Early use of glycoprotein IIb/IIIa inhibitors in non-ST-elevation acute myocardial infarction: observations from the National Registry of Myocardial Infarction 4

The Value of Medical Registries and Observational Studies Early in Pandemics: The COVID-19 Experience

Whereas randomized clinical trials remain the gold standard for evaluating new therapies for infections, we argue that registries and observational studies early in the Covid-19 pandemic provided invaluable understanding of the natural history and preliminary data on risk factors and possible treatments. We review the data from the current pandemic, the history of registries in general and their value in public health emergencies. Lessons from these experiences should be incorporated into rigorous planning for the next pandemic.

Receptor GP IIb/IIIa as an Indicator of Risk in Vascular Events

Type 2 diabetes causes a significant risk of cardiovascular diseases, leading to 70% of deaths in patients with diabetes. The effective treatment of diabetes significantly reduces the risk of requiring the involvement of specialists from various fields of medicine. This research aimed to assess the risk of cardiovascular events based on selected biochemical parameters (glycoprotein [GP] IIb/IIIa, von Willebrand factor [vWf], fibrinogen) and their changes in response to physical exercise. The research group consisted of 52 patients with type 2 diabetes with micro- or macro-angiopathy at a mean age of 63.80 years (8.79). The control group consisted of 50 healthy volunteers (17 women and 33 men) at a mean age of 51.16 years (6.39). All the patients consented to have their venous blood tested to measure complete blood counts. Activated GP IIb/IIIa receptors were labeled and analyzed by flow cytometry. Mean values of vWF factor were higher when compared with the control group (196.59% [80.32%] vs 148.06% [90.34%], respectively). The GP IIb/IIIa receptor expression was much higher in test patients than in the control group (3.91% [2.91%] vs 2.79% [2.51%]). Physical exercise had a positive influence on GP IIb/IIIa receptor expression and vWF, decreasing their baseline percentage values.

Adherence to Cardiac Practice Guidelines in the Management of Non-ST-Elevation Acute Coronary Syndromes: A Systematic Literature Review

BACKGROUND

In the management of non-ST-elevation acute coronary syndrome (NSTACS) a gap between guideline-recommended care and actual practice has been reported. A systematic overview of the actual extent of this gap, its potential impact on patient-outcomes, and influential factors is lacking.

OBJECTIVE

To examine the extent of guideline adherence, to study associations with the occurrence of adverse cardiac events, and to identify factors associated with guideline adherence.

METHOD

Systematic literature review, for which PUBMED, EMBASE, CINAHL, and the Cochrane library were searched until March 2016. Further, a manual search was performed using reference lists of included studies. Two reviewers independently performed quality-assessment and data extraction of the eligible studies.

RESULTS

Adherence rates varied widely within and between 45 eligible studies, ranging from less than 5.0 % to more than 95.0 % for recommendations on acute and discharge pharmacological treatment, 34.3 % - 93.0 % for risk stratification, and 16.0 % - 95.8 % for performing coronary angiography. Seven studies indicated that higher adherence rates were associated with lower mortality. Several patient-related (e.g. age, gender, co-morbidities) and organization-related (e.g. teaching hospital) factors influencing adherence were identified.

CONCLUSION

This review showed wide variation in guideline adherence, with a substantial proportion of NST-ACS patients possibly not receiving guideline-recommended care. Consequently, lower adherence might be associated with a higher risk for poor prognosis. Future research should further investigate the complex nature of guideline adherence in NST-ACS, its impact on clinical care, and factors influencing adherence. This knowledge is essential to optimize clinical management of NSTACS patients and could guide future quality improvement initiatives.

Thrombosis formation on atherosclerotic lesions and plaque rupture

Atherosclerosis is a silent chronic vascular pathology that is the cause of the majority of cardiovascular ischaemic events. The evolution of vascular disease involves a combination of endothelial dysfunction, extensive lipid deposition in the intima, exacerbated innate and adaptive immune responses, proliferation of vascular smooth muscle cells and remodelling of the extracellular matrix, resulting in the formation of an atherosclerotic plaque. High-risk plaques have a large acellular lipid-rich necrotic core with an overlying thin fibrous cap infiltrated by inflammatory cells and diffuse calcification. The formation of new fragile and leaky vessels that invade the expanding intima contributes to enlarge the necrotic core increasing the vulnerability of the plaque. In addition, biomechanical, haemodynamic and physical factors contribute to plaque destabilization. Upon erosion or rupture, these high-risk lipid-rich vulnerable plaques expose vascular structures or necrotic core components to the circulation, which causes the activation of tissue factor and the subsequent formation of a fibrin monolayer (coagulation cascade) and, concomitantly, the recruitment of circulating platelets and inflammatory cells. The interaction between exposed atherosclerotic plaque components, platelet receptors and coagulation factors eventually leads to platelet activation, aggregation and the subsequent formation of a superimposed thrombus (i.e. atherothrombosis) which may compromise the arterial lumen leading to the presentation of acute ischaemic syndromes. In this review, we will describe the progression of the atherosclerotic lesion along with the main morphological characteristics that predispose to plaque rupture, and discuss the multifaceted mechanisms that drive platelet activation and subsequent thrombus formation. Finally, we will consider the current scientific challenges and future research directions.

Lessons learned from negative clinical trials evaluating antithrombotic therapy for ischemic heart disease

The clinical trials that failed to demonstrate significant efficacy may not result in development of new therapy but contribute to better understanding of antithrombotic therapy for ischemic heart disease. Negative trials provide important messages about how to interpret and understand the results of clinical trials and apply these results to clinical practices. Although every aspect of clinical trials may influence the outcomes of trials and interpretation of their results, selection of study subjects, endpoints, and measuring risk/benefit are crucial to success of clinical trial. We will review the recent key negative trials on antithrombotic therapy for ischemic heart disease and discuss about their results and implications. The challenge in the future for the development of antithrombotic therapies is to leverage these "lessons learned" from negative clinical trials to improve the design, conduct, and interpretation of future randomized clinical trials.

