Aspirin versus heparin to prevent myocardial infarction during the acute phase of unstable angina

Revealing the extracellular function of HMGB1 N-terminal region acetylation assisted by a protein semi-synthesis approach

HMGB1 (high-mobility group box 1) is a non-histone chromatin-associated protein that has been widely reported as a representative damage-associated molecular pattern (DAMP) and to play a pivotal role in the proinflammatory process once it is in an extracellular location. Accumulating evidence has shown that HMGB1 undergoes extensive post-translational modifications (PTMs) that actively regulate its conformation, localization, and intermolecular interactions. However, fully characterizing the functional implications of these PTMs has been challenging due to the difficulty in accessing homogeneous HMGB1 with site-specific PTMs of interest. In this study, we developed a streamlined protein semi-synthesis strategy via salicylaldehyde ester-mediated chemical ligations (Ser/Thr ligation and Cys/Pen ligation, STL/CPL). This methodology enabled us to generate a series of N-terminal region acetylated HMGB1 proteins. Further studies revealed that acetylation regulates HMGB1-heparin interaction and modulates HMGB1's stability against thrombin, representing a regulatory switch to control HMGB1's extracellular activity.

Primary Percutaneous Coronary Intervention and Application of the Pharmacoinvasive Approach Within ST-Elevation Myocardial Infarction Care Networks

The management of acute ST-elevation myocardial infarction (STEMI) has transitioned from observation and reactive treatment of hemodynamic and arrhythmic complications to accelerated reperfusion and application of evidence-based treatment to minimize morbidity and mortality. International research established the importance of timely reperfusion therapy and the application of fibrinolysis, primary percutaneous coronary intervention (PCI), and subsequent development of the pharmacoinvasive approach. Clinician thought leaders developed and investigated comprehensive systems of care to optimize the outcomes of patients with STEMI, with a key focus in Canada being the integration of prehospital paramedics in diagnosis, triage, and treatment. This article will review highlights of these interventions and identify future challenges and opportunities in STEMI patient care.

Antithrombotic therapy in the early phase of non-ST-elevation acute coronary syndromes: a systematic review and meta-analysis

Aims

Despite the increasing use of early invasive strategies in non-ST-elevation acute coronary syndromes (NSTE-ACS), optimal initial antithrombotic therapy (ATT) based on the safety/efficacy profile of all guideline-recommended combinations remains crucial for the early management of both medically and invasively treated NSTE-ACS patients.

Methods and results

Randomized controlled trials on ATT in NSTE-ACS/unstable angina reporting early (within 14 days) major adverse cardiovascular events (MACE) and major bleeding were selected. Overall, 3799 studies were screened, 117 clinical trials were assessed as potentially eligible, 20 trials were included in the study. According to treatment and type of intervention, nine different meta-analyses were performed including a total of 88 748 patients. A significant reduction of trial-defined MACE was found for aspirin vs. placebo [odds ratio (OR), 0.57; 95% confidence interval (CI), 0.34–0.96], heparin vs. placebo (OR, 0.38; 95% CI, 0.15–0.97), aspirin + heparin vs. placebo (OR, 0.32; 95% CI, 0.18–0.59), aspirin + heparin vs. aspirin (OR, 0.57; 95% CI, 0.42–0.79), aspirin + low molecular weight heparin (LMWH) vs. aspirin + unfractionated heparin (UFH; OR, 0.81; 95% CI, 0.69–0.95) and aspirin + ticagrelor/prasugrel + heparins vs. aspirin + clopidogrel + heparins (OR, 0.76; 95% CI, 0.62–0.94). A significant decrease in major bleeding was found only for fondaparinux vs. LMWH on the background of aspirin + clopidogrel (OR, 0.52; 95% CI, 0.44–0.62) despite a clear trend towards increased bleeding for heparin compared to aspirin, aspirin + heparin compared to placebo, aspirin + heparin compared to aspirin, aspirin + P2Y12inhibitors + UFH/LMWH compared to aspirin + UFH/LMWH, and aspirin + ticagrelor/prasugrel + heparins compared to aspirin + clopidogrel + heparins.

Conclusion

To our knowledge, these findings are the first to report the safety and efficacy of all the various combinations of currently recommended ATT for the early management of NSTE-ACS, providing a comprehensive evidence-base to guide decisions depending on the patients’ bleeding risk and treatment strategy.

Cellular and Molecular Effects of High-Molecular-Weight Heparin on Matrix Metalloproteinase 9 Expression

Blood sampling with different anticoagulants alters matrix metalloproteinase (MMP-) 9 expression, thus influencing its concentration and diagnostic validity. Here, we aimed to evaluate the effects of different anticoagulants on MMP-9 regulation. MMP-9 expression was assessed in response to ethylenediaminetetraacetic acid, citrate, and high-/low-molecular-weight heparin (HMWH, LMWH) in co-culture experiments using THP-1, Jurkat, and HT cells (representing monocytes, T, and B cells). Triple and double cell line co-culture experiments revealed that HMWH treatment of THP-1 and Jurkat led to a significant MMP-9 induction, whereas other anticoagulants and cell type combinations had no effect. Supernatant of HMWH-treated Jurkat cells also induced MMP-9 in THP-1 suggesting monocytes as MMP-9 producers. HMWH-induced cytokine/chemokine secretion was assessed in co-culture supernatant, and the influence of cytokines/chemokines on MMP-9 production was analyzed. These experiments revealed that Jurkat-derived IL-16 and soluble intercellular adhesion molecule (sICAM-) 1 are able to induce MMP-9 and IL-8 production by THP-1. As a consequence, the increased MMP-9 expression found in HMWH blood samples may be influenced by HMWH-dependent secretion of IL-16 and sICAM-1 by T cells resulting in an increased production of MMP-9 and IL-8 by monocytes. IL-8, in turn, may support MMP-9 and its own expression in a positive autocrine feedback loop.

