Antithrombotic Therapy in Patients With Saphenous Vein and Internal Mammary Artery Bypass Grafts

Initiation of and persistence with P2Y12 inhibitors in patients with myocardial infarction according to revascularization strategy: a nationwide study

BACKGROUND

We aimed to analyse initiation of and persistence with P2Y12 inhibitors after first-time myocardial infarction (MI).

METHODS AND RESULTS

Using Danish nationwide registries, we identified patients ≥30 years with first-time MI during 1 January 2005-30 June 2016 and subsequent prescriptions of P2Y12 inhibitors. Independent factors related to initiation of and persistence with P2Y12 inhibitors were analysed by multivariable logistic regression and a Cox proportional hazards model. Patients were stratified by revascularization strategy: percutaneous coronary intervention (PCI), coronary artery bypass graft (CABG), or medical therapy alone (MTA). Overall, 79 597 MI patients were included with 39 172 undergoing PCI, 2619 CABG, and 16 640 MTA, showing initiation of P2Y12 inhibitors of 93.4%, 49.0%, and 51.5%, respectively. Congestive heart failure, cerebrovascular disease, cardiac dysrhythmias, renal failure, previous bleeding, and oral anticoagulants were associated with less initiation of P2Y12 inhibitors. Female sex was associated with less initiation of P2Y12 inhibitors following MTA. MTA, coronary angiography, cerebrovascular disease, diabetes with complications, previous bleeding, antidiabetics, and ticagrelor as P2Y12 inhibitor were associated with non-persistence, whereas female sex, advanced age, and concomitant pharmacotherapy with angiotensin-converting enzyme inhibitors, beta-blockers, statins, oral anticoagulants, and aspirin were associated with high persistence.

CONCLUSION

Initiation of P2Y12 inhibitors in PCI-treated MI patients was high in contrast to those treated with CABG or MTA and patients with certain comorbidities. Further studies on the benefit-risk ratio of P2Y12 inhibitors in CABG-treated or MTA-treated patients and patients with comorbidities after first-time MI are warranted, as is focus on persistence among patients receiving MTA, patients with comorbidities, and users of ticagrelor.

Aspirin dosage for the prevention of graft occlusion in people undergoing coronary surgery: A systematic review and meta-analysis

Background:

Aspirin is almost always used after coronary artery bypass graft (CABG) surgery; however, it is unclear what optimal dose should be prescribed. In this systematic review, we evaluated the effects of high versus low-dose aspirin in patients after CABG.

Methods:

A comprehensive database search was conducted in several databases from date of inception until February 2018. There were no language restrictions. We included studies that compared different doses of aspirin in patients that had undergone CABG surgery. We included studies that evaluated patient-important outcomes (mortality, cardiovascular events, and gastrointestinal bleeding); and if not reported, we collected data on the surrogate outcome thromboxane B2 (TXB2). We collected relevant data and performed a meta-analysis.

Results:

We identified 5903 references, and after two levels of screening by two independent reviewers, we included three randomized controlled trials in the meta-analysis with a total number of 122 participants. Mean age of trial participants was 65.63 years, and 88.68% were male. We planned to analyze all possible clinical outcomes, including mortality, recurrence, and hospitalization. However, no clinical outcomes are reported by the literature. The surrogate biochemical outcome of serum TXB2 was the only outcome reported by the eligible studies. High-dose aspirin (162–325mg once daily) achieved better suppression of TXB2 than low-dose aspirin (75–100mg once daily) (mean difference [MD], 2.00ng/mL, 95% confidence interval [CI]: 0.72–3.32; participants = 122; studies = 3; I² = 0%).

Conclusions:

We found no clinical trials addressing any of the clinical outcomes of interest. High-dose aspirin was superior to low-dose aspirin in suppressing platelet function, a surrogate outcome. Trials evaluating clinical and patient-important outcomes are needed to better inform medical practice and fill this gap in clinical knowledge.

Antithrombotic therapy in patients receiving saphenous vein coronary artery bypass grafts: a protocol for a systematic review and network meta-analysis

INTRODUCTION

The current evidence for the prevention of saphenous vein graft failure (SVGF) after coronary artery bypass graft (CABG) surgery consists of direct head-to-head comparison of treatments (including placebo) in randomised-controlled trials (RCTs) and observational studies. However, summarising the evidence using traditional pairwise meta-analyses does not allow the inclusion of data from treatments that have not been compared head to head. Exclusion of such comparisons could impact the precision of pooled estimates in a meta-analysis. Hence, to address the challenge of whether aspirin alone or in addition to another antithrombotic agent is a more effective regimen to improve SVG patency, a network meta-analysis (NMA) is necessary. The objectives of this study are to synthesise the available evidence on antithrombotic agents (or their combination) and estimate the treatment effects among direct and indirect treatment comparisons on SVGF and major adverse cardiovascular events, and to generate a treatment ranking according to their efficacy and safety outcomes.