Upstream use of small-molecule glycoprotein iib/iiia inhibitors in patients with non-ST-segment elevation acute coronary syndromes: a systematic overview of randomized clinical trials

BACKGROUND

The use of upstream small-molecule glycoprotein (GP) IIb/IIIa inhibitors in non-ST-segment elevation acute coronary syndromes (NSTE ACS) has been studied in multiple randomized clinical trials. We systematically reviewed the effect of upstream GP IIb/IIIa inhibitor use in NSTE ACS as reported in published clinical trials.

METHODS AND RESULTS

Randomized clinical trials of upstream small-molecule GP IIb/IIIa inhibitors in NSTE ACS were identified through a PubMed and EMBASE search and were included if they contained 30-day outcome data. Odds ratios were generated from the published data and pooled by means of random effects modeling. The primary outcome measures were 30-day death and 30-day death or myocardial infarction. Primary safety measures were major bleeding and transfusion during the index hospitalization. Twelve clinical trials were included, evaluating tirofiban, eptifibatide, and lamifiban. Of these, 7 evaluated upstream GP IIb/IIIa inhibitors versus placebo (n=24 031) and 5 evaluated a strategy of upstream GP IIb/IIIa inhibitors versus upstream placebo with later provisional use at the time of percutaneous coronary intervention (n=19 643). Overall, upstream GP IIb/IIIa inhibitor use was associated with an 11% reduction in 30-day death/myocardial infarction (odds ratio [OR], 0.89; 95% confidence interval [CI], 0.83 to 0.95) but no significant mortality effect (OR, 0.93; 95% CI, 0.83 to 1.05). The risk of major bleeding was 23% higher in patients treated with upstream GP IIb/IIIa inhibitors (OR, 1.23; 95% CI, 1.02 to 1.48). Results were similar when only trials comparing upstream GP IIb/IIIa inhibitors versus placebo were considered: 30-day death/myocardial infarction (OR, 0.88; 95% CI, 0.81 to 0.95); 30-day death (OR, 0.89; 95% CI, 0.76 to 1.03); and major bleeding (OR, 1.17; 95% CI, 0.88 to 1.54). Upstream versus selective use at percutaneous coronary intervention trended toward lower 30-day death/myocardial infarction (OR, 0.91; 95% CI, 0.82 to 1.01) but had no effect on mortality (OR, 1.00; 95% CI, 0.81 to 1.23) and increased major bleeding risk by 34% (OR, 1.34; 95% CI, 1.10 to 1.63).

CONCLUSIONS

In NSTE ACS, treatment with upstream small-molecule GP IIb/IIIa inhibitors provides a significant but modest ischemic benefit when compared with initial placebo. Compared with delayed, selective use at percutaneous coronary intervention, early upstream use is associated with a trend toward fewer ischemic events. However, these modest benefits are associated with an increased risk of bleeding.

Glycoprotein IIb/IIIa inhibitors: an update on the mechanism of action and use of functional testing methods to assess antiplatelet efficacy

The human glycoprotein (GP)IIb/IIIa belongs to a large family of cation-dependent adhesion molecules known as integrins, which share a common heterodimeric structure. The primary function of GPIIb/IIIa is to aid platelet aggregation by transmitting bidirectional signals across the plasma membrane. Since the GPIIb/IIIa receptor is among the key integrins involved in platelet aggregation and, therefore, thrombus formation, the development of GPIIb/IIIa antagonists (e.g., abciximab, eptifibatide and tirofiban) has become an attractive strategy for antiplatelet therapy with an expected strong and specific effect. All three drugs are administered intravenously, and large-scale clinical trials have demonstrated a clear clinical benefit and good safety profile in high-risk patients, especially those undergoing percutaneous coronary intervention. However, the adverse events related to thrombosis or bleeding are still reported in patients undergoing therapy with GPIIb/IIIa antagonists and reflect a variable interindividual responsiveness. Therefore, some form of laboratory monitoring is required to optimize the effects of a drug or to indicate that it needs replacing with other antithrombotic agents, as well as for identifying and enhancing the platelet inhibition in this subgroup of patients to improve the clinical outcome and reduce bleeding complications. As such, the aim of this article is to provide an update on the mechanism of action and use of functional testing methods to assess antiplatelet efficacy in patients undergoing therapy with GPIIb/IIIa antagonists.

Failure to adhere to protocol specified radiation therapy guidelines was associated with decreased survival in RTOG 9704--a phase III trial of adjuvant chemotherapy and chemoradiotherapy for patients with resected adenocarcinoma of the pancreas

PURPOSE

In Radiation Therapy Oncology Group 9704, as previously published, patients with resected pancreatic adenocarcinoma received continuous infusion 5-FU and concurrent radiotherapy (5FU-RT). 5FU-RT treatment was preceded and followed by randomly assigned chemotherapy, either 5-FU or gemcitabine. This analysis explored whether failure to adhere to specified RT guidelines influenced survival and/or toxicity.

METHODS AND MATERIALS

RT requirements were protocol specified. Adherence was scored as per protocol (PP) or less than per protocol (<PP). Scoring occurred after therapy but before trial analysis and without knowledge of individual patient treatment outcomes. Scoring was done for all tumor locations and for the subset of pancreatic head location.

RESULTS

RT was scored for 416 patients: 216 PP and 200 <PP. For all pancreatic sites (head, body/tail) median survival (MS) for PP vs. <PP was 1.74 vs. 1.46 years (log-rank p = 0.0077). In multivariate analysis, PP vs. <PP score correlated more strongly with MS than assigned treatment arm (p = 0.014, p = NS, respectively); for patients with pancreatic head tumors, both PP score and gemcitabine treatment correlated with improved MS (p = 0.016, p = 0.043, respectively). For all tumor locations, PP score was associated with decreased risk of failure (p = 0.016) and, for gemcitabine patients, a trend toward reduced Grade 4/5 nonhematologic toxicity (p = 0.065).

CONCLUSIONS

This is the first Phase III, multicenter, adjuvant protocol for pancreatic adenocarcinoma to evaluate the impact of adherence to specified RT protocol guidelines on protocol outcomes. Failure to adhere to specified RT guidelines was associated with reduced survival and, for patients receiving gemcitabine, trend toward increased nonhematologic toxicity.

