. ; Research Unit for Perioperative Platelet Function, Medical University of Graz, Graz, Austria.

Background: Autologous platelet-rich plasma (PRP) has been widely used for the treatment of sports injuries. It has been associated with improved healing and regeneration of soft tissues in elite athletes. Athletes are commonly receiving nonsteroidal anti-inflammatory drugs (NSAIDs). As yet, the effect of these drugs on platelet function in PRP formulations has not been taken into consideration.

Hypothesis: The function of platelets in PRP produced under the influence of NSAIDs is inhibited and may lessen a possible healing effect on the site of injury.

Study Design: Controlled laboratory study.

Methods: PRP was collected from patients receiving NSAIDs after elective orthopaedic surgery, and platelet function was evaluated using light transmission aggregometry (LTA). Results were compared with those obtained from healthy volunteers without a history of NSAID intake during the previous 2 weeks. Two different systems for blood collection and PRP production (Arthrex ACP double-syringe system and standard 4.5-mL sodium citrate blood collection tubes) were used and compared regarding the quality of PRP that was produced.

Results: For both groups, the baseline platelet counts of whole blood and the platelet counts of PRP formulations were found to be in the normal range. Both collection systems for PRP produced comparable results without significant differences between the groups. Platelet function testing with LTA revealed significantly impaired platelet aggregation in both PRP preparations, obtained from patients taking NSAIDs, irrespective of the type of NSAID (P < .001). All subjects from the control group showed normal platelet aggregation patterns when tested with LTA.

Conclusion: Autologous PRP produced from subjects after NSAID medication shows significantly impaired platelet function and may result in lower quality regarding the content of bioactive compounds.

Clinical Relevance: If required, the administration of NSAIDs should be performed after blood collection for preparation of autologous PRP; otherwise, the therapeutic effect may be limited.
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http://dx.doi.org/10.1177/2325967115588896DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4622369PMC
June 2015

Comparison of functional fibrinogen (FF/CFF) and FIBTEM in surgical patients - a retrospective study.

Clin Chem Lab Med 2016 Mar;54(3):453-8

Background: Fibrinogen-based clot firmness is reported as the maximum amplitude (MA) when using the citrated functional fibrinogen (CFF) assay in thrombelastography (TEG), and as the maximum clot firmness (MCF) together with several clot amplitude parameters when using the FIBTEM assay in thromboelastometry (ROTEM). Concern is currently being raised that these two tests have different platelet inhibiting performance and consequently provide different values. This is relevant for the clinical setting of fibrinogen replacement. We aim herein to compare the parameters of these two fibrinogen-based clot quality tests and their correlation with the plasma fibrinogen level as determined by the Clauss method.

Methods: In total 261 whole blood samples taken from 163 clinical routine surgical patients were analyzed with TEG 5000 and ROTEM tests, and correlation with Clauss fibrinogen level was assessed.

Results: Using TEG, the overall fibrin-based clot firmness measured in the CFF assay was significantly higher than the MCF measured by FIBTEM assay. Both assays showed significantly positive correlations with the fibrinogen levels measured using the Clauss method. However, individual values of Clauss fibrinogen concentration corresponded with different values for the two viscoelastometric tests; e.g. within the range of 1.9-2.1 g/L Clauss fibrinogen the median of CFF MA was 16.3 mm whereas FIBTEM MCF was 12.0 mm.

Conclusions: We showed herein by measurements of citrated whole blood samples from surgical patients that CFF MA values were different from FIBTEM MCF values measured in the same sample. Awareness that these whole blood assays provide different clot amplitude results is mandatory, particularly if they are being considered as tools for guiding fibrinogen supplementation. Thromboembolic side effects caused by a potentially too high fibrinogen substitution must also kept in mind in this context.
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http://dx.doi.org/10.1515/cclm-2015-0345DOI Listing
March 2016

N-terminal pro-B-type Natriuretic Peptides' Prognostic Utility Is Overestimated in Meta-analyses Using Study-specific Optimal Diagnostic Thresholds.

