Clopidogrel and Bleeding After Coronary Artery Bypass Graft Surgery

Effect of anti-platelet therapy on peri-operative blood loss in patients undergoing off-pump coronary artery bypass grafting

Purpose:

The purpose of this study was to review the effect of the pre-operative use of clopidogrel and aspirin on peri-operative bleeding, blood product transfusion, and resource utilization after coronary artery bypass grafting (CABG).

Materials and Methods:

A total of 1200 patients who underwent off-pump CABG (OPCABG) between 2010 and 2012 were retrospectively studied. Patients were divided into three groups: group 1: discontinued aspirin and clopidogrel 6 days prior to surgery (n = 468), group 2: discontinued both drugs 3 to 5 days prior to surgery (n = 621), and group 3: discontinued both drugs 2 days prior to surgery (n = 111). The bleeding pattern and blood product transfusion were studied and compared between the groups. Patients having history of other drugs affecting the coagulation profile, other organ dysfunction, on-pump CABG, and the combined procedure were excluded from the study.

Results:

Group 2 patients had a higher rate of bleeding and a reduced mean value of hemoglobin (Hb) as compared to other groups. The same results were seen in blood and blood product transfusion. Patients of group 2 and group 3 were associated with higher blood loss in terms of drainage at 12 and 24 hours. Post-operatively, this was statistically significant. Re-exploration was statisitically significant in group 3 patients (9.01%) than in group 2 (2.58%) and group 1 (1.07%) patients.

Conclusion:

The pre-operative use of clopidogrel and aspirin in patients undergoing OPCABG showed limited clinical benefits; however, its use significantly increased the risk of bleeding and blood transfusion, thus increasing morbidity and resource utilization. Hence, clopidogrel and aspirin should be stopped at least 6 days prior to surgery.

Impact of Clopidogrel Stop Interval on Major Adverse Bleeding Events in Cardiac Surgery

Background

Major societal guidelines recommend a 5-day stop interval before cardiac surgery for patients with acute coronary syndrome receiving clopidogrel. Yet, many such patients present with high acuity, generating surgeon inclination toward use of shorter stop intervals. Thus, this study aimed to determine the impact of the duration and timing of the interval of clopidogrel cessation on adverse bleeding events.

Methods

Patients who underwent cardiac surgery between 2009 and 2016 at a tertiary-care centre were included in this retrospective cohort study. Multivariable logistic regression models adjusted for clopidogrel stop interval, age, urgency of procedure, and procedure type were used to quantify the effect of clinically relevant baseline demographic characteristics on incidence of massive transfusion as well as hemorrhagic complication outcomes.

Results

A total of 5748 patients underwent cardiac surgery. In this cohort, 1743 patients (30.3%) received clopidogrel preoperatively, and 884 (50.7%) of these patients discontinued clopidogrel 5 days before presenting to the operating room. The administration of clopidogrel 1-2 days before surgery (odds ratio 1.97; 95% confidence interval: 1.18 to 3.29) was an independent predictor for massive transfusions and hemorrhagic complications (odds ratio 1.85; 95% confidence interval: 1.01 to 3.37). The 3-4 day group did not have an increased risk of major bleeding complications. The risk for both massive transfusions and hemorrhagic complications also increased with the urgency and complexity of surgery.

Conclusion

A clopidogrel stop interval of 3-4 days preoperatively was not associated with an increased risk for major bleeding complications.

Role of Using a Thromboelastometry-Based Protocol for Transfusion Management in Combined Coronary Artery Bypass Grafting and Valve Surgery: A Randomized Clinical Trail

The aim of this study was to evaluate the impact of using a thromboelastometry-based protocol on transfusion requirements in patients undergoing combined coronary artery bypass grafting (CABG) and valve surgery. 80 adult patients scheduled for elective combined CABG and valve surgery were included in this clinical trial study. Patients were randomly allocated to the thromboelastometry (ROTEM) (n = 40) or control groups (n = 40). In the ROTEM group, transfusion was directed according to a thromboelastometry-based protocol. In the control group, transfusion was conducted according to the routine practices including conventional coagulation testing and clinical judgments. Finally, transfusion requirements were compared between groups. Use of thromboelastometry- based protocol resulted in 67% reduction in blood products units' consumption as well as 23% in the percentage of patients transfused. This reduction was especially evident in relation to fresh frozen plasma (FFP) and platelet consumption. No significant differences were found both in the percentage of patients receiving RBC and number of transfused RBC units. Using thromboelastometry tests incorporated a protocol results in reduction of transfusion requirements in patients undergoing elective combined CABG and valve surgery.

