Incremental effect of clopidogrel on important outcomes in patients with cardiovascular disease: a meta-analysis of randomized trials

Outcomes Associated with 50 mg/d and 100 mg/d Aspirin for the Prevention and Management of Cardiovascular Disease in Chinese Elderly: Single-Center Interim Analysis of a Multicenter, Prospective, Observational Study

Purpose

Although aspirin can effectively reduce the occurrence of atherothrombosis, it is significantly associated with increased bleeding, with elderly individuals being at increased risk of cardiovascular diseases (CVD) and hemorrhage. This study aims to evaluate the efficacy and safety of aspirin 50 mg/d and 100 mg/d for the prevention and management of CVD in Chinese elderly.

Patients and Methods

The Low-dose Aspirin for Primary and Secondary Prevention of Cardiovascular Disease in the Elderly Study (LAPIS) is a multicenter, prospective, observational cohort study, this study was a single-center interim analysis of LAPIS. Patients aged ≥60 and required long-term aspirin for primary and secondary prevention of CVD were eligible. From Apr 1, 2019 to Feb 28, 2022, 165 patients who received 50 mg/d aspirin and 261 patients who received 100 mg/d aspirin were included in the study. The incidence of major cardiovascular events (MACEs), bleeding events, and gastrointestinal adverse events were compared between two groups.

Results

After adjusting for patient characteristics using propensity score matching, aspirin 100 mg/d was associated with increased incidence rates of total bleeding events (28.34 vs.17.25 events/100 patient-years, HR 1.671, 95% CI 1.024–2.712, P = 0.040) and minor bleeding events (27.63 vs.15.92 events/100 patient-years, HR 1.738, 95% CI 1.056–2.861, P = 0.031), whereas the incidence of MACE (6.35 vs 6.65 events/100 patient-years, HR 0.921, 95% CI 0.399–2.127, P = 0.848) and gastrointestinal adverse events (12.73 vs.10.42 events/100 patient-years, HR 1.206, 95% CI 0.623–2.337, P = 0.578) were similar between the two groups. Multivariate Cox analysis identified that aspirin dose (100 mg/d vs. 50 mg/d, HR 1.918, 95% CI 1.137–3.235, P = 0.015), concomitant use of other antiplatelets (HR 1.748, 95% CI 1.009–3.028, P = 0.046) and anticoagulants (HR 2.501, 95% CI 1.287–4.862, P = 0.007) were independently associated with bleeding events.

Conclusion

50 mg/d aspirin may be preferred to balance the safety and effectiveness in Chinese individuals over 60 years of age who need long-term aspirin for the prevention and management of CVD.

Trial Registration

ChiCTR1900021980 (chictr.org.cn). Registered on 19 March 2019.

Impact of clopidogrel and potent P2Y12-inhibitors on mortality and stroke in patients with acute coronary syndrome or undergoing percutaneous coronary intervention

Administration of a P2Y12-receptor antagonist in addition to aspirin is mandatory in patients with acute coronary syndromes (ACS) or undergoing percutaneous coronary intervention (PCI) to reduce the occurrence of thrombotic events; however, their impact on mortality and stroke is unclear. We aimed to evaluate the influence of moderate (clopidogrel) or potent (prasugrel/ticagrelor) P2Y12-receptor inhibition on major cardiovascular outcomes among patients with ACS or undergoing PCI. Systematic literature search was performed to find randomised, controlled clinical trials comparing the clinical impact of clopidogrel with placebo or prasugrel/ticagrelor versus clopidogrel. Outcome measures included cardiovascular death, myocardial infarction (MI), total stroke and intracranial haemorrhage (ICH). Random-effects model with Mantel-Heanszel weighting was used to pool outcomes into a meta-analysis. Four studies comparing clopidogrel with placebo and five trials comparing clopidogrel with new P2Y12-receptor inhibitors were identified including a total of 107,473 patients. Compared to placebo, clopidogrel reduced the risk of cardiovascular death (odds ratio [OR]: 0.93; 95% confidence interval [CI]: 0.87–0.99, p=0.02), MI (OR 0.80; 95%CI 0.74–0.88, p<0.00001) and stroke (OR 0.84; 95%CI 0.72–0.97, p=0.02), without influencing risk for ICH (OR 0.96;& 95%CI 0.69–1.33, p=0.79). Treatment with prasugrel/ticagrelor provided additional benefit over clopidogrel regarding cardiovascular mortality (OR 0.86; 95%CI 0.78–0.94, p=0.002) and MI (OR: 0.83; 95%CI 0.74–0.93, p<0.001), but no advantage in stroke (OR: 1.06; 95%CI 0.88–1.26, p=0.55) and in ICH (OR: 1.16; 95%CI 0.75–1.81; p=0.49) was observed. Increased potency of P2Y12-receptor inhibition is associated with decreased risk in cardiovascular death and MI; however, this association is not true in case of stroke, where potent P2Y12-receptor antagonists have no incremental benefit over clopidogrel.

