Effect of preoperatively continued aspirin use on early and mid-term outcomes in off-pump coronary bypass surgery: a propensity score-matched study of 1418 patients

Background

To date, effect of preoperatively continued aspirin administration in off-pump coronary artery bypass grafting (CABG) is less known. We aimed to assess the effect of preoperatively continued aspirin use on early and mid-term outcomes in patients receiving off-pump CABG.

Methods

From October 2009 to September 2013 at the Fuwai Hospital, 709 preoperative aspirin users were matched with unique 709 nonaspirin users using propensity score matching to obtain risk-adjusted outcome comparisons between the two groups. Early outcomes were in-hospital death, stroke, intra- and post-operative blood loss, reoperation for bleeding and blood product transfusion. Major adverse cardiac events (death, myocardial infarction or repeat revascularization), angina recurrence and cardiogenic readmission were considered as mid-term endpoints.

Results

There were no significant differences among the groups in baseline characteristics after propensity score matching. The median intraoperative blood loss (600 ml versus 450 ml, P = 0.56), median postoperative blood loss (800 ml versus 790 ml, P = 0.60), blood transfusion requirements (25.1% versus 24.4%, P = 0.76) and composite outcome of in-hospital death, stroke and reoperation for bleeding (2.8% versus 1.6%, P = 0.10) were similar in aspirin and nonaspirin use group. At about 4 years follow-up, no significant difference was observed among the aspirin and nonaspirin use group in major adverse cardiac events free survival estimates (95.7% versus 91.5%, P = 0.23) and freedom from cardiogenic readmission (88.5% versus 85.3%, P = 0.77) whereas the angina recurrence free survival rates was 83.7% and 73.9% in the aspirin and nonaspirin use group respectively (P = 0.02), with odd ratio for preoperative aspirin estimated at 0.71 (95% confidence interval, 0.49-1.04, P = 0.08).

Conclusions

Preoperatively continued aspirin use was not associated with increased risk of intra- and post-operative blood loss, blood transfusion requirements and composite outcome of in-hospital death, stroke and reoperation for bleeding in off-pump CABG. Preoperative aspirin use tended to decrease the hazard of mid-term angina recurrence.

Evaluation of differences in patient and physician perception of benefit and risks of aspirin and antifibrinolytic therapy in cardiac surgery

It is unclear whether physicians and patients have similar concerns and preferences when considering benefit and risks of aspirin and antifibrinolytic therapy for cardiac surgery. We surveyed both groups to ascertain their perceptions and preferences for treatment in this setting. Both preoperative and postoperative cardiac surgical patients and the physician craft groups caring for them (cardiology, surgery, anaesthesia/critical care), were provided with estimates of benefits and risks of aspirin and antifibrinolytic therapy. All study participants were asked to stipulate the minimal absolute risk reduction required for them to agree to such therapy. When compared with the cardiac surgical patients they treat, physicians required a smaller thrombotic risk reduction with aspirin whilst accepting its known increased risk of bleeding. This was significantly different in a high-risk stroke setting (incidence 5%) where the required relative risk reduction with aspirin use for physicians was 20% versus patients 40% (P <0.001); and for myocardial infarction, physicians 20% versus patients 36% (P=0.051). For antifibrinolytic therapy, the tolerated increased relative risk of stroke for physicians was 20% versus patients 10% (P=0.004), and for myocardial infarction, physicians 16.7% versus patients 4.2% (P <0.001). The three physician craft groups had comparable tolerances of thrombotic risk. Patient and physician preferences for perioperative aspirin and antifibrinolytic therapy sometimes differ based on risk benefit analysis.

Traumatic intracranial hemorrhage correlates with preinjury brain atrophy, but not with antithrombotic agent use: a retrospective study

BACKGROUND

The impact of antithrombotic agents (warfarin, clopidogrel, ASA) on traumatic brain injury outcomes is highly controversial. Although cerebral atrophy is speculated as a risk for acute intracranial hemorrhage, there is no objective literature evidence.

MATERIALS AND METHODS

This is a retrospective, consecutive investigation of patients with signs of external head trauma and age ≥60 years. Outcomes were correlated with antithrombotic-agent status, coagulation test results, admission neurologic function, and CT-based cerebral atrophy dimensions.

