Guideline on antiplatelet and anticoagulation management in cardiac surgery

Incidence of inferior vena cava thrombosis detected by transthoracic echocardiography in the immediate postoperative period after adult cardiac and general surgery

Venous thromboembolism is an important complication after general and cardiac surgery. Using transthoracic echocardiography, this study assessed the incidence of inferior vena cava (IVC) thrombosis among a total of 395 and 289 cardiac surgical and major surgical patients in the immediate postoperative period after cardiac and major surgery, respectively. All transthoracic echocardiography was performed by a specialist intensivist within 24 hours after surgery with special emphasis on using the subcostal view in the supine position to visualise the IVC. Of the 395 cardiac surgical patients studied, the IVC was successfully visualised using the subcostal view in 315 patients (79.8%) and eight of these patients (2.5%) had a partially obstructive thrombosis in the IVC. In 250 out of 289 (85%) general surgical patients, the IVC was also clearly visualised, but only one patient (0.4%) had an IVC thrombosis (2.5 vs 0.4%, P <0.05). In summary, visualisation of the IVC was feasible in most patients in the immediate postoperative period after both adult cardiac and major surgery. IVC thrombosis appeared to be more common after adult cardiac surgery than general surgery. A large prospective cohort study is needed to define the risk factors for IVC thrombus and whether early thromboprophylaxis can reduce the incidence of IVC thrombus after adult cardiac surgery.

Guideline for the surgical treatment of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and its prevalence is ∼1-2% of the general population, but higher with increasing age and in patients with concomitant heart disease. The Cox-maze III procedure was a groundbreaking development and remains the surgical intervention with the highest cure rate, but due to its technical difficulty alternative techniques have been developed to create the lesions sets. The field is fast moving and there are now multiple energy sources, multiple potential lesion sets and even multiple guidelines addressing the issues surrounding the surgical treatment of AF both for patients undergoing this concomitantly with other cardiac surgical procedures and also as stand-alone procedures either via sternotomy or via videothoracoscopic techniques. The aim of this document is to bring together all major guidelines in this area into one resource for clinicians interested in surgery for AF. Where we felt that guidance was lacking, we also reviewed the evidence and provided summaries in those areas. We conclude that AF surgery is an effective intervention for patients with all types of AF undergoing concomitant cardiac surgery to reduce the incidence of AF, as demonstrated in multiple randomized studies. There is some evidence that this translates into reduced stroke risk, reduced heart failure risk and longer survival. In addition, symptomatic patients with AF may be considered for surgery after failed catheter intervention or even as an alternative to catheter intervention where either catheter ablation is contraindicated or by patient choice.

Immediate surgical coronary revascularisation in patients presenting with acute myocardial infarction

Background

The number of patients presenting with acute myocardial infarction (AMI) and being untreatable by interventional cardiologists increased during the last years. Previous experience in emergency coronary artery bypass grafting (CABG) in these patients spurred us towards a more liberal acceptance for surgery. Following a prospective protocol, patients were operated on and further analysed.

Methods

Within a two year interval, 127 patients (38 female, age 68±12 years, EuroScore (ES) II 6.7±7.2%) presenting with AMI (86 non-ST-elevated myocardial infarction (NSTEMI), 41 STEMI) were immediately accepted for emergency CABG and operated on within six hours after cardiac catheterisation (77% three-vessel-disease, 47% left main stem stenosis, 11% cardiogenic shock, 21% preoperative intraaortic balloon pump (IABP), left ventricular ejection fraction 48±15%).

Results

30-day-mortality was 6% (8 patients, 2 NSTEMI (2%) 6 STEMI (15%), p=0.014). Complete revascularisation could be achieved in 80% of the patients using 2±1 grafts and 3±1 distal anastomoses. In total, 66% were supported by IABP, extracorporal life support (ECLS) systems were implanted in two patients. Logistic regression analysis revealed the ES II as an independent risk factor for mortality (p<0.001, HR 1.216, 95%-CI-Intervall 1.082-1.366).

