Early platelet recovery following cardiac surgery with cardiopulmonary bypass

Comparing acute normovolumic hemodilution with autologous platelet-rich plasma for blood preservation during aortic surgery : study protocol for a randomized controlled clinical trial

BACKGROUND

Both acute normovolumic hemodilution (ANH) and autologous platelet-rich plasma (aPRP) have been demonstrated blood-protective effects in cardiac aortic surgery; however, the efficacies of the two methods have not been compared. This study aims to compare the effects of aPRP and ANH prior to aortic surgery on postoperative bleed and other outcomes.

METHODS AND ANALYSIS

This is a prospective, single-center, double-blind controlled clinical trial including 160 patients randomized 1:1 to receive aPRP (test group) or autologous whole blood (ANH, control group). The primary objective is to compare the drainage volumes in the two groups at 24, 48, and 72 h postoperatively. Secondary outcomes include input of allogeneic blood and blood products and durations of aortic block, extracorporeal circulation, deep hypothermic arrest of circulation, tracheal extubation, hospital stay, requirement for secondary surgical hemostasis, and application of intra-aortic balloon pump or extracorporeal membrane oxygenation in the two groups. In addition, heart rate, systolic blood pressure, diastolic blood pressure, central venous pressure, and thromboelastography recorded before blood reservation (T1), after blood reservation (T2), before blood transfusion (T3), and after the blood is returned (T4) to the transfusion will be compared between the two groups of patients.

DISCUSSION

This study will demonstrate if the use of aPRP could reduce the risk of bleeding after aortic surgery compared with ANH. The results are expected to have practical clinical applications in terms of more effective blood protection and shorter hospital stay.

TRIAL REGISTRATION

This study was registered with the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ) with the ID ChiCTR 1900023351.Registered on May 23, 2019.

TRIAL STATUS

Recruiting start date: July 1, 2019; expected recruiting end date: July 1, 2024 Version number and date: Version 2 of 05-04-2019.

Cold-stored platelets for acute bleeding in cardiac surgical patients: a narrative review

PURPOSE

Cold-stored platelets (CSP) are an increasingly active topic of international research. They are maintained at 1-6 °C, in contrast to standard room-temperature platelets (RTP) kept at 20-24 °C. Recent evidence suggests that CSP have superior hemostatic properties compared with RTP. This narrative review explores the application of CSP in adult cardiac surgery, summarizes the preclinical and clinical evidence for their use, and highlights recent research.

SOURCE

A targeted search of MEDLINE and other databases up to 24 February 2022 was conducted. Search terms combined concepts such as cardiac surgery, blood, platelet, and cold-stored. Searches of trial registries ClinicalTrials.gov and WHO International Clinical Trials Registry Platform were included. Articles were included if they described adult surgical patients as their population of interest and an association between CSP and clinical outcomes. References of included articles were hand searched.

PRINCIPAL FINDINGS

When platelets are stored at 1-6 °C, their metabolic rate is slowed, preserving hemostatic function for increased storage duration. Cold-stored platelets have superior adhesion characteristics under physiologic shear conditions, and similar or superior aggregation responses to physiologic agonists. Cold-stored platelets undergo structural, metabolic, and molecular changes which appear to "prime" them for hemostatic activity. While preliminary, clinical evidence supports the conduct of trials comparing CSP with RTP for patients with platelet-related bleeding, such as those undergoing cardiac surgery.

CONCLUSION

Cold-stored platelets may have several advantages over RTP, including increased hemostatic capacity, extended shelf-life, and reduced risk of bacterial contamination. Large clinical trials are needed to establish their potential role in the treatment of acutely bleeding patients.

Efficacy of autologous plateletpheresis in adult aortic surgery: study protocol for a randomised controlled trial

INTRODUCTION

Perioperative coagulopathy is common in patients undergoing aortic surgery, increasing the risk of excessive blood loss and subsequent allogeneic transfusion. Blood conservation has become a vital part of cardiovascular surgery, but measures to protect platelets from destruction by cardiopulmonary bypass (CPB) are still lacking. Autologous platelet concentrate (APC) may have potential benefits for intraoperative blood preservation, but its efficacy has not been studied extensively. This study aims to evaluate the efficacy of APC as a blood conservation technique to reduce blood transfusion in adult aortic surgery.