Pharmacogenomics and Global Precision Medicine in the Context of Adverse Drug Reactions: Top 10 Opportunities and Challenges for the Next Decade

In a move indicative of the enthusiastic support of precision medicine, the U.S. President Barack Obama announced the Precision Medicine Initiative in January 2015. The global precision medicine ecosystem is, thus, receiving generous support from the United States ($215 million), and numerous other governments have followed suit. In the context of precision medicine, drug treatment and prediction of its outcomes have been important for nearly six decades in the field of pharmacogenomics. The field offers an elegant solution for minimizing the effects and occurrence of adverse drug reactions (ADRs). The Clinical Pharmacogenetics Implementation Consortium (CPIC) plays an important role in this context, and it aims at specifically guiding the translation of clinically relevant and evidence-based pharmacogenomics research. In this forward-looking analysis, we make particular reference to several of the CPIC guidelines and their role in guiding the treatment of highly relevant diseases, namely cardiovascular disease, major depressive disorder, cancer, and human immunodeficiency virus, with a view to predicting and managing ADRs. In addition, we provide a list of the top 10 crosscutting opportunities and challenges facing the fields of precision medicine and pharmacogenomics, which have broad applicability independent of the drug class involved. Many of these opportunities and challenges pertain to infrastructure, study design, policy, and science culture in the early 21st century. Ultimately, rational pharmacogenomics study design and the acquisition of comprehensive phenotypic data that proportionately match the genomics data should be an imperative as we move forward toward global precision medicine.

Risk of Stroke in Patients with Stable Coronary Artery Disease Undergoing Percutaneous Coronary Intervention versus Optimal Medical Therapy: Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Stroke is a rare but serious adverse event associated with percutaneous coronary intervention (PCI). However, the relative risk of stroke between stable patients undergoing a direct PCI strategy and those undergoing an initial optimal medical therapy (OMT) strategy has not been established yet. This study sought to investigate if, in patients with stable coronary artery disease (SCAD), an initial strategy PCI is associated with a higher risk of stroke than a strategy based on OMT alone.

METHODS

We performed a meta-analysis of 6 contemporary randomized control trials in which 5673 patients with SCAD were randomized to initial PCI or OMT. Only trials with stent utilization more than 50% were included. Study endpoint was the rate of stroke during follow up.

RESULTS

Mean age of patients ranged from 60 to 65 years and stent utilization ranged from 72% to 100%. Rate of stroke was 2.0% at a weighted mean follow up of 55.3 months. On pooled analysis, the risk of stroke was similar between patients undergoing a PCI plus OMT and those receiving only OMT (2.2% vs. 1.8%, OR on fixed effect = 1.24 95%CI: 0.85-1.79). There was no heterogeneity among the studies (I2 = 0.0%, P = 0.15). On sensitivity analysis after removing each individual study the pooled effect estimate remains unchanged.

