Thrombin-specific anticoagulation with bivalirudin versus heparin in patients receiving fibrinolytic therapy for acute myocardial infarction: the HERO-2 randomised trial

Confidence distributions for treatment effects in clinical trials: Posteriors without priors

An attractive feature of using a Bayesian analysis for a clinical trial is that knowledge and uncertainty about the treatment effect is summarized in a posterior probability distribution. Researchers often find probability statements about treatment effects highly intuitive and the fact that this is not accommodated in frequentist inference is a disadvantage. At the same time, the requirement to specify a prior distribution in order to obtain a posterior distribution is sometimes an artificial process that may introduce subjectivity or complexity into the analysis. This paper considers a compromise involving confidence distributions, which are probability distributions that summarize uncertainty about the treatment effect without the need for a prior distribution and in a way that is fully compatible with frequentist inference. The concept of a confidence distribution provides a posterior-like probability distribution that is distinct from, but exists in tandem with, the relative frequency interpretation of probability used in frequentist inference. Although they have been discussed for decades, confidence distributions are not well known among clinical trial statisticians and the goal of this paper is to discuss their use in analyzing treatment effects from randomized trials. As well as providing an introduction to confidence distributions, some illustrative examples relevant to clinical trials are presented, along with various case studies based on real clinical trials. It is recommended that trial statisticians consider presenting confidence distributions for treatment effects when reporting analyses of clinical trials.

Bleeding characteristics and mortality outcomes following ST-elevation myocardial infarction thrombolysis: a 5-year analysis in an Asian population

BACKGROUND

Bleeding outcomes are crucial primary safety endpoints in studies involving thrombolytic agents. This study aimed to determine the incidence, characteristics and mortality outcomes of bleeding following ST-elevation myocardial infarction (STEMI) thrombolysis in an Asian population.

METHODS

This single-centre retrospective study included all STEMI patients who received thrombolytic therapy from 2016 to 2020 in a Malaysian tertiary hospital. Total population sampling was used in this study. The primary outcome was bleeding events post-thrombolysis, categorised using the Thrombolysis in Myocardial Infarction (TIMI) bleeding criteria. Inferential statistics were used to determine the associations between relevant variables.

RESULTS

Data from 941 patients were analysed. A total of 156 (16.6%) STEMI patients bled post-thrombolysis. Major, minor, and minimal TIMI occurred in 7 (0.7%), 17 (1.8%), and 132 (14.0%) patients, respectively. Age 65 years (P=0.031) and Malaysian Chinese (P=0.008) were associated with a higher incidence of bleeding post-thrombolysis. Conversely, foreigners (P=0.032) and current smoker (P=0.007) were associated with a lower incidence of bleeding. Both TIMI major (P<0.001) and TIMI minor (P<0.001) were associated with a higher incidence of all-cause in-hospital mortality among STEMI patients. TIMI minor bleeding was significantly higher in the streptokinase recipients. The bleeding sites were comparable between streptokinase and tenecteplase recipients, except for a significantly higher incidence of gastrointestinal bleeding in the streptokinase recipients (P=0.027).

CONCLUSION

In our Asian population, the incidence of total bleeding events following STEMI thrombolysis is comparable to that previously reported. The development of TIMI major and minor bleeding complications is associated with higher mortality.

Chromogenic and Clot-Based Bivalirudin Assays for Monitoring Anticoagulation

BACKGROUND

Direct thrombin inhibitors (DTIs) are usually monitored with the activated partial thromboplastin time (aPTT) or activated clotting time (ACT). Both are complex assays with multiple enzymatic steps, and performance may be influenced by physiologic and pathologic factors unrelated to the DTI. Simpler systems, such as clot-based dilute thrombin time (dTT) and chromogenic anti-factor IIa assays, have been developed for monitoring DTIs, but there is limited data on their performance in clinical settings.

METHODS

Medical records of patients who received bivalirudin between March 2020 and April 2022 at a single institution were reviewed for demographic data and adverse outcomes. Plasma samples drawn for aPTT testing were analyzed with chromogenic anti-IIa and dTT bivalirudin assays. Results were compared to bivalirudin dosing.

RESULTS

Results of aPTT assays from 32 patients were compared with the chromogenic (n = 136) and dTT (n = 120) bivalirudin assays. Correlations between the aPTT and the chromogenic and dTT assays were poor (Spearman coefficients 0.55 and 0.62, respectively). There was a stronger correlation when results of the chromogenic and dTT assays were compared to each other (Spearman coefficient 0.92). When assay results were compared to bivalirudin dose, there were stronger correlations with the chromogenic and dTT assays than with the aPTT (Spearman coefficients 0.51, 0.63 and 0.22, respectively).

CONCLUSIONS

There was considerable variation between results of specific bivalirudin assays and the aPTT. While bivalirudin assay results correlated better with administered drug dose, suggesting improving reliability, more studies are needed to determine if there is correlation between testing and clinical outcomes.