Evaluation of the performance of echocardiography in acute coronary syndrome patients during their stay in coronary units

OBJECTIVES

To evaluate the frequency and the factors associated with performance of echocardiography in acute coronary syndrome (ACS) patients during their stay in intensive care units or coronary care units (ICU/CCU).

METHODS

Retrospective cohort study including all patients diagnosed with acute coronary syndrome-unstable angina (UA), acute myocardial infarction (AMI)-included in the 'ARIAM' Spanish multi-centre register. The study period was from June 1996 to December 2005. The follow-up period is limited to the time of stay in the Intensive Care Units or Coronary Care Units (ICUs/CCUs). A univariate analysis was carried out on the patients with UA and AMI according to whether or not echocardiograms were performed during their stay in ICU/CCU. In addition the data was evaluated for any temporal variation in the performance of echocardiography, and two multivariate analyses were carried out to evaluate the factors associated with performance of echocardiography in UA and AMI patients.

RESULTS

The study period included 45,688 AMI patients and 17,277 UA patients. Echocardiograms were performed in 26.87% AMI patients and 16.75% UA patients. In total, 15,172 echocardiograms were performed in ACS patients (23.6%). The multivariate analysis demonstrated that the variables associated with the performance of echocardiography in UA were: Killip and Kimball class, cigarette smoking, family history of cardiovascular events, cardiogenic shock, uncontrolled angina, mechanical ventilation and treatment with ACE inhibitors, while the presence of previous AMI was associated with fewer echocardiograms being performed. In AMI, the multivariate analysis showed the following variables to be associated with the performance of echocardiography: Killip and Kimball class, Q-AMI, right heart failure, the need for insertion of Swan-Ganz catheter, cardiogenic shock, high-degree AV block and the administration of ACE inhibitors, while age was associated with fewer being performed. Over the 10 years of the study period, there was a discrete but significant increase in the use of echocardiography in patients in ICU/CCU.

CONCLUSIONS

Echocardiography is not commonly used in ACS patients while in ICU/CCU. UA and AMI patients who did have echocardiograms during their stay in ICU/CCU were chiefly those presenting heart failure and major complications, and represent a subpopulation with poor prognosis. The performance of echocardiography in ACS patients increased slightly over the length of their stay in ICU/CCU.

Platelet function in patients with diabetes mellitus: from a theoretical to a practical perspective

Patients with diabetes mellitus have an increased prevalence of vascular disease. Pathologic thrombosis associated with atherosclerotic plaque rupture is a major cause of morbidity and mortality. Platelets are intimately involved in the initiation and propagation of thrombosis. Evidence suggests that platelets from patients with type 2 diabetes have increased reactivity and baseline activation compared to healthy controls. We review the pathophysiology of platelet hyperreactivity in DM patients and its implications in clinical practice, with particular focus on acute coronary syndromes, percutaneous coronary intervention, and novel antiplatelet agents.

Upstream treatment of acute coronary syndrome in the ED

Rapid risk stratification, selection of downstream management options, and institution of initial pharmacotherapy are essential to ensure that patients admitted to the emergency department with acute coronary syndromes receive optimal care. A broad range of antiplatelet and antithrombotic medications is available that permits tailoring of initial pharmacotherapy to each patient's risk status. In the urgent setting, thienopyridines (clopidogrel and prasugrel) carry limitations including response variability and increased risk for bleeding in patients requiring subsequent coronary artery bypass graft surgery. Glycoprotein IIb-IIIa receptor inhibitors, although they are highly effective in preventing ischemic events, must be used with care to reduce bleeding risk. Bivalirudin, a relatively new direct thrombin inhibitor, represents another upstream option but is costly and does not have approval for this indication. Simplified institutional management paradigms can streamline the process of selecting appropriate pharmacotherapy and aid in care delivery that will optimize patient outcomes.

Eptifibatide: The evidence for its role in the management of acute coronary syndromes

Introduction:

Acute coronary syndromes and non-Q-wave myocardial infarction are often initiated by platelet activation. Eptifibatide is a cyclic heptapeptide and is the third inhibitor of glycoprotein (Gp) IIb/IIIa that has found broad acceptance after the specific antibody abciximab and the nonpeptide tirofiban entered the global market. Gp IIb/IIIa inhibitors act by inhibiting the final common pathway of platelet aggregation, and play an important role in the management of acute coronary syndromes.

Aims:

This review assesses the evidence for therapeutic value of eptifibatide as a Gp IIb/IIIa inhibitor in patients with acute coronary syndromes.

Evidence review:

Several large, randomized controlled trials show that eptifibatide as adjunctive therapy to standard care in patients with non-ST segment elevation acute coronary syndrome is associated with a significant reduction in the incidence of death or myocardial infarction. Data are limited regarding the use of eptifibatide in patients with ST segment elevation myocardial infarction. Cost-effectiveness analysis indicates that eptifibatide is associated with a favorable cost-effectiveness ratio relative to standard care. According to US cost-effectiveness analysis about 70% of the acquisition costs of eptifibatide are offset by the reduced medical resource consumption during the first year. Eptifibatide was well tolerated in most of the trials. Bleeding is the most commonly reported adverse event, with most major bleeding episodes occurring at the vascular access site. Major intracranial bleeds, stroke, or profound thrombocytopenia rarely occurred during eptifibatide treatment.

Place in therapy:

Eptifibatide has gained widespread acceptance as an adjunct to standard anticoagulation therapy in patients with acute coronary syndromes, and may be particularly useful in the management of patients with elevated troponin or undergoing percutaneous coronary interventions.

Oral antiplatelet therapy for acute and chronic management of NSTE ACS: residual ischemic risk and opportunities for improvement

Introduction

Non-ST-segment elevation acute coronary syndromes (NSTE ACS) are highly prevalent in the United States and globally, and are associated with significant morbidity and mortality.