Anesthesiology 2015 Aug;123(2):264-71

From the Department of Anaesthesia, University of Kwa-Zulu Natal, Inkosi Albert Luthuli Central Hospital, Durban, South Africa (D.P., D.S.); Department of Anaesthesia, Greys Hospital, Pietermaritzburg, South Africa (L.R.); Department of Anaesthetics, Inkosi Albert Luthuli Central Hospital, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa (B.M.B.); Department of Anaesthesia and Intensive Care Medicine, University Hospital Basel, Basel, Switzerland (G.A.L.-B.); Cardioncology Unit, European Institute of Oncology, Milan, Italy (D.M.C.); Departments of Aged Care, Northern Clinical Research Centre, The Northern Hospital, Epping, Victoria, Australia, and Department of Medicine, Austin and Northern Health, The University of Melbourne, Victoria, Australia (C.P.W.C., K.W.L.); Department of Vascular and General Surgery and Angiology, Pomeranian Medical University, Szczecin, Poland (M.C.); Department of Anaesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, Austria (S.I.F., E.M.); Department for Anesthesia and Intensive Care, Clinic for Cardiovascular and Thoracic Surgery, Clinical Center Nis, School of Medicine, University of Nis, Nis, Serbia (R.J.J.); Departments of Urology, Stepping Hill Hospital, Stockport and Wrightington, Wigan, and Leigh NHS Foundation Trust, Wigan, United Kingdom (R.M.); Department of Medicine and Health, Linköping University and Department of Anaesthesiology and Intensive Care, Linköping University Hospital, Linköping, Sweden (A.O.); Department of General Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas (M.P.P.); Department of Vascular Surgery, University of Aberdeen and Aberdeen Royal Infirmary, NHS Grampian, Foresterhill, Aberdeen, United Kingdom (S.R.); Department of Cardio logy, University of Melbourne, Northern Health, Epping, Victoria, Australia (W.J.V.G.); Cardiac Diagnostics Unit, M. Pirogow Provincial Specialist Hospital, Lodz, Poland (M.W.); and D

Background: N-terminal fragment B-type natriuretic peptide (NT-proBNP) prognostic utility is commonly determined post hoc by identifying a single optimal discrimination threshold tailored to the individual study population. The authors aimed to determine how using these study-specific post hoc thresholds impacts meta-analysis results.

Methods: The authors conducted a systematic review of studies reporting the ability of preoperative NT-proBNP measurements to predict the composite outcome of all-cause mortality and nonfatal myocardial infarction at 30 days after noncardiac surgery. Individual patient-level data NT-proBNP thresholds were determined using two different methodologies. First, a single combined NT-proBNP threshold was determined for the entire cohort of patients, and a meta-analysis conducted using this single threshold. Second, study-specific thresholds were determined for each individual study, with meta-analysis being conducted using these study-specific thresholds.

Results: The authors obtained individual patient data from 14 studies (n = 2,196). Using a single NT-proBNP cohort threshold, the odds ratio (OR) associated with an increased NT-proBNP measurement was 3.43 (95% CI, 2.08 to 5.64). Using individual study-specific thresholds, the OR associated with an increased NT-proBNP measurement was 6.45 (95% CI, 3.98 to 10.46). In smaller studies (<100 patients) a single cohort threshold was associated with an OR of 5.4 (95% CI, 2.27 to 12.84) as compared with an OR of 14.38 (95% CI, 6.08 to 34.01) for study-specific thresholds.

Conclusions: Post hoc identification of study-specific prognostic biomarker thresholds artificially maximizes biomarker predictive power, resulting in an amplification or overestimation during meta-analysis of these results. This effect is accentuated in small studies.
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http://dx.doi.org/10.1097/ALN.0000000000000728DOI Listing
August 2015

High Residual Collagen-Induced Platelet Reactivity Predicts Development of Restenosis in the Superficial Femoral Artery After Percutaneous Transluminal Angioplasty in Claudicant Patients.

Cardiovasc Intervent Radiol 2016 Feb 8;39(2):190-4. Epub 2015 Jul 8.

Division of Angiology, Department of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036, Graz, Austria.

Purpose: Although platelet reactivity is routinely inhibited with aspirin after percutaneous angioplasty (PTA) in peripheral arteries, the restenosis rate in the superficial femoral artery (SFA) is high. Interaction of activated platelets and the endothelium in the region of intervention could be one reason for this as collagen in the subendothelium activates platelets.