METHODS AND ANALYSIS

This is a prospective, single-centre, single-blind randomised controlled trial. A total of 344 adult patients undergoing aortic surgery with CPB will be enrolled and randomised to either the APC group or the control group with a 1:1 randomisation ratio. Patients in the APC group will receive autologous plateletpheresis before heparinisation, while those in the control group will not. The primary outcome is the perioperative packed red blood cell (pRBC) transfusion rate. Secondary endpoints include the volume of perioperative pRBC transfusion; drainage volume within 72 hours post-surgery; postoperative coagulation and platelet function; and the incidence of adverse events. Data will be analysed according to the intention-to-treat principle.

ETHICS AND DISSEMINATION

This study was approved by the institutional review board of Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College (no. 2022-1806). All procedures included in this study will be performed in adherence to the Helsinki Declaration. The results of the trial will be published in an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Register (ChiCTR2200065834).

Blood protection of autologous platelet-rich plasma in long-time aortic root reconstruction: A retrospective study

OBJECTIVE

This study aimed to investigate the blood protective effect of autologous platelet-rich plasma in aortic root reconstruction under longtime cardiopulmonary bypass.

METHOD

Patients who underwent aortic root reconstruction between August 2018 and August 2022 were included and divided into experimental and control groups according to whether autologous platelet-rich plasmapheresis was used or not. The experimental group included 112 patients (90 males aged 39.00 [28.75-49.00] years), and the control group included 112 patients (90 males aged 37.00 [27.00-46.25] years). The clinical data for example EuroSCORE II cardiovascular surgery risk score, blood routine and other indicators were collected from the two groups.

RESULTS

The transfusion volume of allogeneic red blood cells in the experimental group (52 cases without blood transfusion, 23 cases with 1-2 units, 15 cases with 3-4 units, and 22 cases with 5 units and above) was significantly lower than that in the control group (32 cases without transfusion, 34 cases with 1-2 units, 22 cases with 3-4 units, and 24 cases with 5 units or more) (Z = -2.06, p < 0.05). Resternotomy/thoracotomy occurred in 11 cases (9.8%) in the experimental group and 23 cases (20.5%) in the control group (RR = 2.37, 95% CI: 1.1-5.14, p < 0.05). The number of bleeding events in the experimental group (18 cases, 16.1%) was significantly less than that in the control group (33 cases, 29.5%) (RR = 2.18, 95% CI: 1.14-4.17, p < 0.05).

CONCLUSIONS

The application of autologous platelet-rich plasma in a long-time cardiopulmonary bypass aortic root reconstruction can reduce the amount of allogeneic blood transfusion and the occurrence of bleeding events, which is beneficial for blood protection.

Validity and Utility of Early Parameters in TEG6s Platelet Mapping to Assess the Coagulation Status During Cardiovascular Surgery With Cardiopulmonary Bypass

Background The aim of this retrospective observational study was to explore the early predictive parameters for maximum amplitudein the kaolin with heparinase (HKH) assay (MA_HKH) of TEG6s Platelet Mapping in cardiovascular surgery including cardiopulmonary bypass (CPB) period. The relationship between each parameter of the assay and laboratory data was also assessed. Methods We included the patients who underwent TEG6s Platelet Mapping during cardiovascular surgery under CPB between November 2021 and May 2022. The correlation between MA_HKH and the early parameters was assessed. The association between each parameter of Platelet Mapping and a combination of fibrinogen concentration > 150 mg/dL and platelet count > 100,000µL was also evaluated by the receiver operating characteristic (ROC) curve. Results In 23 patients who underwent TEG6s Platelet Mapping during the study period, 62 HKH assay data including 59 pairs of data (HKH assay and laboratory data) were analyzed. K and angle, but not R, were significantly correlated with MA_HKH (r [95% CI]: -0.90 [-0.94, -0.83], p < 0.0001 for K, and 0.87 [0.79, 0.92], p < 0.0001 for angle). Furthermore, ROC curves suggested that these parameters predicted a combination of fibrinogen concentration > 150 mg/dL and platelet count > 100,000/µL with high accuracy. Similar results were confirmed in the heparinized blood samples obtained during CPB. Conclusion These findings suggest that not only MA_KHK but also K and angle, which are early parameters in the HKH assay, provide clinically significant information that will facilitate rapid decision-making regarding coagulation strategies during cardiovascular surgery including the CPB period.