Discussion

The key role of platelet-mediated thrombosis in the pathogenesis of NSTE ACS is confirmed by the proven clinical benefits of antiplatelet agents (aspirin and a P2Y₁₂ adenosine diphosphate [ADP] receptor antagonist) in this setting. Despite the documented advantages and broad use of antiplatelet therapy, the long-term morbidity and mortality rates remain significant, and the bleeding risk remains substantial. Residual risk can be attributed, at least in part, to the fact that thrombosis continues in the presence of current treatments because aspirin and P2Y₁₂ ADP receptor antagonists each block only one of multiple platelet activation pathways, and thus do not impact other platelet activation pathways, such as the one triggered by interaction of thrombin with protease-activated receptor (PAR)-1, thereby exposing patients to continued accumulation of thrombotic events.

Conclusion

These considerations suggest that novel therapies with a different mechanism of action, when used in combination with current antiplatelet agents, may provide more comprehensive inhibition of platelet activation and additional reductions in morbidity and mortality, potentially without incremental bleeding risk.

Lipoproteins, platelets and atherothrombosis

Atherosclerosis and thrombosis associated with the rupture of vulnerable plaque are the main causes of cardiovascular events, including acute coronary syndrome. Low-density lipoprotein (LDL) plays a key role in the pathogenesis of atherothrombotic processes. LDLs modify the antithrombotic properties of the vascular endothelium and change vessel contractility by reducing the availability of endothelial nitric oxide and activating proinflammatory signaling pathways. In addition, LDLs also influence the functions and interactions of cells present in atherosclerotic lesions, whether they come from the circulation or are resident in vessel walls. In fact, LDLs entering affected vessels undergo modifications (e.g. oxidation, aggregation and glycosylation) that potentiate their atherogenic properties. Once modified, these intravascular LDLs promote the formation of foam cells derived from smooth muscle cells and macrophages, thereby increasing the vulnerability of atherosclerotic plaque. Moreover, they also increase the thrombogenicity of both plaque and blood, in which circulating tissue factor levels are raised and platelet reactivity is enhanced. This review focuses on the importance of native and modified LDL for the pathogenesis of atherothrombosis. It also discusses current studies on LDL and its effects on the actions of vascular cells and blood cells, particularly platelets, and considers novel potential therapeutic targets.

Underutilization of clopidogrel and glycoprotein IIb/IIIa inhibitors in non-ST-elevation acute coronary syndrome patients: the Canadian global registry of acute coronary events (GRACE) experience

BACKGROUND

There are limited contemporary data on the early use of clopidogrel or glycoprotein (Gp) IIb/IIIa inhibitors, alone versus combination therapies, in non-ST-elevation acute coronary syndrome (NSTE-ACS).

METHODS

This study included 5,806 Canadian NSTE-ACS patients with elevated cardiac biomarker and/or ST deviation on presentation in the prospective GRACE between 2003-2007. We stratified the study population according to the management strategy (non-invasive vs invasive) and into low-(GRACE risk score <or=108), intermediate- (109-140), and high-risk groups (>or=141).

RESULTS

Overall, 3,893 patients (67.1%) received early (<or=24 hours of admission) antiplatelet therapy; the rates of use were 76%, 73%, and 57% in the low-, intermediate-, and high-risk groups, respectively (P for trend < .001). Only 54% of the conservatively managed patients and 12% of the invasively managed patients received early clopidogrel and GpIIb/IIIa inhibitors, respectively. High-risk patients were less likely (adjusted odds ratio = 0.48, 95% CI 0.39-0.59, P < .001) to receive early clopidogrel or GpIIb/IIIa inhibitors, whereas in-hospital catheterization was an independent positive predictor (adjusted odds ratio = 2.02, 95% CI 1.74-2.34, P < .001) of use.

CONCLUSIONS

In this contemporary NSTE-ACS population, both clopidogrel and GpIIb/IIIa inhibitors were targeted toward patients treated with an invasive strategy but paradoxically toward the lower-risk group. In particular, clopidogrel appeared to be underused among conservatively managed patients despite its proven efficacy, whereas GpIIb/IIIa inhibitors were administered to only a minority of the high-risk patients with elevated cardiac biomarkers. Our findings emphasize the ongoing need to promote the optimal use of evidence-based antiplatelet therapies among high-risk patients with NSTE-ACS.

The usage patterns of cardiac bedside markers employing point-of-care testing for troponin in non-ST-segment elevation acute coronary syndrome: results from CRUSADE

BACKGROUND

Point-of-care (POC) testing may expedite the care of emergency department (ED) patients suspected of having acute coronary syndromes (ACS). We evaluated the use patterns of cardiac bedside markers or POC testing for troponin in patients with non-ST-segment elevation (NSTE) ACS.

METHODS

NSTE ACS data were collected from the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the American College of Cardiology/American Heart Association (ACC/AHA) Guidelines (CRUSADE) registry. We compared hospital and patient characteristics, in-hospital events, and process-of-care variables between hospitals to those that did not use POC testing in > or = 50% of enrolled patients. We examined characteristics, in-hospital events, and process-of-care differences between patients with negative vs positive troponin POC testing results.

RESULTS

Of 568 hospitals, 74 (16,276 patients) had high POC usage compared with 197 hospitals (50,782 patients) with no troponin POC usage. From the high POC usage hospitals, 12,604 patients had recorded troponin POC test results. Hospitals with high POC usage had a shorter ED length of stay and were less likely to administer aspirin, beta-blockers, and heparin during the first 24 hours of care. Patients with positive troponin POC results were more often older, minority, female, Medicare-insured, diabetic, and renally impaired. They had fewer electrocardiograms within 10 minutes but were more likely to get aspirin, beta-blockers, glycoprotein IIb/IIIa inhibitors, and heparin within 24 hours of arrival. They also had longer ED lengths of stay, received fewer in-hospital and interventional procedures, and had more adverse clinical events.

CONCLUSION

Differences existed in how hospitals used POC testing and the care given based on those results. Positive POC results are associated with expedited and higher use of anti-ischemic therapies.