A Historical Perspective on the Reversal of Anticoagulants

There has been a landmark shift in the last several decades in the management and prevention of thromboembolic events. From the discovery of parenteral and oral agents requiring frequent monitoring as early as 1914, to the development of direct oral anticoagulants (DOACs) that do not require monitoring or dose adjustment in the late 20th century, great advances have been achieved. Despite the advent of these newer agents, bleeding continues to be a key complication, affecting 2 to 4% of DOAC-treated patients per year. Bleeding is associated with substantial morbidity and mortality. Although specific reversal agents for DOACs have lagged the release of these agents, idarucizumab and andexanet alfa are now available as antagonists. However, the efficacy of these reversal agents is uncertain, and complications, including thrombosis, have not been adequately explored. As such, guidelines continue to advise the use of nonspecific prohemostatic agents for patients requiring reversal of the anticoagulant effect of these drugs. As the indications for DOACs and the overall prevalence of their use expand, there is an unmet need for further studies to determine the efficacy of specific compared with nonspecific pro-hemostatic reversal agents. In this review, we will discuss the evidence behind specific and nonspecific reversal agents for both parenteral and oral anticoagulants.

The outcomes of reperfusion therapy with streptokinase versus tenecteplase in ST-elevation myocardial infarction (STEMI): a propensity-matched retrospective analysis in an Asian population

Background Fibrinolysis using streptokinase or tenecteplase remains the primary reperfusion strategy for ST-elevation myocardial infarction (STEMI) in many Asian countries, including Malaysia. Comparative outcomes of these two fibrinolytic agents in the Asian population were inconclusive despite being widely used. Aim We aimed to assess and compare the outcomes of streptokinase versus tenecteplase in STEMI reperfusion of an Asian population. Method This single-centre retrospective study analysed data on STEMI patients who received fibrinolytic therapy from 2016 to 2020 in the Emergency Department of the largest tertiary hospital in Malaysia. Total population sampling was used in this study. Based on the propensity score matching, 359 patients receiving streptokinase were matched against 359 patients receiving tenecteplase by incorporating 16 variables that potentially affect mortality. 30-day mortality, stroke and major bleeding were the primary outcome measures. Results There was no significant difference in 30-day mortality between streptokinase (n = 39, 11.2%) and tenecteplase (n = 46, 13.2%) groups (p = 0.418). The rates of ischemic strokes [streptokinase (n = 1, 0.3%) versus tenecteplase (n = 3, 0.9%), p = 0.624], intracranial haemorrhage [streptokinase (n = 3, 0.9%) versus tenecteplase (n = 1, 0.3%), p = 0.624] and major bleeding [streptokinase (n = 4, 1.1%) versus tenecteplase (n = 3, 0.9%), p = 0.624], were comparable for the two groups. The incidences of failed thrombolysis were significantly higher in the tenecteplase arm. Hypotension and allergic reaction were significantly higher in the streptokinase arm. Conclusion Streptokinase and tenecteplase are fibrinolytic agents with similar efficacy and safety in STEMI reperfusion therapy in our Asian population.

Reperfusion After Fibrinolytic Therapy (RAFT): An open-label, multi-centre, randomised controlled trial of bivalirudin versus heparin in rescue percutaneous coronary intervention

BACKGROUND

The safety and efficacy profile of bivalirudin has not been examined in a randomised controlled trial of patients undergoing rescue PCI.

OBJECTIVES

We conducted an open-label, multi-centre, randomised controlled trial to compare bivalirudin with heparin ± glycoprotein IIb/IIIa inhibitors (GPIs) in patients undergoing rescue PCI.

METHODS

Between 2010-2015, we randomly assigned 83 patients undergoing rescue PCI to bivalirudin (n = 42) or heparin ± GPIs (n = 41). The primary safety endpoint was any ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) bleeding at 90 days. The primary efficacy endpoint was infarct size measured by peak troponin levels as a multiple of the local upper reference limit (Tn/URL). Secondary endpoints included periprocedural change in haemoglobin adjusted for red cells transfused, TIMI (Thrombolysis in Myocardial Infarction) bleeding, ST-segment recovery and infarct size determined by the Selvester QRS score.

RESULTS

The trial was terminated due to slow recruitment and futility after an interim analysis of 83 patients. The primary safety endpoint occurred in 6 (14%) patients in the bivalirudin group (4.8% GPIs) and 3 (7.3%) in the heparin ± GPIs group (54% GPIs) (risk ratio, 1.95, 95% confidence interval [CI], 0.52-7.3, P = 0.48). Infarct size was similar between the two groups (mean Tn/URL, 730 [±675] for bivalirudin, versus 984 [±1585] for heparin ± GPIs, difference, 254, 95% CI, -283-794, P = 0.86). There was a smaller decrease in the periprocedural haemoglobin level with bivalirudin than heparin ± GPIs (-7.5% [±15] versus -14% [±17], difference, -6.5%, 95% CI, -0.83-14, P = 0.0067). The rate of complete (≥70%) ST-segment recovery post-PCI was higher in patients randomised to heparin ± GPIs compared with bivalirudin.

CONCLUSIONS

Whether bivalirudin compared with heparin ± GPI reduces bleeding in rescue PCI could not be determined. Slow recruitment and futility in the context of lower-than-expected bleeding event rates led to the termination of this trial (ANZCTR.org.au, ACTRN12610000152022).

Reacting to prognostic covariate imbalance in randomised controlled trials

Clinical trialists may regard an observed imbalance on a prognostic covariate as sufficiently troubling to warrant action.

OBJECTIVE

To elucidate the issues associated with selecting, and switching between, an unadjusted versus an adjusted analysis in response to an observed covariate imbalance.

STUDY DESIGN AND SETTING

Simulation study performed under the null hypothesis of no treatment effect using data from a large secondary prevention trial of statin therapy. The operating characteristics of three reaction strategies to baseline imbalances observed post-hoc were assessed.