METHODS

We will perform a systematic review of RCTs evaluating antithrombotic agents in patients undergoing CABG. A comprehensive English literature search will be conducted using electronic databases and grey literature resources to identify published and unpublished articles. Two individuals will independently and in duplicate screen potential studies, assess the eligibility of potential studies and extract data. Risk of bias and quality of evidence will also be evaluated independently and in duplicate. We will investigate the data to ensure its suitability for NMA, including adequacy of the outcome data and transitivity of treatment effects. We plan to estimate the pooled direct, indirect and the mixed effects for all antithrombotic agents using a NMA.

ETHICS AND DISSEMINATION

Due to the nature of the study, there are no ethical concerns nor informed consent required. We anticipate that this NMA will be the first to simultaneously assess the relative effects of multiple antithrombotic agents in patients undergoing CABG. The results of this NMA will inform clinicians, patients and guideline developers the best available evidence on comparative effects benefits of antithrombotic agents after CABG while considering the side effect profile to support future clinical decision-making. We will disseminate the results of our systematic review and NMA through a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42017065678.

Use of preoperative aspirin in combined coronary and valve operations

BACKGROUND

The aim of this study was to determine the relationship between preoperative aspirin use and postoperative outcomes in patients undergoing combined coronary artery bypass grafting and valve operations.

METHODS

All combined coronary artery bypass grafting and valve procedures from 2008 to 2015 at our institution were identified. After exclusions, patients were stratified according to those that received preoperative aspirin and those who did not. Propensity score methodology was used to match the 2 groups using baseline and operative characteristics. Logistic regression models were then developed to assess differences in postoperative outcomes between groups.

RESULTS

Of the 563 patients identified, 534 met inclusion criteria: preoperative aspirin = 327 (61.2%), no preoperative aspirin = 207 (38.8%). After propensity matching, 194 patient pairs were analyzed, with no significant differences in preoperative characteristics. No significant differences were observed between the preoperative aspirin and no preoperative aspirin groups in rates of 30-day mortality (3.6% vs 4.1%, P = 1.00), major adverse cardiovascular events (23.2% vs 24.2%, P = .91), or 30-day readmission (12.4% vs 11.9%, P = 1.00), among others.

CONCLUSION

Preoperative aspirin use in patients undergoing combined coronary artery bypass grafting and valve operations was not associated with significant differences in major postoperative outcomes. Large-scale, randomized trials are needed to better establish the role of preoperative aspirin in this population.

Dual Antiplatelet Therapy After Coronary Artery Bypass Grafting in the Setting of Acute Coronary Syndrome

After acute coronary syndrome (ACS), dual antiplatelet therapy (DAPT) is the standard of care for both invasive management with percutaneous intervention and noninvasive (medical) management. Conversely, studies using dual antiplatelet in the population of patients presenting with ACS who undergo coronary artery bypass grafting (CABG) are conflicting. The appropriate antiplatelet regimen after CABG remains an area of controversy. Plaque stability, prevention of graft closure, and secondary thrombosis form the basis for using a second antiplatelet drug, whereas the additional risk of bleeding and lack of conclusive evidence should also be considered. After an extensive literature search, 12 clinical trials with efficacy outcomes were identified. Most of the studies are retrospective, nonrandomized single-center trials. A few large patient populations have been examined using database information. To date, there is only 1 prospective, multicenter, randomized trial published. Recommendations from national guidelines differ, proposing single antiplatelet therapy with aspirin or DAPT with the combination of aspirin and clopidogrel. The purpose of this report is to review the available clinical trial data and provide guidance to practitioners when caring for this patient population. In conclusion, there is no clear consensus regarding the use of DAPT in patients after CABG. If not contraindicated, it is reasonable to use DAPT, starting in the postoperative period, in patients presenting with ACS. Large, multicenter, randomized clinical trials are needed to definitively investigate the role of DAPT in patients with ACS after CABG.

Reduced Effect of Aspirin and Clopidogrel Following Hybrid Coronary Revascularization

OBJECTIVE

Reduced effect of antiplatelet therapy following coronary artery bypass grafting is associated with reduced graft patency. We sought to evaluate the impact of hybrid coronary revascularization on the effect of aspirin and clopidogrel and whether high baseline platelet aggregation, high postoperative levels of platelet turnover, and acute-phase response may contribute to the effect.

METHODS

We prospectively studied platelet aggregation (VerifyNow and Multiplate Analyzer), platelet turnover (immature platelets, mean platelet volume, and thrombopoietin), and acute-phase reactants (C-reactive protein, von Willebrand factor, and coagulation factor VIII) in 40 patients undergoing elective hybrid coronary revascularization (off-pump surgical revascularization through J-hemisternotomy followed by percutaneous coronary intervention [PCI]). Preoperative blood samples on- and off-aspirin were compared with blood samples obtained postoperatively, following PCI when dual antiplatelet therapy had been initiated and at 1-year follow-up.

RESULTS

The antiplatelet effect of aspirin was significantly reduced in the early postoperative period as measured by VerifyNow Aspirin but not by Multiplate ASPI test. The antiplatelet effect of clopidogrel was significantly reduced following PCI as measured by VerifyNow P2Y12 and Multiplate ADP test. The level of baseline aggregation did not predict the antiplatelet effect of aspirin or clopidogrel, and no association was found between platelet aggregation and postoperative platelet turnover or acute-phase reaction.