Diabetes and acute coronary syndromes

Diabetic patients with acute coronary syndromes (ACSs) are at a high risk for subsequent cardiovascular events but derive, at the same time, greater benefit from evidence-based therapy than non-diabetic individuals. State-of-the-art anti-thrombotic therapy includes a triple anti-platelet combination - aspirin, clopidogrel and glycoprotein (GP) IIb/IIIa receptor inhibitors - and unfractionated heparin or enoxaparin. For low- or medium-risk individuals, a treatment based on aspirin, clopidogrel and bivalirudin is a valuable alternative. Prasugrel, a new and more potent inhibitor of the platelet P2Y(12) receptor, has to be regarded as the most promising anti-thrombotic agent for diabetic patients with ACS. This agent may replace clopidogrel - and possibly GP IIb/IIIa inhibitors - in the future. In addition to aggressive anti-thrombotic therapy, diabetic patients should undergo systematic early invasive angiography if presenting with non-ST-segment elevation ACS, and immediate percutaneous coronary intervention if presenting with ST-segment elevation myocardial infarction. Indeed, the benefit derived from these strategies appears to be more pronounced in the diabetic population than in non-diabetic individuals. Despite the benefit, multiple surveys have demonstrated that, in the setting of ACS, diabetic patients receive evidence-based therapy less frequently than non-diabetic counterparts.

Re-evaluating risk factors for periprocedural complications during percutaneous coronary intervention in patients with unstable angina/non-ST-elevation myocardial infarction: who may benefit from more intensive antiplatelet therapy?

PURPOSE OF REVIEW

Controversy regarding the optimal antiplatelet/antithrombotic regimen indicates a need to re-evaluate the place of these agents in treating patients with unstable angina/non-ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention.

RECENT FINDINGS

Although clinical trial data suggest that glycoprotein IIb-IIIa inhibition benefits moderate-risk to high-risk patients, recent studies question the use of intensive antiplatelet therapy in lower risk patients. The resultant shift towards less intensive alternative regimens raises questions about identifying patients in whom an alternative strategy is preferable. The concept of risk stratification for coronary intervention has evolved from lesion-based categorization to include clinical factors, for example, elevated levels of cardiac troponin.

SUMMARY

Risk factors for periprocedural complications during percutaneous coronary intervention can be divided into anatomic (unprotected left main stenting, bifurcation lesions, and diffuse disease) and clinical (older age, diabetes, renal disease, left ventricular function, recent myocardial damage, and female sex) factors. These may interact additively or synergistically, increasing the likelihood of complications in patients who might otherwise have been considered at low risk. We need to reconsider, therefore, how we identify appropriate options and, hopefully, optimize clinical outcomes. This review evaluates risk factors for periprocedural complications in an effort to determine patients who may benefit most from intensive antiplatelet regimens.

Guidelines to practice gap in the use of glycoprotein IIb/IIIa inhibitors: from ISAR-REACT to overreact?

Adjunctive use of glycoprotein IIb/IIIa inhibitors (GPI) is associated with favorable outcomes following percutaneous coronary intervention (PCI). Guidelines for use of GPI have been published by various national societies including National Institute of Clinical Excellence (NICE), United Kingdom. The latter has not been updated since publication. The impact of contemporary trials such as ISAR-REACT (which showed no benefit of abciximab and 600 mg of clopidogrel compared with 600 mg of clopidogrel alone, in elective patients) on adherence to NICE guidelines is unknown.

METHODS

We audited use of GPI against NICE guidelines following publication in May 2002. Data were collected from 1,685 patients between September and November in years 2002, 2003, 2004, and 2007.

RESULTS

In 2002 and 2003, only 10.2% and 11.8%, respectively, of patients were noncompliant to NICE guidelines. Over time, there was an increase in patients not given GPI despite meeting NICE criteria. After publication of ISAR-REACT, the comparative figures for noncompliance in 2004 and 2007 were 40.0% and 44.5%. A similar pattern was seen in patients with diabetes; in 2002 and 2003 noncompliance was 16.7% and 11.1%, respectively, and in 2004 and 2007 noncompliance was 38.0% and 44.7%, respectively. Qualitatively, similar findings were recorded in patients with NSTE-ACS. The overall noncompliance to NICE guidelines increased from 11.0% to 42.1% (P < 0.0001) after the ISAR-REACT study.

CONCLUSIONS

We found a decline in compliance to NICE guidelines on GPI usage during PCI. This was likely influenced by contemporary trials demonstrating little or no benefit of GPI in patients undergoing elective PCI who are adequately pretreated with clopidogrel. Our findings suggest the need for a mechanism whereby regular updates to guidelines can be disseminated following new trial evidence.

A critical appraisal of propensity-score matching in the medical literature between 1996 and 2003

Propensity-score methods are increasingly being used to reduce the impact of treatment-selection bias in the estimation of treatment effects using observational data. Commonly used propensity-score methods include covariate adjustment using the propensity score, stratification on the propensity score, and propensity-score matching. Empirical and theoretical research has demonstrated that matching on the propensity score eliminates a greater proportion of baseline differences between treated and untreated subjects than does stratification on the propensity score. However, the analysis of propensity-score-matched samples requires statistical methods appropriate for matched-pairs data. We critically evaluated 47 articles that were published between 1996 and 2003 in the medical literature and that employed propensity-score matching. We found that only two of the articles reported the balance of baseline characteristics between treated and untreated subjects in the matched sample and used correct statistical methods to assess the degree of imbalance. Thirteen (28 per cent) of the articles explicitly used statistical methods appropriate for the analysis of matched data when estimating the treatment effect and its statistical significance. Common errors included using the log-rank test to compare Kaplan-Meier survival curves in the matched sample, using Cox regression, logistic regression, chi-squared tests, t-tests, and Wilcoxon rank sum tests in the matched sample, thereby failing to account for the matched nature of the data. We provide guidelines for the analysis and reporting of studies that employ propensity-score matching.

Variations in the application of cardiac care in Australia

OBJECTIVE

To evaluate the use of clinical practice guidelines for the management of acute coronary syndromes published by the National Heart Foundation (NHF) of Australia and the Cardiac Society of Australia and New Zealand (CSANZ) in patients presenting with chest pain.

DESIGN

Cross-sectional study of consecutive patients admitted with chest pain.

