Antithrombotic therapy in patients with saphenous vein and internal mammary artery bypass grafts

Treatment-Related Cardiovascular Outcomes in Patients with Symptomatic Subclavian Artery Stenosis

Background

Subclavian artery stenosis (SAS) is narrowing of the subclavian artery most commonly caused by atherosclerosis. It serves as a marker for cerebrovascular and myocardial ischemic events.

Methods

A retrospective cohort study was conducted to determine the association of treatment via combination therapy (antiplatelet drug plus either by-pass surgery or percutaneous transluminal angioplasty (PTA) with or without stent implantation) versus antiplatelet drug therapy alone on cardiovascular events and all-cause mortality in Marshfield Clinic patients diagnosed with symptomatic SAS from January 1, 1995 to December 31, 2009.

Results

Of the total 2153 cases, 100 patients were identified as eligible to be included in the study. Of these 100 patients that met inclusion criteria, 30 underwent combination therapy while 70 were managed only with drug treatment. A median length of follow-up was 8.45 years. Adverse cardiovascular events occurred in 5/30 (17%) of combination therapy patients compared to 28/70 (40%) of antiplatelet drug therapy only patients (p = 0.0355). Accordingly, all-cause mortality was higher (47%) in the antiplatelet drug therapy only group than the combination therapy group (13%) [hazard ratio = 3.45, p = 0.0218].

Conclusions

Preliminary findings in this pilot data set suggest that combination therapy (medications plus either surgical or interventional repair) of subclavian artery stenosis is associated with less cardiovascular adverse events and higher survival rates. However, prospective randomized studies with larger number of patients are needed to validate these findings.

A randomized, parallel group, double-blind study of ticagrelor compared with aspirin for prevention of vascular events in patients undergoing coronary artery bypass graft operation: Rationale and design of the Ticagrelor in CABG (TiCAB) trial: An Investigator-Initiated trial

BACKGROUND

For patients with coronary artery disease undergoing coronary bypass surgery, acetylsalicylic acid (ASA) currently represents the gold standard of antiplatelet treatment. However, adverse cardiovascular event rates in the first year after coronary artery bypass grafting (CABG) still exceed 10%. Graft failure, which is predominantly mediated by platelet aggregation, has been identified as a major contributing factor in this context. Therefore, intensified platelet inhibition is likely to be beneficial. Ticagrelor, an oral, reversibly binding and direct-acting P2Y12 receptor antagonist, provides a rapid, competent, and consistent platelet inhibition and has shown beneficial results compared with clopidogrel in the subset of patients undergoing bypass surgery in a large previous trial.

HYPOTHESIS

Ticagrelor is superior to ASA for the prevention of major cardiovascular events within 1 year after CABG.

STUDY DESIGN

The TiCAB trial (NCT01755520) is a multicenter, phase III, double-blind, double-dummy, randomized trial comparing ticagrelor with ASA for the prevention of major cardiovascular events within 12 months after CABG. Patients undergoing CABG will be randomized in a 1:1 fashion to either ticagrelor 90 mg twice daily or ASA 100 mg once daily. The study medication will be started within 24 hours after surgery and maintained for 12 months. The primary end point is the composite of cardiovascular death, myocardial infarction, stroke, and repeat revascularization at 12 months after CABG. The sample size is based on an expected event rate of 13% of the primary end point within the first 12 months after randomization in the control group, a 2-sided α level of .0492 (to preserve the overall significance level of .05 after planned interim analysis), a power of 0.80%, 2-sided testing, and an expected relative risk of 0.775 in the active group compared with the control group and a dropout rate of 2%. According to power calculations based on a superiority design for ticagrelor, it is estimated that 3,850 patients should be enrolled.

SUMMARY

There is clinical equipoise on the issue of optimal platelet inhibition after CABG. The TiCAB trial will provide a pivotal comparison of the efficacy and safety of ticagrelor compared with ASA after CABG.