Conclusions

Quo ad vitam, results of emergency CABG for patients presenting with NSTEMI can be compared with those of elective revascularisation. Complete revascularisation obviously offers a clear benefit for the patients. Mortality in patients presenting with STEMI and cardiogenic shock is substantially high. For these patients, other concepts regarding timing of surgical revascularisation and bridging until surgery need to be taken into consideration.

Time from adenosine di-phosphate receptor antagonist discontinuation to coronary bypass surgery in patients with acute coronary syndrome: meta-analysis and meta-regression

BACKGROUND

Adenosine di-phosphate receptor antagonists (ADPRAs) blunt hemostasis for several days after administration. This effect, aimed at preventing cardiac ischemic complications particularly in patients with acute coronary syndromes (ACS), may increase perioperative bleeding in the case of cardiac surgery. Practice Guidelines recommend withholding ADPRAs for at least 5days prior to surgery, though with a weak base of evidence. The purpose of this study was to systematically review observational and experimental studies of early or late preoperative discontinuation of ADPRAs prior to coronary artery bypass grafting (CABG) for patients with ACS.

METHODS

MEDLINE, EMBASE, the Cochrane Library databases up to December 2011; and reference lists. Observational and experimental studies that compared early ADPRA discontinuation with late discontinuation, or no discontinuation, in patients with ACS undergoing CABG.

RESULTS

There were 19 studies, including 14,046 participants, 395 deaths and 309 reoperations due to bleeding. ADPRA late discontinuation up to CABG was associated with an increased risk of postoperative mortality (OR 1.46, 95% confidence interval (CI) 1.10 to 1.93) and reoperations due to bleeding (OR 2.18; 95% CI 1.47 to 2.62). Between-study heterogeneity was low. Meta-analysis limited to high quality or prospective studies gave consistent results. In most instances, the 95% prediction intervals for summary risk estimates confirmed the risk across study groups.

CONCLUSIONS

ADPRA late discontinuation prior to CABG is associated with an increased risk of death and reoperations due to bleeding in patients with ACS. The confidence in the estimates of risk for late discontinuation is moderate to high.

Prehospitalization antiplatelet therapy and outcomes after saphenous vein graft intervention

Antiplatelet therapy is recommended after coronary artery bypass grafting, because it improves saphenous vein graft (SVG) patency and clinical outcomes. We investigated the association between prehospital antiplatelet regimens and outcomes after SVG intervention. Patients who underwent SVG intervention from 2003 to 2008 were divided into 3 groups: (1) no antiplatelet therapy, (2) the use of aspirin or clopidogrel, and (3) the use of dual antiplatelet therapy (DAPT) at admission. Clinical follow-up examinations were performed at 30 days and 1 year. The primary outcome was the composite of all-cause mortality, myocardial infarction, the need for revascularization, and stroke at 30 days. The relation between antiplatelet therapy and outcomes was adjusted for factors associated with the outcomes. A total of 225 patients underwent SVG intervention, 87% were men, and the mean age was 70 years. Of the 225 patients, 21 (9.4%) were not receiving antiplatelet therapy, 102 (45.3%) were receiving aspirin/clopidogrel, and 102 (45.3%) were receiving DAPT. The patients without antiplatelet therapy were more frequently women, had presented earlier after coronary artery bypass grafting, and were less frequently taking other cardiac-related medications. The patients taking aspirin or DAPT were more often smokers and had a greater peripheral vascular burden. The incidence of the 30-day and 1-year primary outcomes was greater in patients without preadmission antiplatelet use (38.1% vs 14.9% and 13.9%, overall p = 0.01; 52.4% vs 29.5% and 28.3%, overall p = 0.03). After adjustment, antiplatelet use remained associated with the primary outcome. In conclusion, prehospital use of antiplatelet therapy was associated with a lower occurrence of major adverse cardiac events after SVG intervention. We did not find that DAPT improved outcomes compared to single antiplatelet therapy.

Postoperative atrial fibrillation after isolated aortic valve replacement: a cause for concern?

BACKGROUND

Several studies have shown that postoperative atrial fibrillation (POAF) is associated with poorer short-term and long-term outcomes after general cardiac operations. There is, however, a paucity of data on the impact of POAF on outcomes after isolated aortic valve replacement (AVR).