SETTING

Prospective case note review was undertaken in 2380 patients admitted to 27 hospitals across five states in Australia between January 2003 and August 2005. Patients were divided into two groups: those who presented to centres with angiography and percutaneous intervention facilities (n = 1260) and those treated at centres without these facilities (n = 1120).

MAIN OUTCOME MEASURES

The proportion of patients whose care met quality of care standards for diagnostic and risk-stratification procedures and management according to NHF/CSANZ treatment guidelines.

RESULTS

Significant delays were identified in performing electrocardiography, administering thrombolysis, transferring high-risk patients to tertiary centres, and performing revascularisation. Medical therapy was underused, especially glycoprotein IIb/IIIa antagonists in patients with high-risk acute coronary syndromes. Patients treated at centres without interventional facilities were less likely to receive guidelines-based medical therapy and referral for coronary angiography (20.11%) than patients treated at centres with interventional facilities (66.43%; P < 0.001).

CONCLUSION

There are deficits in the implementation and adherence to evidence-based guidelines for managing chest pain in hospitals across Australia, and significant differences between hospitals with and without interventional facilities.

Glycoprotein IIb-IIIa inhibitors in the emergency department for patients with non-ST-elevation acute coronary syndromes: principles and practices

Non-ST-elevation acute coronary syndrome is associated with significant morbidity and mortality. Although the benefit of platelet inhibition by glycoprotein (GP) IIb-IIIa inhibitors in patients undergoing percutaneous coronary intervention (PCI) is well established, emergency physicians and cardiologists have different perspectives regarding their optimum administration, especially upstream before PCI. In this article, two emergency physicians and two cardiologists analyze data and discuss relevant issues, including the ischemic benefits vs. the risk of bleeding associated with GP IIb-IIIa inhibitors in appropriate patients, for example, those with an elevated troponin level or who undergo revascularization. The emergency physicians support early identification of high-risk non-ST-elevation acute coronary syndrome patients and early administration of GP IIb-IIIa inhibitors, which are linked to improved patient outcomes. The cardiologists emphasize risk stratification to identify patients in whom the expected reduction in ischemic complications outweighs the risk of increased bleeding with these agents. GP IIb-IIIa inhibitors should be considered in patients with unstable angina and non-ST-segment elevation myocardial infarction (UA/NSTEMI) in whom PCI is planned, especially those with high-risk features or elevated serum troponin levels. It is reasonable to start this treatment upstream of intervention, pending further studies investigating the optimal timing of initiation of therapy in appropriate patients.

GP IIb-IIIa inhibitors administered upstream: evidence for improved outcomes with conventional and newer antithrombotic agents?

Glycoprotein IIb-IIIa inhibitors provide the most benefit in patients with non-ST-elevation acute coronary syndromes and high-risk features and in those who undergo early invasive treatment. Current guidelines recommend glycoprotein IIb-IIIa inhibition in these patients but offer little guidance as to timing of initiation. Preliminary data suggest superior outcomes with upstream initiation (upon admission to a medical facility) compared with delayed initiation (in the catheterization laboratory, just before percutaneous coronary intervention). The availability of new antiplatelet and antithrombotic drugs renders even more complex the question of the best strategy.

Acute coronary syndromes: unstable angina/non-ST elevation myocardial infarction

Acute coronary syndrome is a major health problem affecting approximately 1.5 million individuals a year. Early diagnosis and appropriate evidence-based therapies improve clinical outcomes significantly. Current data suggest that an early invasive therapy may improve intermediate-term and long-term outcomes, particularly in high-risk individuals. The last few years also have seen significant advances in antiplatelet and antithrombotic therapies for the management of patients who have acute coronary syndrome.

Antiplatelet Therapy in Patients with Unstable Angina and Non–ST-Segment-Elevation Myocardial Infarction: Findings from the CRUSADE National Quality Improvement Initiative

Evidence-based clinical practice guidelines encapsulate current knowledge to guide health care professionals in the treatment of patients with unstable angina or non-ST-segment-elevation myocardial infarction (NSTEMI), yet adherence to guideline recommendations is suboptimal. Guideline adherence may be improved by quality improvement programs such as the CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation?) National Quality Improvement Initiative of the American College of Cardiology-American Heart Association Guidelines. The CRUSADE data have been analyzed to demonstrate that overall guideline adherence is directly associated with mortality and that improvement in guideline adherence saves lives. Also, the CRUSADE data have determined that the real-life mortality risk associated with unstable angina and NSTEMI is greater than suggested by clinical trials. The newer antiplatelet drugs recommended in early intervention and discharge treatment strategies are underused across many segments of the unstable angina-NSTEMI population. Glycoprotein IIb-IIIa inhibitors are underused in high-risk populations, and clopidogrel is markedly underused in patients who are medically managed rather than undergoing percutaneous coronary intervention or coronary artery bypass graft surgery. In addition, often the specialty of the treating physician and the status of the hospital influence the use of antiplatelet therapy. The reasons for underprescribing of antiplatelet drugs by physicians are not entirely clear but may be related to a lack of guideline familiarity and understanding, as well as factors such as drug novelty, safety, and cost. Continued education and data dissemination are therefore vital in promoting the prescription of guideline-recommended drugs, both in the early hospitalization phase and as patients transition to community-based care. The role of the pharmacist is pivotal in ensuring adherence to clinical guidelines by interacting with both the physician and patient.

Impact of renal dysfunction and glucometabolic status on one month mortality after acute myocardial infarction

Patients with impaired glucometabolic status or renal function have a higher mortality after acute myocardial infarction. It is unclear whether this higher risk is independent or related to the quality of care. In a prospective registry, stress hyperglycaemia (SH) was defined as glucose level>140 mg/dl. Renal function was assessed by the glomerular filtration rate (GFR): normal (>/=60), mild (30-60) and severe dysfunction (<30 ml/min/1.72 m(2)). The level of risk was assessed by the TIMI risk index and the quality of care by the rate of use of five guidelines-recommended treatments. Among the 1388 patients included, 23% had diabetes, 16% had SH, renal function was normal in 55%, mildly impaired in 35% and severely impaired in 9.5%. At one month, the mortality rate was higher in patients with SH (18%) as compared with diabetics (9%) or those with normal glucometabolic status (5%). Similarly, the mortality rate was higher in those with impaired renal function. Multivariable analysis identified SH, GFR group, TIMI risk index, ST segment elevation MI and quality of care as independent predictors of one-month mortality. In patients with acute MI, SH and GFR<30 ml/min/m(2) are independent predictors of mortality after adjustment for the level of risk and acute care.