Materials And Methods: A prospective study evaluating on-site platelet reactivity during PTA and its influence on the development of restenosis with a total of 30 patients scheduled for PTA of the SFA. Arterial blood was taken from the PTA site after SFA; platelet function was evaluated with light transmission aggregometry. After 3, 6, 12, and 24 months, duplex sonography was performed and the restenosis rate evaluated.

Results: Eight out of 30 patients developed a hemodynamically relevant restenosis (>50 % lumen narrowing) in the PTA region during the 24-month follow-up period. High residual collagen-induced platelet reactivity defined as AUC >30 was a significant predictor for the development of restenosis [adjusted odds ratio 11.8 (9.4, 14.2); P = .04].

Conclusions: High residual collagen-induced platelet reactivity at the interventional site predicts development of restenosis after PTA of the SFA. Platelet function testing may be useful for identifying patients at risk.
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http://dx.doi.org/10.1007/s00270-015-1172-6DOI Listing
February 2016

Platelet Function Testing Before CABG is Recommended in the Guidelines: But Do We Have Enough Evidence?

J Interv Cardiol 2015 Jun;28(3):233-5

Sinai Center for Thrombosis Research, Sinai Hospital of Baltimore, Maryland.

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http://dx.doi.org/10.1111/joic.12194DOI Listing
June 2015

Impact of preoperative use of P2Y12 receptor inhibitors on clinical outcomes in cardiac and non-cardiac surgery: A systematic review and meta-analysis.

Eur Heart J Acute Cardiovasc Care 2017 Dec 5;6(8):753-770. Epub 2015 May 5.

8 Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, College of Medicine Rochester, USA.

Objective: To review systematically the evidence and perform a meta-analysis of benefits and risks associated with use of P2Y receptor inhibitors in coronary artery bypass graft-, non-cardiac- and device surgery. Data selection and analysis: We performed a meta-analysis of published studies. Patients with preoperative use of clopidogrel, ticagrelor or prasugrel (late discontinuation: <5 days before surgery or no discontinuation) were compared with patients without preoperative use of the respective drug (early discontinuation: ⩾5 days before surgery or no users of P2Y receptor inhibitors). Outcomes evaluated were re-operation for major bleeding, death, myocardial infarction, combined major adverse cardiac events (MACEs) and major haematoma. Using a random effect model, relative risks (RRs) and 95% confidence intervals (CI) were calculated for each outcome.

Results: Fifty-four studies met the selection criteria and included 50,048 patients. Preoperative use of clopidogrel on top of aspirin in patients undergoing coronary artery bypass graft was associated with a 2.5-fold increased risk of re-operation for bleeding (95% CI: 1.92-3.25; p<0.001) and a 1.47-fold increased risk of death (95% CI: 1.25-1.72; p<0.001), but did not diminish the risk for myocardial infarction (RR: 0.96; 95% CI: 0.75-1.25; p=0.18) or MACE (RR: 1.16; 95% CI: 0.90--1.50; p=0.30). In patients undergoing non-cardiac surgery, preoperative use of clopidogrel increased the RR of re-operation for major bleeding by 2.05-fold (95% CI: 1.13-3.73; p=0.002) but did not reduce the RR for MACE or death. Clopidogrel use during cardiac device implantation raised the RR for procedure-related haematoma by 3.0-fold (95% CI: 1.30--6.94; p=0.001). Whereas preoperative ticagrelor use did not increase the risk for mortality (RR: 1.03; 95% CI: 0.49-2.14), preoperative prasugrel use tended to increase the risk for death (RR: 5.06; 95% CI: 0.54-47.65).

Conclusion: Preoperative exposure to clopidogrel on top of aspirin did not reduce the risk of MACE but was associated with increased risk of bleeding and mortality.
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http://dx.doi.org/10.1177/2048872615585516DOI Listing
December 2017

The enigmatic search for optimal DAPT duration.

Eur Heart J 2014 Apr 24;35(15):951-4. Epub 2013 Nov 24.

Sinai Center for Thrombosis Research, Sinai Hospital of Baltimore, Baltimore, MD, USA.