RESULTS

Of 198 consecutive patients, 36% were antithrombotic-negative and 64% antithrombotic-positive. ASA patients had higher arachidonic acid inhibition (p = 0.04) and warfarin patients had higher INR (p<0.001), compared to antithrombotic-negative patients. Antithrombotic-positive intracranial hemorrhage rate (38.9%) was similar to the antithrombotic-negative rate (31.9%; p = 0.3285). Coagulopathy was not present on the ten standard coagulation, thromboelastography, and platelet mapping tests with intracranial hemorrhage and results were similar to those without hemorrhage (p≥0.1354). Hemorrhagic-neurologic complication (intracranial hemorrhage progression, need for craniotomy, neurologic deterioration, or death) rates were similar for antithrombotic-negative (6.9%) and antithrombotic-positive (8.7%; p = 0.6574) patients. The hemorrhagic-neurologic complication rate was increased when admission major neurologic dysfunction was present (63.2% versus 2.2%; RR = 28.3; p<0.001). Age correlated inversely with brain parenchymal width (p<0.001) and positively with lateral ventricular width (p = 0.047) and cortical atrophy (p<0.001). Intracranial hemorrhage correlated with cortical atrophy (p<0.001) and ventricular width (p<0.001).

CONCLUSIONS

Intracranial hemorrhage is not associated with antithrombotic agent use. Intracranial hemorrhage patients have no demonstrable coagulopathy. The association of preinjury brain atrophy with acute intracranial hemorrhage is a novel finding. Contrary to antithrombotic agent status, admission neurologic abnormality is a predictor of adverse post-admission outcomes. Study findings indicate that effective hemostasis is maintained with antithrombotic therapy.

Impact of aspirin and clopidogrel interruption on platelet function in patients undergoing major vascular surgery

Aims

To investigate functional platelet recovery after preoperative withdrawal of aspirin and clopidogrel and platelet function 5 days after treatment resumption.

Methods/Results

We conducted an observational study, which prospectively included consecutive patients taking aspirin, taking clopidogrel, and untreated controls (15 patients in each group). The antiplatelet drugs were withdrawn five days before surgery (baseline) and were reintroduced two days after surgery. Platelet function was evaluated by optical aggregation in the presence of collagen, arachidonic acid (aspirin) and ADP (clopidogrel) and by VASP assay (clopidogrel). Platelet-leukocyte complex (PLC) level was quantified at each time-point. At baseline, platelet function was efficiently inhibited by aspirin and had recovered fully in most patients 5 days after drug withdrawal. PLC levels five days after aspirin reintroduction were similar to baseline (+4±10%; p = 0.16), in line with an effective platelet inhibition. Chronic clopidogrel treatment was associated with variable platelet inhibition and its withdrawal led to variable functional recovery. PLC levels were significantly increased five days after clopidogrel reintroduction (+10±15%; p = 0.02), compared to baseline.

Conclusions

Aspirin withdrawal 5 days before high-bleeding-risk procedures was associated with functional platelet recovery, and its reintroduction two days after surgery restored antiplaletet efficacy five days later. This was not the case of clopidogrel, and further work is therefore needed to define its optimal perioperative management.

Open and robot-assisted radical retropubic prostatectomy in men receiving ongoing low-dose aspirin medication: revisiting an old paradigm?

OBJECTIVE

To assess blood loss, transfusion rates and 90-day complication rates in patients receiving ongoing 100 mg/day aspirin medication and undergoing open radical prostatectomy (RP) or robot-assisted RP (RARP).

PATIENTS AND METHODS

Between February 2010 and August 2011, 2061 open RPs and 400 RARPs were performed. All patients received low-molecular-weight heparin for thrombembolism prophylaxis. Aspirin intake during surgery was recorded in 137 patients (5.5%). Descriptive statistics and multivariable analyses after propensity-score matching for balancing potential differences in patients with and without aspirin medication were used to assess the risk of blood loss above the median in patients undergoing open RP or RARP.

RESULTS

The median blood loss in the open RP cohort with and without aspirin medication was 750 and 700 mL, respectively, and in the RARP cohort it was 200 and 150 mL, respectively. Within the same cohorts, transfusions were administered in 21 and 8% and 0 and 1% of patients, respectively. The 90-day complication rates in patients with ongoing aspirin medication were 5.8, 4.4, 7.3 and 0% for Clavien grades I, II, III and IV complications, respectively. In multivariable analyses and after propensity-score matching, prostate volume (odds ratio 1.03; 95% CI 1.02-1.04; P < 0.01) but not ongoing aspirin medication achieved independent predictor status for the risk of blood loss above the median.

