Clopidogrel as adjunctive antiplatelet therapy during coronary stenting

Mechanisms of thrombosis and research progress on targeted antithrombotic drugs

Globally, the incidence of thromboembolic diseases has increased in recent years, accompanied by an increase in patient mortality. Currently, several targeting delivery strategies have been developed to treat thromboembolic diseases. In this review, we discuss the mechanisms of thrombolysis and current anticoagulant drugs, particularly those with targeting capability, highlighting advances in the accurate treatment of thrombolysis with fewer adverse effects. Such approaches include magnetic drug-loading systems combined with molecular imaging to recanalize blood vessels and systems based on chimeric Arg-Gly-Asp (RGD) sequences that can target platelet glycoprotein receptor. With such progress in targeted antithrombotic drugs, targeted thrombolysis treatment shows significant potential benefit for patients.

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

BACKGROUND

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

HYPOTHESIS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Inability to Reverse Aspirin and Clopidogrel-induced Platelet Dysfunction with Platelet Infusion

Background Platelets are commonly administered to trauma patients to reverse the effects of pre-injury anti-platelet drugs if these individuals are judged to be at risk for ongoing bleeding (i.e., traumatic brain injury). In the U.S. blood banks, platelets are maintained at room temperature and are not infused prior to 72 hours storage due to rigorous screening methods. Recent work suggested that cold refrigerated platelets may be effective at restoring platelet function. We hypothesized that refrigerated platelets might be superior to room temperature platelets in reversing aspirin and clopidogrel-induced platelet dysfunction. Methods Using a cross-over design, 10 healthy, adult subjects underwent platelet removal by apheresis, received anti-platelet drugs (aspirin 325 mg and clopidogrel 75 mg) daily for three days, and then had return of their own platelets (about 3 x 10¹¹ platelets). Five subjects were randomly assigned to receive platelets stored at 4°C, and five received platelets stored at room temperature. One month later, this entire process was repeated with each subject receiving platelets stored by the alternative method. Thus, subjects served as their own controls. At multiple time points during the study in vivo platelet function was assessed by bleeding times, which were measured by a single observer blinded to patient group. Results Bleeding times rose dramatically after anti-platelet drugs were given, but remained well above the normal range (seven minutes) despite reinfusion of platelets. There were no differences in platelet function according to the method of storage. Conclusions Transfusion with autologous platelets appears to be ineffective in reversing the anti-platelet effects of aspirin and clopidogrel. Cold refrigerated platelets were no more effective than room temperature stored platelets in restoring platelet function. This abstract was presented at American College of Surgeons-clinical congress, Boston 10-22-2018. (Khoury L, Cohn S, Panzo M. Inability to Reverse Aspirin and Clopidogrel-Induced Platelet Dysfunction with Platelet Infusion. Journal of the American College of Surgeons. 2018. 227. S265. DOI: 10.1016/j.jamcollsurg.2018.07.546).

Relationship between maximum clot firmness in ROTEM® and postoperative bleeding after coronary artery bypass graft surgery in patients using clopidogrel

Background:

The aim of the present study was to investigate the relationship between maximum clot firmness (MCF) in rotational thromboelastometry (ROTEM^®) and postoperative bleeding in patients on clopidogrel after emergency coronary artery bypass graft surgery (CABG).

Methods:

This observational study recruited 60 patients posted for emergency CABG following unsuccessful primary percutaneous coronary intervention (PCI) while on 600 mg of clopidogrel. The study population was divided into 2 groups on the basis of their MCF in the extrinsically activated thromboelastometric (EXTEM) component of the (preoperative) ROTEM^® test: patients with MCF <50 mm (n = 16) and those with MCF ≥50 mm (n = 44). Postoperative chest tube drainage amount, need for blood product transfusion, postoperative complications, and duration of mechanical ventilation after CABG were recorded.

Results:

No significant differences were observed between the two groups regarding duration of surgery, cardiopulmonary bypass, and aortic cross-clamp time. Chest tube drainage at 6, 12, and 24 h after Intensive Care Unit admission were significantly higher in the patients with MCF below 50 mm. The need for blood product transfusion was higher in the group with MCF <50 mm. In patients who experienced postoperative bleeding of 1000 mL or more, the ROTEM^® parameters of INTEM (Intrinsically activated thromboelastomery) α and MCF, EXTEM α and MCF, and HEPTEM (INTEM assay performed in the presence of heparinase) MCF (but not FIBTEM (Thromboelastometric assay for the fibrin part of the clot) values) were significantly lower than those with postoperative bleeding <1000 mL (P ≤ 0.05).

Conclusions:

When platelet aggregometry is not available, the ROTEM^® test could be useful for the prediction of increased risk bleeding after emergency CABG in patients who have received a loading dose of clopidogrel.

P2Y12 receptor inhibitors: an evolution in drug design to prevent arterial thrombosis

INTRODUCTION

P2Y12 inhibitors are a critical component of dual antiplatelet therapy (DAPT), which is the superior strategy to prevent arterialthrombosis in patients with acute coronary syndromes (ACS) and undergoing stent implantation.. Areas covered: Basic science articles, clinical studies, and reviews from 1992-2017 were searched using Pubmed library to collet impactful literature. After an introduction to the purinergic receptor biology, this review summarizes current knowledge on P2Y12 receptor inhibitors. Furthermore, we describe the subsequent improvements of next-generation P2Y12 receptor inhibitors facing the ambivalent problem of bleeding events versus prevention of arterial thrombosis in a variety of clinical settings. Therefore, we summarize data from relevant preclinical and clinical trials of currently approved P2Y12 receptor inhibitors (clopidogrel, prasugrel, ticagrelor, cangrelor) and provide strategies of drug switching and management of bleeding events. Expert opinion: An enormous amount of pharmacologic and clinical data is available for the application of P2Y12 receptor inhibitors. Today prasugrel, ticagrelor and clopidogrel are the standard of care drugs during dual antiplatelet therapy for ACS patients, but have considerable rates of bleeding. Recent and future clinical trials will provide evidence for subsequent escalation and de-escalation strategies of P2Y12 receptor inhibition. These data may pave the way for an evidence-based, individualized P2Y12 receptor inhibitor therapy.

Balancing between bleeding and thromboembolism after percutaneous coronary intervention in patients with atrial fibrillation. Could triple anticoagulant therapy be a solution?

Introduction

Atrial fibrillation (AF) has nowadays become a common disease as it comes along with medical procedures propagation in the ageing population with coexistent diseases. Hence a need for use of combined anticoagulant and antithrombotic therapy has arisen. According to the 2010 ESC guidelines on myocardial revascularization, short-term triple antithrombotic therapy after percutaneous coronary intervention (PCI) should be given if compelling indications exist.

Aim

To assess bleeding and thromboembolic events depending on the antithrombotic regimen in short- and long-term follow-up in patients with AF after PCI with stent implantation.

Material and methods

A 12-month prospective, non-randomized registry was conducted in the 3^rd Department of Cardiology in the Upper Silesian Medical Center in Katowice from October 2008 to April 2011. One hundred and four patients in two groups – on triple therapy (TT; aspirin + clopidogrel + vitamin K antagonists (VKA; warfarin or acenocoumarol) n = 44) and on dual therapy (DT; aspirin + clopidogrel; n = 60) – were assessed 30 days and 12 months after angioplasty.

