Reperfusion in acute myocardial infarction

During the past decade, the general acceptance of the primary role of thrombosis in acute myocardial infarction (AMI) has led to intense interest in the potential efficacy of reperfusion therapy, particularly thrombolytic therapy, in AMI. Accumulating evidence indicates that systemic thrombolytic therapy administered early after the onset of symptoms of AMI can restore infarct-related artery patency, salvage myocardium, and reduce mortality. Recommendations about the proper use of thrombolytic therapy, contraindications, and concomitant therapies (such as aspirin, heparin, nitrates, beta-adrenergic blocking agents, and calcium channel blockers) are reviewed. Although percutaneous transluminal coronary angioplasty (PTCA) is useful for subsets of patients with AMI (for example, patients with anterior infarctions with persistent occlusion of the infarct-related artery after thrombolytic therapy and those with cardiogenic shock), a conservative strategy, including angiography and PTCA only for postinfarction ischemia, is indicated for most patients with AMI in whom initial thrombolytic therapy is apparently successful. The use of PTCA after failed thrombolysis or as direct therapy for AMI seems promising, although further comparisons of PTCA and intravenous thrombolytic therapy are needed. Ongoing studies should help further define the risk-to-benefit ratio of various reperfusion strategies in different subsets of patients, define time limitations for reperfusion therapy, and provide data on therapeutic modalities that will limit reperfusion injury and therefore enhance salvage of myocardium.     

Cardiogenic shock: thrombolysis or angioplasty?

Cardiogenic shock (CGS) occurs in 3 to 20% of patients presenting with acute myocardial infarction (MI), and it generally involves dysfunction of at least 40% of the total myocardial mass. Prior to the advent of balloon angioplasty and thrombolysis, in-hospital mortality was greater than 75%. This mortality rate has been consistent in reported series despite the advent of cardiac intensive care units, vasopressor, inotropic, and vasodilator therapy. Intra-aortic balloon counterpulsation therapy provides hemodynamic improvement, and it may provide some mortality benefit when used in conjunction with appropriate revascularization. Survival studies have shown that patency of the infarct-related artery is a strong predictor of survival. No randomized trials have been completed to examine which reperfusion therapy best treats this emergent situation. Subgroup analysis of large scale, multicenter trials, although underpowered, has shown no improvement in mortality with use of thrombolytic agents, leading many to advise use of mechanical intervention. In patients who present with acute MI with contraindications to thrombolysis, primary angioplasty is the treatment of choice. At selected centers, primary angioplasty is comparable to or better than thrombolytic therapy for patients presenting with acute MI, with or without CGS. Studies examining angioplasty in patients with CGS have shown high procedural success rates (75%) and reduced in-hospital mortality (44%), particularly in those patients with successful revascularization. Emergency bypass surgery may improve survival, but it is costly, unavailable to many, and often leads to excessive delays in therapy. If available, we believe that primary angioplasty is the treatment of choice for patients with CGS.     

The Relative Merits of Direct Angioplasty versus Intravenous Thrombolytic Therapy for the Treatment of Acute Myocardial Infarction

There is growing interest in the use of angioplasty as the primary method to achieve coronary artery reperfusion in patients with acute myocardial infarction. The use of thrombolytic therapy has been established as effective in many large clinical trials, while only a few small studies have been completed comparing primary angioplasty with thrombolytic therapy. This paper briefly compares the use of these two treatment modalities and concludes that primary angioplasty is the preferred approach in patients with cardiogenic shock and for those patients with large myocardial infarctions who have contraindications to thrombolytic therapy. Other patients with AMI should receive thrombolytic therapy unless there are contraindications to this treatment.     

Fibrinolysis in patients with acute coronary syndrome

The reperfusion therapy including both fibrinolytic therapy and primary percutaneous coronary intervention (PCI) has been established in patients with ST-segment elevation acute myocardial infarction (STEMI). Fibrinolysis has the advantage of universal availability and short time to administration. Because the benefit of fibrinolysis is directly related to the time from symptom onset to treatment as demonstrated in many studies, every effort must be made to minimize any delays between symptom onset and the initiation of a safe and effective reperfusion strategy in patients with STEMI. Although the benefit of fibrinolysis is limited by inadequate reperfusion or reocclusion of the infarct-related artery in a sizable portion of patients, fibrinolysis followed by planned PCI can be one of approaches in patients presenting within 2 or 3 hours from onset of STEMI.     