RESULTS

Unadjusted analyses produced valid p-values irrespective of chance imbalance on a prognostic covariate. Switching to an adjusted analysis introduced no bias when the decision was made without knowledge of the direction of the imbalance. When the decision was based on the direction of the imbalance, the risk of incorrectly declaring the experimental treatment superior was inflated (by up to 48% in the scenarios investigated).

CONCLUSION

Overreaction to baseline imbalances observed post-hoc is unwarranted and we support adherence to the ICH guideline recommendations on the use of covariates. A legitimate case for switching to an adjusted analysis prior to finalisation of the statistical analysis plan (SAP) could nevertheless be potentially made provided that the direction of an observed covariate imbalance is unknown. Investigators should avoid reviewing the distribution of baseline characteristics across randomised groups in an unblinded fashion, for open-label and blinded studies alike, prior to finalisation of the SAP.

WHAT IS NEW

ICH guidelines on adjustment for covariates in RCT analyses appropriately advise against overreaction to baseline imbalances observed post-hoc. CONSORT reporting guidelines nevertheless place an emphasis on comparability of baseline characteristics across randomised groups. We demonstrate through a series of simulation studies why the ICH guidance is sound, but that a switch to an adjusted analysis in reaction to an observed prognostic covariate imbalance could legitimately be made provided that, when reaching the decision, treatment allocation is masked, and the direction of the imbalance is unknown. Trialists should therefore consider preserving the masking of actual treatment assignment when assessing the distribution of baseline characteristics across randomised groups.

Effect of a Quality of Care Improvement Initiative in Patients With Acute Coronary Syndrome in Resource-Constrained Hospitals in China: A Randomized Clinical Trial

Importance

Prior observational studies suggest that quality of care improvement (QCI) initiatives can improve the clinical outcomes of acute coronary syndrome (ACS). To our knowledge, this has never been demonstrated in a well-powered randomized clinical trial.

Objective

To determine whether a clinical pathway-based, multifaceted QCI intervention could improve clinical outcomes among patients with ACS in resource-constrained hospitals in China.

Design, Setting, Participants

This large, stepped-wedge cluster randomized clinical trial was conducted in nonpercutaneous coronary intervention hospitals across China and included all patients older than 18 years and with a final diagnosis of ACS who were recruited consecutively between October 2011 and December 2014. We excluded patients who died before or within 10 minutes of hospital arrival. We recruited 5768 and 0 eligible patients for the control and intervention groups, respectively, in step 1, 4326 and 1365 in step 2, 3278 and 3059 in step 3, 1419 and 4468 in step 4, and 0 and 5645 in step 5.

Interventions

The intervention included establishing a QCI team, training clinical staff, implementing ACS clinical pathways, sequential site performance assessment and feedback, online technical support, and patient education. The usual care was the control that was compared.

Main Outcomes and Measures

The primary outcome was the incidence of in-hospital major adverse cardiovascular events (MACE), comprising all-cause mortality, reinfarction/myocardial infarction, and nonfatal stroke. Secondary outcomes included 16 key performance indicators (KPIs) and the composite score developed from these KPIs.

Results

Of 29 346 patients (17 639 men [61%]; mean [SD] age for control, 64.1 [11.6] years; mean [SD] age for intervention, 63.9 [11.7] years) who were recruited from 101 hospitals, 14 809 (50.5%) were in the control period and 14 537 (49.5%) were in the intervention period. There was no significant difference in the incidence of in-hospital MACE between the intervention and control periods after adjusting for cluster and time effects (3.9% vs 4.4%; odds ratio, 0.93; 95% CI, 0.75-1.15; P = .52). The intervention showed a significant improvement in the composite KPI score (mean [SD], 0.69 [0.22] vs 0.61 [0.23]; P < .01) and in 7 individual KPIs, including the early use of antiplatelet therapy and the use of appropriate secondary prevention medicines at discharge. No unexpected adverse events were reported.

Conclusions and Relevance

Among resource-constrained Chinese hospitals, introducing a multifaceted QCI intervention had no significant effect on in-hospital MACE, although it improved a few of the care process indicators of evidence-based ACS management.

Trial Registration

ClinicalTrials.gov identifier: NCT01398228.

Anticoagulation in the cardiac patient: A concise review

Anticoagulation has multiple roles in the treatment of cardiovascular disease, including in management of acute myocardial infarction, during percutaneous coronary intervention, as stroke prophylaxis in patients with atrial arrhythmias, and in patients with mechanical heart valves. Clinical anticoagulation choices in the aforementioned diseases vary widely, due to conflicting data to support established agents and the rapid evolution of evidence-based practice that parallels more widespread use of novel oral anticoagulants. This review concisely summarizes evidence-based guidelines for anticoagulant use in cardiovascular disease, and highlights new data specific to direct oral anticoagulants.

Modern Management of ST-Segment Elevation Myocardial Infarction

Disruption of intracoronary plaque with thrombus formation resulting in severe or total occlusion of the culprit coronary artery provides the pathophysiologic foundation for ST-segment elevation myocardial infarction (STEMI). Management of STEMI focuses on timely restoration of coronary blood flow along with antithrombotic therapies and secondary prevention strategies. The purpose of this review is to discuss the epidemiology, pathophysiology, and diagnosis of STEMI. In addition, the review will focus on guideline-directed therapy for these patients and review potential associated complications.