[Blood loss control during endoscopic vein harvesting for myocardial revascularization in patients with acute coronary syndrome]

From 5 to 10% of patients presenting with acute coronary syndrome and receiving dual antiplatelet therapy require surgical myocardial revascularization. Dual antiplatelet therapy considerably increases the risk of surgical bleeding. Endoscopic harvesting of the great saphenous vein is a technique that can make it possible to decrease the injury and to minimize blood loss. The study included a total of 32 patients presenting with acute coronary syndrome and undergoing coronary artery bypass grafting. They were subdivided into two groups: Group One (study group) was composed of 17 patients subjected to endoscopic harvesting of the great saphenous vein in the flap. Group Two (comparison group) consisted of 15 patients undergoing an open technique of harvesting of the vein in the flap. During the entire perioperative period, the amount of discharge through drainages from the mediastinum did not differ significantly (958±173 ml for Group One patients and 1005±165 ml for Group Two patients, p=0.47). The amount of discharge from the bed of the great saphenous vein on the lower extremities in Group One patients turned out to be less than in Group Two patients (443±37 ml vs. 570±77 ml, p=0.04). A higher haemoglobin content in the total blood count was observed in the postoperative period in the Study Group patients (90±30 g/l vs. 74±21 g/l, respectively, p=0.03). The necessity to use donor blood preparations in Group One patients turned out to be less (transfusion of erythrocytic mass 0 and 2 (0; 2) doses, p=0.001; fresh frozen plasma 2 (0; 3) and 5 (3; 8) doses, respectively, p=0.0001). The duration of hospital stay amounted to 8±1.1 days in the study group and to 15±4.5 days in the comparison group (p<0.0001). Hence, this approach makes it possible to control blood loss in high-risk patients undergoing coronary artery bypass grafting on the background of dual antiplatelet therapy, to decrease the amount of donor blood, and to reduce the length of hospital stay.

When is the optimal time to discontinue clopidogrel before in-hospital coronary bypass surgery? A closer look at the current literature

BACKGROUND

Clopidogrel and other P2Y12 inhibitors have become the standard of care among patients presenting with acute coronary syndromes. A substantial proportion of these patients require surgical revascularization during index hospitalization.

HYPOTHESIS

Guidelines recommend a 5-day waiting period off clopidogrel before coronary artery bypass grafting (CABG) to reduce hemorrhagic complications. These recommendations are not routinely followed in clinical practice, while recent studies also propose shorter waiting periods off clopidogrel for patients awaiting in-hospital CABG.

METHODS

A preliminary PubMed search was conducted using the following MeSH terms under the publication type "Hemorrhage:" "Clopidogrel," AND "Coronary Artery Bypass." Relevant studies and guidelines were then reviewed and selected based on a predetermined criteria. Studies that formulated the current recommendations for stopping clopidogrel preoperative to CABG are discussed in detail this review.

RESULTS

A comprehensive review of recent evidence illustrates mixed bleeding and transfusion outcomes among CABG patients with preoperative exposure to clopidogrel in less than 5 days.

CONCLUSIONS

The optimal discontinuation time of clopidogrel before CABG is still poorly defined. The recommendation of a 5-day washout period for clopidogrel should be reconsidered to be on par with current clinical practice.

Clopidogrel Adherence to AHA/ACC Guideline in Patients with Open Heart Surgery in a Tertiary Heart Center

Background: Clopidogrel is an antiplatelet drug that is widely prescribed for cardiovascular disease. In cardiac surgery, it is used in patients after coronary artery bypass grafting (CABG) to prevent coagulation disorders. The irrational use of this drug can lead to bleeding and require surgical exploration along with increased therapeutic cost. Therefore, it is essential to study the pattern of clopidogrel use in hospitals. Methods: This study was conducted for a 6-month period to evaluate clopidogrel adherence to American Heart Association/American College of Cardiology (AHA / ACC) Guidelines in patients after coronary artery bypass grafting (CABG) surgery. Patients’ data were recorded in the pre-designed questionnaire, which included demographic data, past medical history, drug history along with the indications of clopidogrel use. Data analysis was performed by SPSS 16 software. Results: A total of 120 patients with a mean age of 61.3 ± 8.9 years old were recruited in to this study. Male to female ratio was 3 times. The main risk factors in patients with ischemic heart disease were male gender (74.2%), hypertension (80%), and smoking (47.5%). In addition to clopidogrel, most of the patients received aspirin (95.8%), followed by heparin (31.7%), and warfarin (5%) or enoxaparin (2.5%). The clopidogrel indications were non ST-elevation myocardial infarction / unstable angina (33.3%), acute ST-elevation myocardial infarction (20.8%), recent myocardial infarction or stroke (3.3%), and CABG off-pump (30%). In 70.8% of cases, the administration of clopidogrel was consistent with AHA / ACC standard guidelines and most of the irrational cases belonged to the usage of the drug after on-pump CABG surgery. Conclusion: The results showed that the rates of adherence to clopidogrel use with the AHA/ACC guidelines for patients who underwent CABG surgery was relatively good, but required further improvement.

Is Preoperative Clopidogrel Resistance a Predictor of Bleeding and Risks in Patients Undergoing Emergency CABG Surgery?

Objective

The aims of this study were to determine whether the detection of preoperative clopidogrel resistance in patients undergoing cardiac surgery while using clopidogrel could play a guiding role in the prediction of postoperative excessive bleeding, transfusion requirements, and risks and to provide clinically significant data.