CONCLUSIONS

Major surgery such as open RP and RARP can be safely performed in patients with ongoing aspirin medication without greater blood loss. Higher 90-day complication rates were not detected in such patients. Differences in transfusion rates between the groups receiving and not receiving ongoing aspirin medication may be explained by a higher proportion of patients with coronary artery disease in the group receiving ongoing aspirin medication. This comorbidity may result in a higher peri-operative threshold for allogenic blood transfusion.

Thrombin based gelatin matrix and fibrin sealant mediated clot formation in the presence of clopidogrel

BACKGROUND

Platelet inhibitors are commonly used to reduce the risk of atherothrombotic events. The aim of this study was to determine the impact of platelet inhibitors, specifically clopidogrel and aspirin, on clot kinetics, strength, and/or structure during the use of thrombin based gelatin matrices and fibrin sealants.

METHODS

Blood was collected and heparinized from donors on clopidogrel (and aspirin) and age matched control donors. Blood component analysis, whole blood platelet aggregometry, and activated clotting time (ACT) were used to monitor compliance to therapy and identify any differences between donor groups. Clot kinetics and strength were analyzed using thrombelastography (TEG). Field Emission Scanning Electron Microscopy (FESEM) was used to analyze clot structure.

RESULTS

Blood component profiles were similar for both donor groups. Aggregometry indicated that aggregation response to adenosine diphosphate (ADP) for clopidogrel donors was 12% of that for the controls (p = 0.0021), an expected result of clopidogrel induced platelet inhibition. However, blood from both donor groups had an elevated thrombin induced aggregation response. Heparinization of donor blood resulted in similarly elevated ACTs for both donor groups. TEG results indicated similar clot kinetics and strength between clopidogrel and control donor groups for blood alone and when clotting was induced using thrombin based gelatin matrices and fibrin sealants. FESEM images supported TEG findings in that similar morphologies were observed in ex vivo formed clots from both donor groups when thrombin based gelatin matrices and fibrin sealants were used.

CONCLUSION

These results suggest that platelet inhibitors do not negatively impact clot kinetics, strength, and structure when clotting is initiated with thrombin based gelatin matrices and fibrin sealants.

Coronary artery bypass grafting: Part 1--the evolution over the first 50 years

Surgical treatment for angina pectoris was first proposed in 1899. Decades of experimental surgery for coronary artery disease finally led to the introduction of coronary artery bypass grafting (CABG) in 1964. Now that we are approaching 50 years of CABG experience, it is appropriate to summarize the advancement of CABG into a procedure that is safe and efficient. This review provides a historical recapitulation of experimental surgery, the evolution of the surgical techniques and the utilization of CABG. Furthermore, data on contemporary clinical outcomes are discussed.

How to manage prasugrel and ticagrelor in daily practice

Prasugrel and ticagrelor are next-generation antiplatelet agents that provide a rapider and more potent inhibition of platelet P2Y12 receptor than clopidogrel. In combination with aspirin, these new P2Y12 inhibitors are now the first line treatments for patients with acute coronary syndrome. However, these potent antiplatelet agents introduce a new paradigm in the daily management of antithrombotic drugs, particularly when an invasive procedure is planned. The pharmacology of these antiplatelet agents, and the results of the main clinical trials, are reviewed with a special focus on good prescription practices (indications, contra-indications, drug interactions), and on peri-operative management. Strategies are proposed for safely reducing the bleeding risk in elderly patients, in patients requiring concomitant oral anticoagulant therapy, or in patients with an increased haemorrhagic risk.