An update on the use of anticoagulant therapy in ST-segment elevation myocardial infarction

INTRODUCTION

Together with antiplatelet therapy, anticoagulants are vital to improve outcomes in patients presenting with ST-segment elevation myocardial infarction. Challenges lie in finding the optimal balance between the risk of bleeding and preventing thrombotic complications such as reinfarction or stent thrombosis. During the last decade, bivalirudin was introduced as a valid alternative to heparin for patients undergoing primary percutaneous coronary intervention. Several trials have been conducted to identify the agent with the best antithrombotic results at the lowest bleeding complication rate. In a rapidly evolving field with changes in vascular access, available P2Y₁₂ inhibitors, and indications for glycoprotein IIb/IIIa inhibitor administration, conflicting evidence became available.

AREAS COVERED

This paper mainly focuses on the evidence above and gives brief discussion to the recent literature on anticoagulation in fibrinolytic therapy and advances in antiplatelet therapy.

EXPERT OPINION

To date, no robust evidence is available challenging unfractionated heparin as the primary choice for anticoagulation in patients presenting with ST-segment elevation myocardial infarction. Further research should include efforts to refine anticoagulation strategies on an individual patient level. For patients undergoing primary percutaneous coronary intervention, bivalirudin could be used as an alternative to unfractionated heparin, while enoxaparin or fondaparinux is an alternative agent for patients treated with fibrinolytic therapy.

In the transition from fibrinolysis to primary PCI, the HERO trials help refine STEMI ECG interpretation and Q wave analysis potentially alters future management

Electrocardiogram sub-studies from the Hirulog Early Reperfusion/Occlusion 1 and 2 trials, which tested bivalirudin as an adjunctive anticoagulant to fibrinolysis in ST-elevation myocardial infarction, have contributed to the literature. The concept of using the presence of infarct lead Q waves to determine reperfusion benefit has subsequently been explored in multiple primary percutaneous coronary intervention studies. The angiographic findings before percutaneous coronary intervention combine with the baseline electrocardiogram to accurately diagnose ST-elevation myocardial infarction and evaluate its potential territory. This review discusses the relative merits of the presence of infarct lead Q waves versus time duration from symptom onset using observational data from cohorts of patients from multiple clinical trials. The presence of infarct lead Q waves at presentation has been repeatedly shown to be superior to time duration from symptom onset in determining prognosis, despite that continuous variable (time duration) statistically should be more powerful than dichotomous variable (Q wave). If quantitative or semi-quantitative measurement of Q waves correlates well with irreversible myocardial injury in vivo (a research goal of many cardiac magnetic resonance imaging studies), Q waves measurements by mirroring ST-elevation myocardial infarction evolution better than the current metric of time duration of symptoms will impact future ST-elevation myocardial infarction reperfusion management. Newer methodology will more quickly capture and transmit electrocardiogram information including infarct lead Q waves potentially before first medical contact, and help differentiate new evolving Q waves of the ongoing ST-elevation myocardial infarction from old changes. Q waves as the new metric in ST-elevation myocardial infarction reperfusion should be tested in upcoming trials.

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.

A Practical Review of the Emerging Direct Anticoagulants, Laboratory Monitoring, and Reversal Agents

Millions of patients in the United States use anticoagulation for a variety of indications, such as the prevention of stroke in those with atrial fibrillation (AF) and the treatment and prevention of venous thrombosis. For over six decades warfarin was the only available oral anticoagulant, but now several DOACs are available and their use has become more prevalent in recent years. In spite of this increased use, many physicians remain reluctant to prescribe DOACs due to concerns about bleeding and reversibility.

Comparison of antithrombotic agents during urgent percutaneous coronary intervention following thrombolytic therapy: A retrospective cohort study

BACKGROUND

The optimal antithrombotic regimen for urgent percutaneous coronary interventions (PCI) following thrombolytic therapy for ST segment myocardial infarction (STEMI) is currently unknown.

METHODS

We performed a retrospective analysis of all patients referred to our institution from January 2005 to July 2014 who underwent urgent PCI within 24 hr after receiving thrombolytic therapy. The patients were divided into three cohorts based on the anticoagulation strategy during PCI-bivalirudin, heparin alone or heparin plus Glycoprotein IIb/IIIa inhibitor (GPI). The primary end point of major adverse cardiovascular events (MACE) was defined as a composite of inpatient death, myocardial infarction (MI) and stroke. Net adverse clinical events (NACE) were defined as a combination of MACE plus major bleeding complications. Univariable, multivariable and propensity-weighted modeling were used to compare MACE and NACE between the three treatment groups.

RESULTS

A total of 695 patients met the inclusion criteria during the study period. In the univariable analysis, there was no significant difference treatment in MACE between the three groups (Bivalirudin: 1.2% vs. Heparin + GPI: 4.4%; Heparin alone: 2.7%, P = 0.11). In the reduced logistic regression model, compared to bivalirudin, the odds of NACE was significantly higher with heparin alone (OR: 3.58, 95% CI: 1.21, 10.54, P = 0.02) or with heparin plus GPI (OR: 9.0, 95% CI: 2.83, 28.64, P <0.001).

CONCLUSION

In STEMI patients undergoing PCI within 24 hr after thrombolytic therapy, bivalirudin was associated with a strong trend toward reduced bleeding complications as compared to heparin alone or heparin plus GPI. The optimal antithrombotic regiment for urgent PCI following thrombolytic therapy is currently unknown. Our study demonstrated that use of bivalirudin during PCI following thrombolytic therapy is associated with a trend toward reduced bleeding complications compared to heparin alone or heparin plus GPI. Large randomized trials of adjunctive anticoagulation during PCI in this complex post-thrombolytic population are warranted. © 2017 Wiley Periodicals, Inc.