Comparison of enoxaparin and unfractionated heparin in patients with non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention: a systematic review and meta-analysis

Background

No randomized trial has been conducted to directly compare enoxaparin with unfractionated heparin (UFH) in patients undergoing percutaneous coronary intervention (PCI) for non-ST-segment elevation acute coronary syndrome (NSTE-ACS). In an era where early invasive strategies are recommended in high risk patients, the effect of enoxaparin and UFH needs to be re-evaluated. The authors performed a meta-analysis to determine whether enoxaparin is superior to UFH in patients with NSTE-ACS undergoing PCI.

Methods

The composite efficacy end point included all-cause mortality and myocardial infarction (MI) in the hospital or within 60 days. Major bleeding, as defined in the individual clinical trials evaluated, was the main safety endpoint within the same time period. Pooled estimates of the difference in outcome between enoxaparin and UFH were calculated using fixed or random effects models.

Results

A total of 8,861 patients from 4 trials were included. In the pooled analysis, rates of death or MI were similar in patients treated with enoxaparin and UFH [risk ratio (RR), 0.89, 95% confidence interval (CI): 0.77-1.02, P=0.09; I² =50%]. Major bleeding was also similar between enoxaparin and UFH (RR, 1.21, 95% CI: 0.94-1.56, P=0.15, I²=39%). A subgroup analysis, including randomized trials only or trials with a large sample size, and a leave-one-out sensitivity analysis, demonstrated similar results with above, respectively.

Conclusions

In patients undergoing PCI for NSTE-ACS, rates for both death/MI and major bleeding were similar between patients treated with enoxaparin and UFH.

Anticoagulant Therapy for Acute Coronary Syndromes

Anticoagulation in conjunction with antiplatelet therapy is central to the management of acute coronary syndromes (ACS). When used effectively it is associated with a reduction in recurrent ischaemic events including myocardial infarction and stent thrombosis as well as a reduction in death. Effective ischaemic risk reduction whilst balancing bleeding risk remains a clinical challenge. This article reviews the current available evidence for anticoagulation in ACS and recommendations from the European Society of Cardiology.

Clinical pathways and management of antithrombotic therapy in patients with acute coronary syndrome (ACS): a Consensus Document from the Italian Association of Hospital Cardiologists (ANMCO), Italian Society of Cardiology (SIC), Italian Society of Emergency Medicine (SIMEU) and Italian Society of Interventional Cardiology (SICI-GISE)

Antiplatelet therapy is the cornerstone of the pharmacologic management of patients with acute coronary syndrome (ACS). Over the last years, several studies have evaluated old and new oral or intravenous antiplatelet agents in ACS patients. In particular, research was focused on assessing superiority of two novel platelet ADP P2Y12 receptor antagonists (i.e., prasugrel and ticagrelor) over clopidogrel. Several large randomized controlled trials have been undertaken in this setting and a wide variety of prespecified and post-hoc analyses are available that evaluated the potential benefits of novel antiplatelet therapies in different subsets of patients with ACS. The aim of this document is to review recent data on the use of current antiplatelet agents for in-hospital treatment of ACS patients. In addition, in order to overcome increasing clinical challenges and implement effective therapeutic interventions, this document identifies all potential specific care pathway for ACS patients and accordingly proposes individualized therapeutic options.

Therapy of unstable angina with the low molecular weight heparins

Unstable angina is in most cases caused by partial or complete coronary artery occlusion due to the disruption of an atherosclerotic plaque and to thrombus formation. An immediate antithrombotic approach is essential to prevent fatal and non-fatal myocardial infarction, and the combination of aspirin and unfractionated heparin has played a pivotal role in the past years. Low molecular weight heparins have improved pharmacokinetic and pharmaco-dynamic properties over unfractionated heparin that have resulted in greater efficacy and safety in the field of venous thromboembolism. Low molecular weight heparins can be administered by once or twice daily subcutaneous injections at fixed, weight-adjusted doses without the need for monitoring. Because of their potential, many recent clinical trials have evaluated their efficacy and safety in the management of patients with unstable angina. Three low molecular weight heparins have so far been tested: nadroparin, dalteparin and enoxaparin. The results of the published trials confirm that the newer compounds are at least as safe and effective as unfractionated heparin, and offer considerable therapeutic advantages. Nevertheless, the different properties of the three compounds and perhaps the different designs of the clinical trials have led to not entirely comparable findings.

Routine invasive strategies versus selective invasive strategies for unstable angina and non-ST elevation myocardial infarction in the stent era

BACKGROUND

People with unstable angina and non-ST elevation myocardial infarction (UA/NSTEMI) are managed with a combination of medical therapy, invasive angiography and revascularisation. Specifically, two approaches have evolved: either a 'routine invasive' strategy whereby all patients undergo coronary angiography shortly after admission and, if indicated, coronary revascularisation; or a 'selective invasive' (also referred to as 'conservative') strategy in which medical therapy alone is used initially, with a selection of patients for angiography based upon evidence of persistent myocardial ischaemia. Uncertainty exists as to which strategy provides the best outcomes for these patients. This Cochrane review is an update of a Cochrane review originally published in 2006, to provide a robust comparison of these two strategies in the early management of patients with UA/NSTEMI.