Platelet Function is Preserved After Moderate Cardiopulmonary Bypass Times But Transiently Impaired After Protamine

OBJECTIVES

Previous studies have described impaired platelet function after cardiopulmonary bypass (CPB). Whether this is still valid in contemporary cardiac surgery is unclear. This study aimed to quantify changes in function and number of platelets during CPB in a present-day cardiac surgery cohort.

DESIGN

Prospective, controlled clinical study.

SETTING

A single-center university hospital.

PARTICIPANTS

Thirty-nine patients scheduled for coronary artery bypass graft surgery with CPB.

INTERVENTIONS

Platelet function and numbers were measured at 6 timepoints in 39 patients during and after coronary artery bypass graft surgery; at baseline before anesthesia, at the end of CPB, after protamine administration, at intensive care unit (ICU) arrival, 3 hours after ICU arrival, and on the morning after surgery.

MEASUREMENTS AND MAIN RESULTS

Platelet function was assessed with impedance aggregometry and flow cytometry. Platelet numbers are expressed as actual concentration and as numbers corrected for dilution using hemoglobin as a reference marker. There was no consistent impairment of platelet function during CPB with either impedance aggregometry or flow cytometry. After protamine administration, a decrease in platelet function was seen with impedance aggregometry and for some markers of activation with flow cytometry. Platelet function was restored 3 hours after arrival in the ICU. During CPB (85.0 ± 21 min), the number of circulating platelets corrected for dilution increased from 1.73 ± 0.42 × 10⁹/g to 1.91 ± 0.51 × 10⁹/g (p < 0.001).

CONCLUSIONS

During cardiac surgery with moderate CPB times, platelet function was not impaired, and no consumption of circulating platelets could be detected. Administration of protamine transiently affected platelet function.

Post-discharge Thromboembolic Events in COVID-19 Patients: A Review on the Necessity for Prophylaxis

Coronavirus disease 2019 (COVID-19) affects the respiratory system of patients and is characterized by pneumonia with hypoxemia. Hospitalized patients and particularly those admitted to intensive care unit (ICU) may encounter a cascade of coagulopathies, which may lead to macrovessel thrombotic events such as pulmonary embolism (PE), deep vein thrombosis (DVT), or arterial thromboembolism (ATE). These events can result in serious life-threatening diseases including cerebrovascular stroke and myocardial infarction. Despite all available information about the incidence, prevention, and treatment of venous thromboembolism (VTE) among hospitalized patients, few data are available on the incidence of both symptomatic and subclinical VTE after discharge. Therefore, there is no precise suggestion or guideline for prophylaxis against VTE in post-discharge period, and some controversies exist over the current guidelines. In the present study, we aimed to review and summarize available literature upon incidence, prevention, diagnosis, and therapeutic approaches for VTE in COVID-19 patients. Also, the pathogenic mechanisms of VTE in infected individuals with COVID-19 were discussed.

Rotational Thromboelastometry in High-Risk Patients on Dual Antithrombotic Therapy After Percutaneous Coronary Intervention

Aims: Patients using antithrombotic drugs after percutaneous coronary intervention (PCI) are at risk for bleeding and recurrent ischemia. We aimed to explore routine and tissue plasminogen activated (tPA) ROTEM results in a post-PCI population on dual antithrombotic treatment.