Methods

Two hundred and twenty-two patients [median age: 59.4 (38-83) years; 38 females] undergoing emergency and elective coronary artery bypass graft (CABG) surgeries in our clinic were evaluated prospectively. Patients with multiple systemic diseases, other than diabetes mellitus (DM) and hypertension (HT), were excluded. Patients receiving clopidogrel were also evaluated for clopidogrel resistance and grouped according to the results of this test. Assessments of platelet functions were performed by multiplate impedance aggregometry method and adenosine diphosphate test.

Results

The use of postoperative fresh blood replacement and platelet transfusion was higher in patients receiving clopidogrel than in those not receiving it (P=0.001, P=0.018). DM, HT, myocardial infarction, and the number of presentation to the emergency room were significantly higher in patients receiving clopidogrel than in those not receiving it (P<0.05). No significant difference was determined between patients with and without clopidogrel resistance regarding the amount of bleeding during and after surgery, erythrocyte suspension and fresh-frozen plasma transfusion rates, preoperative troponin values, ejection fraction values, and length of hospital stays (P>0.05).

Conclusion

We think that resistance studies in patients receiving clopidogrel before cardiac surgery are not efficient to predict bleeding and bleeding-related complications in patients undergoing emergency and elective CABG surgeries.

Stopping antiplatelet medication before coronary artery bypass graft surgery: is there an optimal timing to minimize bleeding?

OBJECTIVES

As the indication for antiplatelet medication expands, patients may be exposed to an increased risk of excessive blood loss when cardiac surgery is required. The optimal timing to stop acetylsalicylic acid (ASA) or ASA combined with clopidogrel (ASA+Clo) before surgery is the subject of controversy.

METHODS

A total of 1065 patients were selected from a prospective randomized study on the effect of a fibrin sealant application in coronary artery bypass graft surgery [Fibrin sealant Induced Blood Exposure Reduction study;

REGISTRATION NUMBER

NTR1386 (http://www.trialregister.nl)], and divided into three groups according to the use of antiplatelet medication within 10 days prior to surgery: (i) ASA only (n = 662), (ii) ASA+Clo (n = 290) or (iii) no antiplatelet medication (n = 113). To investigate if an optimal stop day could be established, we fitted a series of multiple linear regression models, one for each preoperative day (running from Day -10 up to -1). The specific day corresponding to the best fitting model (highest adjusted R(2), with blood loss in the first 48 h postoperatively as the dependent variable) was considered as the best estimate for the optimal stop day. Bootstrap analysis (1000 times) was performed to calculate the corresponding confidence interval. Furthermore, major adverse cardiovascular and cerebral events (MACCE) were evaluated.

RESULTS

We could not estimate an optimal stop day for patients using ASA or ASA+Clo prior to their operation. Last use of ASA on Day -2 or earlier significantly decreased the percentage of patients receiving platelet transfusions compared with continuation until surgery (7 vs 13% for Day -1, P = 0.007). In patients using ASA+Clo, this percentage was reduced from 41 to 10 (P < 0.001). There was no association between stop day and the occurrence of MACCE.

CONCLUSIONS

There is no clinically relevant effect on blood loss indicating an optimal stop day for ASA alone or in combination with Clo. Last use on Day -2 resulted in the reduction of percentage of patients receiving platelet transfusions, especially in the ASA+Clo group.

Is early hip fracture surgery safe for patients on clopidogrel? Systematic review, meta-analysis and meta-regression

INTRODUCTION

Hip fracture is a common presentation in the elderly population, many of whom will be taking the antiplatelet clopidogrel, which has the potential to increase perioperative bleeding. The aim of this systematic review and meta-analysis was to answer the questions: (1) is early hip fracture surgery for patients on clopidogrel associated with worse postoperative outcomes compared to patients not on clopidogrel? (2) is early versus delayed surgery for these patients associated with worse postoperative outcomes?

METHODS

A systematic search was conducted of MEDLINE, EMBASE, Cinahl and AMED databases. Results from patients undergoing early surgery on clopidogrel were compared to a control group not taking clopidogrel. In addition, patients taking clopidogrel undergoing early and delayed surgery were compared.

RESULTS

For patients taking clopidogrel undergoing early surgery, there was no associated increase in overall mortality (OR 0.89; 95% CI: 0.58-1.38) or 30-day mortality (OR 1.10 95% CI: 0.48-2.54). However, there was an associated increase in blood transfusion (OR 1.41 95% CI: 1.00-1.99). There was an associated decreased length of stay in the early surgery versus delayed surgery group (weighted mean difference -7.09 days (95% CI: -10.14 to -4.04).

DISCUSSION

Early surgery appears safe for patients with hip fracture though there may be a small increase in the rate of blood transfusion. However, larger prospective trials are required to confirm these findings.