CONCLUSIONS

In patients with SCAD an initial strategy based on a direct PCI is not associated with an increased risk of stroke during long-term follow up compared to an initial strategy based on OMT alone.

Managing Residual Risk After Myocardial Infarction Among Individuals with Low Cholesterol Levels

About one-half of individuals with an acute myocardial infarction have a low-density lipoprotein cholesterol level of less than 100 mg/dL at the time of occurrence, but remain at risk for recurrent events. This residual risk is likely mediated by multiple factors, including burden of atherosclerosis, residual dyslipidemia, nonlipid risk factors, and suboptimal implementation of lifestyle therapy and evidence-based pharmacologic therapy. This article reviews management options for this high-risk population.

Risk of stroke in patients with high on-clopidogrel platelet reactivity to adenosine diphosphate after percutaneous coronary intervention

Several prospective studies have shown that high on-clopidogrel platelet reactivity (HPR) in patients undergoing percutaneous coronary intervention (PCI) is a risk factor for ischemic events. All studies were insufficiently powered to detect differences in stroke between patients with HPR and those without. Therefore, we performed a systematic review and meta-analysis of available publications aimed at determining whether patients undergoing PCI with HPR are also at increased risk of stroke. We searched for prospective studies enrolling patients undergoing PCI and treated with aspirin and clopidogrel that reported on clinical relevance of HPR to adenosine diphosphate. Study end point was the rate of stroke. We also investigated whether there was an interaction on the relative risk of stroke between HPR, clinical presentation, duration of follow-up, or laboratory methods. Fourteen studies including 11,959 patients were deemed eligible. On pooled analysis, the risk of stroke was higher in patients with HPR compared with patients with no HPR (1.2% vs 0.7%, relative risk on fixed effect 1.84, 95% confidence interval 1.21 to 2.80). There was no heterogeneity among the studies (I(2) = 0%, p = 0.5). Clinical presentation (p = 0.39 for interaction), duration of follow-up (p = 0.87 for interaction), and laboratory method for detection of HPR (p = 0.99 for interaction) did not affect the relative increase in the risk of stroke in patients with HPR compared with patients with no HPR. In conclusion, in patients with coronary artery disease undergoing PCI, the presence of HPR to adenosine diphosphate is a risk factor for stroke.

Challenges and limitations in the interpretation of systematic reviews: making sense of clopidogrel and CYP2C19 pharmacogenetics

From 2010 to 2012, nine systematic reviews reported highly variable conclusions regarding the association between carriage of a cytochrome P450 2C19 loss-of-function allele and the risk of adverse cardiovascular (CV) events in individuals using clopidogrel. Possible contributors to the variable findings include differences in patient populations, CV end points, and statistical models utilized by the systematic reviews, as well as unexplained heterogeneity, inconsistent/incomplete reporting, and risk of publication bias with respect to the primary studies.

Evaluating the clinical usefulness of platelet function testing: considerations for the proper application and interpretation of performance measures

Various diagnostic and prognostic performance measures have been used to describe the clinical usefulness of platelet function testing in the evaluation and management of patients taking P2Y12 inhibitors, which reduce the risk for thrombosis due to their action on the platelet P2Y12 receptor. Platelet function tests are used to confirm the presence of an antiplatelet effect of a P2Y12 inhibitor, and confirmation that the pharmacodynamic effect is associated with a reduction in the rate of thrombosis. Despite this clear association, enthusiasm for the clinical usefulness of platelet function testing has been tempered based on observed sensitivity, specificity, and positive predictive value for the detection of future thrombotic events. However, evaluating the prognostic utility of a test based on diagnostic performance indicators is not appropriate because prognostic tests are not used to diagnose which patients will have events; instead, they are used to assist in risk stratification. Therefore, when evaluating the usefulness of platelet function testing, diagnostic performance measures such as sensitivity, specificity, and predictive values should focus on diagnostic performance in identifying a pharmacodynamic effect, and prognostic performance should be evaluated using prognostic performance measures such as hazard ratios and net reclassification improvement, which are comparable to other well-established risk factors for cardiovascular events.