Comparative efficacy and safety of reperfusion therapy with fibrinolytic agents in patients with ST-segment elevation myocardial infarction: a systematic review and network meta-analysis

BACKGROUND

Fibrinolytic therapy offers an alternative to mechanical reperfusion for ST-segment elevation myocardial infarction (STEMI) in settings where health-care resources are scarce. Comprehensive evidence comparing different agents is still unavailable. In this study, we examined the effects of various fibrinolytic drugs on clinical outcomes.

METHODS

We did a network meta-analysis based on a systematic review of randomised controlled trials comparing fibrinolytic drugs in patients with STEMI. Several databases were searched from inception up to Feb 28, 2017. We included only randomised controlled trials that compared fibrinolytic agents as a reperfusion therapy in adult patients with STEMI, whether given alone or in combination with adjunctive antithrombotic therapy, against other fibrinolytic agents, a placebo, or no treatment. Only trials investigating agents with an approved indication of reperfusion therapy in STEMI (streptokinase, tenecteplase, alteplase, and reteplase) were included. The primary efficacy outcome was all-cause mortality within 30-35 days and the primary safety outcome was major bleeding. This study is registered with PROSPERO (CRD42016042131).

FINDINGS

A total of 40 eligible studies involving 128 071 patients treated with 12 different fibrinolytic regimens were assessed. Compared with accelerated infusion of alteplase with parenteral anticoagulants as background therapy, streptokinase and non-accelerated infusion of alteplase were significantly associated with an increased risk of all-cause mortality (risk ratio [RR] 1·14 [95% CI 1·05-1·24] for streptokinase plus parenteral anticoagulants; RR 1·26 [1·10-1·45] for non-accelerated alteplase plus parenteral anticoagulants). No significant difference in mortality risk was recorded between accelerated infusion of alteplase, tenecteplase, and reteplase with parenteral anticoagulants as background therapy. For major bleeding, a tenecteplase-based regimen tended to be associated with lower risk of bleeding compared with other regimens (RR 0·79 [95% CI 0·63-1·00]). The addition of glycoprotein IIb or IIIa inhibitors to fibrinolytic therapy increased the risk of major bleeding by 1·27-8·82-times compared with accelerated infusion alteplase plus parenteral anticoagulants (RR 1·47 [95% CI 1·10-1·98] for tenecteplase plus parenteral anticoagulants plus glycoprotein inhibitors; RR 1·88 [1·24-2·86] for reteplase plus parenteral anticoagulants plus glycoprotein inhibitors).

INTERPRETATION

Significant differences exist among various fibrinolytic regimens as reperfusion therapy in STEMI and alteplase (accelerated infusion), tenecteplase, and reteplase should be considered over streptokinase and non-accelerated infusion of alteplase. The addition of glycoprotein IIb or IIIa inhibitors to fibrinolytic therapy should be discouraged.

FUNDING

None.

Controversies in the Management of ST Elevation Myocardial Infarction: Thrombin Inhibition

Anticoagulation is essential in patients with ST elevation myocardial infarction (STEMI) to prevent further thrombosis and to maintain patency of the infarct-related artery after reperfusion. The various anticoagulant medications available for use in patients with STEMI include unfractionated heparin (UFH), low-molecular-weight heparin, fondaparinux, and bivalirudin, a direct thrombin inhibitor. The authors review the current anticoagulation strategies for patients with STEMI undergoing primary percutaneous coronary intervention (PCI), fibrinolysis, or no reperfusion. The authors present the latest evidence and controversies on this topic, with a focus on bivalirudin versus UFH in the setting of primary PCI for STEMI.

Thymosin β4 promotes the survival and angiogenesis of transplanted endothelial progenitor cells in the infarcted myocardium

The survival of transplanted stem cells in ischemic tissue is poor. In the present study, the effects of thymosin β4 (Tβ4) on the survival and angiogenesis of endothelial progenitor cells (EPCs) and improvement in cardiac functions after transplantation of Tβ4-treated EPCs in the infarcted myocardium were investigated. EPCs were isolated from bone marrow of adult male rats and incubated in Endothelial Basal Medium-2. Then the cells were treated with Tβ4 at different concentrations (0.05, 0.1 and 0.2 µM), and cells incubated with DMEM were set as controls. MTT assay, Transwell assay and tube formation in Matrigel were used to detect cell viability, migration and angiogenesis, respectively. For examining the protective effect of Tβ4 on EPCs, the cells were also incubated in the condition of hypoxia and serum deprivation. p-Akt expression was also examined using western blot analysis. Rat models of myocardial infarction (MI) were established by ligation of the anterior descending branch of the left coronary artery. At four weeks after intramyocardial injection of Tβ4-treated EPCs, the changes in cardiac functions, size of the scar tissue and density of microvessels were examined by echocardiography, Masson's trichrome staining, immunohistochemistry and fluorescence in situ hybridization (FISH) for the Y-chromosome. Tβ4 enhanced EPC viability, protected the cells from apoptosis in hypoxia and serum deprivation, and promoted the proliferation and migration of the cells and formation of capillary-like structures in the cells. Moreover, Tβ4 increased p-Akt expression in the cells. The cytoprotective and proangiogenic effects of Tβ4 were in a dose-dependent manner. Tβ4-treated EPCs improved cardiac function, enhanced the repair of the infarcted myocardium, and promoted angiogenesis after transplantation in the infarcted myocardium. In conclusion, pretreatment of EPCs with Tβ4 is a novel strategy for the repair of ischemic tissue after transplantation in MI.