METHODS

Data for all patients undergoing isolated first-time AVR between June 2001 and December 2009 was obtained from the Australasian Society of Cardiac and Thoracic Surgeons (ASCTS) National Cardiac Surgery Database Program and a retrospective analysis was conducted. Preoperative characteristics, early postoperative outcome, and late survival were compared between patients in whom POAF developed and those in whom it did not. Propensity score matching was performed to correct for differences between the 2 groups.

RESULTS

Excluding patients with preoperative arrhythmia, isolated first-time AVR was performed in 2,065 patients. POAF developed in 725 (35.1%) of them. Patients with POAF were significantly older (mean age, 72 versus 65 years; p < 0.001) and presented more often with comorbidities, including hypertension, respiratory disease, and hypercholesterolemia (all p < 0.05). From the initial study population, 592 propensity-matched patient pairs were derived; the overall matching rate was 81.7%. In the matched groups, 30-day mortality was not significantly different between the POAF and non-POAF groups (1.5% versus 1%; p = 0.48). Patients with POAF were, however, at an independently increased risk of perioperative complications, including new renal failure, gastrointestinal complications, and 30-day readmission (p < 0.05). Seven-year mortality was not significantly different between POAF and non-POAF groups (78% versus 83%; p = 0.63).

CONCLUSIONS

POAF is a risk factor for short-term morbidity but is not associated with a higher rate of early or late mortality after isolated AVR.

Whole blood viscosity assessment issues III: Association with international normalized ratio and thrombocytopenia

BACKGROUND

Anticoagulant and antiplatelet therapies are being used interchangeably or in combination. While international normalized ratio is assessed to determine anticoagulant's contraindication/need, whole blood viscosity is not assessed to determine the need for antiplatelet.

AIMS

The objective of this study is to investigate whether whole blood viscosity value is associated with levels of international normalized ratio and platelet count.

MATERIALS AND METHODS

De-identified archived clinical pathology data for the year 2008 were audited. All cases of international normalized ratio, which were concomitantly tested for haematocrit and total proteins, were extracted (n=7,387). Whole blood viscosity levels were extrapolated. Whether differences are associated with normal vs. high international normalized ratio and thrombocytopenia vs. thrombocytosis were evaluated.

RESULTS

Multivariate analysis show that whole blood viscosity levels statistically significantly differs between international normalized ratio and platelet counts (p<0.001). Platelet count is statistically significantly lower in low blood viscosity when compared with hyperviscosity and normoviscosity (p<0.001). Conversely, international normalized ratio is statistically significantly higher in low blood viscosity relative to hyperviscosity (p<0.001) and normoviscosity (p<0.002). No difference was observed between hyperviscosity and normoviscosity in platelet count or international normalized ratio.

CONCLUSION

The observation corroborates with previous reports to suggest putting into perspective the specificity of whole blood viscosity relative to stasis, against which antiplatelet is employed. It indicates that low whole blood viscosity is synonymous to high international normalized ratio whereby anticoagulant and antiplatelet therapies are contraindicated. International normalized ratio, platelet count and blood viscosity are laboratory indices to consider in constituting antiplatelet monitoring panel.

Whole blood viscosity issues VI: Association with blood salicylate level and gastrointestinal bleeding

Background:

This series on whole blood viscosity issues has been trying to elucidate the sensitivity, specificity and usefulness of the laboratory parameter in clinical practice. The postulation has been that since antiplatelet is used in the management of stasis, of which blood viscosity is an index, the latter would be useful laboratory indication and/or contraindication.

Aim:

The aim of this study was to observe whether blood level of acetylsalicylic acid differs with the level of whole blood viscosity.

Patients and Methods:

Out of the ten years database, 538 cases that were concomitantly tested for haematocrit, total proteins and blood level of salicylate were selected for this study. A separate nine cases of positive faecal occult blood tests were audited for blood viscosity and reviewed.