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http://dx.doi.org/10.1093/eurheartj/eht487DOI Listing
April 2014

Importance of measurement of platelet reactivity to ADP in patients with coronary artery disease: an historical account.

Expert Rev Cardiovasc Ther 2013 Nov 23;11(11):1547-56. Epub 2013 Oct 23.

Sinai Center for Thrombosis Research, Sinai Hospital of Baltimore, Cardiac Catheterization Laboratory, 2401 W. Belvedere Ave, Baltimore, MD 21215, USA.

The pivotal roles of platelets in physiological hemostasis and pathological thrombosis at the site of plaque rupture are well established. The latter roles provide the fundamental basis for the most widely implemented pharmacologic management of coronary artery disease--dual antiplatelet therapy with aspirin to inhibit platelet thromboxane A2 generation, and a P2Y12 receptor inhibitor to prevent adenosine diphosphate (ADP)-induced platelet activation. Although suboptimal pharmacodynamic efficacy, also described as high on-treatment platelet reactivity to ADP, has been associated with greater risk for post-stenting ischemic event occurrence, enhanced responsiveness is associated with higher risk for bleeding in selected patients. In this review article, we aim to provide an historical account of the one and a half century long journey starting with the first description of platelets through the first report of ex vivo measurement of ADP-induced platelet aggregation, the first demonstration of an association between ADP-induced platelet aggregation and post-stenting ischemic event occurrence, and finally to the most recent description of a 'therapeutic window' concept for P2Y12 receptor inhibitor therapy.
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http://dx.doi.org/10.1586/14779072.2013.839382DOI Listing
November 2013

Consensus and update on the definition of on-treatment platelet reactivity to adenosine diphosphate associated with ischemia and bleeding.

J Am Coll Cardiol 2013 Dec 27;62(24):2261-73. Epub 2013 Sep 27.

Sinai Center for Thrombosis Research, Sinai Hospital of Baltimore, Baltimore, Maryland. Electronic address:

Dual antiplatelet therapy with aspirin and a P2Y12 receptor blocker is a key strategy to reduce platelet reactivity and to prevent thrombotic events in patients treated with percutaneous coronary intervention. In an earlier consensus document, we proposed cutoff values for high on-treatment platelet reactivity to adenosine diphosphate (ADP) associated with post-percutaneous coronary intervention ischemic events for various platelet function tests (PFTs). Updated American and European practice guidelines have issued a Class IIb recommendation for PFT to facilitate the choice of P2Y12 receptor inhibitor in selected high-risk patients treated with percutaneous coronary intervention, although routine testing is not recommended (Class III). Accumulated data from large studies underscore the importance of high on-treatment platelet reactivity to ADP as a prognostic risk factor. Recent prospective randomized trials of PFT did not demonstrate clinical benefit, thus questioning whether treatment modification based on the results of current PFT platforms can actually influence outcomes. However, there are major limitations associated with these randomized trials. In addition, recent data suggest that low on-treatment platelet reactivity to ADP is associated with a higher risk of bleeding. Therefore, a therapeutic window concept has been proposed for P2Y12 inhibitor therapy. In this updated consensus document, we review the available evidence addressing the relation of platelet reactivity to thrombotic and bleeding events. In addition, we propose cutoff values for high and low on-treatment platelet reactivity to ADP that might be used in future investigations of personalized antiplatelet therapy.
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http://dx.doi.org/10.1016/j.jacc.2013.07.101DOI Listing
December 2013

The prognostic value of pre-operative and post-operative B-type natriuretic peptides in patients undergoing noncardiac surgery: B-type natriuretic peptide and N-terminal fragment of pro-B-type natriuretic peptide: a systematic review and individual patient data meta-analysis.

J Am Coll Cardiol 2014 Jan 26;63(2):170-80. Epub 2013 Sep 26.

Population Health Research Institute, Hamilton Health Sciences, Hamilton, Ontario, Canada; Departments of Medicine, Clinical Epidemiology, and Biostatistics, Hamilton Health Sciences, Hamilton, Ontario, Canada.