Pre-hospital management of patients with chest pain and/or dyspnoea of cardiac origin. A position paper of the Acute Cardiovascular Care Association (ACCA) of the ESC

Chest pain and acute dyspnoea are frequent causes of emergency medical services activation. The pre-hospital management of these conditions is heterogeneous across different regions of the world and Europe, as a consequence of the variety of emergency medical services and absence of specific practical guidelines. This position paper focuses on the practical aspects of the pre-hospital treatment on board and transfer of patients taken in charge by emergency medical services for chest pain and dyspnoea of suspected cardiac aetiology after the initial assessment and diagnostic work-up. The objective of the paper is to provide guidance, based on evidence, where available, or on experts’ opinions, for all emergency medical services’ health providers involved in the pre-hospital management of acute cardiovascular care.

Therapy in ST-elevation myocardial infarction: reperfusion strategies, pharmacology and stent selection

OPINION STATEMENT

The estimated annual incidence of new and recurrent myocardial infarction (MI) in the U.S. is 715,000 events. Primary percutaneous coronary intervention (PCI) is the reperfusion strategy of choice in most patients with acute ST-elevation myocardial infarction (STEMI). Recent advances in percutaneous techniques and devices, including manual aspiration catheters and newer generation drug eluting stents and pharmacologic therapies, such as novel antiplatelets and anticoagulants have led to significant improvements in the acute and long-term outcomes for these patients. Implementation of community-wide systems directed to shorten treatment times tied to closely monitored quality improvement processes have led to further advances in STEMI care. Recent data suggests that transradial access for primary PCI is associated with improved outcomes. This contemporary review discusses the strategies for reperfusion, pharmacological therapy and stent selection process involved in STEMI.

Risks and Benefits of Thrombolytic, Antiplatelet, and Anticoagulant Therapies for ST Segment Elevation Myocardial Infarction: Systematic Review

Objectives. Assess the impact of associating thrombolytics, anticoagulants, antiplatelets, and primary angioplasty (PA) on death, reinfarction (AMI), and major bleeding (MB) in STEMI therapy. Methods. Medline search was performed to identify randomized trials comparing these classes in STEMI treatment, at least 500 patients, providing death, AMI, and MB rates. Similar arms were grouped. Correlation between number of drugs and PA and the outcomes was evaluated, as well as correlation between the year of the study and the outcomes. Results. Fifty-nine papers remained after exclusions. 404.556 patients were divided into 35 groups of arms. There was correlation between the number of drugs and rates of death (r = -0.466, P = 0.005) and MB (r = 0.403, P = 0.016), confirmed by multivariate regression. This model also showed that PA is associated with lower mortality and increased MB. Year and period of publication correlated with the outcomes: death (r = -0.380, P < 0.001), MB (r = 0.212, P = 0.014), and AMI (r = -0.231, P = 0.009). Conclusion. The increasing complexity of STEMI treatment has resulted in significant reduction in mortality along with increased rates of MB. Overall, however, the benefits of treatment outweigh the associated risks of MB.

Bivalirudin: an anticoagulant option for percutaneous coronary intervention

Coronary artery thrombosis is usually triggered by platelet-rich thrombus superimposed on a spontaneously or mechanically disrupted atherosclerotic plaque. Thrombin and platelets both play a role in this process. Unfractionated heparin and aspirin have served as cornerstones in the prevention and treatment of intracoronary thrombus, but unfractionated heparin has several limitations that necessitate the use of adjunctive therapies, such as glycoprotein IIb/IIIa receptor inhibitors and clopidogrel, in order to reduce the risk of ischemic events. These combination therapies, however, typically increase the risk for bleeding complications, as well as the cost and complexity of treatment. Bivalirudin (Angiomax, The Medicines Company), a thrombin-specific anticoagulant, does not share heparin's limitations. Bivalirudin appears to provide clinical advantages over unfractionated heparin therapy in acute coronary syndrome patients and those undergoing percutaneous coronary intervention, without increasing cost or complexity of treatment for most patients.

Safety of bivalirudin in percutaneous coronary intervention following thrombolytic therapy

OBJECTIVES

This study was undertaken to evaluate the safety of bivalirudin (BIV) use during percutaneous coronary intervention (PCI), following thrombolytic therapy in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

BIV has emerged as a safer anticoagulant than unfractionated heparin (UFH) during primary PCI; however, its use in patients who receive thrombolytic therapy has not been established.

METHODS

A consecutive series of 104 patients who presented with STEMI treated with full-dose thrombolytics and who subsequently received PCI within 6 hr was identified and analyzed. BIV use was compared with UFH for in-hospital bleeding and ischemic events. The primary end points were the rate of major bleeding and the rate of net adverse clinical events as defined in the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction trial. The study cohort consisted of 104 patients, of whom 47 (45%) received BIV and 57 (55%) received UFH.

RESULTS

Patients on BIV were more frequently preloaded with clopidogrel, while intraprocedural glycoprotein IIb/IIIa inhibitors were used only in UFH patients. In-hospital death, ischemic events, and thrombolysis in myocardial infarction major bleeding occurred more frequently in patients treated with UFH. The net adverse clinical events rate was lower in the intraprocedural BIV group (3 [6.4%] vs. 12 [21.1%] UFH, P = 0.034).