OBJECTIVES

To determine the benefits and harms associated with the following.1. A routine invasive versus a conservative or 'selective invasive' strategy for the management of UA/NSTEMI in the stent era.2. A routine invasive strategy with and without glycoprotein IIb/IIIa receptor antagonists versus a conservative strategy for the management of UA/NSTEMI in the stent era.

SEARCH METHODS

We searched the following databases and additional resources up to 25 August 2015: the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library, MEDLINE and EMBASE, with no language restrictions.

SELECTION CRITERIA

We included prospective randomised controlled trials (RCTs) that compared invasive with conservative or 'selective invasive' strategies in participants with acute UA/NSTEMI.

DATA COLLECTION AND ANALYSIS

Two review authors screened the records and extracted data in duplicate. Using intention-to-treat analysis with random-effects models, we calculated summary estimates of the risk ratio (RR) with 95% confidence intervals (CIs) for the primary endpoints of all-cause death, fatal and non-fatal myocardial infarction (MI), combined all-cause death or non-fatal MI, refractory angina and re-hospitalisation. We performed further analysis of included studies based on whether glycoprotein IIb/IIIa receptor antagonists were used routinely. We assessed the heterogeneity of included trials using Pearson χ² (Chi² test) and variance (I² statistic) analysis. Using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, we assessed the quality of the evidence and the GRADE profiler (GRADEPRO) was used to import data from Review Manager 5.3 (Review Manager) to create Summary of findings (SoF) tables.

MAIN RESULTS

Eight RCTs with a total of 8915 participants (4545 invasive strategies, 4370 conservative strategies) were eligible for inclusion. We included three new studies and 1099 additional participants in this review update. In the all-study analysis, evidence did not show appreciable risk reductions in all-cause mortality (RR 0.87, 95% CI 0.64 to 1.18; eight studies, 8915 participants; low quality evidence) and death or non-fatal MI (RR 0.93, 95% CI 0.71 to 1.2; seven studies, 7715 participants; low quality evidence) with invasive strategies compared to conservative (selective invasive) strategies at six to 12 months follow-up. There was appreciable risk reduction in MI (RR 0.79, 95% CI 0.63 to 1.00; eight studies, 8915 participants; moderate quality evidence), refractory angina (RR 0.64, 95% CI 0.52 to 0.79; five studies, 8287 participants; moderate quality evidence) and re-hospitalisation (RR 0.77, 95% CI 0.63 to 0.94; six studies, 6921 participants; moderate quality evidence) with routine invasive strategies compared to conservative (selective invasive) strategies also at six to 12 months follow-up.Evidence also showed increased risks in bleeding (RR 1.73, 95% CI 1.30 to 2.31; six studies, 7584 participants; moderate quality evidence) and procedure-related MI (RR 1.87, 95% CI 1.47 to 2.37; five studies, 6380 participants; moderate quality evidence) with routine invasive strategies compared to conservative (selective invasive) strategies.The low quality evidence were as a result of serious risk of bias and imprecision in the estimate of effect while moderate quality evidence was only due to serious risk of bias.

AUTHORS' CONCLUSIONS

In the all-study analysis, the evidence failed to show appreciable benefit with routine invasive strategies for unstable angina and non-ST elevation MI compared to conservative strategies in all-cause mortality and death or non-fatal MI at six to 12 months. There was evidence of risk reduction in MI, refractory angina and re-hospitalisation with routine invasive strategies compared to conservative (selective invasive) strategies at six to 12 months follow-up. However, routine invasive strategies were associated with a relatively high risk (almost double the risk) of procedure-related MI, and increased risk of bleeding complications. This systematic analysis of published RCTs supports the conclusion that, in patients with UA/NSTEMI, a selectively invasive (conservative) strategy based on clinical risk for recurrent events is the preferred management strategy.

Risks and benefits of triple oral anti-thrombotic therapies after acute coronary syndromes and percutaneous coronary intervention

The key pathophysiological process underlying symptomatic coronary artery disease, including acute coronary syndromes (ACS), is usually a rupture or an erosion of an atherosclerotic plaque, followed by platelet activation and subsequent thrombus formation. Early clinical trials showed benefit with long-term aspirin treatment, and later-based on large clinical trials-dual anti-platelet therapy (DAPT), initially with clopidogrel, and more recently with prasugrel or ticagrelor, has become the established treatment in the post-ACS setting and after percutaneous coronary intervention (PCI). Treatment with DAPT is recommended for both ST-elevation myocardial infarction and non-ST-elevation ACS, as well as after PCI with stenting, in American and European clinical guidelines. Notwithstanding the benefits observed with DAPT, including third-generation P2Y12 receptor inhibitors plus aspirin, ACS patients remain at high risk for a recurrent cardiovascular event, suggesting that other treatment strategies, including the addition of a third oral anti-platelet agent or a novel oral anticoagulant (NOAC) to standard DAPT regimens, may provide additional benefit for post-ACS patients and for patients undergoing PCI. Adding a third anti-thrombotic agent to DAPT after an ACS event or a PCI procedure has been shown to have modest benefit in terms of ischemic event reduction, but has consistently been associated with increased bleeding complications. Therefore, the quest to optimize anti-thrombotic therapies post-ACS and post-PCI continues unabated but is tempered by the historical experiences to date that indicate that careful patient and dose selection will be critical features of future randomized trials.