Objectives: The objective of this study was to determine whether measuring post-operative B-type natriuretic peptides (NPs) (i.e., B-type natriuretic peptide [BNP] and N-terminal fragment of proBNP [NT-proBNP]) enhances risk stratification in adult patients undergoing noncardiac surgery, in whom a pre-operative NP has been measured.

Background: Pre-operative NP concentrations are powerful independent predictors of perioperative cardiovascular complications, but recent studies have reported that elevated post-operative NP concentrations are independently associated with these complications. It is not clear whether there is value in measuring post-operative NP when a pre-operative measurement has been done.

Methods: We conducted a systematic review and individual patient data meta-analysis to determine whether the addition of post-operative NP levels enhanced the prediction of the composite of death and nonfatal myocardial infarction at 30 and ≥180 days after surgery.

Results: Eighteen eligible studies provided individual patient data (n = 2,179). Adding post-operative NP to a risk prediction model containing pre-operative NP improved model fit and risk classification at both 30 days (corrected quasi-likelihood under the independence model criterion: 1,280 to 1,204; net reclassification index: 20%; p < 0.001) and ≥180 days (corrected quasi-likelihood under the independence model criterion: 1,320 to 1,300; net reclassification index: 11%; p = 0.003). Elevated post-operative NP was the strongest independent predictor of the primary outcome at 30 days (odds ratio: 3.7; 95% confidence interval: 2.2 to 6.2; p < 0.001) and ≥180 days (odds ratio: 2.2; 95% confidence interval: 1.9 to 2.7; p < 0.001) after surgery.

Conclusions: Additional post-operative NP measurement enhanced risk stratification for the composite outcomes of death or nonfatal myocardial infarction at 30 days and ≥180 days after noncardiac surgery compared with a pre-operative NP measurement alone.
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http://dx.doi.org/10.1016/j.jacc.2013.08.1630DOI Listing
January 2014

[Periprocedual management of vitamin K antagonist's with low molecular weight heparins during invasive procedures--Consensus of experts].

Wien Klin Wochenschr 2013 Jul;125(13-14):412-20

AKH Wien, Univ.-Klinik für Innere Medizin I, Währinger Gürtel 18–20, 1090 Wien, Österreich.

Interruption of an ongoing therapy with vitamin K antagonists (VKAs) is necessary in almost all patients undergoing major surgery. The purpose of the following expert recommendations is to provide easy to use guidance for the periprocedural management of patients on VKAs based on current evidence from the literature. Management of anticoagulation during the time of interruption of VKAs is based on balancing the thromboembolic (TE) risk of underlying conditions against the bleeding risk of the surgical procedure. VKAs should be stopped 3–7days prior to surgery. Low molecular weight heparin (LMWH) is used to cover (“bridge”) the progressive pre-operative loss of anticoagulation and the slow post-operative onset of anticoagulant activity of VKAs. Patients with high risk of TE should receive a therapeutic dose of LMWH, patients with a moderate risk of TE should receive half of this dose. Patients with a low risk of TE do not need bridging therapy with LMWH. In case of an uneventful postoperative course, patients with a therapeutic pre-operative dose should be treated post-operatively with the same dose, starting on day 4 in case of major surgery and on day 2 in case of minor procedures. Patients with a half-therapeutic preoperative dose should be treated post-operatively with the same dose, starting on day 3 in case of major surgery and on day 1 in case of minor procedures. Therapy with VKAs should be re-instituted on the second post-operative day based on the preoperative dosage. Procedure-related post-operative thromboprophylaxis should be given irrespective of these recommendations on days without “bridging” anticoagulation.
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http://dx.doi.org/10.1007/s00508-013-0390-7DOI Listing
July 2013

Postoperative B-type natriuretic peptide for prediction of major cardiac events in patients undergoing noncardiac surgery: systematic review and individual patient meta-analysis.

Anesthesiology 2013 Aug;119(2):270-83

Perioperative Research Group, Department of Anaesthetics, Inkosi Albert Luthuli Central Hospital, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa.

Background: It is unclear whether postoperative B-type natriuretic peptides (i.e., BNP and N-terminal proBNP) can predict cardiovascular complications in noncardiac surgery.

Methods: The authors undertook a systematic review and individual patient data meta-analysis to determine whether postoperative BNPs predict postoperative cardiovascular complications at 30 and 180 days or more.