Management of acute myocardial infarct with ST segment elevation

In the management of acute myocardial infarction with ST segment elevation, the primary goal is rapid reperfusion of the initially occluded infarct-related coronary artery. This may be achieved either by catheter using direct coronary angioplasty or by medical therapy in form of thrombolysis. These two methods, their concomitant treatment strategies as well as most recent results of combination therapy are presented and discussed. This results in recommendations for the management of these patients which have to take into account logistic possibilities and minimize time delays.     

急诊应用不同溶栓药物治疗ST段抬高型心肌梗死回顾性分析

目的比较使用瑞替普酶(rPA)、阿替普酶(rt-PA)和重组链激酶(r-SK)对ST段抬高型心肌梗死(STEMI)患者进行静脉溶栓治疗的临床疗效。方法自2003-02~2006-12我院急诊科72例STEMI患者接受静脉溶栓治疗,其中rPA组24例,rt-PA组31例,r-SK组17例,统计治疗后血管再通率、死亡率及观察有无出血、心力衰竭、心源性休克等并发症。结果血管再通率:rPA组87.50%、rt-PA组83.87%及r-SK组70.59%,其中60min及90min再通率rPA组、rt-PA组高于r-SK组。溶栓后30d内再闭塞率、心力衰竭等并发症发生率三组比较差异无统计学意义(P>0.05)。死亡率:rPA组8.33%、rt-PA组6.45%及r-SK组11.76%。出血发生率:rPA组、rt-PA组高于r-SK组。结论rPA、rt-PA及r-SK均适合急诊科内STEMI患者的静脉溶栓治疗,rPA、rt-PA早期再通率高于r-SK。     

The optimum reperfusion pathway for ST elevation acute myocardial infarction: development of a decision framework

There is currently much debate about the relative roles of pharmacological reperfusion (ie, thrombolysis) and mechanical reperfusion (ie, primary percutaneous coronary intervention (PPCI) in the management of patients with acute ST segment elevation acute myocardial infarction (STEMI). Whilst the scientific debate is reaching some resolution in terms of appropriate interpretation of the evidence base, there are still significant resource issues within the UK that limit our ability to implement gold standard reperfusion therapy. Current evidence supports the use of one or other strategy in certain situations depending on various patient-related and logistical factors. This paper reviews the literature and builds the case for developing a strategic approach which includes both mechanical and pharmacological interventions, proposing that these are not mutually exclusive-indeed, that an approach which excludes one of these interventions will not be to the benefit of all patients. There is also a discussion of the role of rescue PPCI, facilitated PPCI and early post thrombolysis angiography in the management of STEMI. Cardiac networks throughout the UK are developing strategies to improve access to these interventions and this paper offers advice on the logical selection of interventions for reperfusion in the context of a clinical decision framework that is evidence-based, pragmatic and develops through a series of scenarios with increasing availability of resources. Four sequential scenarios are presented: the first to set the scene is largely consigned to history; the last, as of yet, is not robustly achievable within the UK, but represents the "optimum reperfusion pathway", to which most cardiac networks are striving. Most of us currently find ourselves in a period of change between the two and will relate to either scenario two or three.     

Coronary Thrombolysis

Randomized trials have demonstrated the overall benefits and risks of thrombolytic therapy for acute myocardial infarction, and have evaluated adjunctive drug therapies, adjunctive and primary angioplasty, various approaches to the timing of thrombolysis, and post-thrombolysis management. Three questions, which remain unanswered, are addressed in this Point-Counterpoint Series. The GUSTO trial provides convincing evidence of the greater efficacy of rt-PA by comparison to SK, but the size of the benefit is uncertain, as are the risk benefit ratios and cost-effectiveness in various patient subgroups. The issues of whether or not routine angiography is appropriate for patients who have received coronary thrombolysis remains unresolved. For the present, clinical guidelines are likely to advise against routine angiography, while many cardiologists, concerned about the shortcomings of available studies, may wish to undertake coronary angiography in many of their patients, even though definitive proof of its benefit is lacking. Although randomized clinical trials suggest a benefit of primary angioplasty over thrombolytic therapy, further studies are required to clarify the comparative benefits in terms of clinically important outcomes and cost-effectiveness.     

