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

Supplemental fibrinogen restores thrombus formation in cardiopulmonary bypass-induced platelet dysfunction ex vivo

BACKGROUND

Major cardiac surgery related blood loss is associated with increased postoperative morbidity and mortality. Platelet dysfunction is believed to contribute to post-cardiopulmonary bypass (CPB)-induced microvascular bleeding. We hypothesised that moderately hypothermic CPB induces platelet dysfunction and that supplemental fibrinogen can restore in vitro thrombus formation.

METHODS

Blood from 18 patients, undergoing first-time elective isolated aortic valve surgery was drawn before CPB, 30 min after initiation of CPB, and after CPB and protamine administration, respectively. Platelet aggregation was quantified by optical aggregometry, platelet activation by flow-cytometric detection of platelet surface expression of P-selectin, annexin V, and activated glycoprotein IIb/IIIa, thrombus formation under flow and effect of supplemental fibrinogen (4 mg ml-1) on in vitro thrombogenesis.

RESULTS

Post-CPB adenosine-diphosphate and TRAP-6-induced aggregation decreased by 40% and 10% of pre-CPB levels, respectively (P<0.0001). Although CPB did not change glycoprotein IIb/IIIa receptor expression, it increased the percentage of unstimulated P-selectin (1.2% vs 7%, P<0.01) positive cells and annexin V mean fluorescence intensity (15.5 vs 17.2, P<0.05), but decreased percentage of stimulated P-selectin (52% vs 26%, P<0.01) positive cells and annexin V mean fluorescence intensity (508 vs 325, P<0.05). Thrombus area decreased from 6820 before CPB to 5230 after CPB (P<0.05, arbitrary units [a.u.]). Supplemental fibrinogen increased thrombus formation to 20 324 and 11 367 a.u. before CPB and after CPB, respectively (P<0.001), thereby restoring post-CPB thrombus area to levels comparable with or higher than pre-CPB baseline.

CONCLUSIONS

Single valve surgery using moderately hypothermic CPB induces partial platelet dysfunction. Thrombus formation was restored in an experimental study design by ex vivo supplementation of fibrinogen.

Novel Platelet Function Analyzer 200 Predicts Blood Transfusion After Elective Cardiac Surgery in Patients Suspended on Dual Antiplatelet Therapy

The value of platelet function test in timing of cardiac surgery remains uncertain. Researches on correlation between Platelet Function Analyzer 200 (PFA-200) and bleeding after elective cardiac surgery are still inadequate. The objective of this study was to investigate the predictive value of PFA-200 in blood transfusion after cardiac surgery. A total of 71 patients on aspirin and P2Y12 receptor inhibitors undergoing cardiac surgery in Fuwai Hospital were enrolled. Platelet function after discontinuing of antiplatelet drugs was assessed by PFA-200 using closure time (CT). PFA-200 results before surgery were included in the statistics. The primary endpoint was postoperative blood transfusion. Seventeen patients (21.9%) received blood transfusion after cardiac surgery. The preoperative PFA-200 CT value in the transfused group was significantly higher than that in the non-transfused group (147.24 ± 85.54 s vs 98.06 ± 61.59 s, P = .011). Using 106 seconds as the dividing point, the incidence of blood transfusion in the elevated PFA-200 (CT > 106 s) group was significantly higher than those in normal PFA-200 (CT ≤ 106 s) group (10/24 patients, 41.9% vs 7/47 patients, 14.7%, P = .012). Multivariate logistic regression analysis showed that PFA-200 CT value > 106 s was an independent predictor of postoperative blood transfusion (OR: 4.05, 95%CI: 1.19-13.86, P = .026). The platelet function test PFA-200 had a predictive value for postoperative blood transfusion in elective cardiac surgery and had a promising prospect in the timing of cardiac surgery.

Effectiveness of Mild to Moderate Hypothermic Cardiopulmonary Bypass on Early Clinical Outcomes

Background: Intraoperative hypothermia is an integral part of cardiopulmonary bypass (CPB), and a precise degree of hypothermia may improve the early clinical outcomes of cardiac surgery. Presently, there is no agreement on an accurate, advantageous temperature range for routine use in CPB. To address this issue, we conducted a retrospective observational study to compare the effects of different hypothermic temperature ranges on primary (inotropic support, blood loss, and platelet count) and secondary (ventilation support and in-hospital stay) outcomes in patients undergoing elective cardiac surgery. Methods: Data were retrieved from the medical database of the Cardiovascular Surgery Department, King Edward Medical University, Lahore-Pakistan (a tertiary care hospital), dating from February 2015 to December 2017. Patients were divided into mild (34 °C to 36 °C), intermediate (31 °C to 33 °C), or moderate (28 °C to 30 °C) hypothermic groups. Results: Out of 275 patients, 245 (89.09%) fit the inclusion criteria. The cohort with mild hypothermic CPB temperatures presented better clinical outcomes in terms of requiring less inotropic support, less blood loss, fewer blood transfusions, improved platelet counts, shorter in-hospital stays, and required less ventilation support, when compared with other hypothermic groups. Conclusions: Mild hypothermic CPB (34 °C to 36 °C) may produce better clinical outcomes for cardiac surgery and improve the quality of health of cardiac patients.