Rapid evaluation of platelet function using the Multiplate® Analyzer

Rapid evaluation of platelet function may be advantageous in the setting of surgical and interventional procedures to tailor treatment of ongoing bleeding. We investigated if platelet function testing performed with the Multiplate® Analyzer (Roche Diagnostics, Mannheim, Germany) only 5 minutes after blood sampling yields reliable test results compared to analyses performed 30 minutes after sampling as currently recommended. We included 48 patients with type II diabetes and stable coronary artery disease treated with aspirin 75 mg daily and 50 healthy individuals not taking any medications. Platelet aggregometry by the Multiplate® Analyzer was performed 5 and 30 minutes after blood sampling using arachidonic acid (1.0 mM), collagen (3.2 µg/ml) and adenosine diphosphate (ADP; 6.5 µM) as agonists. Compliance with aspirin was verified by serum thromboxane B2 measurements. Aggregation levels assessed 5 minutes after blood sampling correlated strongly with those assessed after 30 minutes irrespective of the agonist used (r-values 0.75-0.89, p values <0.0001). Aggregation levels were 4-8% lower and displayed a larger standard deviation when measured 5 minutes after sampling, compared to 30 minutes after sampling. Weak, but significant correlations were observed between platelet aggregation and platelet count (r-values = 0.28-0.39; p values <0.01). The currently recommended 30-minute standing time can be omitted, when platelet aggregation is measured using the Multiplate® Analyzer. Platelet aggregation measured 5 minutes after blood sampling correlates strongly with aggregation measured 30 minutes after sampling, but yields slightly lower aggregation levels. The Multiplate® Analyzer enables rapid on-site evaluation of platelet function.

Safety and Efficacy Outcomes of Preoperative Aspirin in Patients Undergoing Coronary Artery Bypass Grafting

Background:

The administration of aspirin is traditionally discontinued prior to coronary artery bypass grafting (CABG), given a potential risk of excessive postoperative bleeding. Few studies have previously suggested the benefits of continuing aspirin until the time of surgery. The primary aim of this review is to evaluate the effects of preoperative aspirin therapy on several clinically important outcomes in patients undergoing CABG.

Methods:

A meta-analysis of eligible studies of patients undergoing CABG, reporting preoperative aspirin in comparison with no aspirin/placebo and our outcomes, was carried out. The safety outcomes included postoperative bleeding, packed red blood cell (PRBC) transfusion requirements, and reoperation for bleeding. The efficacy outcomes included perioperative myocardial infarction (MI), cerebrovascular accidents (CVAs), and mortality.

Results:

In 8 randomized controlled trials (RCTs; n = 1538), preoperative aspirin increased postoperative bleeding (difference in means = 132.30 mL; 95 % confidence interval [CI] 47.10-217.51; P = .002), PRBC transfusion requirements (difference in means = 0.67 units; 95% CI 0.10-1.24; P = .02), and reoperation for bleeding (odds ratio [OR] = 1.76; 95% CI 1.05-2.93; P = .03). In 19 observational studies (n = 19551), preoperative aspirin increased postoperative bleeding (difference in means = 132.74 mL; 95% CI 45.77-219.72; P = .003) and PRBC transfusion requirements (difference in means = 0.19 units; 95% CI 0.02-0.35; P = .02) but not reoperation for bleeding (OR = 1.13; 95% CI 0.91-1.42; P = .27). Subgroup analyses for RCTs demonstrated that aspirin given at doses ≤ 100 mg/d might not increase the postoperative bleeding, and the dose of 325 mg/d might not be a cutoff value that has clinical and statistical significance. No statistically significant differences in the rate of perioperative MI, CVAs, or mortality were seen between the 2 groups.

Conclusions:

Preoperative aspirin therapy is associated with increased postoperative bleeding, PRBC transfusion requirements, and reoperation for bleeding in patients undergoing CABG. Doses lower than 100 mg/d may minimize the risk of bleeding. Additional RCTs are needed to assess the effects of preoperative aspirin on the safety and efficacy outcomes in patients undergoing CABG.

Comparison of hemostatic agents used in vascular surgery

INTRODUCTION

Over the past 15 years, a wide range of agents have been developed for use in surgical procedures to achieve hemostasis. These agents can be divided into three broad categories: hemostats, sealants and adhesives. They vary widely related to their mechanism of action, composition, ease of application, adherence to wet or dry tissue, immunogenicity and cost.

AREAS COVERED

This article focuses on the agents used in vascular surgery to achieve hemostasis; agents involved in clinical trials are also covered.

EXPERT OPINION

When surgeons achieve rapid hemostasis, potential benefits include better visualization of the surgical area, shorter operative times, decreased requirement for transfusions, better management of an anticoagulated patient, decreased wound healing time and overall improvement in patient recovery time. The need for safe and efficacious hemostatic agents that can provide a range of benefits is clearly a significant surgical issue.

