Multiple Electrode Whole-Blood Aggregometry and Bleeding in Cardiac Surgery Patients Receiving Thienopyridines
ABSTRACT Preoperative treatment with thienopyridines is associated with increased postoperative bleeding in cardiac surgery patients. Patients under treatment with thienopyridines have different levels of platelet dysfunction and the effects of discontinuation are not totally predictable. The present study aimed to determine if a preoperative assessment of platelet function in these patients could provide clinically relevant information regarding the risks of excessive postoperative bleeding and transfusion requirements.
This is a retrospective analysis of prospectively collected data. Patients (n=87) under thienopyridine treatment until at least one week before cardiac surgery were enrolled in the study. Platelet function was assessed preoperatively with multiple electrode aggregometry: the adenosine diphosphate (ADP) test and TRAP (thrombin receptor-associated peptide) test were performed for all patients.
Univariate analysis revealed that postoperative bleeding was associated (p<0.1) with preoperative serum creatinine level, platelet count, CPB (cardiopulmonary bypass) duration, and results from the ADP test and the TRAP test. Multivariable linear regression analysis confirmed the CPB duration (p=0.049) and ADP test (p=0.007) as independently associated with postoperative bleeding. The relationship between the ADP test and postoperative bleeding was investigated with polynomial regression analysis, and a logarithmic equation provided the best fit. The accuracy of prediction was good (area under the curve 0.71, p=0.013), with a cutoff value for the ADP test at 31 U (sensitivity 72%, specificity 66%, negative predictive value 92%, and positive predictive value 29%).
The multiple electrode aggregometry ADP test in patients under thienopyridine treatment and undergoing cardiac surgery is associated with postoperative bleeding and platelet transfusion and provides an accurate preoperative prediction of postoperative bleeding risk.
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ABSTRACT: Background. Drugs that act on the platelet P2Y12 receptor are responsible for postoperative bleeding in cardiac surgery. However, protease-activated receptor (PAR) that reacts to thrombin stimulation might still be active in patients treated with P2Y12 inhibitors. Preoperative platelet function testing could possibly guide the timing of surgery. We investigated the association between P2Y12 receptor and PAR inhibition and bleeding after cardiac surgery. Methods. A retrospective cohort study of 361 patients undergoing cardiac surgery and treated with P2Y12 anti-platelet agents was undertaken. All patients received a preoperative multiplate electrode aggregometry testing of platelet P2Y12 receptor activity (ADPtest) and PAR reactivity with thrombin receptor-activating peptide (TRAP) stimulation. ADPtest and TRAPtest data measured before surgery were analysed for association with postoperative bleeding (ml per 12 h) and severe postoperative bleeding. Results. Both the ADPtest and the TRAPtest were significantly (P=0.001) associated with postoperative bleeding. A threshold of 22 U for the ADPtest yielded a negative predictive value (NPV) of 94% and a positive predictive value (PPV) of 20%, and a threshold of 75 U for the TRAPtest yielded an NPV of 95% and a PPV of 23%. In the subgroup of patients with ADPtest <22 U, TRAPtest >= 75 U was not associated with severe bleeding (NPV of 100% and PPV of 37%). Conclusions. In patients taking P2Y12 receptor inhibitors, residual platelet reactivity to thrombin stimulation limits the risk of severe postoperative bleeding.BJA British Journal of Anaesthesia 09/2014; 113(6). DOI:10.1093/bja/aeu315 · 4.35 Impact Factor
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ABSTRACT: In physiological hemostasis a prompt recruitment of platelets on the vessel damage prevents the bleeding by the rapid formation of a platelet plug. Qualitative and/or quantitative platelet defects promote bleeding, whereas the high residual reactivity of platelets in patients on antiplatelet therapies moves forward thromboembolic complications. The biochemical mechanisms of the different phases of platelet activation - adhesion, shape change, release reaction, and aggregation - have been well delineated, whereas their complete translation into laboratory assays has not been so fulfilled. Laboratory tests of platelet function, such as bleeding time, light transmission platelet aggregation, lumiaggregometry, impedance aggregometry on whole blood, and platelet activation investigated by flow cytometry, are traditionally utilized for diagnosing hemostatic disorders and managing patients with platelet and hemostatic defects, but their use is still limited to specialized laboratories. To date, a point-of-care testing (POCT) dedicated to platelet function, using pertinent devices much simpler to use, has now become available (ie, PFA-100, VerifyNow System, Multiplate Electrode Aggregometry [MEA]). POCT includes new methodologies which may be used in critical clinical settings and also in general laboratories because they are rapid and easy to use, employing whole blood without the necessity of sample processing. Actually, these different platelet methodologies for the evaluation of inherited and acquired bleeding disorders and/or for monitoring antiplatelet therapies are spreading and the study of platelet function is strengthening. In this review, well-tried and innovative platelet function tests and their methodological features and clinical applications are considered.Vascular Health and Risk Management 02/2015; 11:133. DOI:10.2147/VHRM.S44469
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ABSTRACT: Impaired haemostasis represents a major risk factor for bleeding complications in neurosurgical patients. Coagulopathy commonly occurs after (brain) trauma and major haemorrhage or originates from antithrombotic medication. Point of care (POC) devices for bedside assessment of haemostatic parameters are increasingly used in various medical specialties. Results can be instantly implemented into treatment modalities as results are delivered within a very short period. POC coagulation testing has also shown beneficial effects in the treatment of neurosurgical patients. Identification of hyperfibrinolysis is achieved through viscoelastic testing of haemostasis and bedside coagulometry hastens the management of anticoagulated patients in need of urgent neurosurgical procedures. Results of POC testing of platelet function have been correlated with patient outcomes after traumatic brain injury and furthermore, quantification of antiplatelet medication effects on platelet activity is made possible through the use of these devices. Further studies are needed to characterise the potential of POC testing of platelet function. Antiplatelet medication plays an important role in regard to haemorrhagic and thromboembolic risks. Therefore, POC testing of platelet activity may improve treatment modalities in patients undergoing neurosurgical procedures as well as neurointerventional procedures (such as intracranial stent placement). In this article we summarise the available data of POC testing in neurosurgical patients and discuss the potential of these devices in this field. POC technologies have improved patient care in various medical fields and in our view it is likely that this will also apply to the field of neurosurgery.Journal of Clinical Neuroscience 11/2014; 22(2). DOI:10.1016/j.jocn.2014.07.029 · 1.32 Impact Factor