Comparison of three point-of-care testing devices to detect hemostatic changes in adult elective cardiac surgery: a prospective observational study

Background

Bleeding complications in cardiac surgery may lead to increased morbidity and mortality. Traditional blood coagulation tests are not always suitable to detect rapid changes in the patient's coagulation status. Point-of-care instruments such as the TEG (thromboelastograph) and RoTEM (thromboelastometer) have been shown to be useful as a guide for the clinician in the choice of blood products and they may lead to a reduction in the need for blood transfusion, contributing to better patient blood management.

Methods

The purpose of this study was to evaluate the ability of the TEG, RoTEM and Sonoclot instruments to detect changes in hemostasis in elective cardiac surgery with cardiopulmonary bypass and to investigate possible correlations between variables from these three instruments and routine hematological coagulation tests. Blood samples from thirty-five adult patients were drawn before and after surgery and analyzed in TEG, RoTEM, Sonoclot and routine coagulation tests. Data were compared using repeated measures analysis of variance and Pearson's test for linear correlation.

Results

We found significant changes for all TEG variables after surgery, for three of the RoTEM variables, and for one variable from the Sonoclot. There were significant correlations postoperatively between plasma fibrinogen levels and variables from the three instruments.

Conclusions

TEG and RoTEM may be used to detect changes in hemostasis following cardiac surgery with CPB. Sonoclot seems to be less suitable to detect such changes. Variables from the three instruments correlated with plasma fibrinogen and could be used to monitor treatment with fibrinogen concentrate.

The effects of clopidogrel (Plavix) and other oral anticoagulants on early hip fracture surgery

OBJECTIVE

Risk for bleeding complications during and after early hip fracture surgery for patients taking clopidogrel and other anticoagulants have not been defined. The purpose of this study is to assess the perioperative bleeding risks and clinical outcome after early hip fracture surgery performed on patients taking clopidogrel (Plavix) and other oral anticoagulants.

DESIGN

Study design is a retrospective cohort analysis using data extracted from hospital records and state death records.

SETTING

Regional medical center (level II trauma).

METHODS

Data for 1118 patients ≥60 years of age who had surgical treatment for a hip fracture between 2004 and 2008 were reviewed. Eighty-two patients undergoing late surgery (>3 days after admission) were excluded. Patients taking clopidogrel were compared against those not taking clopidogrel. In addition, patients taking clopidogrel only were compared against cohorts of patients taking both clopidogrel and aspirin, aspirin only, warfarin only, or no anticoagulant.

RESULTS

Seventy-four of 1036 patients (7%) were taking clopidogrel, although control groups included 253 patients on aspirin alone, 90 patients on warfarin, and 619 taking no anticoagulants. No significant differences were noted between patients taking clopidogrel and those not taking clopidogrel in estimated blood loss, transfusion requirement, final blood count, hematoma evacuation, hospital length of stay (LOS), or mortality while in hospital or at 1 year. A higher American Society of Anesthesiologists score was seen in the clopidogrel and warfarin groups (P = 0.05 each), increased LOS in the clopidogrel group (P = 0.05), and higher rate of deep vein thrombosis seen in those patients taking warfarin (P = 0.05). Clopidogrel only versus aspirin versus both aspirin and clopidogrel, versus no anticoagulant versus warfarin showed no significant differences in estimated blood loss, transfusion requirement, final blood count, bleeding or perioperative complications, or mortality.

CONCLUSIONS

Patients undergoing early hip fracture surgery who are taking clopidogrel, aspirin, or warfarin (with regulated international normalized ratio) are not at substantially increased risk for bleeding, bleeding complications, or mortality. Comorbidities and American Society of Anesthesiologists scores were significantly higher in the clopidogrel group, which may have resulted in the increased postoperative LOS in this group.

Blood component support in acquired coagulopathic conditions: is there a method to the madness?

Acquired coagulopathies are often detected by laboratory investigation in clinical practice. There is a poor correlation between mild to moderate abnormalities of laboratory test and bleeding tendency. Patients who are bleeding due to coagulopathy are often managed with various blood components including plasma, platelets, and cryoprecipitate. However, prophylactic transfusion of these products in a nonbleeding patient to correct mild to moderate abnormality of a coagulation test especially preprocedure is not evidence-based. This article reviews the management of bleeding due to oral anticoagulants and antiplatelet agents, disseminated intravascular coagulation, chronic liver disease, and trauma.

Haemostatic therapy in coronary artery bypass graft patients with decreased platelet function: comparison of fibrinogen concentrate with allogeneic blood products

BACKGROUND

Patients undergoing coronary artery bypass grafting (CABG) are at risk of postoperative bleeding because of decreased platelet function and cardiopulmonary bypass (CPB)-induced haemostatic impairment. Fibrinogen concentration decreases by 34-42% of the preoperative level by the end of CPB. An inverse relationship between perioperative plasma fibrinogen levels and postoperative bleeding has been reported in CABG patients. Administration of fibrinogen concentrate after weaning from CPB in patients with diffuse microvascular bleeding may help promote haemostasis. We compared patient outcomes following fibrinogen concentrate administration or transfusion of allogeneics in CABG patients with decreased platelet function.