Importance of potent P2Y(12) receptor blockade in acute myocardial infarction: focus on prasugrel

INTRODUCTION

Prasugrel therapy is recommended in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI).

AREAS COVERED

This article reviews the efficacy and safety profile of prasugrel, cost considerations, and its role in clinical practice based on published data. The authors searched PubMed and Ovid databases for English language clinical trial articles involving the use of prasugrel in human subjects and patients, published through June 2012. The keyword "prasugrel" was used. The review focuses on clinical trials, but other articles including Food and Drug Administration documents are also reviewed.

EXPERT OPINION

Prasugrel has a more rapid and greater pharmacodynamic (PD) effect than clopidogrel. No significant drug - drug interactions have been reported. In a large-scale randomized clinical trial, prasugrel was associated with better protection against ischemic event occurrence compared to clopidogrel, but more bleeding in ACS patients undergoing PCI. Adverse outcomes outweighed the benefit of prasugrel in certain subgroups, including patients over the age of 75, those weighing less than 60 kg, and patients with a prior history of stroke or transient ischemic attack. In subsequent PD studies, prasugrel therapy showed suboptimal platelet inhibition in selected patients. In addition, "hyper-responsiveness" to prasugrel may increase the risk of serious bleeding in high-risk patients. More detailed studies are warranted to explore antiplatelet regimens tailored to optimally limit ischemic and bleeding event occurrences. A Phase-III TRILOGY trial (NCT00699998) will indicate the clinical efficacy and safety of prasugrel in patients with non-ST-segment elevation ACS, who are medically managed without coronary revascularization.

Translational platelet research in patients with coronary artery disease: what are the major knowledge gaps?

Translational platelet function investigations performed in the percutaneous coronary intervention (PCI)-treated population receiving clopidogrel have identified high platelet reactivity to ADP (HPR) as a major risk factor for both acute as well as long-term ischaemic event occurrence, including stent thrombosis. Recent studies have highlighted the relation of single nucleotide polymorphisms of genes involved in clopidogrel absorption and metabolism to reduced pharmacokinetic and pharmacodynamic responses to clopidogrel. CYP 2C19 loss-of-function (LoF) allele carriage has been associated with increased thrombotic risk in the PCI population. However, there is no information regarding the utility of platelet function testing to predict outcomes in patients with stable coronary artery disease and in medically managed patients with acute coronary syndromes. Additionally, few studies have included longitudinal assessment of platelet function to assess a potential time-dependent relation to ischaemic event occurrence and no phase-III antiplatelet-therapy trial has included a large enough platelet function sub-study to examine the relation between on-treatment platelet reactivity, bleeding, and ischaemic event occurrence. Therefore, futher studies are needed to delineate the role of platelet function testing across the spectrum of symptomatic coronary artery disease.

Platelet function measurement-based strategy to reduce bleeding and waiting time in clopidogrel-treated patients undergoing coronary artery bypass graft surgery: the timing based on platelet function strategy to reduce clopidogrel-associated bleeding related to CABG (TARGET-CABG) study

BACKGROUND

Aspirin and clopidogrel therapy is associated with a variable bleeding risk in patients undergoing coronary artery bypass graft surgery (CABG). We evaluated the role of platelet function testing in clopidogrel-treated patients undergoing CABG.

