Platelet function tests predict bleeding and thrombotic events after off-pump coronary bypass grafting

Division of Cardiac Surgery, Department of Surgery, School of Medicine, University of Maryland, N4W94 22 S. Greene St., Baltimore, MD 21201, USA.
European Journal of Cardio-Thoracic Surgery (Impact Factor: 3.3). 04/2005; 27(4):584-91. DOI: 10.1016/j.ejcts.2004.12.061
Source: PubMed


A balanced coagulation system after cardiac surgery minimizes bleeding and thrombotic events. However, the best method to monitor this balance has not been established. We used a series of tests of coagulation and platelet function to define the risk of bleeding and thrombotic events after OPCAB.
In 76 patients, routine coagulation tests (i.e. prothrombin time, fibrinogen level, d-dimer, and platelet count), thrombelastography, and whole blood aggregometry were obtained perioperatively and on days 1 and 3 after OPCAB. Intra- and postoperative blood loss was determined. Early patency of venous bypass grafts was determined using CT angiography (Philips Medical, Corp.).
Chest tube output and red cell volume loss at 24 h were 952+/-475 and 190+/-115 ml, respectively. Early graft failure developed in eight patients. Perioperative changes in routine coagulation tests showed no correlation with either bleeding or thrombosis. However, perioperative decline in platelet function as assessed by the area under the impedance curve for whole blood aggregometry correlated with intraoperative blood loss (R=0.42, P<0.05). A perioperative decline in the maximum amplitude of the thrombelastography trace showed a significant correlation with 24h hemoglobin loss (R=0.45, P<0.05). Compared to those with all patent grafts, patients with early graft failure demonstrated a reduction in platelet sensitivity to aspirin by both thrombelastography and aggregometry on day 3.
In contrast to standard coagulation testing, platelet function predicted both bleeding and thrombosis after OPCAB. Titration of perioperative platelet function according to these tests may minimize thrombosis without increasing bleeding.

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Available from: Robert S Poston, Jul 03, 2014
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    • "Postoperative recovery of platelet function has been investigated in literature, mostly by means of LTA performed in citrated blood, which showed increased platelet activity as early as 5 hours after surgery (Boldt et al 1993, 1994). In WBA performed with citrated blood 3.8% using higher dose of collagen (5 μg/mL) moderate recovery of platelet function after off pump cardiac surgery was noted (Poston et al 2005). So far, there are no reports on post- CPB recovery of platelet activity assessed in whole blood aggregometry activated with TRAP-6. "
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    ABSTRACT: The standard method of assessment of platelet function is represented by light transmission aggregometry (LTA), performed in citrated platelet-rich plasma (PRP). With LTA, decrease and subsequent post-cardiopulmonary bypass (CPB) recovery of platelet function have been reported during cardiac surgery. Multiple electrode aggregometry (MEA) may be used as point-of-care method to monitor perioperative changes in platelet function. Since MEA assesses macroaggregation which is influenced by the plasmatic levels of unbound calcium, citrate may be inadequate as anticoagulant for MEA. We used citrate and heparin for MEA samples, to see with which anticoagulant the intraoperative decrease and postoperative recovery in platelet function previously described with other aggregometric methods in cardiac surgery may be observed with MEA. Blood was obtained from 60 patients undergoing routine cardiac surgery and the samples were collected in standard tubes containing unfractionated heparin (50 U/mL) or trisodium citrate (3.2%). The samples were obtained before CPB, at 30 minutes on CPB, end of CPB and on the first postoperative day. MEA was performed using the Multiplate® analyzer. Collagen (COLtest, 100 μg/mL) and TRAP-6 (thrombin receptor activating peptide, TRAPtest, 1mM/mL) were used as aggregation agonists. Platelet aggregometric response decreased significantly during CPB. Platelet aggregation assessed using TRAP-6 as agonist on heparinized blood significantly correlated with the duration of CPB (r = -0.41, p = 0.001, 2-tailed Pearson test). The aggregometric analysis performed on the first postoperative day showed a significant recovery in platelet activity in the samples containing heparin (increase from 30 ± 22 U to 46 ± 27 U for the COLtest and from 70 ± 34 U to 95 ± 32 U for the TRAPtest, p < 0.001, Student's t-test), while no significant recovery of platelet function could be established in the MEA measurements performed with citrated blood. The choice of blood sample anticoagulant used for impedance aggregometry influenced the platelet aggregation response. Postoperative platelet function recovery was only detected in the heparinized samples. Heparin seems to be better suited than citrate for the analysis of impedance aggregometry in heart surgery.
    Full-text · Article · Jul 2008 · Medical Devices: Evidence and Research
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    • "We read with great interest the article entitled 'Platelet function tests predict bleeding and thrombotic events after off-pump coronary bypass grafting' written by Poston and colleagues[1]. Platelet function and bleeding is still a big challenge in cardiac surgery. "

    Preview · Article · Oct 2005 · European Journal of Cardio-Thoracic Surgery
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    Preview · Article · Sep 2005 · European Journal of Cardio-Thoracic Surgery
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