METHODS

Thirty-eight patients with decreased preoperative platelet function in Multiplate aggregometry were included. Patients with bleeding after CPB received either fibrinogen concentrate (guided by the measurement of fibrin clot quality using the FIBTEM thromboelastometric test) or allogeneics.

RESULTS

Twenty-nine of 38 patients received haemostatic therapy (bleeding + fibrinogen group, n = 10; bleeding + allogeneics group, n = 19). Total transfusion (median (interquartile range)) was significantly lower in the bleeding + fibrinogen group (0 (0, 3.8) units), compared with the bleeding + allogeneics group (6 (5, 8) units, p = 0.0073). Bolus administration of fibrinogen concentrate increased FIBTEM maximum clot firmness from 10.5 (9.3, 11) mm after CPB to 20.5 (20, 21.8) mm at the end of surgery. Postoperative outcomes were similar in both groups. No treatment-related complications were observed after fibrinogen concentrate.

CONCLUSIONS

In CABG patients with bleeding after CPB, FIBTEM-guided administration of fibrinogen concentrate resulted in overall decreased transfusion, compared with haemostatic therapy with allogeneics. Fibrinogen concentrate administration increased the fibrin clot quality and helped achieve haemostasis.

Preoperative thienopyridine use and outcomes after surgery: a systematic review

BACKGROUND

Although studies have demonstrated excess risk of ischemic events if aspirin is withheld preoperatively, it is unclear whether preoperative thienopyridine use influences postoperative outcomes.

METHODS

We conducted a systematic review of 37 studies (31 cardiac and 6 noncardiac surgery, 3 randomized, 34 observational) comparing postoperative outcomes in patients who were versus were not exposed to thienopyridine in the 5 days before surgery.

RESULTS

Exposure to thienopyridine in the 5 days preceding surgery (compared with no exposure) was not associated with any reduction in postoperative myocardial infarction (23 studies, 12,872 patients, 3.4% vs 3.0%, odds ratio [OR] 0.98; 95% confidence interval [CI], 0.72-1.34), but was associated with increased risks of stroke (16 studies, 10,265 patients, 1.9% vs 1.4%, OR 1.54; 95% CI, 1.08-2.20), reoperation for bleeding (32 studies, 19,423 patients, 4.3% vs 1.8%, OR 2.62; 95% CI, 1.96-3.49), and all-cause mortality (28 studies, 22,990 patients, 3.7% vs 2.6%, OR 1.38; 95% CI, 1.13-1.69). Results were identical when analyses were restricted to long-term users of thienopyridines who continued versus held the medication in the 5 days before surgery. Although all associations were similar in direction for the subset of patients undergoing noncardiac surgery, 97% of the outcome data in this meta-analysis came from cardiac surgery trials.

CONCLUSIONS

These data support withholding thienopyridines 5 days before cardiac surgery; there was insufficient evidence to make definitive recommendations for elective noncardiac surgery although the direction and magnitude of associations were similar.

Platelet Function after Cessation of Chronic Clopidogrel Therapy

Surgeons increasingly encounter patients on clopidogrel therapy who are preparing to undergo surgery. The goal of this study was to examine the change in platelet function after the common clinical scenario of discontinuing chronic clopidogrel therapy in those patients preparing to undergo an elective surgery, and the time course of platelet function recovery after clopidogrel discontinuation. Patients on clopidogrel therapy scheduled for an elective surgical procedure had their platelet function tested using a Verify Now P2Y12 device (Accumetrics, San Diego, CA). Platelet inhibition was evaluated at baseline before clopidogrel discontinuation, and subsequently studied every other day in the week before their scheduled procedure. Mean platelet inhibition was 32.1 per cent on Day 0 (before clopidogrel discontinuation), decreasing to 3.7 per cent on Day 4. Platelet inhibition decreased significantly after discontinuation of clopidogrel in a time-dependent manner ( P = 0.011), although a considerable interindividual variability of P2Y12 reaction units values was observed over the study period. Patients on concomitant proton pump inhibitors and clopidogrel demonstrated a decreased effect of clopidogrel. In conclusion, individual platelet function monitoring may assist the surgeon in perioperative decision-making in patients receiving clopidogrel therapy preparing to undergo elective surgery.

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.

Temporal trends and practice variations in clopidogrel loading doses in patients with non-ST-segment elevation myocardial infarction, from the National Cardiovascular Data Registry

BACKGROUND

A higher loading dose of clopidogrel achieves a more rapid and consistent degree of platelet inhibition than standard dosing, although the clinical benefit of higher doses has not been clearly established. The use of the different doses in clinical practice is not known. We evaluated the patient, procedural, and hospital characteristics associated clopidogrel loading doses given to patients with non-ST-segment elevation myocardial infarction (NSTEMI).

METHODS

The National Cardiovascular Data Registry ACTION Get With the Guidelines Registry was queried for patients with NSTEMI admitted from 2007 to 2008. Demographic, clinical, and procedural information were collected on standardized data forms. Patients were categorized according to the clopidogrel loading dose received. Temporal trends in the use of different doses were evaluated in quarterly time intervals.