A preliminary study: aspirin discontinuation before elective operations; when is the optimal timing?

Purpose

To evaluate the optimum timing of aspirin cessation before noncardiac surgeries. We have conducted a pilot study to minimize the aspirin cessation time before various surgeries.

Methods

Eighty patients who were taking regular aspirin for secondary prevention undergoing elective surgical operations were enrolled in the study. We separated the patients into two groups. The control group had 35 patients who stopped aspirin intake 10 days before surgery. The study group had 45 patients who stopped their aspirin intake and underwent surgery one day after arachidonic acid aggregation tests were within normal limits. Bleeding, blood loss, and transfusion requirements were assessed perioperatively.

Results

The mean time between aspirin cessation and aspirin nonresponsiveness were found to be 4.2 days with a median value of 4 days. In addition, the mean time between aspirin cessation and operation day were found to be 5.5 days with a median value of 5 days. No perioperative bleeding, thromboembolic or cardiovascular complications were encountered.

Conclusion

Reducing time of aspirin cessation from 7-10 days to 4-5 days is a possibility for patients using aspirin for secondary prevention without increased perioperative complications.

Recommendations for management of antiplatelet therapy in patients undergoing elective noncardiac surgery after coronary stent implantation

Patients commonly undergo noncardiac surgical procedures after implantation of a coronary stent. In the case where surgery cannot be deferred until completing the minimum duration of dual antiplatelet therapy, the Brigham and Women's Hospital Cardiac Catheterization Laboratory recommends using a glycoprotein IIb/IIIa bridging protocol to minimize the risk of perioperative ischemic events. We discuss our algorithm for managing antiplatelet agents, including the newer agents, prasugrel and ticagrelor, in patients undergoing noncardiac surgery after coronary stenting and present our glycoprotein IIb/IIIa bridging strategy along with a review of the relevant pharmacodynamic and clinical evidence.

[Low-dose aspirin doesn't increase surgical bleeding nor transfusion rate in total knee arthroplasty]

OBJECTIVES

Surgical bleeding. transfusion rate and cardiovascular complications were analized in patients undergoing chronic treatment with low-doses aspirin and scheduled to unilateral primary knee arthroplasty.

PATIENTS AND METHODS

We retrospectively studied 117 patients between 2005 and 2006 scheduled for elective knee replacement that received antiplatelet therapy with aspirin (100mg/day). Aspirin medication was maintained or discontinued preoperatively according to medical criteria. We analyzed the biological, clinical and anesthetic data, blood-saving techniques used, surgical bleeding, allogeneic blood transfusion rate, cardiocirculatory complications (myocardial, cerebral or peripheral ischemia), hospital stay and mortality. This population was compared with 190 patients (control group) who underwent the same operation at the same time interval but did not receive aspirin therapy.

RESULTS

The aspirin-treated group was significantly older, with higher weight and poorer health state (higher incidence of ischemic heart disease, cerebral ischemia and diabetes). The hidden and external surgical bleeding and transfusion rate were similar if the aspirin were interrupted or not, preoperatively. Bleeding and transfusion rates were independent of time of interruption of the aspirin. Hospital mortality was zero in the 2 groups. A acute myocardial infarction and a transient stroke happened in two patients wich aspirin treatment was discontinued.

CONCLUSIONS

Preoperative treatment with low doses of aspirin does not increase surgical bleeding and transfusion rate in total knee arthroplasty. Preoperative discontinuation can cause severe cardiocirculatory complications.

Neutralization of heparin activity

Heparin is the mainstay in the treatment and prevention of thrombosis in such diverse clinical settings as venous thromboembolism, acute coronary syndrome, cardiopulmonary bypass, and hemodialysis. However, the major complication of heparin - like that of all anticoagulants - is bleeding. Heparin may need to be reversed in the following settings: clinically significant bleeding; prior to an invasive procedure; at the conclusion of a procedure involving extracorporeal circulation (e.g., cardiopulmonary bypass, dialysis). This chapter discusses protamine sulfate, as well as several other agents that are able to neutralize heparin, including their pharmacological properties, indications, dosing, and efficacy.