Long-Term Outcomes of the Ross Procedure Versus Mechanical Aortic Valve Replacement: Propensity-Matched Cohort Study

BACKGROUND

The ideal aortic valve substitute in young and middle-aged adults remains unknown. We sought to compare the long-term outcomes of patients undergoing the Ross procedure and those receiving a mechanical aortic valve replacement (AVR).

METHODS

From 1990 to 2014, 258 patients underwent a Ross procedure and 1444 had a mechanical AVR at a single institution. Patients were matched into 208 pairs through the use of a propensity score. Mean age was 37.2±10.2 years, and 63% were male. Mean follow-up was 14.2±6.5 years.

RESULTS

Overall survival was equivalent (Ross versus AVR: hazard ratio, 0.91, 95% confidence interval, 0.38-2.16; P=0.83), although freedom from cardiac- and valve-related mortality was improved in the Ross group (Ross versus AVR: hazard ratio, 0.22; 95% confidence interval, 0.034-0.86; P=0.03). Freedom from reintervention was equivalent after both procedures (Ross versus AVR: hazard ratio, 1.86; 95% confidence interval, 0.76-4.94; P=0.18). Long-term freedom from stroke or major bleeding was superior after the Ross procedure (Ross versus AVR: hazard ratio, 0.09; 95% confidence interval, 0.02-0.31; P<0.001).

CONCLUSIONS

Long-term survival and freedom from reintervention were comparable between the Ross procedure and mechanical AVR. However, the Ross procedure was associated with improved freedom from cardiac- and valve-related mortality and a significant reduction in the incidence of stroke and major bleeding. In specialized centers, the Ross procedure represents an excellent option and should be considered for young and middle-aged adults undergoing AVR.

Peripheral artery disease. Part 2: medical and endovascular treatment

The treatment of peripheral artery disease (PAD) focuses on risk factor modification, cardiovascular event reduction, limb viability, and symptom improvement. Hypertension, hyperlipidemia, and diabetes mellitus should all be controlled to recommended target levels, and smoking cessation is vital. Antiplatelet therapies, such as aspirin or clopidogrel, should be administered in all patients unless contraindicated. Whenever possible, patients who present with claudication should be offered a regimen comprised of both medical and exercise therapy, which often results in substantial improvement in symptoms. For patients presenting with more-advanced disease, such as acute limb ischemia, critical limb ischemia, and severely-limiting symptoms of PAD, revascularization is often necessary. As a result of the rapid evolution in endovascular revascularization technology and expertise, many patients with PAD can be treated percutaneously. Therefore, in this Review, we will focus on medical therapy and endovascular revascularization of patients with PAD, with reference to surgical bypass in specific clinical scenarios.

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).

Management of antiplatelet therapy for minimization of bleeding risk before cardiac surgery

Antiplatelet therapy is commonly administered for primary and secondary prevention of stroke, recurrent angina, myocardial infarction, and death in patients with cardiovascular disorders. It also is associated with an increased risk of bleeding. We describe the management of antiplatelet therapy in patients undergoing coronary artery bypass graft surgery. In addition, we provide basic information about the mechanisms of action by which the most common antiplatelet agents inhibit platelet function. This information is integrated with results from pharmacologic studies and clinical trials. Determining the net effect in patients undergoing coronary artery bypass graft surgery requires knowledge about the pharmacokinetics, pharmacodynamics, and clinical efficacy of each drug, and an estimation of the absolute thrombotic versus hemorrhagic risk for each patient.

Balancing the benefit and risk of oral antiplatelet agents in coronary artery bypass surgery

Concern about possible hemorrhagic complications arising from use of oral antiplatelet agents in immediate proximity to coronary artery bypass graft (CABG) surgery leads many clinicians to avoid or discontinue these agents preoperatively. Recent evidence suggests that aspirin and clopidogrel can be used with relative safety in the preoperative period; dual antiplatelet therapy in the 5 days immediately preceding CABG surgery results in a moderate and variable increase in the risk of procedural bleeding. This modest hemorrhagic risk may be acceptable, given the clinical benefits of sustained antiplatelet therapy in preventing graft occlusion and ischemic complications pre- and post-CABG. Because the bleeding risk with aspirin is dose dependent, use of a low dose is preferred post-CABG.