RESULTS

Between January 1, 2007, and December 31, 2008, the use of a 600-mg clopidogrel loading dose increased steadily from 36.4% to 45.5%, whereas the use of 300 mg decreased slightly from 40.1% to 37.1%. Patients loaded with clopidogrel before cardiac catheterization were more likely to receive 300 mg, whereas those receiving a loading dose at the time of catheterization more often received 600 mg. The temporal increase in the use of 600 mg clopidogrel loading doses was not explained by temporal changes in periprocedural loading, use of early invasive management of patients with NSTEMI, or use of antithrombotics or glycoprotein 2b/3a inhibitors.

CONCLUSIONS

Higher loading dose clopidogrel increased between 2007 and 2008. Higher-dose clopidogrel was more frequently used in lower-risk patients undergoing an early invasive strategy and receiving periprocedural loading.

Point-of-care testing in haemostasis

Point-of-care testing (POCT) in haematology has seen a significant increase in both the spectrum of tests available and the number of tests performed annually. POCT is frequently undertaken with the belief that this will reduce the turnaround time for results and so improve patient care. The most obvious example of POCT in haemostasis is the out-of-hospital monitoring of the International Normalized Ratio in patients receiving a vitamin K antagonist, such as warfarin. Other areas include the use of the Activated Clotting Time to monitor anticoagulation for patients on cardio-pulmonary bypass, platelet function testing to identify patients with apparent aspirin or clopidogrel resistance and thrombelastography to guide blood product replacement during cardiac and hepatic surgery. In contrast to laboratory testing, POCT is frequently undertaken by untrained or semi-trained individuals and in many cases is not subject to the same strict quality control programmes that exist in the central laboratory. Although external quality assessment programmes do exist for some POCT assays these are still relatively few. The use of POCT in haematology, particularly in the field of haemostasis, is likely to expand and it is important that systems are in place to ensure that the generated results are accurate and precise.

The use of clopidogrel (Plavix) in patients undergoing nonelective orthopaedic surgery

OBJECTIVE

To assess the effects of Plavix on patients requiring nonelective orthopaedic surgery.

DESIGN

Retrospective cohort study.

SETTING

University-affiliated teaching institutions.

PATIENTS AND PARTICIPANTS

The orthopaedic trauma registry was used to retrospectively identify all patients taking clopidogrel (Plavix; Bristol-Myers Squibb/Sanofi Pharmaceuticals, Bridgewater, NJ) who required nonelective orthopaedic surgery from 2004 to 2008. Twenty-nine patients were identified on Plavix (PG) and 32 matched patients in the control group not taking Plavix (NPG). The Plavix group was separated into those with a surgical delay less than 5 days of the last dose (PG < 5) (n = 28) and a delay greater than 5 days (PG > 5) (n = 1). A randomized age- and injury-matched control group not on Plavix was separated with surgical delay less than 5 days (NPG < 5) (n = 29) and delay greater than 5 days (NPG > 5) (n = 3).

INTERVENTION

A retrospective review was performed comparing pre- and postoperative hemoglobin, blood transfusion requirements, surgical delay, 30-day mortality, and postoperative complications.

MAIN OUTCOME MEASUREMENTS

Statistical analyses were performed using the Student t test and chi square test to identify differences between the groups.

RESULTS

: The mean preoperative hemoglobin of the PG and the NPG was 11.2 g/dL and 12.3 g/dL (P = 0.03). Transfusion rates were similar with 18 of 28 in the PG compared with 13 of 29 in the NPG (P = 0.22). The mean surgical delay between the PG and NPG was 1.88 and 1.68 days (P = 0.64). Overall complications between the PG and NPG was nine of 28 and nine of 29 (P = 0.92). In both groups, two patients had postoperative wound drainage, which resolved without intervention. One patient in each group required revision surgery for nonunion. The 30-day mortality in the Plavix group was zero of 28 (0%) compared with one of 29 (3%) in the control group (cardiac arrest) (P = 0.32).

CONCLUSIONS

In this study, there were no serious complications or increased transfusion requirements in the Plavix group. Avoiding surgical delay for patients on Plavix requiring nonelective orthopaedic surgery appears to be safe. The goal should be early operative intervention to decrease the morbidity and mortality of surgical delay. This is especially true for patients with hip fractures, which was the most common nonelective orthopaedic surgery required of patients on Plavix in this study.

Dual antiplatelet therapy in patients requiring urgent coronary artery bypass grafting surgery: a position statement of the Canadian Cardiovascular Society

Acute coronary syndrome (ACS) guidelines recommend that most patients receive dual antiplatelet therapy with clopidogrel and acetylsalicylic acid (ASA) at the time of presentation to prevent recurrent ischemic events. Approximately 10% of ACS patients require coronary artery bypass grafting surgery (CABG) during the index admission. Most studies show that patients who receive ASA and clopidogrel within five days of CABG have an increase in operative bleeding. Current consensus guidelines recommend discontinuation of clopidogrel therapy at least five days before planned CABG to reduce bleeding-related events. However, high-risk individuals may require urgent surgery without delay, to reduce the risk of potentially fatal ischemic events. The present multidisciplinary position statement provides evidence- based recommendations for the optimal use of dual antiplatelet therapy to balance ischemic and bleeding risks in patients with recent ACS who may require urgent CABG.