新型冠状病毒肺炎防控形势下救治策略调整对急性ST段抬高型心肌梗死患者救治效果

目的 在新型冠状病毒肺炎疫情防控形势下,探讨救治策略改变对急性ST段抬高型心肌梗死(ST-segment elevation acute myocardial infarction, STEMI)患者救治的有效性和安全性。方法 选取河北医科大学第二医院心内科在新型冠状病毒肺炎(COVID-19)防控形势期间收治的急性STEMI患者34例纳入研究组,新型冠状病毒肺炎防控常态化期间收治的急性STEMI患者62例纳入对照组,比较两组一般临床资料、再灌注治疗情况[发病至首次医疗接触时间(Onset-to-FMC)、首次医疗接触时间至导丝通过(FMC to wire,FMC-to-W)时间、心肌梗死溶栓治疗试验(thrombolysis in myocardial infarction, TIMI)血流分级、总缺血时间(从症状发作到导丝通过病变的时间)、首次医疗接触时间至开始溶栓(FMC to needle of thrombolysis, FMC-to-N)时间、溶栓再通比例、24 h内接受再灌注治疗比例、支架植入率、住院天数等]、主要不良心血管事件(major adverse cardiac events, MACE)、出血事件、心功能相关指标。结果 研究组Onset-to-FMC时间和总缺血时间明显延长(P<0.05),接受静脉溶栓治疗比例增高,而接受直接经皮冠状动脉介入治疗(primary percutaneous coronary intervention, pPCI)的患者比例降低(P<0.05),支架置入比例、住院天数低于对照组(P<0.05);两组心功能指标比较,研究组入院时血清BNP高于对照组(P=0.042)。结论 在新型冠状病毒肺炎疫情防控形势下,STEMI患者Onset-to-FMC时间和总缺血时间明显延长,接受静脉溶栓治疗比例增高,接受PPCI的患者比例减少,但出血风险及MACE没有增加。救治策略改变保证了STEMI患者的有效再灌注,没有对STEMI患者救治有效性和安全性产生不利影响。     

Management of coronary heart disease: stable angina, acute coronary syndrome, myocardial infarction

Stable angina should first be treated medically, particularly with aspirin and beta-blockers. Diagnostic stress tests are used in patients who have intermediate probability of CHD to further assess the likelihood of disease,with catheterization reserved for patients who have symptoms despite optimal medical therapy or are at risk for multivessel CHD. The work-up for low-risk unstable angina can involve medical management followed by stress testing. Moderate-to-high risk unstable angina and NSTEMI should be treated with an integrated approach, using medical therapy, cardiac catheterization, and revascularization. Patients who have STEMI require urgent reperfusion either with thrombolytic agents or primary angioplasty. Follow-ing a diagnosis of CHD, patients should undergo intense coronary risk-fac-tor modification to reduce the risk of future events.     

The role of angioplasty in acute myocardial infarction

The role of percutaneous transluminal coronary angioplasty (PTCA) in the management of acute myocardial infarction (AMI) has not yet been precisely defined. The longest experience with PTCA in this setting has been in patients who are not candidates for thrombolytic therapy and in patients in whom thrombolysis has failed. Clinical interest has recently focused on direct use of PTCA (instead of thrombolysis) as the initial approach to reperfusion in AMI. We review the conceptual bases for both thrombolytic therapy and PTCA in AMI, and we then detail the clinical experience with PTCA in a variety of patient populations with AMI to guide use of both therapies in this setting.     