Antithrombotic therapy in cardiac surgery

PURPOSE

To review the perioperative management of antithrombotic therapy in cardiac surgery, including the management of cardiopulmonary bypass (CPB) and off-pump surgery.

METHODS

A review of the relevant English literature over the period 1975-2005 was undertaken, in addition to a review of international practices in antithrombotic therapy in cardiac surgery.

PRINCIPAL FINDINGS

Cardiopulmonary bypass is required in most procedures and makes anticoagulation mandatory. Anticoagulation is, usually, achieved with unfractionnated heparin (UFH). Unfractionated heparin is monitored by point-of-care (POC) testing, such as the activated clotting time or the determination of heparin concentration. The target values of both tests remain empirical, with no clearly validated thresholds. The target value needs to be adjusted according to the POC test, given significant variations between devices and activators. After CABG, the need for antiplatelet therapy is well demonstrated, in order to limit the risk of postoperative death or ischemic events, and improve venous graft patency. Immediately after valvular surgery, antithrombotic therapy should take into account the specific risk carried by each patient and by each prosthetic device. The risk of venous thromboembolism, though poorly defined, is also present in the postoperative period and may require additional attention. Given the frequent exposure to UFH, occurrence of heparin-induced thrombocytopenia is not infrequent in these patients and requires careful individual management.

CONCLUSIONS

Antithrombotic therapy is an essential component of cardiac surgery. Yet, with the exception of antiplatelet agents in CABG patients, antithrombotic therapy is often based on the clinical experience of medical teams more than on an evidence-based assessment of the literature.

Cardioprotective Strategies to Improve Long-Term Outcomes Following Coronary Artery Bypass Surgery

BACKGROUND AND AIM

Cardioprotective strategies implemented to prevent ischemic events in patients at risk for cardiovascular disease have decreased morbidity and prolonged survival. In this review, we have used evidence-based medicine and number-needed-to-treat (NNT) analyses to determine which interventions are most beneficial in minimizing ischemic events and prolonging survival following coronary artery bypass graft (CABG) surgery.

METHODS

Therapeutic interventions available to minimize ischemic events in the post-CABG patient were analyzed using ACC/AHA Classifications and Level of Evidence Criteria. Based on these recommendations, NNT analyses were performed to determine the effectiveness of each intervention compared to the number of patients needed to be treated before a benefit was apparent.

RESULTS

The most beneficial intervention to improve mortality following CABG was the use of high tissue angiotensin-converting enzyme inhibitors, followed by statins and smoking cessation.

CONCLUSIONS

NNT analyses and evidence-based medicine recommendations provide surgeons with cardioprotective strategies to improve long-term outcomes following CABG surgery.

The PRoject of Ex-vivo Vein graft ENgineering via Transfection IV (PREVENT IV) trial: study rationale, design, and baseline patient characteristics

BACKGROUND

Coronary artery bypass graft (CABG) surgery with autologous vein graft (VG) conduit is one of the most frequently performed operations in the United States. Unfortunately, many VGs become occluded during long-term follow-up largely because of neointimal hyperplasia. A novel approach to preventing neointimal hyperplasia is with the double-stranded oligonucleotide edifoligide (Corgentech Inc, South San Francisco, Calif). Edifoligide inhibits E2F, a transcription factor that activates cell-cycle genes responsible for neointimal hyperplasia.

METHODS

PREVENT IV is a phase-III, multicenter, randomized double-blind placebo-controlled trial of ex vivo treatment of autologous VGs with edifoligide in patients undergoing initial CABG surgery. The primary end point is VG failure, defined as death or > or =75% stenosis in a treated VG at 12- to 18-month angiographic follow-up. Secondary end points include major adverse cardiac events through at least 5 years and adverse events through 30 days.