CONCLUSIONS

A transient reduction in the antiplatelet effect of aspirin and clopidogrel was observed after hybrid coronary revascularization despite limited surgical trauma and off-pump technique. Neither baseline platelet aggregation nor postoperatively increased platelet turnover and acute-phase response could explain this finding. ClinicalTrials.gov identifier, NCT02293928.

Relationship between postoperative clopidogrel use and subsequent angiographic and clinical outcomes following coronary artery bypass grafting

Dual antiplatelet therapy with both aspirin and clopidogrel is increasingly used after coronary artery bypass grafting (CABG); however, little is known about the safety or efficacy. We sought to determine the relationship between postoperative clopidogrel and clinical and angiographic outcomes following CABG. We evaluated 3,014 patients from PREVENT IV who underwent CABG at 107 US sites. Postoperative antiplatelet therapy was left to physician discretion. Risk-adjusted angiographic and clinical outcomes were compared in patients taking and not taking clopidogrel 30 days post-CABG. At 30 days, 633 (21%) patients were taking clopidogrel. Clopidogrel users were more likely to have peripheral vascular (15 vs. 11%) and cerebrovascular disease (17 vs. 11%), prior myocardial infarction (MI) (46 vs. 41%), and off-pump surgery (33 vs. 18%). Clopidogrel use was associated with statistically insignificant higher graft failure (adjusted odds ratio 1.3; 95% confidence interval [CI] [1.0, 1.7]; P = 0.05). At 5-year follow-up, clopidogrel use was associated with similar composite rates of death, MI, or revascularization (27 vs. 24%; adjusted hazard ratio 1.1; 95% CI [0.9, 1.4]; P = 0.38) compared with those not using clopidogrel. There was an interaction between use of cardiopulmonary bypass and clopidogrel with a trend toward lower 5-year clinical events with clopidogrel in patients undergoing off-pump CABG. In this observational analysis, clopidogrel use was not associated with better 5-year outcomes following CABG. There may be better outcomes with clopidogrel among patients having off-pump surgery. Adequately powered randomized clinical trials are needed to determine the role of dual antiplatelet therapy after CABG.

Beta-thromboglobulin as a marker of perioperative myocardial infarction in patients undergoing coronary artery bypass grafting following aspirin discontinuation

Perioperative myocardial infarction (PMI) following coronary artery bypass grafting (CABG) is associated with significant morbidity and mortality. The aim of this study was to assess platelet activation and oxidative stress in the setting of PMI in patients undergoing CABG. We studied 108 consecutive patients who stopped taking low-dose aspirin 7-10 days prior to elective isolated on- or off-pump CABG. β-thromboglobulin (β-TG), thromboxane B2 (TXB2) and 8-iso-prostaglandin F2α (8-iso-PGF2α), a marker of oxidative stress, were measured at the baseline and 5-7 days postoperatively. Aspirin (150 mg/d) was administered every morning since 12 hours after CABG. Mean baseline β-TG was 58.5 ± 10.3 IU/ml, TXB2 was 143.6 ± 28.5 ng/ml and 8-iso-PGF2α was 355.2 ± 40.7 pg/ml. Postoperatively, after administration of 4-6 doses of aspirin, β-TG increased by 16.7% and 8-iso-PGF2α increased by 17.2% 5-7 days after surgery (p = 0.005 and p < 0.001, respectively). TXB2 decreased by 99.7% to 410.3 ± 52.1 pg/ml (p < 0.001). Nine patients (8.3%) developed PMI. Baseline β-TG and TXB2, together with postoperative β-TG and 8-iso-PGF2α were higher in PMI patients than in the remaining subjects (all, p < 0.05). Multivariate analysis showed that baseline β-TG (OR: 1.28; 95% CI: 1.05-1.57, p = 0.015) was the only independent predictor of PMI. In conclusion, we demonstrated that increased platelet activation and thromboxane production, observed in patients not taking aspirin till the day of CABG, contribute to the occurrence of PMI in early postoperative period.

Saphenous vein graft failure after coronary artery bypass surgery: pathophysiology, management, and future directions

OBJECTIVE

To review our current understanding of the epidemiology and pathogenesis of vein graft failure (VGF), give an overview of current preventive and interventional measures, and explore strategies that may improve vein graft patency.

BACKGROUND

VGF and progression of native coronary artery disease limit the long-term efficacy of coronary artery bypass graft surgery.

METHODS

We reviewed the published literature on the pathophysiology, prevention, and/or treatment of VGF by searching the MEDLINE (January 1, 1966-January 1, 2012), EMBASE (January 1, 1980-January 1, 2012), and Cochrane (January 1, 1995-January 1, 2012) databases. In addition, we reviewed references from the selected articles for studies not identified in the initial search. Basic science and clinical studies were included; non-English language publications were excluded.

RESULTS

Acute thrombosis, neointimal hyperplasia, and accelerated atherosclerosis are the 3 mechanisms that lead to VGF. Preventive measures include matching and quality assessment of conduit and target vessel, lipid-lowering drugs, antithrombotic therapy, and cessation of smoking. Treatment of VGF includes medical therapy, percutaneous intervention, and redo coronary artery bypass graft surgery. In patients undergoing graft intervention, the use of drug-eluting stents, antiplatelet agents, and embolic protection devices may improve clinical outcomes.