RECOMMENDATIONS

1. All ACS patients should be considered for dual antiplatelet therapy with ASA and clopidogrel at the earliest opportunity, despite the possibility of a need for urgent CABG. 2. For patients who have received clopidogrel and ASA, and require CABG: * Those at high risk of an early fatal event (eg, with refractory ischemia despite optimal medical treatment, and with high-risk coronary anatomy (eg, severe left main stenosis with severe right coronary artery disease), should be considered for early surgery without discontinuation of clopidogrel. * In patients with a high bleeding risk (eg, previous surgery, complex surgery) who are also at high risk for an ischemic event, consideration should be given to discontinuing clopidogrel for three to five days before surgery. * Patients at a lower risk for ischemic events (most patients) should have clopidogrel discontinued five days before surgery. 3. For patients who have CABG within five days of receiving clopidogrel and ASA, the risk of major bleeding and transfusion can be minimized by applying multiple strategies before and during surgery. 4. Patients who receive clopidogrel pre-CABG for a recent ACS indication should have clopidogrel restarted after surgery to decrease the risk of recurrent ACS. 5. For patients with a recent coronary stent, the decision to continue clopidogrel until the time of surgery or to discontinue will depend on the risk and potential impact of stent thrombosis. Restarting clopidogrel after CABG will depend on whether the stented vessel was revascularized, the type of stent and the time from stent implantation. Clopidogrel should be restarted when hemostasis is assured to prevent recurrent acute ischemic events.

Cangrelor: a novel P2Y12 receptor antagonist

Antiplatelet therapy is critical in the prevention of thrombotic complications of acute coronary syndrome and percutaneous coronary interventions. Current antiplatelet agents (aspirin, clopidogrel and glycoprotein IIb/IIIa antagonists) have demonstrated the capacity to reduce major adverse cardiac events. However, these agents have limitations that compromise their clinical utility. The platelet P2Y12 receptor plays a central role in platelet function and is a focus in the development of antiplatelet therapies. Cangrelor is a potent, competitive inhibitor of the P2Y12 receptor that is administered by intravenous infusion and rapidly achieves near complete inhibition of ADP-induced platelet aggregation. This investigational drug has been studied for use during coronary procedures and the management of patients experiencing acute coronary syndrome and is undergoing evaluation for use in the prevention of perioperative stent thrombosis.

Decision making after aspirin, clopidogrel and GPIIb/IIIa inhibitor use

The expanding use of antiplatelet agents in patients who undergo coronary bypass grafting raises the problem of balancing the benefit of this treatment and the risk of increased bleeding after surgery. Aspirin and clopidogrel have different mechanisms of actions, but have in common the irreversibility of the inhibition mechanism. Even if platelets half-life is around 10 days, it is not necessary to wait for this period of time. It can be reasonable to discontinue aspirin two to three days and clopidogrel five days before surgery, even if it was recently suggested to reduce the discontinuation interval to two to three days for the clopidogrel as well. GPIIb/IIIa inhibitors have a short acting action. Reasonably, abciximab has to be stopped, when possible, at least 12 hours before surgery, preferably before 24 hours. On the contrary, tirofiban can also be stopped at the moment of skin incision without harmful effects. Very little is known of eptifibatide, but it seems that it is safe to stop it two to four hours before surgery. Patients with acute coronary syndrome do not need to discontinue any antiplatelet treatment.

Is it possible to safely administer early a loading dose of clopidogrel before coronary angiography to patients who are candidates for percutaneous coronary intervention?

Current American College of Cardiology/American Heart Association guidelines recommend loading clopidogrel >or=6 hours before percutaneous coronary intervention. Other American College of Cardiology guidelines advise withholding clopidogrel for 5 days before coronary artery bypass grafting (CABG) to avoid excessive bleeding. Previously published rules for predicting early CABG after coronary angiography (CA) were developed in selected patients with non-ST-segment elevation-acute coronary syndrome and not tested in community practice settings. Using logistic regression analysis we sought to develop an accurate decision rule to identify patients at higher risk for early CABG, in unselected community hospital patients undergoing diagnostic CA, who were candidates for percutaneous coronary intervention. The study was conducted at a community hospital in Ann Arbor, Michigan. A total of 986 randomly selected records from 2004 were reviewed. Sixty-two percent were men and mean age was 64 years. Twelve percent underwent CABG within 5 days of CA. Of those with previous CABG, only 2% underwent early CABG. From several potential predictor variables examined, age, male gender, previous CABG, history of typical angina pectoris, previous CA, and hypertension were identified through multivariate logistic regression and incorporated in a simple risk score. Sensitivity and specificity of a risk score >12 were 66% (95% confidence interval 56 to 74) and 66% (95% confidence interval 62 to 69), respectively, with an area under the receiver operating characteristics curve of 0.72. In conclusion, early CABG in those undergoing CA can be predicted with only modest accuracy from preprocedure clinical variables.