The emerging role of platelet glycoprotein IIb/IIIa inhibitors in managing high-risk patients with non-ST segment elevation acute coronary syndromes

BACKGROUND

Current practice guidelines recommend administering a platelet glycoprotein IIb/IIIa inhibitor, in conjunction with aspirin and heparin, for patients with non-ST segment elevation (NSTE) acute coronary syndromes (ACS) for whom an early invasive management strategy is planned. However, optimal timing of glycoprotein IIb/IIIa inhibitor administration - 'upstream' in the coronary care unit or 'downstream' when the patient goes to the catheterization laboratory - has not been established.

SCOPE

This paper evaluates recent trial results that help to better define the role of platelet glycoprotein IIb/IIIa inhibitors for treating high-risk patients with NSTE ACS who are scheduled for percutaneous coronary intervention (PCI). The Medline database was searched in February 2007 to retrieve relevant articles. Additional articles were obtained from the reference lists of retrieved articles, as well as from recent scientific meetings and company websites.

FINDINGS

Results of the ISAR-REACT 2 trial indicate that administration of abciximab provides significant benefit for high-risk patients with NSTE ACS undergoing PCI; clopidogrel alone is not enough. In preliminary results of the ACUITY trial, glycoprotein IIb/IIIa inhibitor administration produced an incremental increase in bleeding events but a reduction in ischemic events; there was a trend to better outcomes with upstream administration, even short-term. Moreover, in the cohort of patients who underwent PCI, the composite ischemic endpoint was significantly lower with routine upstream glycoprotein IIb/IIIa inhibitor. Finally, results of the EVEREST pilot study, a mechanistic study evaluating epicardial and tissue level perfusion and cardiac troponin I release, significantly favored upstream administration of tirofiban over downstream glycoprotein IIb/IIIa inhibitor for high-risk patients with NSTE ACS undergoing PCI. Moreover, high bolus dose tirofiban or abciximab administered just before PCI produced similar effects on angiographic outcome and cardiac troponin I release.

CONCLUSIONS

Recent and emerging evidence is clarifying the role of glycoprotein IIb/IIIa inhibitors in treating high-risk patients with NSTE ACS and indicates that these agents are of greatest benefit when given early.

The evolving role of glycoprotein IIb/IIIa inhibitor therapy in contemporary care of acute coronary syndrome patients

Results from clinical trials of glycoprotein IIb/IIIa(GPIIb/IIIa) inhibitors during the past decade have established their current role in the treatment of non-ST-segment elevation acute coronary syndrome and in percutaneous coronary interventions. However, there are still unanswered questions on optimal use of GPIIb/IIIa inhibitors. Moreover, as new concomitant or alternative medications become available, the role of GPIIb/IIIa inhibitors must be reconsidered. This review discusses, in the light of clinical trials recently presented, what we know, what we are learning, and what we still need to learn.

Timing of glycoprotein IIb/IIIa inhibitor use and outcomes among patients with non-ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention (results from CRUSADE)

Although glycoprotein (GP) IIb/IIIa inhibitors are recommended for patients with unstable angina and non-ST-segment elevation myocardial infarction who undergo percutaneous coronary intervention (PCI), the American College of Cardiology/American Heart Association guidelines do not specify optimal timing for their initiation. We compared patient characteristics and clinical outcomes in 30,830 patients with non-ST-segment elevation myocardial infarction included in the CRUSADE initiative (January 2001 to December 2004) who underwent PCI with upstream (>1 hour before PCI) or periprocedural use of GP IIb/IIIa inhibitors. GP IIb/IIIa inhibitors were administered upstream in 43% of patients versus periprocedurally in 57%. Time from arrival to PCI was longer for patients who received GP IIb/IIIa inhibitors upstream (median 25.6 hours) compared with periprocedurally (18.2 hours). Unadjusted incidence of in-hospital death or reinfarction was lower with upstream GP IIb/IIIa inhibitor use (3.8% vs 4.3%, p = 0.046), but after adjusting for patient and hospital characteristics, this difference was not statistically significant. Treatment with upstream GP IIb/IIIa inhibitors was associated with a lower incidence of unadjusted death or reinfarction in patients who underwent PCI <12 hours from hospital arrival. In conclusion, in this observational analysis, overall ischemic outcomes were similar between the 2 groups, but clinical trials are needed to solve the controversy over optional timing of GP IIb/IIIa inhibitor use.

Ausencia de beneficio con triple antiagregación en el síndrome coronario agudo sin elevación persistente del segmento ST, en pacientes no sometidos a intervencionismo precoz

OBJECTIVE

To assess the efficacy and safety of a treatment with clopidogrel when associated or not to the treatment with tirofiban and aspirin for high-risk non-ST segment elevation myocardial infarction (non-STEMI), without early angioplasty.

SETTING

Intensive Care and Coronary Unit (ICCU), in a center with no Hemodynamic Laboratory.

DESIGN

Non randomized clinical trial.

PARTICIPANTS

One hundred and twenty-three patients admitted with the diagnosis of high-risk non-STEMI, defined as patients with chest pain and one of the following: ST segment depression or transient elevation or an elevation in cardiac troponin I (TropIc).

INTERVENTIONS

We included patients admitted in a 24-month period. During the first 12-month period, the patients received tirofiban and clopidogrel (group A). In the second one, clopidogrel was not administered (group B). Urgent cardiac catheterism was requested if recurrent ischemic chest pain with ST segment changes, left ventricular failure or hemodynamic instability were present. PRIMARY VARIABLES: A composite of recurrent ischemic chest pain with ST segment changes or death during ICCU admission was evaluated as an efficacy variable. A variable of safety was defined as the occurrence of intracranial or gastrointestinal bleeding, or any hemorrhagic event accompanied by a drop of at least 3 g/dl of hemoglobin. The rate of urgent cardiac catheterisms was recorded.