Results

All bleeding events occurred more often in the triple anticoagulated group in 30 days (TT 20.5% vs. DT 6.7%; p = 0.03) and after 12 months (TT 38.9% vs. DT 17.2%, p = 0.09). The difference in major bleeding events was not significant after 30 days (TT 9.1% vs. DT 3.3%; p = NS) or 12 months (TT 11.1% vs. DT 6.9%; p = NS). Thromboembolic events after 30 days (DT 5.0% vs. TT 2.3%) and 12 months (TT 11.1% vs. DT 3.4%) were comparable. The percentage of deaths after 30 days (DT 1.7% vs. TT 0.0%, p = NS) increased after 12 months (DT 13.8% vs. TT 0.0%, p = 0.09).

Conclusions

Significantly higher risk of bleeding on TT becomes blurred by a tendency to increased mortality in patients on DT.

Clopidogrel Within Few Hours of Coronary Artery Bypass Grafting Does Significantly Increase the Risk of Bleeding

Background

Postoperative bleeding after coronary artery surgery is partly related to platelet dysfunction. The aim of this study was to evaluate the effects of a single loading dose of clopidogrel (300 mg) before coronary angiography on bleeding and use of blood and blood products after emergency coronary artery bypass surgery (CABG).

Methods

This is a nonrandomized observational prospective study between January, 2006 till December 2009, at a university hospital, we compare the results of a cohort of 65 patients who received 300 mg clopidogrel during coronary angiography that was followed by emergency CABG (group A or study group) to a cohort of 206 patients who underwent elective coronary artery bypass surgery during the same period by the same surgeons in whom clopidogrel was stopped 7 days before surgery (Group B or control group). Emergency surgery was done because of critical coronary anatomy or because of ongoing chest pain. All patients in the two groups were kept on 100 mg of aspirin until the day of surgery. Outcome data used to compare the two groups, Chest tube drainage in first 12 hours (12 h), need for re-exploration and use of blood and blood product transfusion were prospectively collected.

Results

Postoperative bleeding, reoperation rates for bleeding and use of blood products are significantly more in those who received a loading dose of clopedogril within few hours of CABG (group A) compared to those who stopped clopedogril for a week before CABG.

Conclusions

Preoperative 300 mg of clopidogrel is associated with significant increase in post operative bleeding, need for surgical exploration and use of blood and blood product transfusion after CABG.

Comparison of effects of two different formulations of clopidogrel bisulfate tablets on platelet aggregation and bleeding time in healthy Korean volunteers: A single-dose, randomized, open-label, 1-week, two-period, phase IV crossover study

BACKGROUND

Clopidogel bisulfate, an oral antiplatelet agent that works by inhibiting adenosine diphosphate-induced platelet aggregation, is used in the treatment of coronary artery disease, peripheral vascular disease, and cerebrovascular disease. The newly developed generic version of Clopidogrel bisulfate has a mechanism of action comparable to the reference formulation.

OBJECTIVE

The aim of this study was to assess and compare the pharmacodynamic effects and safety profile of these 2 formulations of Clopidogrel bisulfate in healthy volunteers.

METHODS

This was a single-dose, randomized, openlabel, 1-week, 2-period, Phase IV crossover study conducted from July 2008 to February 2009. Healthy volunteers were randomly assigned to receive a 1-week course of the test formulation followed by a 1-week course of the reference formulation (each, 300 mg on day 1, then 75 mg for 6 days), or the reverse sequence, separated by a 2-week washout period. Inhibition of platelet aggregation and the effect on bleeding time were used to evaluate pharmacodynamic effects. Variables included the mean maximal activity (E(max)) of the percent inhibition of platelet aggregation and bleeding time. Blood was sampled at screening, on the morning before each first drug administration (days 1 and 21), the day after the completion of each 7-day treatment course (days 8 and 28), and 7 days after completion of each 7-day treatment course (days 14 and 34). The bioequivalence of the 2 pharmaceutical formulations was tested. The safety profiles included assessment of vital signs, laboratory test results, and the incidence of adverse events and adverse drug reactions.

RESULTS

Two of the original 32 healthy Korean volunteers were excluded because of screening failure or withdrawal of consent. Therefore, 30 volunteers (16 males; mean [SD] age, 28.6 [8.0] years; age range, 19-51 years; mean weight, 62.4 [9.5] kg; weight range, 45-78 kg) were recruited into the study. E(max) and bleeding time did not differ significantly between the 2 groups. The mean change in E(max) was 44.1% (22.5%) and 44.3% (24.2%) and the mean change in bleeding time was 4.8 (3.7) and 4.6 (3.8) minutes after 7 days' administration of the test formulation and the reference formulation, respectively. The geometric mean ratio (90% CI) was 99.5 (82.9-116.2) and was within the bioequivalence acceptance range of 80% to 120%. Vital signs and platelet and neutrophil counts were within normal limits. None of the volunteers experienced any adverse events or adverse drug reactions.

CONCLUSION

In this study of healthy volunteers, there were no significant differences between the 2 tablet formulations of Clopidogrel bisulfate in pharmacodynamic effects or safety profile.

Reduced incidence of clinical restenosis with newer generation stents, stent oversizing, and high-pressure deployment: single-operator experience

BACKGROUND

Over the last 4 years, several newer generation stents have become available, promising to change the scenery of coronary angioplasty (PTCA) with its attendant restenosis rate.

HYPOTHESIS

The aim of this study was to review prospectively the results of a single operator adopting a uniform approach with approximately 0.5 mm stent oversizing and high-pressure (> or = 12-16 bar) deployment and compare them with conventional PTCA in a series of 244 consecutive patients.

METHODS

The study included 203 men and 41 women, aged 59 +/- 11 years, who presented with stable angina and/or positive exercise testing (n = 75), unstable angina (n = 161), or acute myocardial infarction (n = 8). Dilated vessels included the left anterior descending artery (n = 139), the right coronary artery (n = 86), the left circumflex artery (n = 47), the ramus branch (n = 4), or venous grafts (n = 2). Stents were implanted for dissection, suboptimal PTCA result, and electively. Two groups were compared: 83 patients who underwent balloon PTCA alone and 161 patients who also received stent(s).

RESULTS

The two groups had similar demographics, age (58 +/- 10 vs. 59 +/- 11 years), initial vessel stenosis (92 +/- 7 vs. 93 +/- 6%), and left ventricular ejection fraction (51 +/- 9 vs. 51 +/- 8%). Procedural success was also similar (97.6 vs. 99.4%), but as expected the residual stenosis was much lower in the stent group (< or = 0 vs. 17%). The following stents were employed: J & J (n = 1), NIR (n = 117), ACS (n = 59), AVE (n = 9), Inflow GoldFlex (n = 9), Crossflex (n = 5), Wictor (n = 1), Jostent (n = 16), R stent (n = 9), Seaquence (n = 2) and Wallstent (n = 1). Single stents were used in 118 patients, two stents in 31 patients, three in 6 patients, and four in 6 patients. There was one in-hospital death at 3 days unrelated to the procedure. There were no events of subacute stent thrombosis; all patients in the stent group received combined therapy with aspirin and ticlopidine, the latter for 1 month. During 18 +/- 14 months, the clinical restenosis rate was significantly lower in the stent group (6.9%) than in the PTCA group (28.4%) (p = 0.001).

CONCLUSION

In a series of 244 consecutive patients, newer generation stents and a consistent approach of stent oversizing and high-pressure stent deployment by a single operator resulted in high procedural success (99%), lack of stent thrombosis (0%), and a very low clinical restenosis rate (7%).