RESULTS

Enrollment of 3014 patients from 107 sites was completed on October 22, 2003. The baseline and procedural characteristics of the PREVENT IV population are generally well matched to a contemporary population of patients undergoing initial CABG from the Society of Thoracic Surgeons National Database. Angiographic follow-up is ongoing and scheduled to be completed in March 2005.

CONCLUSIONS

The PREVENT IV data will establish whether VG pretreatment with an E2F transcription factor decoy, edifoligide, can improve graft patency and reduce the long-term morbidity and mortality of patients undergoing CABG surgery.

Resistance to Aspirin in Patients After Coronary Artery Bypass Grafting Is Transient

The aim of the present study was to assess the responsiveness of blood platelets to aspirin in patients following coronary artery bypass grafting (CABG) surgery. Aspirin was administered following CABG in 24 operated patients (aged 63.2 +/- 6.3 years). Platelet function was monitored on the 10th postoperative day (A) and 1 month after CABG (B) with the use of whole-blood aggregometry (WBEA) and PFA-100 closure time (PFA-100 CTCEPI). Normal platelet response to aspirin was defined by 3 criteria: the complete inhibition of WBEA induced by arachidonic acid (0.5 mmol/L), partial inhibition of collagen (1 microg/mL)-induced aggregation (WBEA < 14 Omega), and prolongation of PFA-100 CTCEPI (>150 seconds) ("good responders"). Depending on whether 0, 1, 2, or 3 of these 3 criteria were fulfilled, patients were classified as "nonresponders," "weak responders," "incomplete responders," or "good responders," respectively. On the 10th postoperative day, there were 3 good responders, 6 incomplete responders, 11 weak responders, and 4 nonresponders among 24 patients. In contrast, 1 month after CABG within the same group of 24 patients there were 18 good responders, 5 incomplete responders, and 1 weak responder. Using a new methodology to assess impaired platelet responsiveness to aspirin ex vivo, we describe here the transient nature of "aspirin resistance" following CABG. These results indicate the necessity for the prolonged monitoring of the antiplatelet effectiveness of aspirin in the postoperative period after CABG.

The efficacy and safety of perioperative antiplatelet therapy

Widespread adoption of the antiplatelet agents into everyday clinical practice has revolutionized contemporary care of the cardiovascular patient. Major adverse cardiovascular events including death, myocardial infarction, stroke, and recurrent angina have all been shown to be significantly decreased when these agents are employed in the treatment of coronary atherosclerosis, acute coronary syndromes, myocardial infarction, and in the setting of percutaneous coronary intervention. As a growing number of patients on antiplatelet therapy are undergoing various surgical procedures, the potential risks and benefits these drugs pose perioperatively will become increasingly important. Available data indicate that, when used appropriately, these drugs can be used safely prior to surgery. Efficacy in improving surgical outcomes and in preventing adverse cardiovascular events postoperatively has also been demonstrated. The purpose of this review is to examine the perioperative safety and efficacy of the most widely used antiplatelet agents: aspirin; the thienopyridine clopidogrel; and the glycoprotein (GP) IIb/IIIa inhibitors abciximab, eptifibatide, and tirofiban. This information, coupled with emerging platelet monitoring techniques, may help provide additional assistance to the clinician to manage therapy and guide appropriate timing of both cardiac and noncardiac surgery.