CONCLUSIONS

Despite advances in management, VGF remains one of the leading causes of poor in-hospital and long-term outcomes after coronary artery bypass graft surgery. New developments in VGF prevention such as gene therapy, external graft support, fully tissue-engineered grafts, hybrid grafts, and synthetic conduits are promising but unproven. Future efforts to reduce VGF require a multidisciplinary approach with a primary focus on prevention.

Dual anti-platelet therapy after coronary artery bypass grafting: is there any benefit? A systematic review and meta-analysis

BACKGROUND

Anti-platelet therapy is an important component of medical therapy post coronary artery bypass grafting (CABG). While aspirin administration is a Class I indication after CABG, the benefit of concomitant clopidogrel is a controversial issue.

METHODS

We searched OVID Medline, Cochrane, Scopus, and EMBASE for randomized control trials and observational studies comparing aspirin ± placebo to aspirin + clopidogrel after CABG.

RESULTS

Eleven articles (five randomized control trials and six observational studies) including 25,728 patients met inclusion criteria. Early saphenous vein graft occlusion was reduced with the use of dual anti-platelet therapy (risk ratio (RR) = 0.59, 95% CI 0.43-0.82, p = 0.02). In-hospital or 30-day mortality was lower with aspirin + clopidogrel (0.8%) compared to aspirin alone (1.9%) (p < 0.0001), while risk of angina or perioperative myocardial infarction was comparable (RR = 0.60, 95% CI 0.31-1.14, p = 0.12). Patients treated with aspirin + clopidogrel demonstrated a trend towards a higher incidence of major bleeding episodes as compared to patients treated with aspirin alone (RR = 1.17, 95% CI 1.00-1.37, p = 0.05). In a pooled analysis of studies involving off-pump CABG compared to aspirin alone, dual anti-platelet therapy reduced the risk of perioperative myocardial infarction and saphenous graft occlusion by 68% (47% to 71%) and 55% (2% to 79%) respectively.

CONCLUSION

Dual anti-platelet therapy after CABG improved early saphenous vein graft patency, but may increase the risk of bleeding. The use of dual anti-platelet therapy appears to be most beneficial in patients undergoing off-pump CABG. Prospective randomized studies are necessary to determine whether this beneficial effect of dual therapy is also achieved in patients undergoing on pump CABG.

'No-touch' saphenous vein harvesting improves graft performance in patients undergoing coronary artery bypass surgery: a journey from bedside to bench

The saphenous vein is the most commonly used conduit in patients undergoing coronary artery bypass surgery yet its patency is inferior to the internal thoracic artery. Vascular damage inflicted to the vein when using conventional harvesting techniques affects its structure. Endothelial denudation is associated with early vein graft failure while damage of the outermost vessel layers has adverse long-term effects on graft performance. While many in vitro and in vivo experimental studies aimed at improving vein graft patency have been performed to date no significant 'bench to bedside' advances have been made. Among experimental strategies employed is the use of pharmacological agents, gene targeting and external stents. A 'no-touch' technique, where the saphenous vein is removed with minimal trauma and normal architecture preserved, produces a superior graft with long term patency comparable to the internal thoracic artery. Interestingly, many experimental studies are aimed at repairing or replacing those regions of the saphenous vein damaged when harvesting conventionally. 'No-touch' harvesting is superior in coronary artery bypass patients with long-term data published 5years ago. Here we describe a 'bedside to bench' situation where the mechanisms underlying the improved performance of 'no touch' saphenous vein grafts in patients have been studied in the laboratory.

Use of Aspirin and Clopidogrel After Coronary Artery Bypass Graft Surgery

Objective:

To evaluate the evidence for the use of dual antiplatelet therapy (DAPT) with aspirin and Clopidogrel following coronary artery bypass graft (CABG) surgery.

Data Sources:

Literature was accessed through PubMed (1950-November 2011), EMBASE (1976-November 2011), and the Cochrane databases using the terms Clopidogrel and coronary artery bypass graft. Citations from available articles were used for additional references and ClinicalTrials.gov was accessed for abstracts of ongoing studies.

Study Selection Ano Data Extraction:

Peer-reviewed studies that evaluated DAPT use after CABQ surgery in adult humans were assessed for inclusion.

Data Synthesis:

Four randomized clinical trials evaluating surrogate end points and 9 studies (3 subgroup analyses, 6 observational) evaluating clinical outcomes were reviewed. Three clinical trials assessing surrogate end points failed to demonstrate an improvement in graft patency with DAPT use, while 1 clinical trial found an increase in graft patency. As for clinical outcomes, 1 subgroup analysis demonstrated that the benefit of DAPT post-CABG after a non-ST-elevation acute coronary syndrome diminished following surgery, while an observational study demonstrated a trend toward decreased mortality. In post-CABG patients who did not experience acute coronary syndrome, 2 subgroup analyses proved inconclusive and an observational study found DAPT use to be associated with reducing in-hospital mortality, while another observational study was not associated with reduced long-term mortality. Three observational studies in off-pump CABG patients showed that DAPT use was feasible.