Results:

A statistically significant difference is observed with lower blood viscosity being associated with higher salicylate level in comparison of the former between the highest vs. lowest quartiles (p < 0.002). This observation demonstrates the effect of aspirin in lowering blood stasis. Reviewing the positive faecal occult blood cases indicate that gastrointestinal bleeding is characterized by relative hypoviscosity and that hyperviscosity is not present during bleeding complications.

Conclusion:

The findings affirm that whole blood viscosity is a valid clinical laboratory parameter for evidence-based contraindication, indication and monitoring of antiplatelet medication. It calls for better appreciation and clinical utility of whole blood viscosity, which (in the absence of viscometer) can now be extrapolated from haematocrit and total proteins.

Clinical outcomes after hybrid coronary revascularization versus off-pump coronary artery bypass: a prospective evaluation

OBJECTIVE

: Hybrid coronary revascularization is offered as an alternative strategy for patients with multivessel coronary artery disease (CAD). We present our experience and provide a comparative analysis to off-pump coronary artery bypass grafting (OPCAB).

METHODS

: Ninety-one patients with multivessel CAD underwent minimally invasive left internal mammary artery to left anterior descending grafting in combination with percutaneous coronary intervention of nonleft anterior descending targets (HYBRID). The primary end point of this study was major adverse cardiac and cerebrovascular events (MACCE), defined as death, stroke, and nonfatal myocardial infarction. MACCE in the HYBRID group were compared with 4175 contemporaneously performed OPCAB operations by logistic (30-day outcomes) and Cox proportional hazards (long-term survival) regression methods. Propensity scoring was used to adjust for potential selection bias.

RESULTS

: The 30-day MACCE (death/stroke/nonfatal myocardial infarction) rate was 1.1% for the HYBRID group (0%/0%/1.1%) and 3.0% for the OPCAB group (1.8%/1.1%/0.5%) (odds ratio = 0.47, P = 0.48). Angiographic left internal mammary artery evaluation was obtained in 95.6% of patients (87 of 91) revealing FitzGibbon A patency in 98.0% (96 of 98). The reintervention rate at 1 year for the HYBRID group was 5.5% (5 of 91) and was limited to repeat percutaneous coronary intervention. Three-year survival was statistically similar for the two groups (hazard ratio = 0.44, P = 0.18, see Kaplan-Meier figure).

CONCLUSIONS

: Hybrid coronary revascularization may be noninferior to OPCAB with respect to early MACCE and 3-year survival in the treatment of multivessel CAD.

Dual antiplatelet therapy in patients with aspirin resistance following coronary artery bypass grafting: study protocol for a randomized controlled trial [NCT01159639]

BACKGROUND

Coronary artery disease remains the dominant cause of mortality in developed countries. While platelets have been recognized to play a pivotal role in atherothrombosis, the ideal antiplatelet regime after coronary artery surgery remains elusive. The evolution of CABG has presently moved beyond technical improvements to involve modulation of pharmacologic management designed to improve patient outcomes. The aim of this trial will be to test the hypothesis that the addition of clopidogrel to patients with documented postoperative aspirin resistance will reduce the incidence of major cardiovascular events.

METHODS

Patients scheduled for isolated coronary artery surgery will be eligible for the study. Patients in whom postoperative multiple electrode aggregometry documents aspirin resistance will be randomized into two groups. The control group will receive 300 mg of aspirin. The dual antiplatelet group will receive 75 mg of clopidogrel in addition to 300 mg of aspirin. Patients will be followed for 6 months. Major adverse cardiac and cerebrovascular events (death from any cause, myocardial infarction, stroke, hospitalization due to cardiovascular pathology) as well as bleeding events will be recorded.

DISCUSSION

This will be the first trial that will specifically address the issue of dual antiplatelet therapy in patients undergoing coronary artery surgery who have been found to be aspirin resistant. In the event that the addition of clopidogrel proves to be beneficial in this subset of surgical patients, this study could significantly impact their future antiplatelet management. This randomized controlled trial has been registered at the ClinicalTrials.gov website (Identifier NCT01159639).