How do type of preoperative P2Y12 receptor inhibitor and withdrawal time affect bleeding? Protocol of a systematic review and individual patient data meta-analysis

INTRODUCTION

In order to reduce the risk of bleeding in patients on P2Y₁₂ receptor inhibitors presenting for non-emergent coronary artery bypass grafting (CABG), current guidelines recommend a preoperative discontinuation period of at least three, five and seven days for ticagrelor, clopidogrel and prasugrel, respectively, to allow for recovery of platelet function. However, there is still substantial interinstitutional variation in preoperative management and relevant covariates of CABG-related bleeding are largely elusive so far.

METHODS AND ANALYSIS

We will search PubMed (July 2013 to November 2021) and EMBASE (January 2014 to November 2021) using the following terms, MeSH terms and their synonyms: clopidogrel, prasugrel, ticagrelor, dual antiplatelet, P2Y₁₂ receptor inhibitor, CABG, bleeding, haemorrhage. Two independent reviewers will screen all abstracts and full papers for eligibility. Disagreements will be solved by consulting with a third reviewer.The primary outcome is the incidence of Bleeding Academic Research Consortium type-4 bleeding depending on type of P2Y₁₂ receptor inhibitor and preoperative withdrawal period. The secondary outcomes are mortality and ischaemic events according to the Academic Research Consortium 2 Consensus Document. We will perform an individual patient data meta-analysis (IPD-MA) with drug-specific preoperative withdrawal time and adjust for demographic and procedural variables. Subgroup analyses will be performed for anaemic patients and patients undergoing non-emergent versus urgent/emergent surgery.

ETHICS AND DISSEMINATION

This IPD-MA consists of secondary analyses of existing non-identifiable data and meets the criteria for waiver of ethics review by the local Research Ethics Committee. Data sharing and transfer will be subject to a confidentiality agreement and a data use agreement. Findings will be disseminated through peer-reviewed publication and conference presentation.

PROSPERO REGISTRATION NUMBER

CRD42022291946.

Does preoperative dual antiplatelet therapy affect bleeding and mortality after total arch repair for acute type A dissection?

OBJECTIVES

Data are scarce and mixed regarding the impact of preoperative dual antiplatelet therapy (DAPT) on the surgical outcomes of acute type A aortic dissection (ATAAD). We seek to evaluate the impact of DAPT on bleeding-related events and early- and mid-term mortality after total arch replacement and frozen elephant trunk in such patients.

METHODS

This study comprised 48 ATAAD patients on preoperative DAPT and 418 without DAPT (the whole series, i.e. unmatched cohort), from which 45 matched pairs were selected by propensity score (matched cohort). Bleeding-related events (reoperation for bleeding, bleeding of ≥1500 ml within the first 12 h postoperatively or transfusion of ≥10 units of red blood cell or use of recombinant activated factor VII), operative mortality and mid-term survival were compared in the unmatched and matched cohorts. The impact of preoperative DAPT was evaluated with multivariable analysis.

RESULTS

In the unmatched cohort, bleeding of ≥1500 ml/12 h postoperatively was more common in the DAPT group (18.8% vs 8.4%, P = 0.020); operative mortality was 9.7%, which did not differ with DAPT (12.5% vs 9.3%, P = 0.48). Nor did bleeding-related events (54.2% vs 43.5%, P = 0.16) differ significantly between 2 groups. In the matched cohort, neither were drainage of ≥1500 ml/12 h (20% vs 6.7%, P = 0.063) and bleeding-related events (53.3% vs 42.2%, P = 0.30), nor operative mortality (13.8 vs 8.9%, P = 0.50) and mid-term survival (79.3% vs 76.4%, P = 0.93) significantly different between 2 groups. DAPT was not identified as a predictor for operative mortality [odd ratio (OR) 0.97, 95% confidence interval (CI) 0.31-3.08; P = 0.96; adjusted OR 1.28, 95% CI 0.22-7.20; P = 0.78] and bleeding-related events (OR 1.50, 95% CI 0.76-2.95; P = 0.24; adjusted OR 2.03, 95% CI 0.80-3.66; P = 0.14).