Management of patients with recently implanted coronary stents on dual antiplatelet therapy who need to undergo major surgery

About 5% of patients undergoing coronary stenting need to undergo surgery within the next year. The risk of perioperative cardiac ischemic events, particularly stent thrombosis (ST), is high in these patients, because surgery has a prothrombotic effect and antiplatelet therapy is often withdrawn in order to avoid bleeding. The clinical and angiographic predictors of ST are well known, and the proximity to an acute coronary syndrome adds to the risk. The current guidelines recommend delaying non-urgent surgery for at least 6 weeks after the placement of a bare metal stent and for 6-12 months after the placement of a drug-eluting stent, when the risk of ST is reduced. However, in the absence of formal evidence, these recommendations provide little support with regard to managing urgent operations. When surgery cannot be postponed, stratifying the risk of surgical bleeding and cardiac ischemic events is crucial in order to manage perioperative antiplatelet therapy in individual cases. Dual antiplatelet therapy should not be withdrawn for minor surgery or most gastrointestinal endoscopic procedures. Aspirin can be safely continued perioperatively in the case of most major surgery, and provides coronary protection. In the case of interventions at high risk for both bleeding and ischemic events, when clopidogrel withdrawal is required in order to reduce perioperative bleeding, perioperative treatment with the short-acting intravenous glycoprotein IIb-IIIa inhibitor tirofiban is safe in terms of bleeding, and provides strong antithrombotic protection. Such surgical interventions should be performed at hospitals capable of performing an immediate percutaneous coronary intervention at any time in the case of acute myocardial ischemia.

Perioperative management of antiplatelet-drugs in cardiac surgery

The management of coronary patients scheduled for a coronary artery bypass grafting (CABG), who are receiving one or more antiplatelet drugs, is plenty of controversies. It has been shown that withdrawal of antiplatelet drugs is associated with an increased risk of a thrombotic event, but surgery under an altered platelet function also means an increased risk of bleeding in the perioperative period. Because of the conflict recommendations, this review article tries to evaluate the outcome of different perioperative antiplatelet protocols in patients with coronary artery disease undergoing CABG.

An activation-specific platelet inhibitor that can be turned on/off by medically used hypothermia

OBJECTIVE

Therapeutic hypothermia is successfully used, for example, in cardiac surgery to protect organs from ischemia. Cardiosurgical procedures, especially in combination with extracorporeal circulation, and hypothermia itself are potentially prothrombotic. Despite the obvious need, the long half-life of antiplatelet drugs and thus the risk of postoperative bleedings have restricted their use in cardiac surgery. We describe here the design and testing of a unique recombinant hypothermia-controlled antiplatelet fusion protein with the aim of providing increased safety of hypothermia, as well as cardiac surgery.

METHODS AND RESULTS

An elastin-mimetic polypeptide was fused to an activation-specific glycoprotein (GP) IIb/IIIa-blocking single-chain antibody. In silico modeling illustrated the sterical hindrance of a β-spiral conformation of elastin-mimetic polypeptide preventing the single-chain antibody from inhibiting GPIIb/IIIa at 37°C. Circular dichroism spectra demonstrated reverse temperature transition, and flow cytometry showed binding to and blocking of GPIIb/IIIa at hypothermic body temperature (≤32°C) but not at normal body temperature. In vivo thrombosis in mice was selectively inhibited at hypothermia but not at 37°C.

CONCLUSIONS

This is the first description of a broadly applicable pharmacological strategy by which the activity of a potential drug can be controlled by temperature. In particular, this drug steerability may provide substantial benefits for antiplatelet therapy.

Peri-operative management of antiplatelet therapy in patients with coronary artery disease: joint position paper by members of the working group on Perioperative Haemostasis of the Society on Thrombosis and Haemostasis Research (GTH), the working group on Perioperative Coagulation of the Austrian Society for Anesthesiology, Resuscitation and Intensive Care (ÖGARI) and the Working Group Thrombosis of the European Society for Cardiology (ESC)