Methods and Results: In this prospective cohort, 440 patients treated with double antithrombotic therapy after recent PCI and with ≥3 risk factors for either ischemic or bleeding complications were included and compared with a control group (n = 95) consisting of perioperative patients not using antithrombotic medication. Laboratory assessment, including (tPA) ROTEM, was performed one month post-PCI and bleeding/ischemic complications were collected over a five-month follow-up. Patients were stratified by antithrombotic regimen consisting of a P2Y12 inhibitor with either aspirin (dual antiplatelet therapy; DAPT, n = 323), a vitamin K antagonist (VKA, n = 69) or a direct oral anticoagulant (DOAC, n = 48). All post-PCI patients had elevated ROTEM clot stiffness values, but only the DAPT group additionally presented with a decreased fibrinolytic potential as measured with tPA ROTEM. Patients receiving anticoagulants had prolonged clotting times (CT) when compared to the control and DAPT group; EXTEM and FIBTEM CT could best discriminate between patients (not) using anticoagulants (AUC > 0.97). Furthermore, EXTEM CT was significantly prolonged in DAPT patients with bleeding complications during follow-up (68 [62–70] vs. 62 [57–68], p = 0.030).

Conclusion: ROTEM CT has high potential for identifying anticoagulants and tPA ROTEM could detect a diminished fibrinolytic potential in patients using DAPT. Furthermore, the ability of EXTEM CT to identify patients at risk for bleeding may be promising and warrants further research.

Mean platelet volume-to-platelet count ratio after elective cardiac surgical procedures is superior in reflecting platelets metabolic hyperactivity compared to other routine morphological platelet indices: A preliminary report

BACKGROUND

Excessive metabolic excitation of platelets after cardiac procedures may be related to some adverse events but assessment of their metabolic activity is not routine. The purpose of this study was to evaluate which of the basic platelet morphological parameters best reflects their metabolic status.

METHODS

The blood samples of 22cardiac surgical patients (mean age of 62.3 ± 10.3 years) were taken before surgery (BS), and 1, 24 and 48 hours after the operation. Correlations between morphological platelet parameters (platelet count [PLT], mean platelet volume [MPV], platelet distribution width [PDW] and MPV/PLT) and their metabolic activity (total concentration of malondialdehyde [MDA] and MDA/PLT) were estimated.

RESULTS

Significant decline in PLT after operation (from 223 ± 44 × 10¹²/L to 166 ± 57 × 10¹²/L) was accompanied by marked increase in MPV (from 8.4 ± 0.9 fL to 9.1 ± 1.2 fL) and no change of PDW. Consequently, MPV/PLT index increased significantly after procedures from (median with IQR) 0.038 (0.030-0.043) to 0.053 (0.043-0.078). Simultaneously, a significant increase in total platelet MDA content and MDA/PLT was noted reaching peak levels soon after operation. The strongest correlation was observed between MPV/PLT and MDA/PLT (r = 0.56; p < 0.001), although the others were also found to be significant (MDA/PLT vs. MPV; r = 0.35; MDA/PLT vs. PDW; r = 0.34).

CONCLUSIONS

Among basic morphological parameters and indices, the MPV-to-PLT ratio reflects the best metabolic status of platelets in cardiac surgical patients.

Clopidogrel Loading Dose 300 vs. 600 mg in Patients Undergoing One-Stop Hybrid Coronary Revascularization: A Prospective Single-Center Randomized Pilot Study

Background: The optimal loading dose of clopidogrel in one-stop hybrid coronary revascularization (HCR) remains an “evidence-free” zone. This study aimed to compare the major bleeding and ischemic thrombotic events between different clopidogrel loading doses (300 vs. 600 mg) in one-stop HCR.

Methods: In this prospective, single-center, randomized, and parallel pilot study, 100 patients receiving one-stop HCR were randomly assigned to the clopidogrel loading dose 300-mg group or 600-mg group in a 1:1 ratio. Major bleeding events and composite in-hospital ischemic thrombotic and adverse complications were evaluated after the procedure.

Results: The results showed that postoperative mean chest drainage of the first 4 days and total drainage were comparable between the two groups. No differences were found in Bleeding Academic Research Consortium (BARC) coronary artery bypass grafting (CABG) related bleeding (4 vs. 2%, P = 1), PLATelet inhibition and patient Outcomes (PLATO) life-threatening bleeding (20 vs. 26%, P = 0.48), and PLATO major bleeding (70 vs. 76%, P = 0.5) in the two groups. The composite ischemic thrombotic and adverse events were also similar.