METHODS AND RESULTS

One hundred eighty patients on background aspirin with/without clopidogrel therapy undergoing elective first time isolated on-pump CABG were enrolled in a prospective single-center, nonrandomized, unblinded investigation (Timing Based on Platelet Function Strategy to Reduce Clopidogrel-Associated Bleeding Related to CABG [TARGET-CABG] study) between September 2008 and January 2011. Clopidogrel responsiveness (ADP-induced platelet-fibrin clot strength [MA(ADP)]) was determined by thrombelastography; CABG was done within 1 day, 3-5 days, and >5 days in patients with an MA(ADP) >50 mm, 35-50 mm, and <35 mm, respectively. The primary end point was 24-hour chest tube drainage and key secondary end point was total number of transfused red blood cells. Equivalence was defined as ≤25% difference between groups. ANCOVA was used to adjust for confounders. Mean 24-hour chest tube drainage in clopidogrel-treated patients was 93% (95% confidence interval, 81-107%) of the amount observed in clopidogrel-naive patients, and the total amount of red blood cells transfused did not differ between groups (1.80 U versus 2.08 U, respectively, P=0.540). The total waiting period in clopidogrel-treated patients was 233 days (mean, 2.7 days per patient).

CONCLUSIONS

A strategy based on preoperative platelet function testing to determine the timing of CABG in clopidogrel-treated patients was associated with the same amount of bleeding observed in clopidogrel-naive patients and ≈50% shorter waiting time than recommended in the current guidelines.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00857155.

Does Gender have an Influence on Platelet Function and the Efficacy of Oral Antiplatelet Therapy?

The underlying pathophysiology of ischemic complications during acute coronary syndrome involves thrombus generation at sites of plaque rupture and endothelial erosion, in which platelet activation and aggregation play major roles. This review discusses whether there are intrinsic differences in thrombogenicity between genders. In trials of acute coronary syndromes with dual antiplatelet therapy strategies, women tend to experience more ischemic events. Controversy exists surrounding the protective role of estrogens in the premenopausal woman. In vitro studies support the attenuation of platelet function by estrogen. Sufficient data support the presence of gender differences in thrombogenicity to promote further investigation in this area.

The evolution of antiplatelet therapy in cardiovascular disease

The platelet--an anucleate cell--is the bedrock of thrombosis, both physiologically and pathologically. Antagonism of the P2Y(12) receptor for ADP is one of several pathways inhibiting the activation and aggregation of platelets, thereby attenuating coronary thrombosis in response to spontaneous plaque rupture or percutaneous revascularization. The addition of clopidogrel to a background of aspirin therapy was a revolutionary change in the management of ischemic coronary syndromes. Despite this paradigm shift, clopidogrel has certain limitations, including variability in platelet inhibitory effect, which is associated with adverse thrombotic events. In the evolution of antiplatelet treatment strategies, two new P2Y(12) receptor antagonists--prasugrel and ticagrelor--have been added to the armamentarium in the past few years. Both of these drugs confer greater platelet inhibition than clopidogrel. Nevertheless, more-potent platelet inhibition comes with an increased risk of hemorrhagic complications. Cangrelor and elinogrel are novel P2Y(12) inhibitors that show potential in the periprocedural setting with their rapid onset and offset of activity. Successes in P2Y(12) inhibitory therapies have reduced use of glycoprotein IIb/IIIa inhibitors, which block the final pathway leading to platelet aggregation and thrombosis. Newer therapies aimed at various molecular factors are under clinical investigation. Pharmacodynamic platelet function assays and pharmacogenetic testing to individualize and optimize antiplatelet therapy may find their way into clinical use, although much more study is needed.

Paraoxonase-1 Q192R polymorphism and antiplatelet effects of clopidogrel in patients undergoing elective coronary stent placement

BACKGROUND

Recently published data indicate that the paraoxonase-1 (PON1) Q192R genotype-and not as previously shown activity of cytochrome P450 (CYP) 2C19-is the major determinant of metabolic bioactivation of clopidogrel and thereby variability of antiplatelet effect of clopidogrel. We sought to investigate whether the PON1 Q192R gene polymorphism affects platelet reactivity in patients undergoing elective coronary stent placement.