CONCLUSIONS

The use of BIV in patients presenting with STEMI who were pretreated with thrombolytic therapy and who subsequently underwent PCI is safe and is associated with less ischemic and bleeding events when compared with UFH, and should be considered as the first line anticoagulant for these patients during PCI.

New ST-depression: an under-recognized high-risk category of 'complete' ST-resolution after reperfusion therapy

AIM

It is not known if there is an association between resolution of ST-elevation to ST-depression following fibrinolysis and 30-day mortality.

METHODS

In an ECG substudy of HERO-2, which compared bivalirudin to unfractionated heparin following streptokinase in 12,556 patients with ST-elevation myocardial infarction ECGs were recorded at baseline and at 60 minutes after commencing fibrinolysis. The main outcome measure was 30-day mortality.

RESULTS

Using summed ST-segment elevation and five categories of changes in the infarct leads, further ST-elevation, 0-30% ST-resolution, >30-70% (partial) ST-resolution, >70% (complete) ST-resolution, and new ST-depression occurred in 21.7, 24.9, 36.8, 14.8, and 1.8% of patients, with 30-day mortality of 12.3, 11.7, 8.0, 4.2, and 8.1%, respectively. For the comparison of new ST-depression with complete ST-resolution and no ST-depression, p<0.01 with 24-hour mortality 4.5 vs. 1.3%, respectively (p=0.0003). Patients with new ST-depression had similar peak cardiac enzyme elevations as patients with complete ST-resolution without ST-depression. On multivariate analysis including summed ST-elevation at baseline, age, sex, and infarct location, new ST-depression was a significant predictor of 30-day mortality (OR 1.82, 95% CI 1.42-4.29).

CONCLUSIONS

In patients with complete ST-resolution following fibrinolysis, new ST-depression at 60 minutes developed in 10.8% of patients. These patients had higher mortality than patients with complete ST-resolution without ST-depression and represent a high-risk group which could benefit from rapid triage to early angiography and revascularization as appropriate.

Early invasive strategy and outcomes of non-ST-elevation acute coronary syndrome patients: is time really the major determinant?

In non-ST-elevation acute coronary syndromes (ACS), an early invasive strategy is recommended for middle/high-risk patients; however, the optimal timing for coronary angiography is still debated. The aim of this study was to evaluate the prognostic implications of the time of angiography in ACS patients treated in accord with an early invasive strategy. We analyzed the relationship between the time of angiography and outcomes at follow-up in 517 ACS patients, of whom 482 were revascularized with percutaneous coronary intervention (PCI) (86.9%) or coronary artery by-pass graft (13.1%). We also evaluated the influence of clinical, biohumoral and angiographic variables on the patients' outcomes at follow-up. Among patients submitted to angiography at different time intervals from both hospital admission and symptom onset, significant differences neither in mortality nor in cardiac ischemic events at follow-up were observed. At univariate analysis, complete versus partial revascularization, longer hospital stay, higher TIMI risk score, diabetes mellitus, higher discharge creatinine and admission anemia were associated with mortality and cardiac ischemic events at follow-up; a lower left ventricular ejection fraction was associated with mortality; higher peak troponin I and previous PCI were associated with cardiac ischemic events at follow-up. At multivariate analysis longer hospital stay, higher discharge creatinine levels, and previous PCI were independent predictors of cardiac ischemic events at follow-up. Our evaluation in ACS patients treated with an early invasive strategy does not support the concept that angiography should be performed as soon as possible after symptom onset or hospital admission. Rather, an unfavorable long-term outcome is influenced principally by the clinical complexity of patients.

Is There Still a Role for Fibrinolysis in ST-Elevation Myocardial Infarction?

OPINION STATEMENT

Fibrinolysis had long been the reference treatment in patients with ST-Elevation Myocardial Infarction (STEMI). It was associated with a large reduction in mortality as compared with delayed or no reperfusion in patients managed early, within the first 2 hours from the onset of symptoms. Fibrinolysis also had well-known potential complications: cerebral haemorrhage, especially in patients beyond 75 years, and reinfarction. Primary percutaneous intervention (PCI) has overcome most of these limitations, but at a price: PCI-related delays that can reduce the expected benefit of primary PCI compared with fibrinolysis. That primary PCI is today the treatment of choice in patients with STEMI is no longer discussed. However, fibrinolysis should still maintain a role in the management of acute myocardial infarction (AMI) for three reasons. First, fibrinolysis is no longer a stand-alone treatment. Modern fibrinolytic strategies combine immediate fibrinolysis, loading dose of thienopyridines, and transfer to a PCI hospital for rescue or early PCI within 24 hours. These strategies capitalize on the hub-and-spoke networks that have, or should have, been built everywhere to implement primary PCI. The overall clinical results of these modern fibrinolytic strategies are now similar to those of primary PCI. Second, a substantial number of patients cannot be managed with primary PCI within the reasonable time thresholds set by the guidelines. In the case of long PCI-related delays, patients will benefit from fibrinolysis before or during transfer to a PCI hospital. Third, modern fibrinolytic strategies-immediate fibrinolysis followed by rescue or early PCI-may even offer the best results of all in a subset of patients. Patients of less than 75 years, managed within the first 2 hours and who cannot have immediate PCI, will fare better with a modern fibrinolytic strategy than with primary PCI. Guidelines advocate regional networks between hospitals with and without PCI capabilities, an efficient ambulance service and standardization of AMI management through shared protocols. These regional logistics of care are essential to take full advantage of fibrinolysis strategies. In order to check that these strategies are correctly applied, networks need ongoing registries, as well as benchmarking and quality improvement initiatives.