Conclusions:

Evidence for DAPT use following CABG is limited to subgroup analyses, observational studies, and trials with surrogate end points. The majority of clinical trials have failed to demonstrate an improvement in graft patency with DAPT. Current evidence does not support the use of DAPT to improve graft patency, and more evidence from randomized controlled trials assessing clinical outcomes is necessary to make definitive recommendations.

Current practice of antiplatelet and anticoagulation management in post-cardiac surgery patients: a national audit

The Audit and Guidelines Committee of the European Association for Cardio-Thoracic Surgery recently published a guideline on antiplatelet and anticoagulation management in cardiac surgery. We aimed to assess the awareness of the current guideline and adherence to it in the National Health Service through this National Audit. We designed a questionnaire consisting of nine questions covering various aspects of antiplatelet and anticoagulation management in post-cardiac surgery patients. A telephonic survey of the on-call cardiothoracic registrars in all the cardiothoracic centres across the UK was performed. All 37 National Health Service hospitals in the UK with 242 consultants providing adult cardiac surgical service were contacted. Twenty (54%) hospitals had a unit protocol for antiplatelet and anticoagulation management in post-cardiac surgery. Only 23 (62.2%) registrars were aware of current European Association for Cardio-Thoracic Surgery guidelines. Antiplatelet therapy is variable in the cardiac surgical units across the country. Low-dose aspirin is commonly used despite the recommendation of 150-300 mg. The loading dose of aspirin within 24 h as recommended by the guideline is followed only by 60.7% of surgeons. There was not much deviation from the guideline with respect to the anticoagulation therapy.

Hypercoagulable state after off-pump coronary artery bypass grafting: evidence, mechanisms and implications

During the past decade, there has been a dramatic resurgence in the adoption of off-pump technology in coronary artery bypass surgery. This has inspired remarkable advances in the techniques of localized tissue stabilization and a greater understanding of the physiology of beating-heart mobilization and exposure. An avalanche of reports in the literature has demonstrated the early safety and efficacy of the procedure. However, despite abundant evidence validating the safety and efficacy of off-pump coronary artery bypass surgery, considerable controversy still persists regarding the long-term outcomes of this approach to myocardial revascularization. One area of concern, and even greater uncertainty, surrounds the issue of the existence of a hypercoagulable state after off-pump coronary artery bypass surgery. This article evaluates the current best evidence available from randomized controlled trials to assess the impact of off-pump coronary artery bypass surgery on coagulation, fibrinolysis and platelet activation, discusses the issue of hypercoagulability with emphasis on the mechanisms responsible for this actual or potential hypercoagulability, and explores the implications of this issue for clinical practice.

Practice Considerations of Early Aspirin Administration following Coronary Artery Bypass Surgery

Thrombotic occlusion of saphenous vein grafts (SVG), the conduits most commonly used in coronary artery bypass grafting (CABG) surgery, causes significant morbidity and mortality. There is class 1A evidence that early aspirin administration following CABG reduces thrombotic SVG occlusion, as well as overall morbidity and mortality. The American Heart Association/American College of Cardiology and the European Association of Cardiothoracic Surgeons have issued guidelines recommending that 150 to 325 mg aspirin be administered within 6 hours following CABG. We carried out a clinical audit of our practice to identify any reasons for deviation from these standards of care and to implement any corrective measures. We prospectively collected data on 200 consecutive patients who underwent CABG to assess both the compliance in prescribing and administering aspirin and the effect on blood loss and transfusion requirements. Sixty-nine percent of patients received an aspirin loading dose 6 hours postoperatively. The reasons for nonadministration of aspirin were postoperative bleeding (10%), lack of a prescription despite aspirin being clinically indicated (13%), and a prescription for aspirin but no administration (9%). Reasons included inadequate handover between clinical teams (4%), aspirin loading 24 hours preoperatively (2%), and administration after the first 6 hours (3%). Our audit showed that early aspirin administration did not cause further bleeding or increase blood or blood product transfusion. We followed the recommendations in the majority of cases, but there is scope for improvement in this practice and a need to address "gray areas" not covered by the guidelines.

Impaired anti-platelet effect of aspirin, inflammation and platelet turnover in cardiac surgery

A reduced platelet inhibitory response to acetyl salicylic acid (ASA) has been associated with an increased risk of graft thrombotic occlusion after coronary artery bypass grafting (CABG). We performed a prospective, observational study of 18 patients on 100 mg/day ASA before and after CABG. We assessed antiplatelet response to ASA and its relationship with platelet turnover, inflammatory markers, and soluble thrombomodulin (sTM) levels. All patients showed optimal response to ASA preoperatively but had higher values during follow-up. Platelet aggregation and platelet count in the perioperative period were significantly associated (P=0.05). Platelet turnover was defined as the average daily turnover (ADTO). The lowest inhibitory value (28% of patients > or =6 Omega) was recorded at the same time of the highest platelet turnover (>10% daily in 77.77% of patients), one week after CABG. ADTO >10% was associated with an increased risk of platelet aggregation > or =6 Omega. Levels of sTM were significantly higher one week after CABG (median 13 vs. 3 ng/ml preoperatively, P=0.0011). There is a transient impairment in ASA antiplatelet effect after CABG related to an increased platelet turnover caused by the inflammatory process. This could be responsible for the high risk of occlusive thrombosis.