Acute MI in the elderly: choosing the best revascularization method. Risks and benefits of thrombolysis, angioplasty, and bypass surgery

MI is often recognized less promptly in elderly patients than in younger patients; thus, the best opportunity for reperfusion is often missed. If infarction is diagnosed in less than 12 hours and there are no strong contraindications, thrombolytic therapy is appropriate for the elderly. Coronary angioplasty is a suitable alternative if performed promptly, especially because elderly patients are more likely to have contraindications to, or higher mortality from, thrombolysis. Predictors of unfavorable outcome following angioplasty for acute MI in the elderly include multivessel disease, occlusion of the infarcted artery, and cardiogenic shock. CABG surgery (performed during infarction or in the peri-infarct setting) is also an option for those elderly patients who are hemodynamically stable.     

The contemporary management of acute myocardial infarction.

The contemporary management of acute myocardial infarction continues to evolve rapidly. The ultimate goal of therapy is timely, complete, and sustained myocardial reperfusion. There is a powerful time-dependent effect on mortality, and thus the balance between the time and likelihood of maximal reperfusion is crucial in deciding whether to use primary percutaneous balloon angioplasty or thrombolysis as the initial reperfusion strategy. Newer thrombolytic agents allow for equivalent coronary reperfusion compared with the standard accelerated alteplase (tPA) regimen with the advantage of easier dosing regimens. Low molecular weight heparin has been shown to be superior to unfractionated heparin and likely will be the standard of care in the near future. The use of glycoprotein IIb/IIIa inhibitors has been shown to decrease the short- and long-term complication rates in patients with acute coronary syndromes treated medically and with percutaneous coronary interventions; however, the choice of the optimal agent and dosing regimen in various clinical settings remains controversial. Combination therapy with low-dose fibrinolytics, glycoprotein IIb/IIIa inhibitors, and low molecular weight heparin, with or without subsequent early planned percutaneous coronary interventions, may provide the optimal strategy for maximal coronary reperfusion, but the results of large, randomized mortality trials currently underway need to be analyzed. Risk stratification will continue to play a major role in determining which patients should receive a specific therapy. The care of the patient with an acute myocardial infarction will continue to be a challenge requiring the proper selection from the vast pharmaceutic and interventional options available.     

Routine, Early, Coronary Angiography Following Thrombolysis for Acute Myocardial Infarction

Over the last decade the use of thrombolytic therapy for patients with acute myocardial infarction has resulted in a substantial mortality reduction. While the utility of thrombolytic therapy is now widely recognized, the role of post-infarction coronary angiography remains controversial. In this report we examine the early studies which investigated the necessity and timing of angiography following thrombolysis, and review recent data that underscore the importance of achieving early infarct-related arterial patency. In place of a strategy of "selective angiography," we present an argument for routine, early coronary angiography following thrombolytic therapy for acute myocardial infarction.     

急诊经皮冠状动脉腔内成形术与溶栓治疗急性心肌梗死的疗效比较

目的比较急诊经皮冠状动脉腔内成形术(PTCA)与溶栓治疗急性心肌梗死(AMI)的临床疗效.方法46例AMI患者,21例行急诊PTCA治疗,25例行溶栓治疗.结果急诊PTCA组梗死相关血管(IRA)成功开通的有20例,成功率为95%;溶栓组IRA再通有17例,成功率为68%,两组比较,P<0.01.出院前左心室射血分数(LVEF)急诊PTCA组为0.53±0.10,溶栓组为0.54±0.16,病死率分别为5%和4%,两组间差异无显著性(P>0.05).急诊PTCA组的平均费用明显比溶栓组高(P<0.05).结论急诊PTCA与溶栓治疗AMI患者,可使IRA充分有效地开通,故在条件允许的医院,可优先考虑行急诊PTCA治疗AMI.     

Facilitated angioplasty with combo therapy among patients with ST-segment elevation myocardial infarction: a meta-analysis of randomized trials

Introduction

Time to treatment has been shown to be a major determinant of mortality in primary angioplasty. The aim of the current study was to perform a meta-analysis of randomized trials evaluating the benefits from pharmacologic facilitation with adjunctive glycoprotein (Gp) IIb-IIIa inhibitors + reduced lytic therapy vs adjunctive Gp IIb-IIIa inhibitors among patients with ST-segment elevation myocardial infarction (MI).