Heparin versus placebo for non-ST elevation acute coronary syndromes

BACKGROUND

Non-ST elevation acute coronary syndromes (NSTEACS) represent a spectrum of disease including unstable angina and non-ST segment myocardial infarction (NSTEMI). Despite treatment with aspirin, beta-blockers and nitroglycerin, unstable angina/NSTEMI is still associated with significant morbidity and mortality. Although evidence suggests that low molecular weight heparin (LMWH) is more efficacious compared to unfractionated heparin (UFH), there is limited data to support the role of heparins as a drug class in the treatment of NSTEACS. This is an update of a review last published in 2008.

OBJECTIVES

To determine the effect of heparins (UFH and LMWH) compared with placebo for the treatment of patients with non-ST elevation acute coronary syndromes (unstable angina or NSTEMI).

SEARCH METHODS

For this update the Cochrane Heart Group Trials Search Co-ordinator searched the Cochrane Central Register of Controlled Trials on The Cochrane Library (2013, Issue 12), MEDLINE (OVID, 1946 to January week 1 2014), EMBASE (OVID, 1947 to 2014 week 02), CINAHL (1937 to 15 January 2014) and LILACS (1982 to 15 January 2014). We applied no language restrictions.

SELECTION CRITERIA

Randomized controlled trials of parenteral UFH or LMWH versus placebo in people with non-ST elevation acute coronary syndromes (unstable angina or NSTEMI).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed quality of studies and independently extracted data.

MAIN RESULTS

There were no new included studies for this update. Eight studies (3118 participants) were included in this review. We found no evidence for difference in overall mortality between the groups treated with heparin and placebo (risk ratio (RR) = 0.84, 95% confidence interval (CI) 0.36 to 1.98). Heparins compared with placebo, reduced the occurrence of myocardial infarction in patients with unstable angina and NSTEMI (RR = 0.40, 95% CI 0.25 to 0.63, number needed to benefit (NNTB) = 33). There was a trend towards more major bleeds in the heparin studies compared to control studies (RR = 2.05, 95% CI 0.91 to 4.60). From a limited data set, there appeared to be no difference between patients treated with heparins compared to control in the occurrence of thrombocytopenia (RR = 0.20, 95% CI 0.01 to 4.24). Assessment of overall risk of bias in these studies was limited as most of the studies did not give sufficient detail to allow assessment of potential risk of bias.

AUTHORS' CONCLUSIONS

Compared with placebo, patients treated with heparins had a similar risk of mortality, revascularization, recurrent angina, and thrombocytopenia. However, those treated with heparins had a decreased risk of myocardial infarction and a higher incidence of minor bleeding. Overall, the evidence assessed in this review was classified as low quality according to the GRADE approach. The results presented in this review must therefore be interpreted with caution.

[Myocardial revascularization]

Coronary artery disease (CAD) is a leading cause of morbidity and mortality in western countries and is of significant socio-economic importance due to its increasing prevalence. Until percutaneous coronary interventions (PCI) were established, CAD could only be treated by surgical revascularization or pharmacological therapy. In-stent restenosis remains a major problem after stent implantation. However, the use of new materials and stent coatings have led to a significant reduction in in-stent restenosis. Thus, surgical revascularization and PCI are currently of equal value for the treatment of CAD. The decision-making for PCI or surgical revascularization depends on various factors such as number of diseased vessels, complexity of the coronary stenoses, concomitant diseases, and the patient's general condition. The therapeutic regime of every patient should be adjusted to the recommendations of the European and German Society for Cardiology, while controversial and complex cases should be discussed in an interdisciplinary case conference ("heart team").

Acute coronary syndromes: from the emergency department to the cardiac care unit

Acute coronary syndromes result in a significant burden of morbidity and mortality in the United States. This spectrum of acute coronary thrombosis (including unstable angina, non-ST-segment elevation myocardial infarction, and ST-elevation myocardial infarction) has been well studied in large clinical trials. This review details the initial management of patients presenting with possible acute coronary syndromes in the context of care from the emergency department to the cardiac care unit. The importance of a rapid and focused evaluation, risk stratification, and appropriate therapies are discussed.

C-reactive Protein as a Predictor of Adverse outcome in Patients with Acute Coronary Syndrome

Background and Objectives:

The acute-phase reactant C-reactive protein (CRP) has been shown to reflect systemic and vascular inflammation and to predict future cardiovascular events. The objective of this study was to evaluate the prognostic value of CRP in predicting cardiovascular outcome in patients presenting with acute coronary syndromes.

Patients and Methods:

This prospective, single-centered study was carried out by the Department of Pathology in collaboration with the Department of Cardiology, Bolan Medical College Complex Quetta, Balochistan, Pakistan from January 2009 to December 2009. We studied 963 consecutive patients presenting with chest pain to Accident and Emergency Department. Patients were divided into four groups. Group-1 comprised patients with unstable angina; group-2 included patients with acute ST elevation myocardial infarction (STEMI); group-3 comprised patients with Non-ST elevation myocardial infarction (Non-STEMI) and group-4 was the control group. All four groups were followed-up for 90 days for occurrence of cardiovascular events.