Efficacy of clopidrogel on reperfusion and high-sensitivity C-reactive protein in patients with acute myocardial infarction

We investigated the effects of clopidogrel on reperfusion and inflammatory process in STEMI. A total of 175 STEMI patients with similar clinical characteristics were included to this study. One was the standard pharmacological reperfusion therapy group (group 1, n : 90), who received 300 mg aspirin, 70 U/kg bolus, and 12 U/kg/hr continuous infusion of unfractioned heparin and accelerated t-PA. Clopidogrel 450 mg loading and 75 mg/d thereafter was added to standard reperfusion therapy in the other group (group 2, n : 85). The ST-segment resolution, CK-MB, and high-sensitive CRP (hs-CRP) parameters were measured. Complete ST resolution was observed in 32 patients (36.8%) in group 1 and 53 patients (63.8%) in group 2 (P < .001). Also in the first 24 hours, the CK-MB levels of patients in group 1 were significantly higher than those of group 2 (P = .001). The hs-CRP values were greater in group 1 than group 2 at 48th hour (gruop 1: 9.4 ± 0.1 mg/L, group 2: 3.7 ± 1.4 mg/L; P = .000). We concluded that adding clopidogrel to standard treatment in STEMI patients provided early reperfusion and suppression of inflammatory response.

Comparison between ticlopidine and clopidogrel in patients undergoing primary stenting in acute myocardial infarction: results from the CADILLAC trial

OBJECTIVE

The aim of this article is to examine whether clopidogrel and ticlopidine treatments produce similar clinical outcomes for patients receiving primary stenting for acute myocardial infarction (AMI).

BACKGROUND

Prior studies have yielded conflicting results on the relative safety and efficacy of clopidogrel and ticlopidine after stent implantation, warranting an evaluation in primary stenting for AMI.

METHODS

In the multicenter, prospective CADILLAC trial, patients undergoing primary infarct stenting were treated at operator discretion with either ticlopidine (931 patients) or clopidogrel (163 patients) and then followed for 1 year. Baseline clinical and angiographic characteristics were comparable except for baseline TIMI 0/1 flow (72.5% clopidogrel vs. 63.9% ticlopidine, P = 0.04).

RESULTS

Patients receiving clopidogrel had more recurrent ischemia in hospital (6.1 vs. 2.8%, P = 0.02) and at 30 days (10.5 vs. 5.8%, P = 0.02), more moderate and severe bleeding at 30 days (7.4 vs. 2.7%, P = 0.002), and similar rates of stent thrombosis out to 1 year (P = 0.11). By multivariable analysis, clopidogrel use was an independent predictor for recurrent ischemia in hospital (P = 0.0002), and at 30 days (P = 0.012); and of moderate and severe bleeding in hospital (P = 0.002), and at 30 days (P = 0.001).

CONCLUSIONS

Despite thienopyridines similarities, their efficacy may be different within the first 30 days of primary stenting for AMI. A prospective, randomized trial is required to confirm these findings.

Impact of pretreatment with clopidogrel on initial patency and outcome in patients treated with primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: a systematic review

BACKGROUND

The main goal of the initial treatment of ST-segment elevation myocardial infarction is prompt reperfusion of the infarct-related artery. The value of pretreatment with clopidogrel before primary percutaneous coronary intervention is currently unclear.

METHODS AND RESULTS

Studies were retrieved through MEDLINE and Cochrane Controlled Trials Register searches over the past 20 years. Two authors independently performed the study selection and data extraction. Randomized controlled studies were included when the research subjects were unselected patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention. Pilot trials, studies that enrolled patients undergoing rescue percutaneous coronary intervention, and studies with angiographic assessment not performed by a core laboratory or 2 blinded investigators were excluded. Thirty-eight treatment groups, including 8429 patients, were included. Initial patency was higher in treatment groups in which patients received pretreatment with clopidogrel (34.3%; 95% confidence interval, 32.9 to 35.8) compared with those in which patients did not receive clopidogrel before initial coronary angiography (25.8%; 95% confidence interval, 24.5 to 27.1). In multivariate-weighted logistic regression analysis, pretreatment with clopidogrel was an independent predictor of early reperfusion (odds ratio, 1.51; 95% confidence interval, 1.31 to 1.74; P<0.0001) and improved clinical outcome.

CONCLUSIONS

Initial patency and clinical outcome were improved in treatment groups that received pretreatment with clopidogrel. These results in patients undergoing primary percutaneous coronary intervention are in line with the experience of pretreatment with clopidogrel in elective patients, non-ST-elevation coronary syndromes, and thrombolytic studies.

Antiplatelet agents for preventing thrombosis after peripheral arterial bypass surgery

BACKGROUND

Peripheral arterial disease (PAD) may cause occlusions (blockages) in the main arteries of lower limbs. One treatment option is bypass surgery using autologous (the patient's own tissue) vein graft or artificial graft. A number of factors influence occlusion rates, including the material used. To prevent graft occlusion patients are usually treated with antiplatelet, antithrombotic drugs, or a combination of both.

OBJECTIVES

To evaluate whether antiplatelet treatment in patients with symptomatic PAD undergoing infrainguinal bypass surgery improves graft patency, limb salvage and survival.

SEARCH STRATEGY

The authors searched the Cochrane Peripheral Vascular Diseases Group Specialised Register (January 2008) and the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 4). Additional trials were sought through reference lists of papers and proceedings from the vascular surgical society meetings.

SELECTION CRITERIA

For this update the methodological quality of each original trial was assessed independently by review authors (JB, HM, AW) with emphasis on concealment of allocation.

DATA COLLECTION AND ANALYSIS

Details of the selected studies were extracted independently by JB and HM for the update. The treatment and control groups were compared for important prognostic factors and differences described. If any data were unavailable, further information was sought from authors. Data were synthesised by comparing group results. Unit of analysis issues were addressed by subgroup analysis.

MAIN RESULTS

The administration of a variety of platelet inhibitors resulted in improved venous and artificial graft patency when compared to no treatment. However, analysing patients for graft-type indicated that those patients receiving a prosthetic graft were more likely to benefit from administration of platelet inhibitors than patients treated with venous grafts.

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin had a slight beneficial effect on the patency of peripheral bypass grafts but seemed to have an inferior effect on venous graft patency compared with artificial grafts. The effect of aspirin on cardiovascular outcomes and survival was small and not statistically significant. This might be due to the fact that the majority of patients receiving a peripheral graft have an advanced stage of PAD with critical ischaemia. They are usually seriously ill as a result of cardiovascular disease and have high mortality rates, of 20% per year. Additionally, the number of patients included in this analysis might be too small to reach a statistically significant effect for mortality and cardiovascular morbidity.

Clopidogrel and Bleeding after General Surgery Procedures

Although many studies in the cardiothoracic literature exist about the relationship between clopidogrel and postoperative bleeding, there is scarce data in the general surgery literature. We assessed whether there are increased bleeding complications, morbidity, mortality, and resource utilization in patients who are on clopidogrel (Plavix®) within 1 week before undergoing a general surgery procedure. Fifty consecutive patient charts were retrospectively reviewed after identifying patients who had pharmacy orders for clopidogrel and who underwent a general surgery procedure between 2003 and 2007. Patients who took clopidogrel within 6 days before surgery (group I, n = 28) were compared with patients who stopped clopidogrel for 7 days or more (group II, n = 22). A larger percentage of patients who took their last dose of clopidogrel within 1 week of surgery (21.4% vs 9.5%) had significant bleeding after surgery requiring blood transfusion. However, there were no significant differences between the groups in operative or postoperative blood transfusions ( P = 0.12, 0.53), decreases in hematocrit ( P = 0.21), hospital stay ( P = 0.09), intensive care unit stay ( P = 0.41), late complications ( P = 0.45), or mortality ( P = 0.42). Although our cohort is limited in size, these results suggest that in the case of a nonelective general surgery procedure where outcomes depend on timely surgery, clopidogrel taken within 6 days before surgery should not be a reason to delay surgery. However, careful attention must be paid to meticulous hemostasis, and platelets must be readily available for transfusion in the operating room.