Optimal Anticoagulant Therapy in ST Elevation Myocardial Infarction Interventions

Bivalirudin is a direct thrombin inhibitor. It is a new recommendation for the treatment of patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention. Bivalirudin combined with aspirin and P2Y₁₂ inhibitors has proved to be an effective and safe choice for the management of thrombus in coronary artery disease. The use of bivalirudin compared with the combination of heparin plus glycoprotein IIb/IIIa inhibitors as anticoagulant therapy is associated with reduced severe bleeding and inpatient mortality, as well as diminished costs. There is only a slight increase of late stent thrombosis, which may be controlled with the use of thienopyridines.

Age related issues in reperfusion of myocardial infarction

Advances in pharmacological treatment and effective early myocardial revascularization have led to improved clinical outcomes in patients with acute myocardial infarction (AMI). However, it has been suggested that compared to younger subjects, elderly AMI patients are less likely to receive evidence-based treatment. Several reasons have been postulated to explain this trend, including uncertainty regarding the benefits of the commonly used interventions in the older age group as well as increased risk associated with comorbidities. The diagnosis, management, and post-hospitalization care of elderly patients presenting with an acute coronary syndrome (ACS) pose many difficulties at present due, at least in part, to the fact that trial data are scanty as elderly patients have been poorly represented in most clinical trials. Thus it appears that these high-risk individuals are often managed with more conservative strategies, compared to younger patients. This article reviews current evidence regarding management of AMI in the elderly.

Direct thrombin inhibitors

Heparins and vitamin K antagonists have been the primary agents used for anticoagulation in certain cardiovascular and thromboembolic diseases for over 50 years. However, they can be difficult to administer and are fraught with limitations. In response to the need for new anticoagulants, direct thrombin inhibitors (DTIs) have been developed and investigated for their utility in prophylaxis and treatment of venous thromboembolism (VTE), heparin-induced thrombocytopenia (HIT), acute coronary syndromes (ACS), secondary prevention of coronary events after ACS, and nonvalvular atrial fibrillation. Currently, four parenteral direct inhibitors of thrombin activity are FDA-approved in North America: lepirudin, desirudin, bivalirudin and argatroban. Of the new oral DTIs, dabigatran etexilate is the most studied and promising of these agents. This review discusses the clinical indications and efficacy of these direct thrombin inhibitors as well as future directions in anticoagulant therapy.

The prognostic meaning of the full spectrum of aVR ST-segment changes in acute myocardial infarction

AIMS

ST-elevation in lead aVR is known to be associated with a worse prognosis in patients with acute ST elevation myocardial infarction (MI) but the significance of ST depression in lead aVR has been unclear. Infarction of the inferior apex of the left ventricle may not be appreciated on the standard 12-lead electrocardiogram (ECG) except by observing ST depression in lead aVR which is reciprocal to lead V(7). We therefore determined the prognostic value of the full spectrum of aVR ST changes in patients presenting with acute ST elevation MI.

METHODS AND RESULTS

Lead aVR ST level was measured on randomization and 60 min ECGs in 15 315 patients with normal conduction from the HERO-2 trial. The outcome measure was 30-day mortality. aVR ST elevation ≥1 mm was associated with higher 30-day mortality for both inferior (22.5% for ≥1.5 mm and 13.2% for 1 mm) and anterior (23.5% for ≥1.5 mm and 11.5% for 1 mm) infarction. In contrast, deeper aVR ST depression (0, 0.5, 1, and ≥1.5 mm) was associated with higher mortality for anterior infarction (9.8, 13.2, 12.8, and 16.8%, respectively, trend P-value <0.0001) but not for inferior infarction. The resolution of aVR ST depression and ST elevation 60 min after fibrinolysis was associated with lower mortality.

CONCLUSION

There is a U-shaped relationship between 30-day mortality and aVR ST level in patients presenting with anterior but not inferior ST elevation MI.

Quality of acute myocardial infarction care and outcomes in 33,997 patients aged 80 years or older: findings from Get With The Guidelines-Coronary Artery Disease (GWTG-CAD)

OBJECTIVES

To determine the adherence to national guidelines and in-hospital mortality of older patients with acute myocardial infarction (AMI) using a national database.

BACKGROUND

Prior studies have demonstrated that older patients are less likely to receive evidence-based therapies.

METHODS

Using data from the GWTG-CAD, we examined care and in-hospital outcomes among AMI patients treated at 416 US centers from 2000 to 2009. Evidence-based medical therapy, other quality measures, and in-hospital post-AMI mortality were analyzed.

RESULTS

A total of 156,677 patients were included in the study; 21.7% (n = 33,997) were aged ≥80 years, 33.0% (n = 51,773) 65 to 79 years, and 45.3% (n = 70,907) 18 to 64 years. Older patients had higher prevalence of comorbidities compared to younger patients. Overall, compliance with evidence-based medical treatment upon admission and discharge was high, but age-related differences in care were seen for most measures. After multivariate adjustment, the mortality of the patients aged ≥80 years was substantially higher compared to the youngest cohort (adjusted OR 3.4, 95% CI 3.2-3.8, P < .0001). There were substantial improvements in AMI quality measures over time in each age group.

CONCLUSIONS

Among AMI patients aged ≥80 years, the use of evidence-based therapies was high and significant improvements over time have been observed in a national quality improvement program. Nevertheless, there remain important age-related gaps in care and outcomes, suggesting opportunities exist to improve prognosis in this high-risk population.