Results:

The CRP was elevated (>3 mg/L) among 27.6% patients in Group-1; 70.9% in group- 2; 77.9% in group-3 and 5.3% in the control group. Among cases with elevated CRP, 92.1% had a cardiac event compared to 34.3% among patients with CRP £3 mg/L (P < 0.0001). The mortality was significantly higher (P < 0.0001) in group-2 (8.9%) and group-3 (11.9%) as compared to group-1 (2.1%). There was no cardiac event or mortality in Group-4.

Conclusions:

Elevated CRP is a predictor of adverse outcome in patients with acute coronary syndromes and helps in identifying patients who may be at risk of cardiovascular complications.

[Myocardial revascularization]

Coronary artery disease (CAD) is a leading cause of morbidity and mortality in western countries and is of significant socio-economic importance due to its increasing prevalence. Until percutaneous coronary interventions (PCI) were established, CAD could only be treated by surgical revascularization or pharmacological therapy. In-stent restenosis remains a major problem after stent implantation. However, the use of new materials and stent coatings have led to a significant reduction in in-stent restenosis. Thus, surgical revascularization and PCI are currently of equal value for the treatment of CAD. The decision-making for PCI or surgical revascularization depends on various factors such as number of diseased vessels, complexity of the coronary stenoses, concomitant diseases, and the patient's general condition. The therapeutic regime of every patient should be adjusted to the recommendations of the European and German Society for Cardiology, while controversial and complex cases should be discussed in an interdisciplinary case conference ("heart team").

Prehospital Use of Aspirin Rarely Is Associated with Adverse Events

Introduction:

Aspirin is commonly administered for acute coronary syndromes in the prehospital setting. Few studies have addressed the incidence of adverse effects associated with prehospital administration of aspirin. Objective: To determine the incidence of adverse events following the administration of aspirin by prehospital personnel.

Methods:

Multi-center, retrospective, case series that involved all patients who received aspirin in the prehospital setting from (01 August 1999–31 January 2000). Patient encounter forms of the emergency medical services (EMS) of a metropolitan fire department were reviewed. All patients who had a potential cardiac syndrome (i.e., chest pain, dyspnea) as documented on the EMS forms were included in the review. Exclusion criteria included failure to meet inclusion criteria, and chest pain secondary to apparent noncardiac causes (i.e., trauma). Hospital charts were reviewed from a subset of patients at the participating hospitals. The major outcome was an adverse event following prehospital administration of aspirin. This outcome was evaluated during the EMS encounter, at emergency department discharge, or at six and 24-hours post-aspirin ingestion. An adverse event secondary to aspirin ingestion was defined as anaphylaxis or allergic reactions, such as rash or respiratory changes.

Results:

A total of 25,600 EMS encounter forms were reviewed, yielding 2,399 patients with a potential cardiac syndrome. Prior to EMS arrival, 585 patients had received aspirin, and 893 were administered aspirin by EMS personnel. No patients had an adverse event during the EMS encounter. Of these patients, 229 were transported to participating hospitals and 219 medical records were available for review with no adverse reactions recorded during their hospital course.

Conclusion:

Aspirin is rarely associated with adverse events when administered by prehospital personnel for presumed coronary syndromes.

[Therapy strategies for acute coronary syndrome and after coronary interventions. Antiplatelet agents and anticoagulants]

There is ongoing development of new therapeutic regimens in the use of antithrombotic agents and anticoagulants focussing on acute coronary syndrome (ACS) with an increasing impact on current guidelines over the last years. This was especially accompanied by an increase in innovative percutaneous coronary interventional (PCI) methods in patients with ACS, non-ST-segment elevation myocardial infarction (NSTEMI) or ST-segment elevation myocardial infarction (STEMI) with a need for therapeutics with more sufficient and effective antiplatelet action. On the other hand, newer direct and indirect thrombin inhibitors with primary use in prevention and therapy of thromboembolic events have been shown to have beneficial and even superior effects in ACS with or without PCI. The current review aims to report on the evidence-based use of approved antithrombotic agents and anticoagulants in ACS with special focus on PCI according to the actualized European guidelines.

Early invasive versus conservative strategies for unstable angina and non-ST elevation myocardial infarction in the stent era

BACKGROUND

In patients with unstable angina and non-ST elevation myocardial infarction (UA/NSTEMI) two strategies are possible, either a routine invasive strategy where all patients undergo coronary angiography shortly after admission and, if indicated, coronary revascularization; or a conservative strategy where medical therapy alone is used initially, with selection of patients for angiography based on clinical symptoms or investigational evidence of persistent myocardial ischemia.

OBJECTIVES

To determine the benefits of an invasive compared to conservative strategy for treating UA/NSTEMI in the stent era.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 1), MEDLINE and EMBASE were searched (1996 to February 2008) with no language restrictions.

SELECTION CRITERIA

Included studies were prospective trials comparing invasive with conservative strategies in UA/NSTEMI.

DATA COLLECTION AND ANALYSIS

We identified five studies (7818 participants). Using intention-to-treat analysis with random-effects models, summary estimates of relative risk (RR) with 95% confidence interval (CI) were determined for primary end-points of all-cause death, fatal and non-fatal myocardial infarction, all-cause death or non-fatal myocardial infarction, and refractory angina. Further analysis of included studies was undertaken based on whether glycoprotein IIb/IIIa receptor antagonists were used routinely. Heterogeneity was assessed using Chi(2) and variance (I(2) statistic) methods.