CONCLUSIONS

In patients with ATAAD undergoing total arch replacement and frozen elephant trunk, although preoperative DAPT led to more postoperative bleeding, it did not increase bleeding-related events nor operative mortality nor mid-term death. The results of this study imply that for patients with ATAAD, emergency surgical repair, even if as extensive as total arch repair, should not be contraindicated or delayed simply because of ongoing DAPT.

Platelet Reactivity in Patients With Acute Coronary Syndromes Awaiting Surgical Revascularization

BACKGROUND

Dual antiplatelet therapy is recommended for patients with acute coronary syndromes (ACS). Approximately 10% to 15% of these patients will undergo coronary artery bypass graft (CABG) surgery for index events, and current guidelines recommend stopping clopidogrel at least 5 days before CABG. This waiting time has clinical and economic implications.

OBJECTIVES

This study aimed to evaluate if a platelet reactivity-based strategy is noninferior to standard of care for 24-h post-CABG bleeding.

METHODS

In this randomized, open label noninferiority trial, 190 patients admitted with ACS with indications for CABG and on aspirin and P2Y₁₂ receptor inhibitors, were assigned to either control group, P2Y₁₂ receptor inhibitor withdrawn 5 to 7 days before CABG, or intervention group, daily measurements of platelet reactivity by Multiplate analyzer (Roche Diagnostics GmbH, Vienna, Austria) with CABG planned the next working day after platelet reactivity normalization (pre-defined as ≥46 aggregation units).

RESULTS

Within the first 24 h of CABG, the median chest tube drainage was 350 ml (interquartile range [IQR]: 250 to 475 ml) and 350 ml (IQR: 255 to 500 ml) in the intervention and control groups, respectively (p for noninferiority <0.001). The median waiting period between the decision to undergo CABG and the procedure was 112 h (IQR: 66 to 142 h) and 136 h (IQR: 112 to 161 h) (p < 0.001), respectively. In the intention-to-treat analysis, a 6.4% decrease in the median in-hospital expenses was observed in the intervention group (p = 0.014), with 11.2% decrease in the analysis per protocol (p = 0.003).

CONCLUSIONS

A strategy based on platelet reactivity-guided is noninferior to the standard of care in patients with ACS awaiting CABG regarding peri-operative bleeding, significantly shortens the waiting time to CABG, and decreases hospital expenses. (Evaluation of Platelet Aggregability in the Release of CABG in Patients With ACS With DAPT; NCT02516267).

Platelet Function Testing in Patients on Antiplatelet Therapy before Cardiac Surgery

Based on variable pharmacodynamic responsiveness and platelet reactivity recovery after discontinuation of P2Y12 receptor inhibitors, preoperative platelet function testing may individualize discontinuation and be a part of transfusion algorithm triggering targeted postpump hemostatic management.

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

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.

Assessment of platelet function after discontinuation of ticagrelor

BACKGROUND

Patients presenting with acute coronary syndromes (ACS) are often treated by percutaneous coronary intervention (PCI) with insertion of coronary artery stents and a majority receive dual antiplatelet therapy (DAPT), usually a combination of a COX-1 inhibitor (aspirin) and a P2Y₁₂ inhibitor (eg ticagrelor). Not seldom the question arises as to when DAPT should be discontinued prior to interventional surgery. This study was done with the primary aim of investigating thrombocyte function immediately prior to and after discontinuation of ticagrelor.

MATERIALS AND METHODS

In this prospective, longitudinal, observational study including 24 patients, venous blood was obtained from patients on day 0, before stopping maintenance dose of 90 mg ticagrelor twice daily, and then on days 1, 3, 5, and 8, after discontinuation. Samples were analyzed using Multiplate^® and VerifyNow^® .

RESULTS

Prior to urgent surgery platelet aggregation >30 aggregation units (Multiplate^® ) and >208 P2Y₁₂ reaction units (VerifyNow^® ) have been shown to correlate with reduced risk of peri- and postoperative bleeding risk. On day 3 after ticagrelor discontinuation, 100% (P = .016) and 67% (P=<.001) of patients had reached these levels on Multiplate^® and VerifyNow^® , respectively. On day 5, the corresponding figures were 100% (P = .016) and 78% (P=<.001).

CONCLUSION

Discontinuation of ticagrelor for 3 days resulted in return of adequate platelet function in all patients on Multiplate^® and in a majority of patients on VerifyNow^® , indicating a lower bleeding risk. A bedside test for platelet function may be considered if time to anticipated surgery is less than 5 days after ticagrelor discontinuation.