Preoperative evaluation and preparation of the patient for cardiac surgery

Cardiac surgery is associated with significant morbidity, mortality, and socioeconomic costs. Preoperative assessment assists the clinician in identifying potential complications and facilitates discussion of these risks with the patient. Careful patient selection and preparation during preoperative evaluation may minimize morbidity, mortality, and resource use. This article outlines a system-based approach to preoperative evaluation and preparation of the patient undergoing cardiac surgery.

The impact of intravenous aspirin administration on platelet aspirin resistance after on-pump coronary artery bypass surgery

Aspirin resistance continues to be a major challenge in patients after coronary artery bypass grafting (CABG). We investigated the impact of intravenous aspirin on platelet function in this clinical setting. Forty-two patients received 100 mg of oral aspirin once daily, beginning on day 1 after the operation. Between day 6 and 8 post operation one oral dose was replaced by an intravenous dose of 300 mg. Platelet function analyzer (PFA-100) closure times (CT), turbidimetric platelet aggregation (TPA) and impedance platelet aggregation (IPA) induced by arachidonic acid (AA), collagen and ADP were measured prior to and 1 h and 24 h after intravenous aspirin. Results obtained prior to the intravenous aspirin were compared with respective values from 120 healthy individuals. Despite the postoperative oral aspirin that was given once daily, ADP-induced TPA (ADPTPA) and IPA values induced by AA, ADP or collagen were significantly greater in patients than in controls, while PFA-100 CT were significantly shorter. Intravenous aspirin induced a significant reduction of platelet aggregability as measured by collagen/epinephrine (CEPI) CT, TPA and IPA induced by AA and collagen 1 h and 24 h after administration. Intravenous aspirin was not found to influence collagen/ADP (CADP) CT and IPA induced by ADP. Concomitantly, the number of patients with laboratory aspirin resistance as measured by CEPI-CT and TPA but not by IPA induced by AA or collagen dropped significantly. Agreement in the detection of aspirin responders and non-responders among platelet function tests was poor. Our findings indicate that the intravenous aspirin appears to be a promising approach for reducing laboratory aspirin resistance during the postoperative phase of CABG.

Preoperative evaluation and preparation of the patient for cardiac surgery

Cardiac surgery is associated with significant morbidity, mortality, and socioeconomic costs. Preoperative assessment assists the clinician in identifying potential complications and facilitates discussion of these risks with the patient. Careful patient selection and preparation during preoperative evaluation may minimize morbidity, mortality, and resource use. This article outlines a system-based approach to preoperative evaluation and preparation of the patient undergoing cardiac surgery.

Evidence for using clopidogrel alone or in addition to aspirin in post coronary artery bypass surgery patients

Clopidogrel is recommended with aspirin for patients who undergo coronary artery bypass grafting (CABG) after non-ST elevation myocardial infarctions. Cardiothoracic surgeons widely use clopidogrel in addition to aspirin for post-CABG patients, including those with stable coronary artery disease. The aim of this study was to systematically review the published research to determine whether clopidogrel use after CABG is based on good trial data. Studies reporting safety and/or efficacy data for clopidogrel use with or without aspirin after on- or off-pump CABG were included. Fourteen studies met the inclusion criteria, of which 11 were reported trials and 3 are ongoing trials. Subgroup retrospective analyses of previously reported large trials of patients presenting with acute coronary syndromes (n = 1) or patients with stable coronary artery disease (n = 3) did not show a clear clinical benefit of clopidogrel when given in addition to aspirin after CABG. In contrast, there was a trend toward increased major and minor bleeding after the use of clopidogrel plus aspirin. Two small prospective trials providing data on surrogate end points and 5 small trials involving off-pump CABG patients were not of good quality to draw meaningful conclusions. In conclusion, summarized data based on subgroup analyses, surrogate end points, and observational cohort studies fail to demonstrate a clear beneficial effect of clopidogrel alone or in combination with aspirin on clinical outcomes after CABG.

Coronary vein graft disease: pathogenesis and prevention

Not long after coronary artery bypass grafting surgery was described, several reports presented follow-up angiographic data on large cohorts of patients, demonstrating that approximately one-half of saphenous vein grafts fail within 10 to 15 years of surgery and that graft failure is associated with worse clinical outcomes. Three processes are responsible for vein graft failure. Thrombosis, intimal hyperplasia and accelerated atherosclerosis contribute to graft failure in the acute, subacute and late postoperative periods, respectively. Studies have shown that perioperative antiplatelet therapy can reduce early thrombosis and graft failure. As in native coronaries, intensive lipid lowering can attenuate the process of atherosclerosis in vein grafts. Intimal hyperplasia in the vein graft is thought to be an adaptation of the vein to higher pressures in the arterial circulation. This process is further promoted by the loss of inhibition from the endothelial layer, which is injured during surgery. A new 'no-touch' technique for harvesting grafts may be effective in preventing disruption to the endothelial layer, and subsequent intimal hyperplasia and graft loss. Off-pump surgery and endoscopic vein harvesting, which are known to reduce surgical morbidity, have been shown to be no worse than on-pump surgery and open vein harvesting, respectively, in terms of vein graft patency. Various gene therapies can prevent intimal hyperplasia in animal models, but human data obtained so far have been disappointing. Placing an external stent around a vein graft may reduce tangential wall stress and subsequent intimal hyperplasia.