METHODS AND RESULTS

The study included 760 consecutive patients undergoing elective coronary stent placement after loading with clopidogrel 600 mg. Platelet function was assessed by adenosine diphosphate-induced (ADP 5 and 20 μmol/L) platelet aggregation and by flow-cytometric analysis of platelet surface protein expression before clopidogrel, at the time of coronary stent placement, and before discharge after coronary stent placement. PON1 Q192R genotype [NM_000446.5:c.575A>G single nucleotide polymorphism (rs662)] was analyzed by TaqMan polymerase chain reaction. Residual platelet aggregation (ADP 5 μmol/L) at predischarge was 8.0% (3.0% to 17.0%) [median (interquartile range)] in PON1 QQ192 patients (n=384), 8.0% (3.0% to 15.0%) in PON1 QR192 (n=304), and 11.0% (3.0% to 18.0%) in PON1 RR192 (n=72; P=0.603). By multivariable linear regression, residual platelet aggregation was not associated with PON1 QQ192/QR192 (partial η(2)<0.001, P=0.728) but with CYP2C19*2 loss-of-function allele (partial η(2)=0.045, P<0.001) as well as any CYP2C19*17 gain-of-function allele (partial η(2)=0.012, P=0.004). All other platelet assays also showed no significant association between PON1 Q192R genotype and antiplatelet effect of clopidogrel. The 1-year incidence of death and myocardial infarction did not differ between PON1 Q192R genotypes.

CONCLUSIONS

On-treatment platelet reactivity in patients undergoing coronary stent placement after loading with clopidogrel 600 mg was not associated with PON1 Q192R genotype.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00457236.

Antiplatelet combinations for prevention of atherothrombotic events

Antiplatelet therapy plays a fundamental role in reducing atherothrombotic events by several pathways. The present work reviews available evidence on antiplatelet therapy both for primary prevention and in the presence of established peripheral, cerebral, or cardiac ischemic disease. Due to the importance of adherence to therapy to achieve optimal effects, special attention is given to the use of fixed-dose oral formulations in the clinical subset of patients in whom double antiplatelet therapy has proven indications.

Interaction between clopidogrel and proton-pump inhibitors and management strategies in patients with cardiovascular diseases

Dual antiplatelet therapy (DAPT) with clopidogrel and aspirin has been successful in reducing ischemic events in a wide range of patients with cardiovascular diseases. However, the anti-ischemic effects of DAPT may also be associated with gastrointestinal (GI) complications including ulceration and bleeding particularly in ‘high risk’ and elderly patients. Current guidelines recommend the use of proton-pump inhibitors (PPIs) to reduce the risk of GI bleeding in patients treated with DAPT. However, pharmacodynamic studies suggest an effect of PPIs on clopidogrel metabolism with a resultant reduction in platelet inhibitory effects. Similarly, several observational studies have demonstrated reduced clopidogrel benefit in patients who coadministered PPIs. Although recent US Food and Drug Administration and European Medicines Agency statements discourage PPI (particularly omeprazole) and clopidogrel coadministration, the 2009 AHA/ACC/SCAI PCI guidelines do not support a change in current practice in the absence of adequately powered prospective randomized clinical trial data. The data regarding pharmacologic and clinical interactions between PPI and clopidogrel therapies are herein examined and treatment strategies are provided.

Genetic testing for CYP450 polymorphisms to predict response to clopidogrel: current evidence and test availability. Application: pharmacogenomics

The anti-platelet agent clopidogrel bisulfate (sold under the trade name Plavix in the United States) is a widely prescribed medication for the prevention of blood clots in patients with acute coronary syndrome, in those who have suffered other cardiovascular disease-related events such as ischemic stroke, and in patients who are undergoing percutaneous coronary intervention. Response to clopidogrel varies substantially due to genetic and acquired factors. Patients who experience recurrent cardiovascular ischemic or thrombotic events while taking clopidogrel are typically described as non-responsive or resistant.