Society of Cardiovascular Anesthesiologists Clinical Practice Improvement Advisory for Management of Perioperative Bleeding and Hemostasis in Cardiac Surgery Patients

Bleeding after cardiac surgery is a common and serious complication leading to transfusion of multiple blood products and resulting in increased morbidity and mortality. Despite the publication of numerous guidelines and consensus statements for patient blood management in cardiac surgery, research has revealed that adherence to these guidelines is poor, and as a result, a significant variability in patient transfusion practices among practitioners still remains. In addition, although utilization of point-of-care (POC) coagulation monitors and the use of novel therapeutic strategies for perioperative hemostasis, such as the use of coagulation factor concentrates, have increased significantly over the last decade, they are still not widely available in every institution. Therefore, despite continuous efforts, blood transfusion in cardiac surgery has only modestly declined over the last decade, remaining at ≥50% in high-risk patients. Given these limitations, and in response to new regulatory and legislature requirements, the Society of Cardiovascular Anesthesiologists (SCA) has formed the Blood Conservation in Cardiac Surgery Working Group to organize, summarize, and disseminate the available best-practice knowledge in patient blood management in cardiac surgery. The current publication includes the summary statements and algorithms designed by the working group, after collection and review of the existing guidelines, consensus statements, and recommendations for patient blood management practices in cardiac surgery patients. The overall goal is creating a dynamic resource of easily accessible educational material that will help to increase and improve compliance with the existing evidence-based best practices of patient blood management by cardiac surgery care teams.

Multiple electrode aggregometry and thromboelastography in thrombocytopenic patients with haematological malignancies

BACKGROUND

In thrombocytopenic patients better assessment of bleeding risk than that provided by platelet count alone is required. Multiplate® aggregometry and thromboelastography (TEG) could be used, but information on their role in such patients is limited. The primary aim of this study was to investigate the feasibility of Multiplate® analyses in patients with haematological malignancies. A secondary aim was to explore whether a multiple logistic regression model combining Multiplate®, TEG, clinical and laboratory variables was associated with risk of bleeding.

MATERIALS AND METHODS

This was an exploratory, prospective observational study of thrombocytopenic patients with haematological malignancies. Total platelet count (TPC), white blood cell count, C-reactive protein (CRP) level, temperature and bleeding status were recorded daily. TEG and Multiplate® analyses with four agonists were performed on weekdays.

RESULTS

Ten patients were enrolled into the study. The median number of days in a study period was 21. Bleeding was observed on 64 of 298 study days. TPC <20×109/L and <10×109/L occurred on 119 and 25 days, respectively. When TPC was <33×109/L, many samples showed no aggregation, regardless of bleeding status. Despite this, the odds of World Health Organization (WHO) grade 2 bleeding decreased significantly as aggregation increased and Multiplate® had a negative predictive value (NPV) of 96% and a positive predictive value (PPV) of 19% for significant bleeding. In the multiple logistic regression model collagen-activated Multiplate® aggregation, TEG angle, TEG reaction time and CRP significantly affected the odds of WHO grade 2 bleeding. The combined model had a NPV of 99% and a PPV of 19%.

DISCUSSION

Our findings suggest that the markers of platelet function and haemostasis provided by Multiplate® aggregometry and TEG may add information to support prediction of bleeding, although platelet count still remains the most accessible analysis for routine testing.

Adrenaline enhances in vitro platelet activation and aggregation in blood samples from ticagrelor-treated patients

BACKGROUND

Temporarily improved platelet reactivity may reduce the bleeding in patients on antiplatelet therapy who have ongoing bleeding or who are in need of acute surgery. Adrenaline can bind to adrenergic α2A-receptors on platelets and potentially enhance platelet reactivity.

OBJECTIVE

To assess if adrenaline can improve adenosine diphosphate (ADP)-induced platelet aggregation and activation in blood samples from patients on dual antiplatelet therapy with acetylsalicylic acid (ASA) and the ADP-receptor antagonist ticagrelor.

METHODS

Blood samples were collected from a total of forty acute coronary syndrome patients on dual antiplatelet therapy with ASA and ticagrelor. ADP-induced platelet aggregation (by impedance aggregometry) and activation (by flow cytometry) were assessed before and after supplementation with adrenaline and/or platelet concentrate.