Aspirin resistance: disparities and clinical implications

Abstract Aspirin is one of the most widely prescribed drugs for the prevention of thrombosis in patients with vascular disease. Yet, aspirin is unable to prevent thrombosis in all patients. The term "aspirin resistance" has been used to broadly define the failure of aspirin to prevent a thrombotic event. Whether this is directly related to aspirin itself through biochemical aspirin resistance or treatment failure, or if it is because of aspirin's inability to overcome the thrombogenic aspects of the disease process itself, has not been elucidated. This can have dramatic clinical implications for a variety of vascular disease subsets and is cause for concern, considering the high prevalence of aspirin use for both primary and secondary prevention. Disparities exist in the rates of aspirin resistance among certain patient populations, such as women, patients with diabetes mellitus, and those with heart failure, and across clinical conditions, such as cardiovascular and cerebrovascular disease. Clinical trial data from studies observing resistance have revealed that regardless of study size, dose of aspirin, control for drug interactions and adherence, or assay used to measure platelet function, aspirin resistance is associated with an increased risk for adverse events. Although the evidence is mounting, there has yet to be a consensus on the appropriate clinical response to aspirin resistance.

Deep venous thrombosis of the neck and pulmonary embolism in patients with a central venous catheter admitted to cardiac rehabilitation after cardiac surgery: a prospective study of 815 patients

Central venous catheters (CVCs) are widely used for therapeutic purposes and to measure hemodynamic variables that cannot be recorded from a peripheral vein. However, the method can involve complications. In cardiac surgery, CVCs are electively placed in the right internal jugular vein but there is little information on deep venous thrombosis (DVT) in catheterized veins (CVC-related DVT) or on secondary pulmonary embolism (PE). The impact of CVC-related DVT and PE in cardiac surgery and measures to prevent PE were assessed. We used ultrasonography (US) to check the point of insertion of CVC in 815 patients in the intensive cardiac rehabilitation unit after heart surgery. In this series, 386 patients (48%) had CVC-related DVT; those already receiving anticoagulant, and considered at low risk, continued that therapy, while those taking an antiplatelet agent (aspirin 100 mg daily) but deemed at high risk of PE from the US findings were given an anticoagulant instead. Only patients with CVC-related DVT at low risk of PE continued taking aspirin. At 3 months, there were no cases of PE among patients receiving an anticoagulant, but six on antiplatelet had non-fatal PE. The prevalence of PE in the whole series of 815 patients was 0.7%. CVC-related DVT is a frequent complication of heart surgery. Anticoagulant therapy started early does not prevent thrombus formation but probably prevents PE, whereas antiplatelet gives no such protection. Sonographic screening of the CVC removal in intensive care unit may be useful for avoiding PE after CVC-related DVT.

Aspirin in coronary artery bypass surgery: new aspects of and alternatives for an old antithrombotic agent

The success of coronary artery bypass graft surgery (CABG) depends mainly on the patency of the graft vessels. Aortocoronary vein graft disease is comprised of three distinct but interrelated pathological processes: thrombosis, intimal hyperplasia and atherosclerosis. Early thrombosis is a major cause of vein graft attrition during the first month after CABG, while during the remainder of the first year, intimal hyperplasia forms a template for subsequent atherogenesis, which thereafter predominates. Platelets play a crucial role in the pathophysiology of graft thrombosis and aspirin is the primary antiplatelet drug that has been shown to improve vein graft patency within the first year after CABG. Nevertheless, a significant number of grafts still occlude in the early postoperative period despite 'appropriate' aspirin treatment. Moreover, laboratory investigations showed that the expected inhibition of platelet function is not always achieved. This has been called 'aspirin nonresponse' or 'aspirin resistance', although a uniform definition is lacking. The finding that a considerable number of patients show an impaired antiplatelet effect of aspirin after CABG brought new insight into the discussion concerning poor patency rates of bypass grafts: the early period after CABG shows a coincidence of an increased risk for bypass thrombosis (amongst others, due to platelet activation and endothelial cell disruption of the graft) and an increased prevalence of aspirin resistance. Hitherto, the underlying mechanisms of aspirin resistance are uncertain and largely hypothetical; amongst others, increased platelet turnover, enhanced platelet reactivity, systemic inflammation, and drug-drug interaction are discussed. Up to now available data concerning the clinical outcome of aspirin resistant CABG patients are limited, and there is evidence that platelets of patients with graft thrombosis are more likely to be resistant to aspirin compared with patients without thrombotic events. Many publications concerning aspirin resistance are available today, but reports addressing this topic in CABG patients are sparse. This review summarises recent insights into the antiplatelet treatment after CABG and describes the clinical benefit, but also the therapeutic failure of the well-established drug aspirin. Moreover, possible pharmacological approaches to improve antithrombotic therapy in aspirin nonresponders among CABG patients are discussed.