[Haemorrhage and morbidity associated with the use of tranexamic acid in cardiac surgery: a retrospective, multicentre cohort study]

INTRODUCTION

Postoperative bleeding is common complication, affecting up to 20% of patients, after cardiac bypass surgery. Fibrinolysis is one of the causes of this excessive bleeding, and for this reason the use of tranexamic acid is recommended. The problem with using this is that there are numerous guidelines and differences in the dose to be administered. Our aim was to evaluate whether there were any differences in postoperative bleeding and morbidity after cardiac surgery with the administering of different tranexamic acid doses in three university hospitals.

MATERIAL AND METHODS

A retrospective, multicentre cohort study was conducted. A total of 146 patients who were subjected to elective cardiac bypass surgery according to the anaesthetic-surgical protocol of each hospital were included in the study. The clinical histories were reviewed, and they were divided into two groups according to the tranexamic acid dose: Group A (high doses), initial dose of 20mg/kg and continuous infusion of 4 mg/kg/hour until closure of the sternotomy. A further 100mg was added to prime the bypass machine. Group B (low doses), initial dose of 10mg/kg followed by a continuous infusion of 2mg/kg/hour until closure of the sternotomy. A further 50mg was added to prime the bypass machine. Variables, such as age, sex, weight, height, type of surgical procedure (valvular, coronary or mixed), haematocrit, INR, and preoperative platelet count, time and temperature of the bypass machine, and haematocrit on sternum closure, were recorded. Among the post-operative variables collected were: debit due to drainage at 6, 12 and 24 hours after surgery, number and type of blood products transfused in the first 24 hours, need for further surgery due to haemorrhage, CVA, TIA, or a new acute myocardial infarction, convulsions, and mortality.

RESULTS

The incidence of increased bleeding (patients in the 90 percentile) was higher in Group B at all the study evaluation times (P<.05). The incidence of further surgery due to bleeding, and the need for transfusion of ≥ 3 units of packed red cells was lower in Group A (5.56%) than in Group B (13.89%). There were no significant differences in the requirements for blood products transfusions between the groups. As regards associated morbidity, there was one isolated case of convulsion and a perioperative AMI in another case in Group A, and three cases of perioperative AMI in Group B.

CONCLUSIONS

Elevated doses of tranexamic acid in cardiac bypass surgery appear to significantly reduce bleeding in the first hours after surgery compared to low doses. However, this decrease did not lead to a reduction in the needs for blood products.

Combined clopidogrel and aspirin treatment up to surgery increases the risk of postoperative myocardial infarction, blood loss and reoperation for bleeding in patients undergoing coronary artery bypass grafting

OBJECTIVES

Recent guidelines suggest that patients undergoing coronary artery bypass grafting (CABG) should discontinue clopidogrel and aspirin (ASA) 5 and 2-10 days, respectively, before surgery to reduce postoperative bleeding and its complications. The aim of our study was to evaluate the relationship between the timing of discontinuing clopidogrel + ASA and early clinical outcomes in patients undergoing CABG.

METHODS

Four thousand three hundred and thirty consecutive patients underwent isolated CABG from April 2004 to February 2009. Of these, 926 patients received double antiplatelet therapy in the 14 days prior to surgery. Patients were stratified into three groups: clopidogrel + ASA within 5 and 2 days, respectively, before surgery (Group A, n = 287); clopidogrel within 5 days + ASA stopped 2-10 days before surgery or clopidogrel stopped 5 days + ASA within 2 days of surgery (Group B, n = 308) and clopidogrel + ASA discontinued >5 and 10 days, respectively, before surgery (control group, n = 331).

RESULTS

Overall mortality was 0.8%. The incidence of postoperative myocardial infarction (MI) was 5.2, 1 and 1.8% in Groups A, B and control, respectively (P = 0.004). Reoperation for bleeding occurred in 4.5, 2.9 and 1.2% (P = 0.04) and total chest drainage was 761 ± 473, 720 ± 421 and 687 ± 302 ml in Groups A, B and control, respectively (P = 0.06). Multivariable analysis revealed that Group A was an independent predictor of postoperative MI (P = 0.02), reoperation for bleeding (P = 0.02), blood transfusions (P = 0.003) and blood losses (P = 0.015).