Conclusions: In patients receiving one-stop HCR, clopidogrel 600 mg loading dose did not increase major bleeding events compared with 300 mg. More sufficient data is necessary to evaluate the potential benefits of 600 mg loading dose in one-stop HCR.

Hemostasis and fibrinolysis in COVID-19 survivors 6 months after intensive care unit discharge

BACKGROUND

The prothrombotic phenotype has been extensively described in patients with acute coronavirus disease 2019 (COVID-19). However, potential long-term hemostatic abnormalities are unknown.

OBJECTIVE

To evaluate the changes in routine hemostasis laboratory parameters and tissue-type plasminogen activator (tPA) rotational thromboelastometry (ROTEM) 6 months after COVID-19 intensive care unit (ICU) discharge in patients with and without venous thromboembolism (VTE) during admission.

METHODS

Patients with COVID-19 of the Maastricht Intensive Care COVID cohort with tPA ROTEM measurement at ICU and 6-month follow-up were included. TPA ROTEM is a whole blood viscoelastic assay that illustrates both clot development and fibrinolysis due to simultaneous addition of tissue factor and tPA. Analyzed ROTEM parameters include clotting time, maximum clot firmness (MCF), lysis onset time (LOT), and lysis time (LT).

RESULTS

Twenty-two patients with COVID-19 were included and showed extensive hemostatic abnormalities before ICU discharge. TPA ROTEM MCF (75 mm [interquartile range, 68-78]-59 mm [49-63]; P ≤ .001), LOT (3690 seconds [2963-4418]-1786 seconds [1465-2650]; P ≤ .001), and LT (7200 seconds [6144-7200]-3138 seconds [2591-4389]; P ≤ .001) normalized 6 months after ICU discharge. Of note, eight and four patients still had elevated fibrinogen and D-dimer concentrations at follow-up, respectively. In general, no difference in median hemostasis parameters at 6-month follow-up was observed between patients with (n=14) and without (n=8) VTE, although fibrinogen appeared to be lower in the VTE group (VTE-, 4.3 g/L [3.7-4.7] vs VTE+, 3.4 g/L [3.2-4.2]; P = .05).

CONCLUSIONS

Six months after COVID-19 ICU discharge, no persisting hypercoagulable or hypofibrinolytic profile was detected by tPA ROTEM. Nevertheless, increased D-dimer and fibrinogen concentrations persist up to 6 months in some patients, warranting further exploration of the role of hemostasis in long-term morbidity after hospital discharge.

Managing the coagulopathy associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) has allowed for significant surgical advancements, but accompanying risks can be significant and must be expertly managed. One of the foremost risks is coagulopathic bleeding. Increasing levels of bleeding in cardiac surgical patients at the time of separation from CPB are associated with poor outcomes and mortality. CPB-associated coagulopathy is typically multifactorial and rarely due to inadequate reversal of systemic heparin alone. The components of the bypass circuit induce systemic inflammation and multiple disturbances of the coagulation and fibrinolytic systems. Anticipating coagulopathy is the first step in managing it, and specific patient and procedural risk factors have been identified as predictors of excessive bleeding. Medication management pre-procedure is critical, as patients undergoing cardiac surgery are commonly on anticoagulants or antiplatelet agents. Important adjuncts to avoid transfusion include antifibrinolytics, and perfusion practices such as red cell salvage, sequestration, and retrograde autologous priming of the bypass circuit have varying degrees of evidence supporting their use. Understanding the patient's coagulation status helps target product replacement and avoid larger volume transfusion. There is increasing recognition of the role of point-of-care viscoelastic and functional platelet testing. Common pitfalls in the management of post-CPB coagulopathy include overdosing protamine for heparin reversal, imperfect laboratory measures of thrombin generation that result in normal or near-normal laboratory results in the presence of continued bleeding, and delayed recognition of surgical bleeding. While challenging, the effective management of CPB-associated coagulopathy can significantly improve patient outcomes.