An increasing number of patients suffering from cardiovascular disease, especially coronary artery disease (CAD), are treated with aspirin and/or clopidogrel for the prevention of major adverse events. Unfortunately, there are no specific, widely accepted recommendations for the perioperative management of patients receiving antiplatelet therapy. Therefore, members of the Perioperative Haemostasis Group of the Society on Thrombosis and Haemostasis Research (GTH), the Perioperative Coagulation Group of the Austrian Society for Anesthesiology, Reanimation and Intensive Care (ÖGARI) and the Working Group Thrombosis of the European Society of Cardiology (ESC) have created this consensus position paper to provide clear recommendations on the perioperative use of anti-platelet agents (specifically with semi-urgent and urgent surgery), strongly supporting a multidisciplinary approach to optimize the treatment of individual patients with coronary artery disease who need major cardiac and non-cardiac surgery. With planned surgery, drug eluting stents (DES) should not be used unless surgery can be delayed for ≥12 months after DES implantation. If surgery cannot be delayed, surgical revascularisation, bare-metal stents or pure balloon angioplasty should be considered. During ongoing antiplatelet therapy, elective surgery should be delayed for the recommended duration of treatment. In patients with semi-urgent surgery, the decision to prematurely stop one or both antiplatelet agents (at least 5 days pre-operatively) has to be taken after multidisciplinary consultation, evaluating the individual thrombotic and bleeding risk. Urgently needed surgery has to take place under full antiplatelet therapy despite the increased bleeding risk. A multidisciplinary approach for optimal antithrombotic and haemostatic patient management is thus mandatory.

Perioperative assessment of platelet function in patients under antiplatelet therapy

Platelets play a central role in primary hemostasis. Analysis of platelet function is therefore a cornerstone in the global assessment of the coagulation status in the perioperative setting, primarily in patients receiving antiplatelet medication, such as cyclooxygenase-1 inhibitors, adenosine diphosphate antagonists and glycoprotein IIb/IIIa inhibitors. In these patients, knowledge of residual platelet function is highly warranted in order to maintain an optimal and individual balance perioperatively between platelet function and inhibition - that is, bleeding and thrombosis. Traditional laboratory-based assays, such as light-transmission aggregometry and flow cytometry, are the clinical standards of platelet function testing today. Light-transmission aggregometry is one of the most widely used tests to identify and diagnose defects in platelet function. The majority of the conventional laboratory-based techniques are labor intensive, costly and time consuming, and require a high degree of experience and expertise to perform and interpret. Therefore, new automated technologies have been developed to measure platelet function more rapidly and easily, and several techniques can be used at the bedside, including whole blood aggregometry, high shear-induced platelet function assessment or viscoelastic measurement techniques. All methods assessing platelet function are summarized and their limitations are discussed in this article, emphasizing their perioperative use.

Transfusion requirements in 811 patients during and after cardiac surgery: a prospective observational study

OBJECTIVE

To identify patients at risk for intra- and postoperative blood product transfusion in a mixed adult cardiac surgical patient population.

DESIGN

A prospective, observational study.

SETTING

A single-center university hospital.

PARTICIPANTS

Patients (n = 811) undergoing cardiac surgery from January 1, 2008, to November 30, 2008.

INTERVENTIONS

The outcome in terms of transfusion of red blood cells (RBCs), fresh frozen plasma (FFP), and/or pooled platelets within the first 24 hours after surgery was studied. Pre- and perioperative risk factors for bleeding and transfusion of blood products were studied.

MEASUREMENTS AND MAIN RESULTS

The majority of RBCs and FFP (>70%) were given to a minority of patients (<12%). The type of surgical procedure, previous cardiac surgery, and emergency operations were all significantly associated with the transfusion of RBCs, FFP, and platelets. Antithrombotic therapy was not significantly associated with the transfusion requirement in the mixed group of cardiac patients. However, in the low-risk procedures such as coronary artery bypass graft surgery, ongoing antithrombotic therapy at the time of the operation significantly increased the risk of transfusion in this otherwise low-risk category of surgery.

CONCLUSIONS

The identification of high-risk patients is necessary to optimize the perioperative management of bleeding complications. Because of the high variability in transfusion requirements, a specifically tailored patient intervention based on the individual's risk profile appears more likely to improve patient outcome compared with general interventions given to the entire patient group.

Reoperation for bleeding in patients undergoing coronary artery bypass surgery: incidence, risk factors, time trends, and outcomes

BACKGROUND

Reoperation for bleeding represents an important complication in patients undergoing coronary artery bypass surgery (CABG). Yet, few studies have characterized risk factors and patient outcomes of this event.