MAIN RESULTS

In the all-study analysis, mortality during initial hospitalization showed a trend to hazard with an invasive strategy (RR 1.59, 95% CI 0.96 to 2.64). The invasive strategy did not reduce death on longer-term follow up. Myocardial infarction rates assessed at 6 to 12 months (5 trials) and 3 to 5 years (3 trials) were significantly decreased by an invasive strategy (RR 0.73, 95% CI 0.62 to 0.86; and RR 0.78, 95% CI 0.67 to 0.92 respectively). The incidence of early (< 4 month) and intermediate (6 to 12 month) refractory angina were both significantly decreased by an invasive strategy (RR 0.47, 95% CI 0.32 to 0.68; and RR 0.67, 95% CI 0.55 to 0.83 respectively), as were early and intermediate rehospitalization rates (RR 0.60, 95% CI 0.41to 0.88; and RR 0.67, 95% CI 0.61 to 0.74 respectively). The invasive strategy was associated with a two-fold increase in the RR of peri-procedural myocardial infarction (as variably defined) and a 1.7-fold increase in the RR of (minor) bleeding with no hazard of stroke.

AUTHORS' CONCLUSIONS

Compared to a conservative strategy for UA/NSTEMI, an invasive strategy is associated with reduced rates of refractory angina and rehospitalization in the shorter term and myocardial infarction in the longer term. However, the invasive strategy is associated with a doubled risk of procedure-related heart attack and increased risk of bleeding and procedural biomarker leaks. Available data suggest that an invasive strategy may be particularly useful in those at high risk for recurrent events.

Heparin and low-molecular weight heparins in thrombosis and beyond

Heparin and its improved version, low-molecular weight heparin (LMWH), are known to exert polypharmacological effects at various levels. Early studies focused on the plasma anti-Xa and anti-IIa pharmacodynamics of different LMWHs. Other important pharmacodynamic parameters for heparin and LMWH, including effects on vascular tissue factor pathway inhibitor (TFPI) release, inhibition of inflammation through NFkappaB, inhibition of key matrix-degrading enzymes, selectin modulation, inhibition of platelet-cancer cell interactions, and inflammatory cell adhesion, help explain the diverse clinical impact of this class of agents in thrombosis and beyond.

Acute coronary syndromes: diagnosis and management, part I

The term acute coronary syndrome (ACS) refers to any group of clinical symptoms compatible with acute myocardial ischemia and includes unstable angina (UA), non-ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI). These high-risk manifestations of coronary atherosclerosis are important causes of the use of emergency medical care and hospitalization in the United States. A quick but thorough assessment of the patient's history and findings on physical examination, electrocardiography, radiologic studies, and cardiac biomarker tests permit accurate diagnosis and aid in early risk stratification, which is essential for guiding treatment. High-risk patients with UA/NSTEMI are often treated with an early invasive strategy involving cardiac catheterization and prompt revascularization of viable myocardium at risk. Clinical outcomes can be optimized by revascularization coupled with aggressive medical therapy that includes anti-ischemic, antiplatelet, anticoagulant, and lipid-lowering drugs. Evidence-based guidelines provide recommendations for the management of ACS; however, therapeutic approaches to the management of ACS continue to evolve at a rapid pace driven by a multitude of large-scale randomized controlled trials. Thus, clinicians are frequently faced with the problem of determining which drug or therapeutic strategy will achieve the best results. This article summarizes the evidence and provides the clinician with the latest information about the pathophysiology, clinical presentation, and risk stratification of ACS and the management of UA/NSTEMI.

Acute coronary syndromes: diagnosis and management, part I

The term acute coronary syndrome (ACS) refers to any group of clinical symptoms compatible with acute myocardial ischemia and includes unstable angina (UA), non-ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI). These high-risk manifestations of coronary atherosclerosis are important causes of the use of emergency medical care and hospitalization in the United States. A quick but thorough assessment of the patient's history and findings on physical examination, electrocardiography, radiologic studies, and cardiac biomarker tests permit accurate diagnosis and aid in early risk stratification, which is essential for guiding treatment. High-risk patients with UA/NSTEMI are often treated with an early invasive strategy involving cardiac catheterization and prompt revascularization of viable myocardium at risk. Clinical outcomes can be optimized by revascularization coupled with aggressive medical therapy that includes anti-ischemic, antiplatelet, anticoagulant, and lipid-lowering drugs. Evidence-based guidelines provide recommendations for the management of ACS; however, therapeutic approaches to the management of ACS continue to evolve at a rapid pace driven by a multitude of large-scale randomized controlled trials. Thus, clinicians are frequently faced with the problem of determining which drug or therapeutic strategy will achieve the best results. This article summarizes the evidence and provides the clinician with the latest information about the pathophysiology, clinical presentation, and risk stratification of ACS and the management of UA/NSTEMI.