Preoperative autologous platelet pheresis reduces allogeneic platelet use and improves the postoperative PaO2/FiO2 ratio in complex aortic surgery: a retrospective analysis

OBJECTIVES

An autologous platelet-rich plasma pheresis (aPP) strategy can harvest partial whole blood that is separated into erythrocytes, plasma and platelets, and can reduce blood loss and transfusion during cardiovascular surgery using cardiopulmonary bypass (CPB). However, the blood and organ conservation effects of this technique have not been confirmed in the context of complex aortic surgery.

METHODS

Perioperative records of 147 adult patients who underwent complex aortic surgery were analysed retrospectively.

RESULTS

All patients received regular blood conservation treatment, and 57 patients received aPP. Whether or not the participants were propensity matched, decreased platelet and cryoprecipitate transfusions were found in the aPP group (both P < 0.001), but there were non-significant differences in erythrocyte transfusion, Sequential Organ Failure Assessment scores and other outcomes when compared with the same parameters in the non-aPP group. The aPP group had a higher arterial oxygen partial pressure to inhaled oxygen concentration ratio on postoperative days 1, 2 and 7 than the non-aPP group (P < 0.001, P < 0.001 and P = 0.048, respectively).

CONCLUSIONS

The utilization of aPP was associated with a reduction in allogeneic platelet and cryoprecipitate transfusions as well as minor lung-protective effects during complex aortic surgery using CPB.

Autologous platelet-rich plasma separation technology used in the same patient receiving 2 complicated aortic surgeries within a short time period: A case report

RATIONALE

Autologous platelet-rich plasma (PRP) separation technology has been widely used in various clinical therapies, and has achieved good results, especially in aortic surgeries.

PATIENT CONCERNS

A 50-year-old man who was diagnosed with aortic dissection (Stanford B type), a thoracoabdominal aortic aneurysm, and grade 2 hypertension underwent 2 complicated aortic surgeries within 4 months. DIAGNOSES:: aortic dissection (Stanford B type).

INTERVENTIONS

PRP separation used as a blood protection measure was employed in both 2 surgeries.

OUTCOMES

The patient's coagulation function recovered well after the surgeries. The amount of allogeneic blood products used in the perioperation was small.

LESSONS

PRP separation technology combined with blood salvage and warming of blood and fluid transfusion in the aortic surgery has been proved to be feasible and beneficial.

Perioperative point of care platelet function testing and postoperative blood loss in high-risk cardiac surgery patients

Postoperative coagulopathic bleeding is common in cardiac surgery and associated with increased morbidity and mortality. Platelet function is affected by multiple factors, including patient and procedural characteristics. Point-of-care (POC) multiple electrode aggregometry (MEA) can rapidly detect and quantify platelet dysfunction and could contribute to optimal patient blood management. In patients undergoing CABG and heart valve surgery platelet function was assessed using POC MEA at four different perioperative timepoints in response to stimulation with four specific receptor agonists (ADP, AA, COL, TRAP). Postoperative bleeding was recorded during 24 h after surgery. Regression analyses were performed to establish associations between perioperative platelet function and postoperative blood loss. Ninety-nine patients were included in the study. Fifty-nine patients (60%) were on antiplatelet therapy (APT) at time of surgery. ADP- and AA-induced platelet aggregation declined during CPB and after decannulation from CPB, with a maximum decrease of 55% for ADP (35 vs. 77 AU at baseline; P < 0.001) and 78% for ASPI (14 vs. 64 AU at baseline; P < 0.001). A linear relationship was present between ADP-induced platelet aggregometry at baseline and postoperative blood loss (r = -0.249; P = 0.015). In aspirin users, the maximum decline in platelet function between baseline and CPB decannulation was related to postoperative blood loss (r = 0.308; P = 0.037). In multivariate analysis, a reduced ADP platelet function prior to surgery remained associated with postoperative blood loss (r = -0.239; P = 0.012). Reduced ADP-induced platelet aggregation at baseline is associated with increased postoperative blood loss in high-risk cardiac surgery patients.

Antiplatelet effects of ticagrelor versus clopidogrel after coronary artery bypass graft surgery: A single-center randomized controlled trial

OBJECTIVE

The study objective was to compare the onset of platelet inhibition (inhibition of platelet aggregation) between ticagrelor 90 mg twice per day and clopidogrel 75 mg once per day in patients receiving coronary artery bypass grafting.