Monitoring platelet function to reduce the risk of ischemic and bleeding complications

Patients with acute coronary syndromes and patients who undergo coronary stent implantation frequently receive dual antiplatelet therapy with aspirin and a thienopyridine. A wide variability exists in the inhibitory response to the thienopyridine clopidogrel among individuals, but this variability can be detected by a variety of platelet function assays. Several studies have demonstrated an association between high platelet reactivity post clopidogrel and subsequent cardiac events. To be adopted into routine clinical practice, platelet function assays must not only be able to identify at-risk patients, but they must also determine the appropriate thresholds for nonresponsiveness that provide appropriate sensitivity and specificity for subsequent adverse events. Prospective, randomized trials should determine whether therapeutic interventions guided by platelet function tests can safely and effectively reduce thrombotic events in at-risk patients. The use of platelet function monitoring to guide the timing of surgery after the discontinuation of antiplatelet therapy also merits further study.

Potential unrecognised costs of clopidogrel pretreatment in acute coronary syndrome

OBJECTIVE

To examine adherence in clinical practice to the American College of Cardiology/American Heart Association (ACC/AHA) guideline recommendations of observing a 5-day waiting period after clopidogrel administration before undergoing coronary artery bypass graft (CABG) surgery and to examine the costs of waiting.

METHODS

This retrospective study used a nationwide inpatient database (Solucient ACTracker) to identify patients who were admitted for acute coronary syndrome (ACS), and who had same-stay CABG. Cost of additional days of stay was estimated using regression analysis.

RESULTS

The recommended 5-day waiting was adhered to in 16.9% (n=3,809) of patients. The percentage of patients with ACS undergoing CABG surgery on day 0 was 14.6%. Adherence to the waiting was higher for teaching and rural hospitals; and in female and elderly patients and urgent admissions.

CONCLUSIONS

The recommended 5-day waiting for CABG surgery after clopidogrel treatment is poorly adhered to in clinical practice. This study was unable to determine specific reasons for the low adherence; however, there may be a compromise between the clinically urgent need for revascularisation and increased risk of bleeding, as well as economic costs associated with waiting. The cost of an additional hospital day in this group of patients was approximately £1,400 per day or £7,000 for 5 days. Thus, a full 5-day wait would have a significant economic impact on hospital costs.

Impact of clopidogrel in patients with acute coronary syndromes requiring coronary artery bypass surgery: a multicenter analysis

OBJECTIVES

The purpose of our multicenter study was to examine the impact of pre-operative administration of clopidogrel on reoperation rates, incidence of life-threatening bleeding, inpatient length of stay, and other bleeding-related outcomes in acute coronary syndrome (ACS) patients requiring cardiopulmonary bypass (coronary artery bypass graft surgery [CABG]) in a broad cross section of U.S. hospitals.

BACKGROUND

There is relative uncertainty about the relationship between clopidogrel and CABG-associated outcomes in the setting of ACS.

METHODS

A retrospective cohort analysis was performed of randomly selected ACS patients requiring CABG in 14 hospitals across the U.S. Patients exposed to clopidogrel were compared with those not exposed to clopidogrel within 5 days prior to surgery.

RESULTS

Of the 596 patients enrolled in the study, 298 had been exposed to clopidogrel within 5 days (Group A). Patients in Group A were more than 3-fold more likely to require reoperation for assessment of bleeding than patients not exposed to clopidogrel (6.4% vs. 1.7% Group B, p = 0.004). Major bleeding occurred in 35% of Group A patients versus 26% of Group B patients (p = 0.049). Length of stay was greater in Group A compared with Group B (9.7 +/- 6.0 days vs. 8.6 +/- 4.7 days, unadjusted p = 0.016). After logistic regression analysis, clopidogrel exposure within 5 days of CABG was the strongest predictor of reoperation (odds ratio [OR]: 4.60, 95% confidence interval [CI]: 1.45 to 14.55) and major bleeding (OR: 1.824, 95% CI: 1.106 to 3.008).

CONCLUSIONS

After ACS, patients who undergo CABG within 5 days of receiving clopidogrel are at increased risk for reoperation, major bleeding, and increased length of stay. These risks must be balanced by the clinical benefits of clopidogrel use demonstrated in randomized clinical trials.

Antiplatelet therapy in acute coronary syndromes

Acute coronary syndromes (ACS), characterized by unstable angina or a non-ST-segment elevation myocardial infarction, are caused by rupture of an atherosclerotic plaque, leading to platelet activation and aggregation, thrombus formation, and microembolization. Antiplatelet therapy is a cornerstone of therapy. Combined with aspirin, clopidogrel provides significant benefit for patients across the ACS spectrum. However, clopidogrel has limitations given its slow onset and the inconsistent level of inhibition that it achieves. Newer thienopyridine and non-thienopyridine P2Y12 receptor agonists offer the advantages of a rapid onset of action and greater and more consistent platelet inhibition.