Novel thromboresistant materials

The development of a clinically durable small-diameter vascular graft as well as permanently implantable biosensors and artificial organ systems that interface with blood, including the artificial heart, kidney, liver, and lung, remain limited by surface-induced thrombotic responses. Recent breakthroughs in materials science, along with a growing understanding of the molecular events that underlay thrombosis, has led to the design and clinical evaluation of a variety of biologically active coatings that inhibit components of the coagulation pathway and platelet responses by surface immobilization or controlled release of bioactive agents. This report reviews recent progress in generating synthetic thromboresistant surfaces that inhibit (1) protein and cell adsorption, (2) thrombin and fibrin formation, and (3) platelet activation and aggregation.

The effect of preoperative clopidogrel on bleeding after coronary artery bypass surgery

INTRODUCTION

Clopidogrel treatment is associated with a reduction in thrombotic complications in coronary stent placement, improved outcome after acute coronary syndromes, and decreased mortality in patients with coronary artery disease. The purpose of this study was to analyze the effect of preoperative clopidogrel exposure on bleeding complications, blood transfusions requirements, and reoperations in patients undergoing coronary artery bypass grafting (CABG).

PATIENTS AND METHODS

This study included 320 patients from a single institution that underwent an isolated CABG who were discharged between July 2003 and June 2004. The cohort of 320 patients was classified into 3 groups. The control group consisted of 255 patients that did not receive clopidogrel or stopped clopidogrel 7 days before surgery but were treated with aspirin instead. Clopidogrel I consisted of 25 patients that were taking clopidogrel within 3 days of surgery, and Clopidogrel II consisted of 40 patients that were taking clopidogrel 4 to 7 days before surgery. Patients were compared based on preoperative data (age, gender, use of clopidogrel, preoperative hemoglobin, and ejection fraction), intraoperative data (cross-clamp time), postoperative data (chest tube output, rate of reoperation, units of transfused blood, length of stay in the intensive care unit, and length of intubation).

RESULT

There were no significant differences among the 3 groups concerning age, sex, ejection fraction, or preoperative hemoglobin. There were no differences in length of intensive care unit stay and length of intubation among the 3 groups of patients. Patients in the clopidogrel I group had more units of blood transfused than either the control or the Clopidogrel II group (p=0.027). There is also a trend toward more chest tube output in clopidogrel I group compared with the control group. Fifteen patients (4.6%) of the total group required reoperation secondary to bleeding: 2 (8.0%) in the Clopidogrel I group, 2 (5%) in the clopidogrel II group, and 11 (4.3%) in the control group (p=0.41).

CONCLUSION

This study demonstrated that clopidogrel within 3 days preoperatively increases the requirement for blood transfusion in patients undergoing CABG. Waiting more than 3 days after the last dose of clopidogrel decreases blood transfusion requirements. There is also a trend toward more postoperative bleeding for those patients that took clopidogrel within 3 days before their CABG. The reoperation rate of patients that took clopidogrel within 3 days of their procedure required almost twice as many reoperations as the patients that did not take clopidogrel.

Benefits and risks of clopidogrel pretreatment before coronary artery bypass grafting in patients with ST-elevation myocardial infarction treated with fibrinolytics in CLARITY-TIMI 28

The Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis in Myocardial Infarction 28 (CLARITY-TIMI 28) trial was a randomized, double-blind, placebo-controlled study of clopidogrel in 3,491 patients receiving fibrinolytic therapy for ST-segment elevation myocardial infarction. Patients were randomized to clopidogrel or placebo begun at the time of fibrinolysis. This analysis reports the outcomes among the 136 patients in the trial population who underwent coronary artery bypass grafting (CABG) during the index hospitalization. There was no difference in the rates of TIMI major or minor bleeding between the clopidogrel and placebo groups from randomization to the end of follow-up (13.6% vs. 14.3%, P = 1.0) or from the time of CABG to the end of follow-up (9.1% vs. 11.4%, P = 0.78). When any day for study medication discontinuation < or = 5 days prior to CABG was chosen as a cut point to evaluate bleeding risk for clopidogrel vs. placebo, there was no excess bleeding in the clopidogrel group. Among patients undergoing CABG, there was a trend toward reduction in the risk of cardiovascular death, recurrent MI, or recurrent ischemia requiring urgent revascularization at 30 days for those taking clopidogrel (OR 0.66, 95% CI 0.27-1.5; P = 0.37), consistent with the benefit seen in the overall trial population (OR 0.80, CI 0.65-0.97; P = 0.03). In conclusion, early clopidogrel treatment among CLARITY-TIMI 28 patients undergoing CABG was not associated with an increase in the rate of peri-operative bleeding and showed a trend toward reduction in 30-day ischemic events.

[Rational minimally invasive treatment of pAOD: when should a conservative approach, PTA, or stent be chosen?]

In order to obtain optimal results and satisfied patients, rational therapy of pAOD should strictly follow national and international society guidelines. In particular cases an individual therapeutic concept seems justified beyond these guidelines. Based on clinical data and driven by costs, aortic and iliac lesions may be treated by PTA or selective stent placement with equal results; however, long-term data justify also primary, direct stenting. For treatment of infrainguinal and popliteal stenotic lesions primary stenting should be restricted to PTA failure (dissection, recoil, occlusion); except for treatment of extended lesions, primary stenting compared to PTA alone seems beneficial in terms of midterm patency. Endovascular procedures below the knee and at the toe should be limited to existing limb-threatening ischemia in order to save the extremity; whether PTA or stenting is advantageous has not yet determined.

Effect of Clopidogrel on Midterm Graft Patency following Off-Pump Coronary Revascularization Surgery

OBJECTIVE

The aim of the study was to evaluate the effect of clopidogrel on midterm graft patency following off-pump coronary revascularization surgery.

DESIGN

Ninety-four consecutive patients who underwent off-pump coronary artery bypass grafting between 1997 and 2002 were studied (58 men, 36 women; 61.7 +/- 9.8 years). The initial 36 patients (control group) received 75 to 160 mg acetyl salicylic acid (ASA) as an antiplatelet agent, whereas the consecutive 58 patients (clopidogrel group) received 75 mg clopidogrel postoperatively in addition to ASA. Intraoperatively, graft flow was assessed with transit-time flowmetry in all patients and the peripheral anastomoses were assessed with epicardial ultrasound in 28 patients. Sixty-two patients underwent angiography after a mean of 185 +/- 92 days. A total of 82 grafts were evaluated angiographically. Grafts with TIMI flow 2 and 3 were assessed as patent.

RESULTS

At angiographic follow-up, the overall graft patency rate was 84% (31/37) in the control group and 93% (42/45) in the clopidogrel group (P value was not significant [ns]). Graft patency rates for left internal mammary artery (LIMA) grafts were 92% (23/25) versus 96% (28/29) (ns), and for saphenous vein grafts were 66% (7/11) versus 87% (14/16) (ns), respectively.