The drug's oxidation is mainly dependent on the cytochrome P450 enzyme 2C19 (CYP2C19). Patients with certain genetic variants in CYP2C19 have been found to have lower levels of the active metabolite, less platelet inhibition, and greater risk of major adverse cardiovascular events such as heart attack, stroke, and death. Testing for CYP2C19 polymorphisms may identify patients who will not respond adequately to the standard clopidogrel regimen and who should, consequently, be given an alternate treatment strategy. This article outlines the evidence concerning pharmacogenetic testing for clopidogrel response, including data on clinical validity and clinical utility, and summarizes the currently available tests marketed for this purpose.

Patient characteristics associated with the choice of triple antithrombotic therapy in acute coronary syndromes

Evidence regarding the use of dual antiplatelet therapy and oral anticoagulation (i.e., triple therapy) in acute coronary syndromes (ACS) is limited. We evaluated the characteristics associated with the choice of triple therapy in ACS. Using the Get With The Guidelines (GWTG) Coronary Artery Disease national registry, we studied patients with ACS at 361 sites in the United States from 2004 to 2007. Both univariate analysis and multivariate logistic regression analysis were used to assess the factors associated using triple therapy on discharge. The Generalized Estimating Equation method was used to account for within-hospital clustering in modeling. A total of 86,304 patients presented with ACS during the study period. At discharge, 3,933 patients (4.6%) were prescribed triple therapy, 60,716 patients (70.4%) received dual antiplatelet therapy, 2,348 patients (2.7%) received single antiplatelet therapy plus oral anticoagulation, 19,065 patients (22.1%) received antiplatelet monotherapy, and 242 patients (0.3%) received oral anticoagulation alone. Patients with a history of atrial fibrillation (odds ratio 7.01, 95% confidence interval 6.06 to 8.12; p <0.001), documented new-onset atrial fibrillation (odds ratio 3.76, 95% confidence interval 2.87 to 4.93; p <0.001), or history of atrial flutter (odds ratio 3.38, 95% confidence interval 2.15 to 5.32; p <0.001) were more frequently discharged with triple therapy. In conclusion, for patients with ACS, atrial fibrillation and atrial flutter were most strongly associated with the use of triple therapy; however, this therapy was used less often than dual or single antiplatelet therapy.

Expanding the recognition and assessment of bleeding events associated with antiplatelet therapy in primary care

Antiplatelet therapy is an evidence-based, guideline-recommended, worldwide standard of care for treatment of patients with atherothrombosis. However, clinical implementation of the guidelines is suboptimal, in part because of physician and patient nonadherence. The increased risk of bleeding associated with antiplatelet therapy is often the reason for nonadherence, and several programs have been created to increase adherence to guideline treatment recommendations. Despite the relative success of such initiatives, including Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines, Guidelines Applied in Practice, and the American Heart Association's Get With the Guidelines and a Science Advisory, a current estimate is that less than 50% of atherothrombotic patients are taking antiplatelet therapies as recommended by national guidelines. A PubMed and MEDLINE search of the literature (January 1, 1983-May 15, 2008) was performed to examine the bleeding risks associated with various antiplatelet therapies. Relevant clinical trials, observational registry data, and other studies relevant to treatment and guideline recommendations were selected from articles generated through specific search terms. This comprehensive review contributes to the understanding of the benefit-to-risk ratio of antiplatelet therapy for patients with atherothrombosis.

Expanding the recognition and assessment of bleeding events associated with antiplatelet therapy in primary care

Antiplatelet therapy is an evidence-based, guideline-recommended, worldwide standard of care for treatment of patients with atherothrombosis. However, clinical implementation of the guidelines is suboptimal, in part because of physician and patient nonadherence. The increased risk of bleeding associated with antiplatelet therapy is often the reason for nonadherence, and several programs have been created to increase adherence to guideline treatment recommendations. Despite the relative success of such initiatives, including Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines, Guidelines Applied in Practice, and the American Heart Association's Get With the Guidelines and a Science Advisory, a current estimate is that less than 50% of atherothrombotic patients are taking antiplatelet therapies as recommended by national guidelines. A PubMed and MEDLINE search of the literature (January 1, 1983-May 15, 2008) was performed to examine the bleeding risks associated with various antiplatelet therapies. Relevant clinical trials, observational registry data, and other studies relevant to treatment and guideline recommendations were selected from articles generated through specific search terms. This comprehensive review contributes to the understanding of the benefit-to-risk ratio of antiplatelet therapy for patients with atherothrombosis.