Results: The authors identified 18 eligible studies (n = 2,051). For the primary outcome of 30-day mortality or nonfatal myocardial infarction, BNP of 245 pg/ml had an area under the curve of 0.71 (95% CI, 0.64-0.78), and N-terminal proBNP of 718 pg/ml had an area under the curve of 0.80 (95% CI, 0.77-0.84). These thresholds independently predicted 30-day mortality or nonfatal myocardial infarction (adjusted odds ratio [AOR] 4.5; 95% CI, 2.74-7.4; P < 0.001), mortality (AOR, 4.2; 95% CI, 2.29-7.69; P < 0.001), cardiac mortality (AOR, 9.4; 95% CI, 0.32-254.34; P < 0.001), and cardiac failure (AOR, 18.5; 95% CI, 4.55-75.29; P < 0.001). For greater than or equal to 180-day outcomes, natriuretic peptides independently predicted mortality or nonfatal myocardial infarction (AOR, 3.3; 95% CI, 2.58-4.3; P < 0.001), mortality (AOR, 2.2; 95% CI, 1.67-86; P < 0.001), cardiac mortality (AOR, 2.1; 95% CI, 0.05-1,385.17; P < 0.001), and cardiac failure (AOR, 3.5; 95% CI, 1.0-9.34; P = 0.022). Patients with BNP values of 0-250, greater than 250-400, and greater than 400 pg/ml suffered the primary outcome at a rate of 6.6, 15.7, and 29.5%, respectively. Patients with N-terminal proBNP values of 0-300, greater than 300-900, and greater than 900 pg/ml suffered the primary outcome at a rate of 1.8, 8.7, and 27%, respectively.

Conclusions: Increased postoperative BNPs are independently associated with adverse cardiac events after noncardiac surgery.
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http://dx.doi.org/10.1097/ALN.0b013e31829083f1DOI Listing
August 2013

Platelet function measurement-based strategy to reduce bleeding and waiting time in clopidogrel-treated patients undergoing coronary artery bypass graft surgery: the timing based on platelet function strategy to reduce clopidogrel-associated bleeding related to CABG (TARGET-CABG) study.

Circ Cardiovasc Interv 2012 Apr 6;5(2):261-9. Epub 2012 Mar 6.

Sinai Center for Thrombosis Research, Baltimore, MD 21215, USA.

Background: Aspirin and clopidogrel therapy is associated with a variable bleeding risk in patients undergoing coronary artery bypass graft surgery (CABG). We evaluated the role of platelet function testing in clopidogrel-treated patients undergoing CABG.

Methods And Results: One hundred eighty patients on background aspirin with/without clopidogrel therapy undergoing elective first time isolated on-pump CABG were enrolled in a prospective single-center, nonrandomized, unblinded investigation (Timing Based on Platelet Function Strategy to Reduce Clopidogrel-Associated Bleeding Related to CABG [TARGET-CABG] study) between September 2008 and January 2011. Clopidogrel responsiveness (ADP-induced platelet-fibrin clot strength [MA(ADP)]) was determined by thrombelastography; CABG was done within 1 day, 3-5 days, and >5 days in patients with an MA(ADP) >50 mm, 35-50 mm, and <35 mm, respectively. The primary end point was 24-hour chest tube drainage and key secondary end point was total number of transfused red blood cells. Equivalence was defined as ≤25% difference between groups. ANCOVA was used to adjust for confounders. Mean 24-hour chest tube drainage in clopidogrel-treated patients was 93% (95% confidence interval, 81-107%) of the amount observed in clopidogrel-naive patients, and the total amount of red blood cells transfused did not differ between groups (1.80 U versus 2.08 U, respectively, P=0.540). The total waiting period in clopidogrel-treated patients was 233 days (mean, 2.7 days per patient).

Conclusions: A strategy based on preoperative platelet function testing to determine the timing of CABG in clopidogrel-treated patients was associated with the same amount of bleeding observed in clopidogrel-naive patients and ≈50% shorter waiting time than recommended in the current guidelines.

Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00857155.
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http://dx.doi.org/10.1161/CIRCINTERVENTIONS.111.967208DOI Listing
April 2012

Usefulness of pre-operative copeptin concentrations to predict post-operative outcome after major vascular surgery.

Am J Cardiol 2011 Oct 26;108(8):1188-95. Epub 2011 Jul 26.

3rd Department of Medicine, Cardiology and Emergency Medicine, Wilhelminenhospital, Vienna, Austria.

The aim of this study was to investigate whether preoperative determination of plasma copeptin levels in addition to plasma N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) could help improve risk stratification in patients who undergo major vascular surgery. One hundred ninety-eight consecutive patients who underwent major vascular surgery (58.6% infrainguinal aortic reconstruction, 23.7% abdominal aortic aneurysm surgery, 17.7% carotid endarterectomy) were included in this study. Patients were monitored for in-hospital and long-term (2-years) major adverse cardiac events, consisting of cardiac death, nonfatal myocardial infarction, and emergent coronary revascularization. Overall, 40 patients (20.2%) reached the primary end point, and most of these events occurred during the index hospital stay (n = 18 [45%]). In univariate Cox regression analysis, increasing concentrations of copeptin were significant determinants of outcome as a continuous variable (hazard ratio [HR] 1.012, p = 0.005) and as a dichotomized variable according to the recommended cutoff of 14.0 pmol/L (HR 4.116, p <0.001). Subgroup analyses revealed that especially patients at low estimated risk according to plasma NT-pro-BNP levels were at significantly higher risk for worse outcomes with higher copeptin levels (HR 5.983, p = 0.002). In multivariate Cox regression analysis, copeptin concentrations >14 pmol/L were significant independent predictors of outcome (HR 2.842, p = 0.002) in addition to type of surgery, history of myocardial infarction, elevated levels of cardiac troponin T, and NT-pro-BNP levels. In conclusion, the results of this study suggest that preoperative determination of this new biomarker could substantially improve prediction of perioperative and postoperative outcomes in vascular surgery patients.
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http://dx.doi.org/10.1016/j.amjcard.2011.06.024DOI Listing
October 2011

The predictive ability of pre-operative B-type natriuretic peptide in vascular patients for major adverse cardiac events: an individual patient data meta-analysis.

J Am Coll Cardiol 2011 Jul;58(5):522-9

Perioperative Research Unit, Department of Anaesthetics, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Congella, South Africa.

Objectives: The aims of this study were to perform an individual patient data meta-analysis of studies using B-type natriuretic peptides (BNPs) to predict the primary composite endpoint of cardiac death and nonfatal myocardial infarction (MI) within 30 days of vascular surgery and to determine: 1) the cut points for a natriuretic peptide (NP) diagnostic, optimal, and screening test; and 2) if pre-operative NPs improve the predictive accuracy of the revised cardiac risk index (RCRI).

Background: NPs are independent predictors of cardiovascular events in noncardiac and vascular surgery. Their addition to clinical risk indexes may improve pre-operative risk stratification.

Methods: Studies reporting the association of pre-operative NP concentrations and the primary study endpoint, post-operative major adverse cardiovascular events (defined as cardiovascular death and nonfatal MI) in vascular surgery, were identified by electronic database search. Secondary study endpoints included all-cause mortality, cardiac death, and nonfatal MI.

Results: Six data sets were obtained, 5 for BNP (n = 632) and 1 for N-terminal pro-BNP (n = 218). An NP level higher than the optimal cut point was an independent predictor for the primary composite endpoint (odds ratio: 7.9; 95% confidence interval: 4.7 to 13.3). BNP cut points were 30 pg/ml for screening (95% sensitivity, 44% specificity), 116 pg/ml for optimal (highest accuracy point; 66% sensitivity, 82% specificity), and 372 pg/ml for diagnostic (32% sensitivity, 95% specificity). Subsequent to revised cardiac risk index stratification, reclassification using the optimal cut point significantly improved risk prediction in all groups (net reclassification improvement 58%, p < 0.000001), particularly in the intermediate-risk group (net reclassification improvement 84%, p < 0.001).