CONCLUSION

The observed trend toward higher patency rates in patients treated with clopidogrel did not reach statistical significance. Further larger studies are necessary to confirm these preliminary results.

The clinical potential of a point-of-care assay to assess interindividual variability in platelet aggregation among patients taking clopidogrel

Clopidogrel is an important component of medical therapy for patients with acute coronary syndromes and those receiving coronary artery stents. Despite use of clopidogrel, a significant number of patients experience recurrent adverse ischemic events. Interindividual variability of platelet aggregation in response to clopidogrel may be an explanation for some of these recurrent events, and small trials have linked "clopidogrel resistance" as measured by platelet function tests to adverse events. Additionally, the degree of clopidogrel-induced platelet inhibition appears to be a factor determining bleeding risk at coronary artery bypass grafting. A point-of-care device that could accurately and rapidly measure the degree of platelet inhibition among patients taking clopidogrel could be clinically valuable. Such a device would have the potential to allow therapeutic decision-making based on the degree of platelet inhibition, especially for patients undergoing percutaneous coronary intervention or coronary artery bypass grafting.

A point-of-care assay to measure platelet aggregation in patients taking clopidogrel

Clopidogrel is an important component of medical therapy for patients with acute coronary syndromes and those receiving coronary stents. Despite the use of clopidogrel, a significant number of patients experience recurrent adverse ischemic events. Inter-individual variability of platelet aggregation in response to clopidogrel may provide an explanation for some of these recurrent events, and small trials have linked clopidogrel resistance, as measured by platelet function tests, to adverse events. The VerifyNowTM P2Y12 assay (Accumetrics, Inc., CA, USA) is a point-of-care device that can accurately and rapidly measure the degree of platelet inhibition in patients taking clopidogrel. This assay can identify patients with a poor response to clopidogrel, and could potentially lead to change in therapy.

Oral antiplatelet therapy and percutaneous coronary intervention

The benefit of oral antiplatelet therapy following percutaneous coronary intervention (PCI) with intracoronary stent implantation is well established. Combined aspirin with clopidogrel or ticlopidine therapy is superior to aspirin alone in reducing thrombotic events after stent placement. Clopidogrel is the drug of choice, given that its efficacy is comparable to ticlopidine and it has a superior safety profile. Despite dual antiplatelet therapy, patients remain at risk of recurrent vascular events. Optimal timing, duration and dosage of antiplatelet therapy remain controversial. Recent evidence suggests additional benefit with clopidogrel pretreatment, high clopidogrel loading dose and long-term dual antiplatelet therapy post-PCI in high-risk patients.

Effect of Clopidogrel Premedication in Off-Pump Cardiac Surgery

Background— Premedication with clopidogrel has reduced thrombotic complications after percutaneous coronary revascularization procedures. However, because of the enhanced and irreversible platelet inhibition by clopidogrel, patients requiring surgical revascularization have a higher risk of bleeding complications and transfusion requirements. A principal benefit of surgical coronary revascularization without cardiopulmonary bypass is its lower hemorrhagic sequelae. The purpose of this study was to evaluate the effect of preoperative clopidogrel administration in the incidence of hemostatic reexploration, blood product transfusion rates, morbidity, and mortality in patients undergoing off-pump coronary artery bypass graft surgery using a large patient sample and a risk-adjusted approach.

Methods and Results— Two hundred eighty-one patients (17.9%) did and 1291 (82.1%) did not receive clopidogrel before their surgery, for a total of 1572 patients undergoing isolated off-pump coronary artery bypass graft surgery between January 2000 and June 2002. Risk-adjusted logistic regression analyses and a matched pair analyses by propensity scores were used to assess the association between clopidogrel administration and reoperation as a result of bleeding, intraoperative and postoperative blood transfusions received, and the need for multiple transfusions. Hemorrhage-related preoperative risk factors identified in the literature and those found significant in a univariate model were used. The clopidogrel group had a higher likelihood of hemostatic reoperations (odds ratio [OR], 5.1; 95% confidence interval [CI], 2.47 to 10.47; P <0.01) and an increased need in overall packed red blood cell (OR, 2.6; 95% CI, 1.94 to 3.60; P <0.01), multiple unit (OR, 1.6; 95% CI, 1.07 to 2.48; P =0.02), and platelet (OR, 2.5; 95% CI, 1.77 to 3.66; P <0.01) transfusions. Surgical outcomes and operative mortality (1.4% versus 1.4%; P =1.00) were not statistically different.

Conclusions— Clopidogrel administration in the cardiology suite increases the risk for hemostatic reoperation and the requirements for blood product transfusions during and after off-pump coronary artery bypass graft surgery.

Antiplatelet Therapy after Percutaneous Coronary Intervention

There is intense interest in the relationship between inflammation, thrombosis, platelet aggregation, and hyperlipidemia in patients with coronary artery disease. The specific role of inflammation with its linkage to the coagulation cascade has been well studied. A number of inflammatory markers have been identified which can be used for risk stratification in patients with acute coronary syndromes. Patients with acute coronary syndromes at the time of presentation often have an underlying inflammatory state which needs therapy with antiplatelet regimens including now increasingly frequently clopidogrel in addition to the standard of aspirin. In those patients who are treated medically for their acute coronary syndromes, long-term treatment with dual antiplatelet therapy has been documented to be associated with improved outcome. In patients who undergo an invasive approach with placement of intracoronary stents, the importance of dual antiplatelet therapy is increased. Drug-eluting stents are now used in approximately 90% of all interventional procedures. There is evidence to suggest that while these patients have improved outcome in terms of a decreased need for subsequent procedures to treat restenosis, there is the potential for late subacute stent thrombosis. When late subacute stent thrombosis occurs, it results in mortality or infarction in 40-60% of patients. Dual antiplatelet therapy is therefore recommended for an increasingly longer time in this patient group. At the present time, protocols indicate 3 months for one of the drug-eluting stents and 6 months for the other. However, increasingly longer antiplatelet therapy is being used clinically. Assessment of platelet function during follow-up is as yet early. There are issues about which specific test to use and the definition of platelet hyperreactivity. In the future, more individually targeted therapy may be possible if we can more adequately assess the degree of hyperreactivity and underlying inflammation.

Day case transradial coronary angioplasty: A four-year single-center experience

We examined the safety and feasibility of elective outpatient transradial coronary angioplasty (PCI). Four hundred and forty two patients underwent procedures over a 4-year period. Over 95% had an excellent angiographic result and 85% were discharged the same day. Radial access was successful in 417 (94%) patients. There were no major vascular complications. One patient died of a subacute stent thrombosis. Outpatient transradial PCI is safe and feasible for the majority of elective PCI cases.

Addition of clopidogrel to aspirin in 45,852 patients with acute myocardial infarction: randomised placebo-controlled trial

BACKGROUND

Despite improvements in the emergency treatment of myocardial infarction (MI), early mortality and morbidity remain high. The antiplatelet agent clopidogrel adds to the benefit of aspirin in acute coronary syndromes without ST-segment elevation, but its effects in patients with ST-elevation MI were unclear.

METHODS

45,852 patients admitted to 1250 hospitals within 24 h of suspected acute MI onset were randomly allocated clopidogrel 75 mg daily (n=22,961) or matching placebo (n=22,891) in addition to aspirin 162 mg daily. 93% had ST-segment elevation or bundle branch block, and 7% had ST-segment depression. Treatment was to continue until discharge or up to 4 weeks in hospital (mean 15 days in survivors) and 93% of patients completed it. The two prespecified co-primary outcomes were: (1) the composite of death, reinfarction, or stroke; and (2) death from any cause during the scheduled treatment period. Comparisons were by intention to treat, and used the log-rank method. This trial is registered with ClinicalTrials.gov, number NCT00222573.