METHODS AND RESULTS

We evaluated 528 686 CABG patients at >800 hospitals in the Society of Thoracic Surgeons National Cardiac Database (2004 to 2007). Clinical features and in-hospital outcomes were evaluated in patients with and without reoperation for bleeding after CABG. Logistic regression was used to identify predictors of risk of this event and to estimate weights for an additive risk score. A total of 12 652 CABG patients (2.4%) required reoperation for bleeding. These rates remained fairly stable over time (2.2%, 2.3%, 2.5%, and 2.4% from 2004 to 2007, respectively). Although overall operative mortality was 4.5-fold higher in patients requiring reoperation for bleeding versus those who did not (2.0% versus 9.1%), this mortality risk declined significantly over time (11.3%, 9.5%, 8.8%, and 8.2% from 2004 to 2007, respectively, P for trend=0.0006). Factors associated with higher risk for reoperation were identified by multivariable analysis (c statistic=0.60) and summarized into a simple bedside risk score. The risk-score performed well when tested in the validation set (Hosmer-Lemeshow P=0.16).

CONCLUSIONS

Reoperation for bleeding remains an important morbid event after CABG. Nonetheless, death in patients with this complication has decreased over time. Our risk tool should allow estimation of patients risk for reoperation for bleeding and promote preventive measures when feasible in this at-risk group.

Platelet-directed therapies and coronary artery bypass grafting

Coronary artery bypass grafting (CABG) is effective in reducing cardiovascular morbidity and mortality in certain high-risk groups. Despite improvement in surgical technique, hemorrhagic complications are a major concern and are likely to affect perioperative morbidity and mortality, length of stay, and hospital expenditures. The use of platelet-directed therapies in this setting is effective in decreasing ischemic complications, yet these agents simultaneously increase the risk of bleeding. Concern about potential hemorrhagic risk from antiplatelet agents in proximity to CABG may influence physicians to discontinue these agents. The benefit of low-dose aspirin given preoperatively is likely to outweigh any hemorrhagic risk. Dual antiplatelet therapy with aspirin and clopidogrel (or aspirin and prasugrel) is associated with a significant increased risk of bleeding and its complications. Additional research is needed to properly evaluate the ischemic benefit versus bleeding risk of aspirin and clopidogrel. Whether reversible P2Y(12) receptor antagonists will mitigate the bleeding risk is unclear at the present time and will require large prospective studies.

Laboratory assessment and perioperative management of patients on antiplatelet therapy: from the bench to the bedside

The contribution of platelets in the pathophysiology of thromboses has established antiplatelet therapy as a cornerstone for prevention or treatment of these disorders. However, patients on antiplatelet drugs undergoing surgery face the life-threatening dilemma between the risk of perioperative thrombosis by ceasing therapy and restoring platelet function versus the risk of surgical bleeding by its continuation. According to their mechanism of action, antiplatelet drugs can be conventionally classified as agents that inhibit cyclooxygenase, block the platelet adenosine diphosphate P2Y12 receptor, inhibit phosphodiesterase, or block platelet glycoprotein IIb/IIIa. Although several tests have been developed to assess platelet inhibition by most of these compounds, studies to date have not been able to reliably evaluate the diagnostic efficiency of these tests to predict hemorrhage and/or blood loss, and accordingly perioperative assessment of drug-induced platelet inhibition cannot be recommended as yet. Although several management options are available to counteract the hemorrhagic risk of surgical patients using antiplatelet agents, perioperative discontinuation of these drugs is the preferable choice wherever possible. The use of platelet transfusions should be limited where necessary to the treatment of major, life-threatening bleeding. The contribution of newer hemostatic agents, such as desmopressin and recombinant activated factor VII, is yet to be fully determined, and there remain many challenges and unresolved issues in the clinical care of these patients.

Management of surgical patients receiving anticoagulation and antiplatelet agents

BACKGROUND

Temporary interruption of long-term anticoagulation and antiplatelet therapy during surgical procedures exposes patients to thrombotic risk. Continuation of these agents, however, is associated with an increased risk of bleeding. Managing anticoagulation can be a particular challenge in the emergency setting.

METHODS

A literature review of published articles sourced using the keywords heparin, warfarin, perioperative, antiplatelet, aspirin and surgery was undertaken. A management plan for all likely situations was developed.

RESULTS AND CONCLUSION

Based on an individual assessment of risk factors for arterial or venous thromboembolism and the risk of perioperative bleeding, it is possible to form an anticoagulant and antiplatelet management plan likely to achieve a low incidence of bleeding and thrombosis. A multidisciplinary approach is desirable.