METHODS

In a single-center, randomized, open-label study, 140 patients receiving coronary artery bypass grafting were randomly assigned to the aspirin + ticagrelor group or the aspirin + clopidogrel group in a 1:1 ratio. Participants in the aspirin + ticagrelor group took aspirin 100 mg once per day and ticagrelor 90 mg twice per day. Participants in the aspirin + clopidogrel group took aspirin 100 mg once per day and clopidogrel 75 mg once per day. Platelet function was determined before study treatment (0 hours); at 2 hours, 8 hours, 24 hours, and 72 hours after medication; and during follow-up at 30 days after surgery.

RESULTS

Inhibition of platelet aggregation at 2 hours after the first drug administration was greater for the aspirin + ticagrelor group than for the aspirin + clopidogrel group (34.2% [interquartile range, 9.1-66.0] vs 5.3% [interquartile range, -14.3-22.0], P < .001) and at all times in the study period (P < .001). More patients reached inhibition of platelet aggregation maximum within 24 hours in the aspirin + ticagrelor group than in the aspirin + clopidogrel group (52.9% vs 27.5%, P = .006). The average inhibition of platelet aggregation maximum from 2 to 24 hours was still greater in the aspirin + ticagrelor group than in the aspirin + clopidogrel group (72.3% ± 15.4% vs 49.2% ± 46.8%, P < .001). There were no differences in terms of bleeding or major adverse cardiac events between the 2 groups.

CONCLUSIONS

In patients receiving coronary artery bypass grafting, the onset of action was faster and the peak inhibition of platelet aggregation was higher with ticagrelor than with clopidogrel.

Perioperative management and monitoring of antiplatelet agents: a focused review on aspirin and P2Y12 inhibitors

Platelets play pivotal roles in hemostasis as well as pathological arterial thrombosis. The combination of aspirin and a P2Y₁₂ inhibitor has become the mainstay therapy in the ageing population with cardiovascular conditions, particularly during and after percutaneous coronary intervention. A number of novel P2Y₁₂ inhibitors has become available in the recent years, and they markedly vary in pharmacokinetic and pharmacodynamic properties. Perioperative physicians today face a challenge of preventing hemorrhage due to platelet inhibitors, while minimizing thrombotic risks. There are several point-of-care platelet function tests available in the peri-procedural assessment of residual platelet aggregation. However, these platelet function tests are not standardized in terms of sample processing, agonist type and potency as well as methods of detecting platelet activity. Understanding the differences in pharmacological properties of antiplatelet agents, principles of platelet function tests, and pertinent hemostatic strategies may be useful to anesthesiologists and intensivists who manage perioperative issues associated with antiplatelet agents. The objectives of this review are: 1) to discuss clinical data on aspirin and P2Y₁₂ inhibitors relating to perioperative bleeding, 2) to outline different features of point-of-care platelet function tests, and 3) to discuss therapeutic options for the prevention and treatment of bleeding associated with antiplatelet agents.

Platelets protect lung from injury induced by systemic inflammatory response

Systemic inflammatory responses can severely injure lungs, prompting efforts to explore how to attenuate such injury. Here we explored whether platelets can help attenuate lung injury in mice resulting from extracorporeal circulation (ECC)-induced systemic inflammatory responses. Mice were subjected to ECC for 30 min, then treated with phosphate-buffered saline, platelets, the GPIIb/IIIa inhibitor Tirofiban, or the combination of platelets and Tirofiban. Blood and lung tissues were harvested 60 min later, and lung injury and inflammatory status were assessed. As expected, ECC caused systemic inflammation and pulmonary dysfunction, and platelet transfusion resulted in significantly milder lung injury and higher lung function. It also led to greater numbers of circulating platelet-leukocyte aggregates and greater platelet accumulation in the lung. Platelet transfusion was associated with higher production of transforming growth factor-β and as well as lower levels of tumour necrosis factor-α and neutrophil elastase in plasma and lung. None of these platelet effects was observed in the presence of Tirofiban. Our results suggest that, at least under certain conditions, platelets can protect lung from injury induced by systemic inflammatory responses.