FINDINGS

Allocation to clopidogrel produced a highly significant 9% (95% CI 3-14) proportional reduction in death, reinfarction, or stroke (2121 [9.2%] clopidogrel vs 2310 [10.1%] placebo; p=0.002), corresponding to nine (SE 3) fewer events per 1000 patients treated for about 2 weeks. There was also a significant 7% (1-13) proportional reduction in any death (1726 [7.5%] vs 1845 [8.1%]; p=0.03). These effects on death, reinfarction, and stroke seemed consistent across a wide range of patients and independent of other treatments being used. Considering all fatal, transfused, or cerebral bleeds together, no significant excess risk was noted with clopidogrel, either overall (134 [0.58%] vs 125 [0.55%]; p=0.59), or in patients aged older than 70 years or in those given fibrinolytic therapy.

INTERPRETATION

In a wide range of patients with acute MI, adding clopidogrel 75 mg daily to aspirin and other standard treatments (such as fibrinolytic therapy) safely reduces mortality and major vascular events in hospital, and should be considered routinely.

Percutaneous coronary interventions for coronary artery disease: the long and short of optimizing medical therapy

Atherosclerosis is a dynamic process and timely introduction of pharmacological treatment can have a significant bearing on the patient's health and outcome. In addition to treating the culprit lesion mechanically, admission for percutaneous coronary interventions (PCI) for coronary artery disease (CAD) gives an opportunity for the interventional cardiologist to optimize medical therapy. The aim of this review is to provide an overview of the current medical literature pertaining to cardiovascular (CV) risk reduction and vascular event prevention in the setting of PCI, with emphasis on antiplatelet therapies, beta-blockers, HMG-Co A reductase inhibitors (statins) and angiotensin-converting enzyme inhibitors, with regard to therapy optimization during PCI and for chronic CAD. We discuss the effects of these oral therapies in reducing ischaemic events, thus augmenting the benefits of PCI, as well as preventing recurrent CV events after the procedure.

Heparin in interventional radiology: a therapy in evolution

Interventional radiology techniques made possible by the antithrombotic properties of heparin have revolutionized treatment for a myriad of disorders. Newer low-molecular-weight heparins (LMWHs) offer several advantages over unfractionated heparin (UFH), especially in chronic settings. They are increasing in popularity for use during vascular procedures. However, LMWH shares limitations with UFH such as heterogeneity, nonspecificity, and induction of thrombocytopenia. These drawbacks have led to a search for the next generation of antithrombotic agents. Homogeneous drugs targeting specific coagulation cascade molecules are now available. The number of alternative anticoagulant drug combinations presents clinicians with a confusing array of choices. The strengths and weaknesses of UFH, LMWH, and direct antithrombin agents are presented. The promising future of LMWH and hirudins is discussed.

Bisphosphonates as anti-inflammatory agents in ankylosing spondylitis and spondylarthropathies

NSAIDs remain the cornerstone of the treatment of ankylosing spondylitis (AS) and spondylarthropathies (SpA), and have been successfully used for a long time in these diseases. However, some patients remain refractory or intolerant to NSAIDs and new effective treatments have recently emerged, namely TNF-alpha-blocker agents. Other therapeutic options targeting the bone, such as bisphosphonates, have also been tried in refractory AS or SpA patients. The anti-inflammatory properties of bisphosphonates give the rationale for the use of these compounds in AS and SpA, and include the inhibition of antigen presenting cells, the modulation of pro-inflammatory cytokine generation, and also a decreased bone mass in AS. Open trials using pamidronate gave favourable results, and one controlled study comparing the efficacy of pamidronate 10 versus 60mg showed that the 60mg dose was effective in AS. Further studies are required to confirm these preliminary data and to better determine the optimal regimen (dosage and rhythm) of administration.

Guidelines for percutaneous coronary interventions. The Task Force for Percutaneous Coronary Interventions of the European Society of Cardiology

In patients with stable CAD, PCI can be considered a valuable initial mode of revascularization in all patients with objective large ischaemia in the presence of almost every lesion subset, with only one exception: chronic total occlusions that cannot be crossed. In early studies, there was a small survival advantage with CABG surgery compared with PCI without stenting. The addition of stents and newer adjunctive medications improved the outcome for PCI. The decision to recommend PCI or CABG surgery will be guided by technical improvements in cardiology or surgery, local expertise, and patients' preference. However, until proved otherwise, PCI should be used only with reservation in diabetics with multi-vessel disease and in patients with unprotected left main stenosis. The use of drug-eluting stents might change this situation. Patients presenting with NSTE-ACS (UA or NSTEMI) have to be stratified first for their risk of acute thrombotic complications. A clear benefit from early angiography (<48 h) and, when needed, PCI or CABG surgery has been reported only in the high-risk groups. Deferral of intervention does not improve outcome. Routine stenting is recommended on the basis of the predictability of the result and its immediate safety. In patients with STEMI, primary PCI should be the treatment of choice in patients presenting in a hospital with PCI facility and an experienced team. Patients with contra-indications to thrombolysis should be immediately transferred for primary PCI, because this might be their only chance for quickly opening the coronary artery. In cardiogenic shock, emergency PCI for complete revascularization may be life-saving and should be considered at an early stage. Compared with thrombolysis, randomized trials that transferred the patients for primary PCI to a 'heart attack centre' observed a better clinical outcome, despite transport times leading to a significantly longer delay between randomization and start of the treatment. The superiority of primary PCI over thrombolysis seems to be especially clinically relevant for the time interval between 3 and 12 h after onset of chest pain or other symptoms on the basis of its superior preservation of myocardium. Furthermore, with increasing time to presentation, major-adverse-cardiac-event rates increase after thrombolysis, but appear to remain relatively stable after primary PCI. Within the first 3 h after onset of chest pain or other symptoms, both reperfusion strategies seem equally effective in reducing infarct size and mortality. Therefore, thrombolysis is still a viable alternative to primary PCI, if it can be delivered within 3 h after onset of chest pain or other symptoms. Primary PCI compared with thrombolysis significantly reduced stroke. Overall, we prefer primary PCI over thrombolysis in the first 3 h of chest pain to prevent stroke, and in patients presenting 3-12 h after the onset of chest pain, to salvage myocardium and also to prevent stroke. At the moment, there is no evidence to recommend facilitated PCI. Rescue PCI is recommended, if thrombolysis failed within 45-60 min after starting the administration. After successful thrombolysis, the use of routine coronary angiography within 24 h and PCI, if applicable, is recommended even in asymptomatic patients without demonstrable ischaemia to improve patients' outcome. If a PCI centre is not available within 24 h, patients who have received successful thrombolysis with evidence of spontaneous or inducible ischaemia before discharge should be referred to coronary angiography and revascularized accordingly--independent of 'maximal' medical therapy.

Clopidogrel administration prior to coronary artery bypass grafting surgery: the cardiologist's panacea or the surgeon's headache?