Methods

We obtained results from all randomized trials comparing facilitated PCI with adjunctive Gp IIb-IIIa inhibitors and reduced lytic therapy vs adjunctive Gp IIb-IIIa inhibitors among patients with ST-segment elevation MI (STEMI). The literature was scanned by formal searches of electronic databases (MEDLINE and CENTRAL) from January 1990 to December 2007. The following key words were used: randomized trial, MI, reperfusion, primary angioplasty, pharmacologic facilitation, facilitated angioplasty, combo therapy, fibrinolysis, thrombolysis, half-dose lytic therapy, duteplase, reteplase, tenecteplase, alteplase, abciximab, tirofiban, eptifibatide, and Gp IIb-IIIa inhibitors. Angiographic end points were the rate of preprocedural and postprocedural thrombolysis in MI (TIMI) 3 flow. Clinical end points assessed were mortality and reinfarction at 30-day follow-up, whereas major bleeding complications were assessed as safety end point. No language restriction was applied.

Results

We identified 6 randomized trials, including 2684 patients with STEMI. Even though combo therapy was associated with a significant improvement in preprocedural TIMI 3 flow (44.3% vs 15.2%, P < .0001, P_het < .0001), it did not improve the rate of postprocedural TIMI 3 flow (91.5% vs 91.2%, P = .12). No benefits were observed in terms of 30-day mortality (4.2% vs 4.6%, P = .66, P_het = .22) and/or 30-day reinfarction (1.3% vs 1.3%, P = .84). However, combo therapy was associated with higher risk of major bleeding complications (5.8% vs 3.9%, P = .03).

Conclusions

This meta-analysis shows that among patients with STEMI undergoing primary angioplasty, pharmacologic facilitation with combined reduced-dose thrombolytic therapy and Gp IIbIIIa inhibitors is not superior to Gp IIb-IIIa inhibitors alone and, thus, may not be routinely recommended. However, future randomized trials should investigate whether this strategy may further improve outcome when applied within the first hours from symptoms onset, especially in patients undergoing transferring for primary angioplasty.     

STEMI院前溶栓的研究进展

溶栓治疗在STEMI的治疗非常广泛,院前溶栓的疗效得到广泛认可,但院前溶栓的开展受到多种因素的限制,需加强多方面的交流合作。随着对STEMI的公众宣教,急救医疗服务系统人员的培训,急救车辆设备和溶栓药物的配备,院前院内无缝连接绿色通道的建立,会让更多的STEMI患者得到溶栓获益。从而降低STEMI的死亡率,改善其预后。     

利声显经静脉心肌声学造影评价冠心病再灌注治疗的价值

目的　探讨利声显经静脉心肌声学造影 (MCE)在冠心病再灌注治疗疗效评价中的价值。方法　在 9例行溶栓治疗 (Ⅰ组 )、10例行经皮冠脉成形术和冠脉内支架植入术 (Ⅱ组 )以及 6例行冠脉旁路移植术 (Ⅲ组 )共 2 5例冠心病患者中分别于治疗前后行MCE检查 ,分析利声显输注和递增触发时的心肌多普勒信号并描绘时间 强度曲线 ,测量平台期心肌显影强度A、曲线上升平均斜率 β以及A·β乘积在治疗前后的变化。 结果　Ⅰ组溶栓后A、β及A·β值均显著增加 ( P <0 .0 5～ 0 .0 1) ;Ⅱ组术后 β值显著增加 ( P <0 .0 5 ) ,但A及A·β乘积无明显改变 ;Ⅲ组术后 β及A·β乘积均显著增加 ( P <0 .0 5 ) ,但A值变化未达统计学意义。结论　MCE为评价冠心病再灌注治疗疗效提供了简便、安全和可靠的新途径。     

Current practices with thrombolytic therapy

This article discusses the current approach of using thrombolytic therapy as treatment for acute myocardial infarction (MI). The etiology of acute MI is reviewed along with recent research findings from definitive clinical trials. The mechanism of action of thrombolysis is described, and the available and investigational thrombolytic agents are compared. Complications of thrombolytic therapy and assessment indicators of reperfusion are presented. Key aspects of the nurse's role in the management of thrombolytic therapy are highlighted.