CONCLUSIONS

Clopidogrel in combination with ASA up to the time of surgery is associated with an increased risk of postoperative MI, blood loss and reoperation for bleeding in patients undergoing CABG.

Surgical patch angioplasty of the left main coronary artery

Isolated ostial stenosis of the left main coronary artery (LMCA) is rare, occurring in <1% of the patients undergoing coronary angiography. Surgical patch angioplasty (SPA) offers an alternative to conventional coronary artery bypass grafting (CABG) in such cases and is advantageous in restoring more physiological myocardial perfusion, maintaining ostial patency and preserving conduit material. However, a number of early technical failures and high perioperative mortality have limited the generalized uptake of this procedure, and only recently have advances in myocardial protection and novel surgical approaches to the LMCA resulted in a resurgence of the technique. A systematic literature search identified 45 studies incorporating 478 patients undergoing SPA. A variety of patch materials were used, including the pericardium, saphenous vein and internal mammary and pulmonary arteries. Patients were followed up for a mean of 54.4 months. The 30-day mortality was 1.7% and cardiac specific mortality 3.3% at last follow-up. Encouragingly, 92.4% of reported cases (n = 182) showed complete angiographic patency at last follow-up. Our results indicate that SPA may be a viable alternative to CABG in the surgical management of isolated ostial LMCA stenosis. However, no randomized trials have been performed, and it is clear that careful patient selection is essential in minimizing morbidity and mortality in the short- and long-term. Further research is required to allow a direct comparison of SPA to techniques with a more substantial evidence base such as CABG and percutaneous coronary intervention, and to define the optimal patch graft material, elucidating that any beneficial effects arterial patches may have on long-term patency.

A prospective randomized study comparing fibrin sealant to manual compression for the treatment of anastomotic suture-hole bleeding in expanded polytetrafluoroethylene grafts

OBJECTIVE

The ideal hemostatic agent for treatment of suture-line bleeding at vascular anastomoses has not yet been established. This study evaluated whether the use of a fibrin sealant containing 500 IU/mL thrombin and synthetic aprotinin (FS; marketed in the United States under the name TISSEEL) is beneficial for treatment of challenging suture-line bleeding at vascular anastomoses of expanded polytetrafluoroethylene (ePTFE) grafts, including those further complicated by concomitant antiplatelet therapies.

METHODS

Over a 1-year period ending in 2010, ePTFE graft prostheses, including arterio-arterial bypasses and arteriovenous shunts, were placed in 140 patients who experienced suture-line bleeding that required treatment after completion of anastomotic suturing. Across 24 US study sites, 70 patients were randomized and treated with FS and 70 with manual compression (control). The primary end point was the proportion of patients who achieved hemostasis at the study suture line at 4 minutes after start of application of FS or positioning of surgical gauze pads onto the study suture line.

RESULTS

There was a statistically significant difference in the comparison of hemostasis rates at the study suture line at 4 minutes between FS (62.9%) and control (31.4%) patients (P < .0001), which was the primary end point. Similarly, hemostasis rates in the subgroup of patients on antiplatelet therapies were 64.7% (FS group) and 28.2% (control group). When analyzed by bleeding severity, the hemostatic advantage of FS over control at 4 minutes was similar (27.8% absolute improvement for moderate bleeding vs 32.8% for severe bleeding). Logistic regression analysis (accounting for gender, age, intervention type, bleeding severity, blood pressure, heparin coating of ePTFE graft, and antiplatelet therapies) found a statistically significant treatment effect in the odds ratio (OR) of meeting the primary end point between treatment groups (OR, 6.73; P < .0001), as well as statistically significant effects for intervention type (OR, 0.25; P = .0055) and bleeding severity (OR, 2.59; P = .0209). The safety profile of FS was excellent as indicated by the lack of any related serious adverse events.

CONCLUSIONS

The findings from this phase 3 study confirmed that FS is safe and its efficacy is superior to manual compression for hemostasis in patients with peripheral vascular ePTFE grafts. The data also suggest that FS promotes hemostasis independently of the patient's own coagulation system, as shown in a representative population of patients with vascular disease under single- or dual-antiplatelet therapies.