Use of antiplatelet agents for prevention of ischemic stroke

Overall management to lower risk for ischemic stroke is multifaceted. Management includes measures to treat risk factors for accelerated atherosclerosis and stroke, antithrombotic therapies to lower the risk for thromboembolism, and surgery to treat a defined arterial or cardiac lesion. Treatment decisions are made on a case-by-case basis, with most patients receiving some combination of medication and recommendations for lifestyle modification. Some patients will also undergo surgical or endovascular interventions. This article discusses antithrombotic treatment for ischemic stroke prevention, placing major emphasis on the indications for and administration of antiplatelet therapy.

Clopidogrel and coronary stents: risks and benefits

Clopidogrel has become increasingly important in the management of patients with coronary stents. Clopidogrel is an oral agent that acts on the adeno-sine diphosphate receptor to irreversibly inhibit platelet aggregation. Along with aspirin, clopidogrel has a significant role in the treatment of atherothrombotic diseases. Recent concerns about late stent thrombosis highlight the need for long-term therapy with clopidogrel in addition to aspirin in these populations. This article reviews the role of clopidogrel in the treatment of atherothrombotic diseases and after coronary intervention, as well as the current approach in the prevention of stent thrombosis. It also discusses experimental and upcoming drugs that may be superior to clopidogrel.

Appropriate use of drug-eluting stents: balancing the reduction in restenosis with the concern of late thrombosis

Restenosis is a serious occurrence that can lead not only to recurrent angina and repeat revascularisation but also to acute coronary syndromes. Drug-eluting stents revolutionised interventional cardiology owing to their pronounced ability to reduce restenosis compared with bare-metal stents. Attention has now shifted to safety of these devices because of evidence suggesting an association with late stent thrombosis. Findings of randomised clinical trials have not shown that drug-eluting stents result in excess mortality after 4-5 years of follow-up. Current recommendations are that individuals with a drug-eluting stent should receive at least 12 months of uninterrupted dual antiplatelet treatment; patients must understand the importance of this long-term regimen. Patients' assessment should focus on bleeding abnormalities, pre-existing disorders that need anticoagulation treatment, and possible future surgical procedures, since these factors could all contraindicate use of drug-eluting stents. Many people will do well with a bare-metal stent, whereas for individuals with a high likelihood of restenosis and late thrombosis, medical management or surgical revascularisation might be preferred options.

Cost-effectiveness of clopidogrel: seeing through the smoke

BACKGROUND

The authors reviewed various recommendations and practices for cost-effectiveness analysis. They also performed a PubMed search for clopidogrel and cost-effectiveness from 2004 to early 2008 to obtain original analyses published in English to look for possible associations of assumptions and conclusions with reported pharmaceutical support.

RESULTS

. Inclusion of incident cases and truncation at a sensible follow-up time more appropriately reflect the burden to be assumed by third-party payers. Extending the time horizon too far runs the risk of decreasing any relation with future reality. Parsimony cannot justify simplifications that omit relevant issues such as noncoronary costs, which worsen the calculated cost-effectiveness ratio of clopidogrel by 5% to 27%. The choice of the population to be analyzed has a major effect on cost-effectiveness: pharmaceutically sponsored studies published between 2004 and early 2008 focused on high-risk patients and have routinely shown more favorable cost-effectiveness ratios for clopidogrel than studies without pharmaceutical support.

CONCLUSION

. Any entity hoping to make the cost-effectiveness ratio of clopidogrel look more favorable would prefer the isolated, cohort approach and limit the analysis to high-risk patients most likely to benefit from it. This approach ignores the reality of medical policies and does not address the most relevant questions regarding the optimum use of clopidogrel.