Percutaneous coronary intervention in patients with acute coronary syndrome: focus on bivalirudin

Previously, indirect thrombin inhibitors such as unfractionated heparin or low-molecular-weight heparin were used as a standard anticoagulation during percutaneous coronary intervention to prevent procedural thrombotic complications but at a risk of hemorrhagic complications. More recently, bivalirudin, a member of the direct thrombin inhibitor class, has been shown to have 1) predictable pharmacokinetics, 2) ability to inhibit free- and clot-bound thrombin, 3) no properties of platelet activation, 4) avoidance of heparin-induced thrombocytopenia, and 5) a significant reduction of bleeding without a reduction in thrombotic or ischemic endpoints compared to heparin and glycoprotein IIbIIIa inhibitors when used in patients presenting with acute coronary syndrome who are planned for an invasive treatment strategy.

Heparin versus placebo for acute coronary syndromes

BACKGROUND

Acute coronary syndromes (ACS) represent a spectrum of disease including unstable angina (UA) and non-ST segment myocardial infarction (NSTEMI). Despite treatment with aspirin, beta-blockers and nitroglycerin, UA/NSTEMI is still associated with significant morbidity and mortality. Although emerging evidence suggests that low molecular weight heparin (LMWH) is more efficacious compared to unfractionated heparin (UFH), there is limited data to support the role of heparins as a drug class in the treatment of ACS.

OBJECTIVES

To determine the effect of heparins (UFH and LMWH) compared with placebo for the treatment of patients with ACS.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials on The Cochrane Library (issue 4, 2002), MEDLINE (1966 to May 2002), EMBASE (1980 to May 2002) and CINAHL (1982 to May 2002). Authors of included studies and pharmaceutical industry representatives were contacted to determine if unpublished studies which met the inclusion criteria were available.

SELECTION CRITERIA

Randomized controlled trials of parenteral UFH or LMWH versus placebo in people with ACS (UA or NSTEMI).

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed quality of studies. Data were extracted independently by two reviewers. Study authors were contacted to verify and clarify missing data.

MAIN RESULTS

Eight studies (3118 participants) were included in this review. We found no evidence for difference in overall mortality between the groups treated with heparin and placebo (RR = 0.84, 95% CI 0.36 to 1.98). Heparins reduced the occurrence of MI (RR = 0.40, 95% CI 0.25 to 0.63, NNT = 33). An increase in the incidence of minor bleeds (RR = 6.80, 95% CI 1.23 to 37.49, NNH = 17).

AUTHORS' CONCLUSIONS

Compared to placebo, patients treated with heparins had similar risk of mortality, revascularization, recurrent angina, major bleeding and thrombocytopenia. However, those treated with heparins had decreased risk of MI and a higher incidence of minor bleeding.

Management of non-ST-Segment Elevation Myocardial Infarction

Non-ST-segment elevation myocardial infarction (NSTEMI) is a major cause of cardiovascular morbidity and mortality in the United States. It represents the highest risk category of non-ST-segment elevation acute coronary syndromes (NSTEACS), for which timely diagnosis and appropriate therapy are paramount to improve outcomes. Evidence-based treatment, with combination of antiplatelet and anticoagulant therapy, and with serious consideration of early coronary angiography and revascularization along with anti-ischemic medical therapy, is the mainstay of management for NSTEMI. Aggressive risk-factor control after the acute event is imperative for secondary prevention of cardiovascular events. Applying in practice the American College of Cardiology/American Heart Association (ACC/AHA) guideline recommendations results in improved outcomes.

Early invasive versus conservative strategies for unstable angina & non-ST-elevation myocardial infarction in the stent era

BACKGROUND

In patients with unstable angina and non-ST-elevation myocardial infarction (UA/NSTEMI) two strategies are possible: a routine invasive strategy where all patients undergo coronary angiography shortly after admission and, if indicated, coronary revascularization; or a conservative strategy where medical therapy alone is used initially with selection of patients for angiography based on clinical symptoms or investigational evidence of persistent myocardial ischemia.

OBJECTIVES

To determine the benefits of an invasive compared to a conservative strategy for treating UA/NSTEMI in the stent era.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (Issue 3 2005), MEDLINE and EMBASE were searched from 1996 to September 2005 with no language restrictions.

SELECTION CRITERIA

Included studies were prospective trials comparing invasive with conservative strategies in UA/NSTEMI.

DATA COLLECTION AND ANALYSIS

We identified 5 studies (7818 participants). Using intention-to-treat analysis with random effects models, summary estimates of relative risk (95% confidence interval [CI]) were determined for primary end-points of all-cause death, fatal and non-fatal myocardial infarction; all-cause death or non-fatal myocardial infarction; and refractory angina. Further analysis of included studies was undertaken based on whether glycoprotein IIb/IIIa receptor antagonists were used routinely. Heterogeneity was assessed using chi-square and variance (I(2)) methods.

MAIN RESULTS

In the all-study analysis, mortality during initial hospitalization showed a trend to hazard with an invasive strategy; relative risk 1.59 (95% CI 0.96 to 2.64). Mortality and myocardial infarction assessed at 2-5 years in two trials were significantly decreased by an invasive strategy with relative risk of 0.75 (95% CI 0.62 to 0.92) and 0.75 (95% CI 0.61 to 0.91) respectively. The composite end-point of death or non-fatal myocardial infarction was significantly decreased by an invasive strategy at several time points after initial hospitalization. The incidence of early (<4 months) and intermediate (6-12 months) refractory angina were both significantly decreased by an invasive strategy; relative risk 0.47 (95% CI 0.32 to 0.68) and 0.67 (95% CI 0.55 to 0.83) respectively, as were early and intermediate rehospitalization rates with relative risk 0.60 (95% CI 0.41 to 0.88) and 0.67 (95% CI 0.61 to 0.74) respectively. The invasive strategy was associated with a two-fold increase in the relative risk of peri-procedural myocardial infarction (as variably defined) and a 1.7-fold increase in the relative risk of bleeding.