Preventing atherothrombotic events in peripheral arterial disease: the use of antiplatelet therapy

Patients with peripheral arterial disease (PAD) are at increased risk of generalized atherothrombotic events. Epidemiologic data shows a high rate of co-prevalence of PAD and atherosclerosis in other vascular beds. Aggressive risk-factor modification and antiplatelet therapy has become the cornerstone of treatment to prevent ischaemic events associated with PAD. Recent clinical trials have confirmed the clinical benefit of clopidogrel and ticlopidine in patients with PAD, agents that irreversibly inhibit the binding of adenosine diphosphate to its platelet receptor. In the clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE) trial, clopidogrel was associated with an overall risk reduction of 8.7% (compared with aspirin, P=0.043) in myocardial infarction (MI), ischaemic stroke and vascular death. These results demonstrated that long-term administration of clopidogrel was effective in preventing ischaemic events in patients with atherosclerotic vascular disease including PAD. Aspirin and/or clopidogrel are the antiplatelet agents of choice for the reduction of atherothrombotic events in patients with PAD.

Indobufen: an updated review of its use in the management of atherothrombosis

Indobufen inhibits platelet aggregation by reversibly inhibiting the platelet cyclooxygenase enzyme thereby suppressing thromboxane synthesis. Clinical trials have evaluated the efficacy of oral indobufen in the secondary prevention of thromboembolic complications in patients with or without atrial fibrillation, in the prevention of graft occlusion after coronary artery bypass graft (CABG) surgery and in the treatment of intermittent claudication. In the secondary prevention of thromboembolic events indobufen 200 mg once or twice daily was significantly more effective than no treatment although not as effective as ticlopidine 250 mg once or twice daily, during 1-year nonblind clinical trials. Compared with placebo, indobufen 100 mg twice daily significantly reduced the risk of stroke in a small 28-month trial of patients at increased risk of systemic embolism (50% had atrial fibrillation). Furthermore, in patients with nonrheumatic atrial fibrillation and a recent cerebrovascular event enrolled in the 1-year Studio Italiano Fibrillazione Atriale (SIFA) trial, indobufen 100 or 200 mg twice daily was as effective as warfarin (titrated to produce an international normalised ratio of 2.0 to 3.5) in the secondary prevention of thromboembolic events; the incidences of the composite end-point of major vascular events (10.6 vs 9.0%) and recurrent stroke (5 vs 4%) were similar between treatments. In 2 large 12-month trials, the Studio Indobufene nel Bypass Aortocoronarico (SINBA) and the UK study, indobufen 200 mg twice daily was as effective as aspirin (acetylsalicylic acid) 300 or 325 mg plus dipyridamole 75 mg 3 times daily in the prevention of early and late occlusion of saphenous grafts in patients after CABG surgery. Indobufen 200 mg twice daily for 6 months significantly improved walking capacity compared with placebo, and caused a more pronounced improvement in both pain-free and total walking distance than either pentoxifylline 300 mg or aspirin 500 mg twice daily in separate 6- and 12-month studies of patients with intermittent claudication. Oral indobufen up to 200 mg twice daily was generally well tolerated in >5000 patients with atherosclerotic disease. Adverse events (predominantly gastrointestinal), reported by 3.9% of patients, rarely required withdrawal from treatment. In the SINBA and UK studies, fewer adverse events and less gastrointestinal bleeding were seen with indobufen than with aspirin plus dipyridamole treatment, while in the SIFA trial, noncerebral bleeding events occurred significantly less frequently in indobufen than warfarin recipients (0.6 vs 5.1%) and major bleeding events occurred only in the warfarin group.

CONCLUSION

Indobufen is as effective as warfarin in the prophylaxis of thromboembolic events in at risk patients with nonrheumatic atrial fibrillation, as aspirin plus dipyridamole in the prevention of CABG occlusion and may be more effective than aspirin or pentoxifylline in improving walking capacity in patients with intermittent claudication. The improved tolerability profile of indobufen (favourable gastric tolerance and reduced haemorrhagic complications) compared with aspirin 300 to 325 mg 3 times daily or warfarin, in addition to a similar antiplatelet effect, suggests indobufen can be considered a drug with a definite role in the management of atherothrombotic events. In particular, indobufen may be an effective alternative for at risk patients with nonrheumatic atrial fibrillation in whom anticoagulant therapy is contraindicated or who are at higher risk of bleeding.