Conclusions: Pre-operative NP levels can be used to independently predict cardiovascular events in the first 30 days after vascular surgery and to significantly improve the predictive performance of the revised cardiac risk index.
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http://dx.doi.org/10.1016/j.jacc.2011.04.018DOI Listing
July 2011

Peri-operative platelet function testing: the potential for reducing ischaemic and bleeding risks.

Thromb Haemost 2011 Aug 20;106(2):248-52. Epub 2011 Apr 20.

Sinai Center for Thrombosis Research, 2401 W. Belvedere Ave, Baltimore, MD 21215, USA.

The pivotal role of platelet activation and reactivity during atherothrombotic event occurrence associated with acute coronary syndromes (ACS) or percutaneous coronary interventions (PCI) is well established. Numerous translational research studies have established a threshold level of platelet reactivity during dual antiplatelet therapy above which a higher risk for ischaemic event occurrence has been observed. The clinical validity of these threshold values in reducing ischemic event occurrence with modified P2Y12 receptor therapy is currently under investigation in large-scale clinical trials. The association between on-treatment platelet reactivity measured by an ex vivo assay and the occurrence of bleeding events is less established. Currently, there is limited evidence of an association between platelet inhibition and coronary artery bypass grafting (CABG)- related bleeding in patients on clopidogrel therapy indicating that preoperative platelet function monitoring may guide both the timing of elective CABG and the administration of blood products in patients needing surgery. However, in the absence of a large-scale prospective clinical trial, routine platelet function monitoring and modification of timing of surgery based on platelet function monitoring are currently not recommended.
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http://dx.doi.org/10.1160/TH11-02-0063DOI Listing
August 2011

Controversies in oral antiplatelet therapy in patients undergoing aortocoronary bypass surgery.

Ann Thorac Surg 2010 Sep;90(3):1040-51

Department of Anesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, Austria.

Oral antiplatelet therapy with aspirin and clopidogrel is a major strategy to prevent thrombotic events in patients with acute coronary syndromes and patients undergoing percutaneous coronary interventions. Although this therapy is associated with both short- and long-term clinical efficacy, irreversible platelet inhibition and ischemic events associated with premature withdrawal especially in patients treated with drug-eluting stents constitute a particular limitation in patients undergoing surgery. The current review article is focused on the central role of platelets in the occurrence of ischemic events, the significance of antiplatelet therapy, the potential hazards of drug withdrawal in patients needing coronary artery bypass grafting, and future perspectives.
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http://dx.doi.org/10.1016/j.athoracsur.2010.04.041DOI Listing
September 2010

Aspirin resistance.

Prog Cardiovasc Dis 2009 Sep-Oct;52(2):141-52

Sinai Center for Thrombosis Research, Baltimore, MD, USA.

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http://dx.doi.org/10.1016/j.pcad.2009.05.001DOI Listing
September 2009

Effect of long-term clopidogrel treatment on platelet function and inflammation in patients undergoing coronary arterial stenting.

Am J Cardiol 2009 Jun 8;103(11):1546-50. Epub 2009 Apr 8.

Sinai Center for Thrombosis Research, Baltimore, Maryland, USA.

A clopidogrel loading dose administered during stenting attenuates inflammation marker release. However, less is known of the anti-inflammatory effect of clopidogrel maintenance therapy. Platelet reactivity to adenosine diphosphate and inflammation markers were measured in 110 consecutive patients (69 clopidogrel-naive patients and 41 patients receiving long-term clopidogrel therapy for >6 months) before nonemergent stenting by turbidimetric aggregometry and flow cytometry and multianalyte profiling, respectively. All patients were treated with aspirin. Prestenting adenosine diphosphate-induced platelet aggregation, P-selectin, and activated glycoprotein IIb/IIIa expression were lower in patients receiving long-term clopidogrel therapy compared with the clopidogrel-naive group (p <0.001), accompanied by lower levels of selected inflammation markers (p < or = 0.05). Additionally, there were strong correlations between platelet aggregation and flow cytometric measurements (p < or = 0.04) and between specific inflammation markers (p < or = 0.02). In conclusion, in addition to markedly lowering platelet reactivity to adenosine diphosphate, long-term clopidogrel therapy is associated with an anti-inflammatory effect.
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http://dx.doi.org/10.1016/j.amjcard.2009.01.367DOI Listing
June 2009