RESULTS

Adrenaline supplementation (770 nmol L-1) increased median ADP-induced aggregation from 15 (25-75th percentiles: 10-20) to 26 (18-38) aggregation units. The effect was independent of concomitant platelet supplementation. Adrenaline also increased ADP-induced platelet activation: from 40% (36-54%) to 83% (74-88%) platelets with active fibrinogen receptor (binding PAC-1) and from 13% (7-21%) to 35% (18-50%) P-selectin-expressing platelets.

CONCLUSIONS

Adrenaline potentiated ADP-induced platelet aggregation and activation in blood samples from ticagrelor-treated patients. Adrenaline infusion may be a new method to enhance platelet function in ticagrelor-treated patients who are in need of acute surgery or have ongoing bleeding. In vivo studies are needed to confirm the present results.

Total arterial revascularization in patients with acute myocardial infarction - feasibility and outcomes

BACKGROUND

In acute situations such as acute myocardial infarction (AMI) with indication for coronary artery bypass grafting (CABG), total arterial revascularization (TAR) is often rejected in favour of saphenous vein (SV) grafting, which is assumed to allow for quicker vessel harvesting, a simpler anastomosis technique, and thus quicker revascularization and fewer bleeding complications. The aim of this study was to evaluate whether reluctance to apply TAR in AMI is still justified from a technical point of view in the current era and whether superiority of TAR results is also evident in emergency patients with AMI undergoing CABG.

METHODS

In this retrospective analysis of 434 consecutive patients undergoing CABG for AMI with either TAR or with a combination of one internal mammary artery and SV grafts between 2008 and 2014, procedural data, short-term and mid-term outcome were compared. Propensity score matching of the groups was performed.

RESULTS

After propensity score matching, 250 patients were included in the analysis (TAR group: n = 98; SV group n = 152). The procedural time (TAR group: 211 min vs. SV group: 200 min, p = 0.46) did not differ between the groups. Erythrocyte transfusion rates were higher in the SV group (76% vs. 57%; p < 0.001). Rates of re-exploration for bleeding did not differ. Thirty-day mortality rates were comparable (TAR group: 3.4% vs. SV group: 4.5%, p = 0.68). Kaplan-Meier analysis until 7 years postoperatively revealed a tendency for improved survival after TAR (75% vs. 62%; log-rank p = 0.12).

CONCLUSION

TAR neither impairs rapid revascularization nor reduces its safety in patients with AMI. It may result in improved long-term outcome and should be preferred in the clinical setting of AMI.

Desmopressin for treatment of platelet dysfunction and reversal of antiplatelet agents: a systematic review and meta-analysis of randomized controlled trials

Essentials The optimal management of patients with platelet dysfunction undergoing surgery is unclear. This meta-analysis compared perioperative administration of desmopressin to placebo. Desmopressin reduced red cell transfusions, blood loss and risk of re-operation due to bleeding. There were too few events to determine if there was a change in the risk of thrombotic events.

SUMMARY

Background Platelet dysfunction, including that caused by antiplatelet agents, increases the risk of perioperative bleeding. The optimal management of patients with platelet dysfunction undergoing surgery is unclear. Objectives To assess whether desmopressin reduces perioperative allogeneic red cell transfusion and bleeding in patients with platelet dysfunction. Patients/Methods We searched for randomized controlled trials in The Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Embase, the Transfusion Evidence Library and the ISI Web of Science to 7th July 2016. Data were pooled using mean difference (MD), relative risks or Peto odds ratios (pOR) using a random-effects model. Results Ten trials with 596 participants were identified, all in the setting of cardiac surgery. Platelet dysfunction was due to antiplatelet agents in six trials and cardiopulmonary bypass in four trials. Patients treated with desmopressin were transfused with fewer red cells (MD, -0.65 units; 95% Confidence Interval [CI], -1.16 to -0.13 units), lost less blood (MD, -253.93 mL; 95% CI, -408.01 to -99.85 mL) and had a lower risk of re-operation due to bleeding (pOR, 0.39; 95% CI, 0.18-0.84). The GRADE quality of evidence was very low to moderate, suggesting considerable uncertainty over the results Conclusions Desmopressin may be a useful agent to reduce bleeding and transfusion requirements for people with platelet dysfunction or with a history of recent antiplatelet drug administration undergoing cardiac surgery.

Noteworthy Literature Published in 2016 for Cardiothoracic Critical Care

In 2016, demand for the presence of cardiothoracic anesthesiologists outside of the cardiac operating rooms continues to expand. This article is the second in this annual series to review relevant contributions in postoperative cardiac critical care that may impact the cardiac anesthesiologist. We explore the use of extracorporeal membrane oxygenation (ECMO), management of postoperative atrial fibrillation, coagulopathy, respiratory failure, and role of quality in cardiac surgery.