Guideline on antiplatelet and anticoagulation management in cardiac surgery

This document presents a professional view of evidence-based recommendations around the issues of antiplatelet and anticoagulation management in cardiac surgery. It was prepared by the Audit and Guidelines Committee of the European Association for Cardio-Thoracic Surgery (EACTS). We review the following topics: evidence for aspirin, clopidogrel and warfarin cessation prior to cardiac surgery; perioperative interventions to reduce bleeding including the use of aprotinin and tranexamic acid; the use of thromboelastography to guide blood product usage; protamine reversal of heparin; the use of factor VIIa to control severe bleeding; anticoagulation after mechanical, tissue valve replacement and mitral valve repair; the use of antiplatelets and clopidogrel after cardiac surgery to improve graft patency and reduce thromboembolic complications and thromboprophylaxis in the postoperative period. This guideline is subject to continuous informal review, and when new evidence becomes available. The formal review date will be at 5 years from publication (September 2013).

[Perioperative hemostasis management]

Hemostasis management plays an important role in surgery. Anti-platelet drugs and oral anticoagulants are taken by an increasing number of patients. Perioperative management must take into account bleeding as well as thromboembolic risks when withholding these medications. Patients with inherited or acquired hemostatic disorders should receive interdisciplinary care in order to optimise perioperative substitution therapy. For the diagnosis of acquired coagulopathy secondary to massive bleeding, point of care tests have been introduced that should help focus substitution therapy in emergency situations. However, physicians should be aware of the limitations of these methods, and a full diagnostic workup should be done in order to uncover hemorrhagic diatheses not detected by point of care testing.

Effects of atorvastatin and aspirin combined therapy on inflammatory responses in patients undergoing coronary artery bypass grafting

This study was conducted to compare the effects of atorvastatin plus aspirin combined therapy on inflammatory responses, endothelial cell function, and blood coagulation system in patients undergoing coronary artery bypass grafting (CABG) to aspirin monotherapy. The patients were randomized into atorvastatin plus aspirin combined therapy group and aspirin monotherapy group. Reduced total cholesterol in the combined therapy group was found in a short term of medication for 14 days. On postoperative day (POD)-14, inhibitory effects of the combined therapy on whole blood aggregation as well as platelet activation assessed by flow cytometry were stronger than those of the monotherapy. Furthermore, cytokine, cytokine receptors, c-reactive protein and alpha1-acid glycoprotein in the combined therapy group were down-regulated on POD-14. At the same time, circulating levels of thromboxane A(2), vascular endothelial growth factor and thrombin-antithrombin III complex as well as P-selectin, L-selectin and intercellular adhesion molecule-1 were down-regulated, while E-selectin and transforming growth factor-beta1 was up-regulated. Atorvastatin plus aspirin combined therapy may improve inflammatory responses, accelerated platelet function, vascular endothelial cell function, blood coagulation system at the early stage such as 14th day after CABG. In conclusion, atorvastatin and aspirin combined therapy may bring beneficial effects to the patient after CABG.

Normalization of platelet reactivity in clopidogrel-treated subjects

BACKGROUND

Aspirin (ASA) + clopidogrel are commonly used in acute coronary syndrome (ACS), but persistent antiplatelet effects may complicate surgery.

METHODS AND RESULTS

To study the possibility of normalizing platelet reactivity after ASA + clopidogrel treatment, 11 healthy subjects received a 325-mg ASA + clopidogrel loading dose (300 or 600 mg dependent on study arm), followed by 81 mg of ASA + 75 mg of clopidogrel daily for 2 days. Platelet reactivity was assessed by light transmittance aggregometry (LTA) [challenged by adenosine diphosphate (ADP), arachidonic acid (AA), collagen, and thrombin receptor activating peptide (TRAP)] and flow cytometry for platelet activation by GPIIb/IIIa receptor exposure pretreatment, 4 and 72 h postload. To normalize platelet reactivity, increasing amounts of pooled platelets from five untreated volunteers [volunteers (V)-platelet-rich plasma (PRP)] were added ex vivo to the subject's PRP (S-PRP). At both 4 and 72 h, 40% and 50% V-PRP were needed to overcome platelet disaggregation in the 300 or 600 mg arms, respectively, after ADP challenge; an additional 10% V-PRP fully normalized aggregation. Recovery of function was linear with each incremental increase of V-PRP. ADP-induced GPIIb/IIIa activation showed the same pattern as LTA (r = 0.74). Forty percent V-PRP was required to normalize platelet function to AA, collagen, and TRAP.

CONCLUSION

Our results suggest that the pre-operative transfusion of 10 platelet concentrate units (the equivalent of 40% V-PRP) after a 300-mg clopidogrel loading or 12.5 units (50% V-PRP) after a 600 mg loading may adequately reverse clopidogrel-induced platelet disaggregation to facilitate postoperative hemostasis. An additional 2.5 units fully normalized platelet function. The potential clinical implications of our observations could include shorter hospitalizations and reduced bleeding complications. But these observations should be fully explored in an in vivo clinical setting with clopidogrel-treated patients before and after surgery.