AIMS

Thrombotic complications after percutaneous coronary intervention procedures have decreased in past years mainly due to the use of clopidogrel antiplatelet therapy. However, the risk of bleeding due to enhanced and irreversible platelet inhibition in patients who will require surgical coronary revascularization instead has not been adequately addressed in the literature. The purpose of this study was to evaluate the effect of pre-operative clopidrogel exposure in haemorrhage-related re-exploration rates, peri-operative transfusion requirements, morbidity, and mortality in patients undergoing coronary artery bypass grafting (CABG) surgery.

METHODS AND RESULTS

A study population of 2359 patients undergoing isolated CABG between January 2000 and June 2002 was reviewed. Of these, 415 (17.6%) received clopidogrel prior to CABG surgery, and 1944 (82.4%) did not. A risk-adjusted logistic regression analysis was used to assess the association between clopidogrel pre-medication (vs. no) and haemostatic re-operation, intraoperative and post-operative blood transfusion rates, and multiple transfusions received. Haemorrhage-related pre-operative risk factors identified from the literature and those found significant in a univariate model were used. Furthermore, a sub-cohort, matched-pair by propensity scores analysis, was also conducted. The clopidogrel group had a higher likelihood of haemostatic re-operation [OR = 4.9, (95% CI, 2.63-8.97), P < 0.01], an increase in total packed red blood cell transfusions [OR = 2.2, (95% CI, 1.70-2.84), P < 0.01], multiple unit blood transfusions [OR = 1.9, (95% CI, 1.33-2.75), P < 0.01] and platelet transfusions [OR = 2.6, (95% CI, 1.95-3.56), P < 0.01]. Surgical outcomes and operative mortality [OR = 1.5, (95% CI, 0.36-6.51), P = 0.56] were not significantly different.

CONCLUSION

Pre-operative clopidogrel exposure increases the risk of haemostatic re-operation and the requirements for blood and blood product transfusion during, and after, CABG surgery.

Anticoagulant and antiplatelet agents: their clinical and device application(s) together with usages to engineer surfaces

An essential aspect of the treatment of patients with cardiovascular disease is the use of anticoagulant and antiplatelet agents for the prevention of further ischaemic events and vascular death resulting from thrombosis. Aspirin and heparin have been the standard therapy for the management of such conditions to date. Recently, numerous more potent platelet inhibitors together with anticoagulant agents have been developed and tested in randomized clinical trials. This article reviews the current state of the art of antiplatelet and anticoagulant therapy in light of its potential clinical efficacy. It then focuses on the usages of these agents in order to improve the performance of clinical devices such as balloon catheters, coronary stents, and femoropopliteal bypass grafting and extra corporeal circuits for cardiopulmonary bypass. The article then goes on to look at the usage of these agents more specifically heparin, heparan, hirudin, and coumarin in the development of more biocompatible scaffolds for tissue engineering.

Antiplatelet Agents: Current Drugs and Future Trends

Antiplatelet drugs in clinical use are discussed in terms of their mechanisms of action and the relevancy of that to the physiology of platelets and the pathophysiology of arterial thrombosis. Current clinical usage is outlined in detail for each drug. Experimental antiplatelet drugs also are discussed.

Lipophilicity-related inhibition of blood platelet aggregation by nipecotic acid anilides

Using N-[4-(hexyloxy)phenyl]piperidine-3-carboxamide (17c) as a structural lead, a number of isomers, derivatives, and ring-opened analogs were synthesized and tested for their ability to block the in vitro aggregation of human platelets induced by adenosine 5'-diphosphate (ADP). For the most active compounds, inhibition of the platelet aggregation triggered by arachidonic acid (AA) and ADP-induced intraplatelet calcium mobilization was also demonstrated. Based on quantitative structure-activity relationships (QSARs), we proved the impact of hydrophobicity on antiplatelet activity by a nonlinear (parabolic or bilinear) relationship between pIC(50) and lipophilicity, as assessed by RP-HPLC capacity factors and ClogP (i.e. calculated 1-octanol-water partition coefficients). This study highlighted the following additional SARs: quasi-isolipophilic isomers of 17c (isonipecotanilides and pipecolinanilides) and ring-opened analogs (e.g. anilide of beta-alanine) exhibited lower antiplatelet activity; methylation of the piperidine nitrogen of 17c has no effect, whereas alkylation with an n-propyl group decreases the activity by a factor of approximately 2, most likely due to a conformation-dependent decrease in lipophilicity.

Antiplatelet agents in patients undergoing percutaneous coronary intervention: how many and how much?

Antiplatelet agents play a major role in patients undergoing percutaneous coronary intervention (PCI). Stent thrombosis and the demand for improved clinical outcomes have driven the need for aggressive antiplatelet and anticoagulant regimens and newer, more efficacious, therapies. The benefits of intravenous glycoprotein (GP) IIb/IIIa antagonists and clopidogrel in high-risk patients undergoing PCI appear complementary. In low- to intermediate-risk patients, clopidogrel pre-treatment and a maintenance dose of aspirin + clopidogrel for at least 1 year after PCI are supported by the data, although the optimal duration of clopidogrel treatment beyond 1 year remains hotly contested. The next generation of clinical trials will examine the benefits of antiplatelet and antithrombotic agents as adjunctive therapy with drug-eluting stents. A better understanding of our patients' overall risk will add to procedural success and more durable outcomes.

Cilostazol, clopidogrel or ticlopidine to prevent sub-acute stent thrombosis: a meta-analysis of randomized trials

BACKGROUND

Sub-acute thrombosis is a serious complication of coronary artery stenting. Clopidogrel plus aspirin is the accepted prophylactic regimen, but has yet to be proven superior to ticlopidine plus aspirin, and a new regimen combining cilostazol and aspirin has been introduced.

METHODS

We conducted a meta-analysis of all trials that compared >or=2 oral anti-thrombotic strategies in patients undergoing coronary stent placement to determine which treatment optimally prevents adverse cardiac events in the 30 days following stent insertion. We used meta-regression to compare all strategies to a shared control strategy: ticlopidine plus aspirin. We also compared randomized trials to historically controlled and other non-randomized trials. We conducted sensitivity analysis and subgroup analysis to assess for possible heterogeneity.

RESULTS

In comparison to ticlopidine plus aspirin the odds-ratios for cardiac events, with 95% confidence intervals were: aspirin alone, 4.29 (3.09-5.97), coumadin plus aspirin, 2.65 (2.18-3.21), clopidogrel plus aspirin, 1.06 (0.86-1.31), cilostazol plus aspirin, 0.73 (0.47-1.14). Among trials that compared clopidogrel plus aspirin to ticlopidine plus aspirin, historically controlled trials were statistically distinct from randomized trials. The analysis of cilostazol was sensitive to the small size of the included studies.

CONCLUSIONS

Neither clopidogrel plus aspirin nor cilostazol plus aspirin can be statistically distinguished from ticlopidine plus aspirin for the prevention of adverse cardiac events in the 30 days after stenting. A randomized trial including cilostazol is warranted.

Does Clopidogrel Increase Blood Loss Following Coronary Artery Bypass Surgery?

BACKGROUND

Clopidogrel (Plavix) is a potent inhibitor of platelet aggregation used concomitantly with percutaneous coronary interventions and in patients with acute coronary syndromes. Its favorable effects on preventing thrombus formation may have deleterious effects on hemostasis in patients undergoing coronary surgery.

METHODS

Data were collected prospectively on 312 consecutive urgent or emergent coronary artery bypass patients from July 1999 through April 2001 at a tertiary care center. Patients were stratified into three groups: clopidogrel within 4 days of operation (n = 41), clopidogrel continued until 5 to 8 days before operation (n = 39), and clopidogrel discontinued more than 8 days before operation or were never taking clopidogrel (n = 232).