AUTHORS' CONCLUSIONS

An early invasive strategy is preferable to a conservative strategy in the treatment of UA/NSTEMI.

Heparin therapy leads to platelet activation and prolongation of PFA-100 closure time

BACKGROUND

Heparin is used in the treatment of venous and arterial thromboembolic events, including unstable angina. Once unfractionated heparin is discontinued during the acute phase of unstable angina, it has been demonstrated that the disease process may be reactivated within hours. It is hypothesized that this reactivation may be a result of direct platelet activation by heparin that can linger even after the drug itself has been stopped. Prior studies have shown that heparin can either increase or decrease platelet activation. More recent studies have also shown conflicting effects of unfractionated heparin on PFA-100 testing.

METHODS

We studied the in-vitro effects of unfractionated heparin on platelet function and PFA-100 testing. Unfractionated heparin was incubated with whole blood taken from 18 healthy volunteers. Platelet activation and aggregation was assessed with and without the presence of heparin.

RESULTS

Platelet aggregation and activation were increased in the presence of heparin. Unfractionated heparin also significantly prolonged collagen/adenosine diphosphate closure time but did not affect collagen/epinephrine closure time.

CONCLUSIONS

Unfractionated heparin leads to direct platelet activation and increases platelet aggregation in vitro. Unfractionated heparin causes prolongation of the collagen/adenosine diphosphate closure time in PFA-100 testing, possibly as a result of direct binding to von Willebrand factor in solution and interference with von Willebrand factor-glycoprotein Ib binding.

Treating non-ST-segment elevation ACS. Pros and cons of current strategies

NSTE-ACS is a complex clinical event characterized by a variable degree of myocardial ischemia and triggered, in most patients, by a rupture of a vulnerable plaque that leads to acute intraluminal nonocclusive thrombosis. Traditionally, acute management strategies for NSTE-ACS have been aimed at identification of vascular areas with discrete atheroma and revascularization of the affected myocardium. Studies that have evaluated invasive strategies in NSTE-ACS suggest that the rates of hard clinical events are similar for both intensive medical treatment and early invasive management strategies. As shown recently in the Cooperative Cardiovascular Project study, intensive therapy with beta-blockers appears to be a viable management option that has comparable outcomes in most patients with NSTE-ACS. Although several different treatment strategies have been advocated in the management of NSTE-ACS, the available evidence-based information does not fully support some of these traditional approaches. Future prospective, well-controlled trials are needed to fully ascertain the role of invasive and other medical management strategies in patients with NSTE-ACS. Long-term aggressive management of established risk factors for CAD is unquestionably the most prudent and cost-effective therapeutic approach in the long-term management in patients recovering from NSTE-ACS.

[Acute coronary syndrome in the prehospital phase]

Cardiovascular diseases are the number one cause of death in Germany. In 2002 about 70,000 people died of acute myocardial infarction (AMI) and of these 37% died before arrival at hospital which underlines the relevance of adequate prehospital care. The generic term acute coronary syndrome (ACS) was introduced because a single pathomechanism accounts for the different forms and comprises unstable angina pectoris (iAP), non-ST-elevation myocardial infarction (NSTEMI), ST-elevation myocardial infarction (STEMI) and sudden cardiac death (SCD). Characteristic features are retrosternal pain, vegetative symptoms and radiation of pain into the adjoining regions. Further differentiation can only be achieved by the 12-lead ECG, as cardiac-specific enzymes do not play a role in prehospital decisions. Prehospital delays should be avoided, history and physical examination should be brief but focused, vital parameters should be assessed and monitored. Basic treatment for ACS should comprise inhalative oxygen, nitrates, morphine, aspirin and beta-blockers. If STEMI is diagnosed, patients with symptoms <12 h should undergo fibrinolytic therapy unless there is primary percutaneous coronary intervention (PCI) available within 90 min or if contraindicated. Heparin should be given to patients with STEMI depending on the choice of fibrinolytic agent, it otherwise results in a higher risk of bleeding, but in patients with iAP or NSTEMI it reduces mortality. All patients must be accompanied by the emergency physician during transportation and should be brought to a hospital with primary PCI, especially those with complicated ACS. Treatment of complications depends largely on the type, persistence and severity.

Contemporary management of acute coronary syndrome

This review focuses on the modern management of the non-ST elevation acute coronary syndromes (unstable angina and non-ST elevation myocardial infarction). Patients with these syndromes are at varying degrees of risk of (re)infarction and death. This risk can be reliably predicted by clinical, electrocardiographic, and biochemical markers. Aspirin, clopidogrel, heparin (unfractionated or low molecular weight), and anti-ischaemic drugs should be offered to all patients, irrespective of the predicted level of risk. Patients at high risk should also receive a glycoprotein IIb/IIIa receptor inhibitor and should undergo early coronary arteriography with a view to percutaneous or surgical revascularisation. Lower risk patients should undergo non-invasive testing. When inducible myocardial ischaemia is exhibited coronary arteriography should follow. When non-invasive testing is negative, a conservative management strategy is safe.