RESULTS

Neither the rate of the efficacy variable (19.6 % in group A and 19.4% in group B; p = 0.97), nor the rate of the safety variable (3.5% and 2.9% of patients in groups A and B, p = 1) showed statistically significant difference. There was no statistically significant difference in the rate of urgent cardiac catheterism (19.6% in group A and 13.4% in group B; p = 0.35).

CONCLUSIONS

In the early course of high-risk non-STEMI with a conservative management strategy, the addition of clopidogrel to tirofiban does not change the rate of ischemic events, death, need of urgent catheterism or hemorrhagic events.

Platelet inhibitors in non-ST-segment elevation acute coronary syndromes and percutaneous coronary intervention: glycoprotein IIb/IIIa inhibitors, clopidogrel, or both?

The role of glycoprotein (Gp) IIb/IIIa receptor antagonists remains controversial and these agents are infrequently utilized during non-ST-segment elevation acute coronary syndromes (NSTE-ACS) despite American Heart Association/American College of Cardiology guidelines. Despite recommendations, the NRMI-4 (National Registry of Myocardial Infarction 4) and CRUSADE (Can rapid risk stratification of unstable angina patients suppress adverse outcomes with early implementation of the ACC/AHA guidelines?) registries observed that only 25%-32% of eligible patients received early Gp IIb/IIIa therapy, despite a 6.3% absolute mortality reduction in NRMI-4 and a 2% absolute mortality reduction in CRUSADE. A pooled analysis of Gp IIb/IIIa data from these registries suggest a major reduction in mortality (Odds Ratio = 0.43, 95% Confidence Index 0.25-0.74, p = 0.002) with early Gp IIb/IIIa therapy, yet clinicians fail to utilize this option in NSTE-ACS. The evidence-based approach to NSTE-ACS involves aspirin, clopidogrel, low-molecular weight heparins, or unfractionated heparin in concert with Gp IIb/Ila receptor antagonists, however, newer percutaneous coronary intervention (PCI)-based trials challenge current recommendations. Novel strategies emerging in NSTE-ACS include omitting Gp IIb/Ila inhibitors altogether or using Gp IIb/IIIa inhibitors with higher doses of clopidogrel in selected patients. The ISAR-REACT (Intracoronary stenting and antithrombotic regimen-Rapid early action for coronary treatment) and ISAR-SWEET (ISAR-Is abciximab a superior way to eliminate elevated thrombotic risk in diabetics) trials question the value of abciximab when 600 mg of clopidogrel concurrently administered during PCI. The CLEAR-PLATELETS (Clopidogrel loading with eptifibatide to arrest the reactivity of platelets) and PEACE (Platelet activity extinction in non-Q-wave MI with ASA, clopidogrel, and eptifibatide) trials suggest more durable platelet inhibition when Gp IIb/IIIa inhibitors are used with higher doses clopidogrel. The ISAR-COOL (ISAR: Cooling off strategy) trial found no difference in ischemic outcomes when Gp IIb/IIIa inhibitors were excluded and ARMYDA-2 (Antiplatelet therapy for reduction of myocardial damage during angioplasty) suggested higher doses of clopidogrel are more appropriate during PCI when Gp IIb/IIIa inhibitors are not utilized. This constellation of new trials forces reconsideration of current recommendations in regards to patient risk stratification, choice of antithrombotic therapy, doses, and timing. These new data will impact emerging guidelines and updates are currently in progress.

Utilization of glycoprotein IIb/IIIa inhibitors in non-ST-elevation acute myocardial infarction in a tertiary referral medical center in a developing country

We analyze the patterns of utilization of glycoprotein (GP) IIb/IIIa inhibitors in patients with non-ST-elevation myocardial infarction (NSTEMI) in a tertiary medical center in a developing country and we compare it to data from the national registry of myocardial infarction 4 (NRMI 4) in the USA. GP IIb/IIIa inhibitors were used in 28% of patients. The significant multivariate predictors of GP IIb/IIIa inhibitors utilization were Age <70 years (p=0.05), TIMI score > or =4 (p=0.002), and the absence of congestive heart failure (p=0.01) or prior infarction (p=0.04). Our results show striking similarity to what has been reported by the NRMI 4 registry, in terms of the overall underutilization of GP IIb/IIIa inhibitors in NSTEMI patients, and particularly in elderly patients and women. These findings underscore the importance of initiating a worldwide campaign to educate physicians about the pivotal role of GP IIb/IIIa inhibitors in the management of patients with NSTEMI.

Evolution of clinical practice guidelines: evidence supporting expanded use of medicines

Previous studies have shown that the primary factor underlying increased spending on pharmaceuticals has been the rising utilization of medications, rather than increases in unit drug price. This study examined the evolution of clinical practice guidelines to assess possible reasons for the rising drug volume. Clinical practice guidelines from 1970 to the present were reviewed for the six most prevalent treatable medical conditions/risk factors listed as priority areas by the Institute of Medicine. We searched the National Guidelines Clearinghouse, PubMed and Medline databases, and Web sites of relevant national organizations for US clinical practice guidelines published through January 2005. Information pertaining to the therapeutic regimen (eg, the frequency and duration of recommended treatment, when treatment should be initiated, the patient population for whom the guideline was intended) was abstracted and entered into evidence tables. Changes in guidelines were distributed across three themes that recommended evidence-based increases in medication use, including: (1) changes in the size of the treatable population; (2) changes in the number and type of recommended pharmaceutical therapeutic options, including movement from monotherapy to combination therapy, treatment of comorbidities, and use of newer types of medicines; and (3) changes in the therapeutic regimen, including a shift from episodic care to preventive and chronic care. Many of these changes point to an important, but not often noticed, addition of secondary prevention of disease effects to the objectives of medical care. These trends are likely to continue with important economic, clinical, and policy ramifications.