RESULTS

Preoperative and intraoperative characteristics were similar among all groups. Mediastinal and pericardial chest tube losses in the first 24 hours were 1,044 +/- 750 mL in the clopidogrel within 4 days group, 528 +/- 250 mL in the clopidogrel 5 to 8 days group, and 573 +/- 329 mL in the clopidogrel more than 8 days group (p < 0.01). The mean total blood product transfusions were 12.2 +/- 15.4 U, 1.2 +/- 2.0 U, and 2.6 +/- 5.7 U, respectively (p < 0.001). Reoperation for bleeding was noted in 14.6%, 2.6%, and 1.7%, respectively (p = 0.002). The median hospital lengths of stay for the three groups were 9 days, 7 days, and 7 days, respectively (p = 0.018). There were no statistically significant differences in mortality rate, myocardial infarction, stroke, mediastinitis, or postoperative renal failure among the groups. Multivariable analysis revealed that clopidogrel within 0 to 4 days of operation was an independent predictor of transfusion requirements (OR 4.22, 95% confidence interval [CI] 2.07, 9.34, p = 0.001), intensive care unit (ICU) length of stay (OR 3.14, 95% CI 1.40, 7.04, p = 0.006), and total hospital length of stay (coefficient 7.65, se 2.41, p = 0.002).

CONCLUSIONS

Clopidogrel within 4 days of coronary bypass surgery is associated with increased blood losses and reoperation for bleeding and, according to multivariable models, is an independent risk factor for increased transfusion requirements and prolonged ICU and hospital length of stay.

Antithrombotic therapy during percutaneous coronary intervention: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This chapter about antithrombotic therapy during percutaneous coronary intervention (PCI) is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading, see Guyatt et al, CHEST 2004;126:179S-187S). Among the key recommendations in this chapter are the following: For patients undergoing PCI, we recommend pretreatment with aspirin, 75 to 325 mg (Grade 1A). For long-term treatment after PCI, we recommend aspirin, 75 to 162 mg/d (Grade 1A). For long-term treatment after PCI in patients who receive antithrombotic agents such as clopidogrel or warfarin, we recommend lower-dose aspirin, 75 to 100 mg/d (Grade 1C+). For patients who undergo stent placement, we recommend the combination of aspirin and a thienopyridine derivative (ticlopidine or clopidogrel) over systemic anticoagulation therapy (Grade 1A). We recommend clopidogrel over ticlopidine (Grade 1A). For all patients undergoing PCI, particularly those undergoing primary PCI, or those with refractory unstable angina or other high-risk features, we recommend use of a glycoprotein (GP) IIb-IIIa antagonist (abciximab or eptifibatide) [Grade 1A]. In patients undergoing PCI for ST-segment elevation MI, we recommend abciximab over eptifibatide (Grade 1B). In patients undergoing PCI, we recommend against the use of tirofiban as an alternative to abciximab (Grade 1A). In patients after uncomplicated PCI, we recommend against routine postprocedural infusion of heparin (Grade 1A). For patients undergoing PCI who are not treated with a GP IIb-IIIa antagonist, we recommend bivalirudin over heparin during PCI (Grade 1A). In PCI patients who are at low risk for complications, we recommend bivalirudin as an alternative to heparin as an adjunct to GP IIb-IIIa antagonists (Grade 1B). In PCI patients who are at high risk for bleeding, we recommend that bivalirudin over heparin as an adjunct to GP IIb-IIIa antagonists (Grade 1B). In patients who undergo PCI with no other indication for systemic anticoagulation therapy, we recommend against routine use of vitamin K antagonists after PCI (Grade 1A).

[Drug prescription in the post-percutaneous coronary interventions period: results of the ECART study]

Among 1000 French cardiologists, the ECART study investigated drug prescription in 1041 patients with coronary heart disease, before and after percutaneous coronary interventions. The baseline drug prescription rate CAD patients were the following: beta-blockers 96%, antiplatelets agents 85%, statines 56%, nitrates 36%, calcium blockers 26% and ACE inhibitors 8.7%. The main changes in patients having undergone PCI were: a significant increase in antiplatelets agents (to 97%), ACE inhibitors (to 29%) and statins (to 94%), a significant decrease in nitrates (to 23%). The calcium blockers rate remains unchanged at 26%. Those results are discussed in the field of evidence based medicine and are compared with data from previous drug prescription studies in post myocardial infarction or in secondary prevention.

Guidelines on the management of secondary prophylaxis of vascular events in stable patients in primary care

Atherothrombosis, thrombus formation superimposed on an existing atherosclerotic plaque, is an acute process leading to ischaemic events such as myocardial infarction, stroke and critical limb ischaemia. Patients presenting with clinical conditions associated with atherothrombosis are at increased risk of subsequent vascular events. The beneficial effect of antiplatelet therapies for short-term and long-term secondary prevention of atherothrombotic events has been established. These guidelines aim to provide evidence-based recommendations that will assist in the antiplatelet-mediated secondary prophylaxis of vascular events in patients with stable cardiovascular disease treated in the primary healthcare setting. Medline and the Cochrane library were accessed using free-text strategies in the domains of antiplatelet agents and antithrombotics. Development of the guidelines was driven by a series of Steering Committee meetings, in which the quality of relevant studies was assessed and identified using narrative summary. These guidelines present evidence and recommendations for the treatment of numerous atherothrombotic indications depending on individual patient circumstances.

The role of clopidogrel in the management of acute coronary syndromes

BACKGROUND

Despite significant advances in the management of coronary heart disease, myocardial infarction (MI) is still associated with a mortality rate of 45%. Acetylsalicylic acid (ASA) has been the oral antiplatelet drug of choice until recently. Thienopyridines such as clopidogrel have been shown to provide significant benefits in the management of acute coronary syndromes (ACS), either as an alternative to or in combination with ASA therapy.

OBJECTIVE

The purpose of this article was to review the available scientific literature evaluating the use of clopidogrel in the management of ACS.

METHODS

Relevant published data were identified through searches of the English-language literature indexed on MEDLINE and International Pharmaceutical Abstracts through April 2003. Search terms included thienopyridines, platelet aggregation inhibitors, clopidogrel, ticlopidine, acute coronary syndrome, myocardial infarction, and percutaneous coronary intervention. Pertinent conference abstracts were also included.

RESULTS

The results of 3 large clinical trials-Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE), Effect of Pretreatment with Clopidogrel and Aspirin Followed by Long-Term Therapy in Patients Undergoing Percutaneous Coronary Intervention (PCI-CURE), and Clopidogrel for the Reduction of Events During Observation (CREDO)-support prolonged use of clopidogrel (up to 12 months) in combination with ASA in patients with non-ST-segment elevation MI and patients undergoing a percutaneous coronary intervention (PCI). A significant increase in bleeding events was observed in the group that received clopidogrel plus ASA compared with ASA alone in the CURE (major bleeding, P = 0.001; minor bleeding, P < 0.001) and PCI-CURE (minor bleeding, P = 0.03) trials. Use of the combination of clopidogrel and ASA with other antiplatelet and/or anticoagulant agents has not been studied extensively.

CONCLUSIONS

Use of the combination of clopidogrel and ASA for up to 9 months is recommended for the medical management of non-ST-segment elevation MI and after a PCI. The increased risk of bleeding must be taken into account, and use of this combination with other agents that affect bleeding risk should be considered carefully.