Six- and twelve-month follow-up of the phase I Thrombolysis in Myocardial Infarction (TIMI) trial

Risk Factors of Suboptimal Coronary Blood Flow after a Percutaneous Coronary Intervention in Patients with Acute Anterior Wall Myocardial Infarction

BACKGROUND AND AIMS

Primary percutaneous coronary intervention (PCI) is regarded as the most preferred strategy in ST-segment elevation myocardial infarction (STEMI). Thrombolysis in Myocardial Infarction (TIMI) flow grade has been an important and cohesive predictor of outcomes in STEMI patients. We sought to evaluate potential variables associated with the risk of suboptimal TIMI flow after PCI in patients with anterior wall STEMI.

METHODS

We evaluated 107 patients admitted to our hospital between 1 January 2019 and 31 December 2021 with a diagnosis of anterior wall STEMI treated with primary PCI.

RESULTS

Suboptimal TIMI flow grade (≤2) after PCI occurred in 14 (13%) patients while grade 3 was found in 93 (87%) of them presenting with anterior wall STEMI. Failure to achieve optimal TIMI 3 flow grade after PCI was associated with lower TIMI grade prior to PCI (OR 0.5477, 95% CI 0.2589-0.9324, p = 0.02), greater troponin concentration before (OR 1.0001, 95% CI 1-1.0001, p = 0.0028) and after PCI (OR 1.0001, 95% CI 1-1.0001, p = 0.0452) as well as lower mean minimal systolic blood pressure (OR 0.9653, 95% CI 0.9271-0.9985, p = 0.04).

CONCLUSIONS

Among predictors of suboptimal TIMI flow grade after PCI, we noted lower TIMI grade flow pre-PCI, greater serum troponin concentrations in the periprocedural period and lower mean minimal systolic blood pressure.

Diagnosis of coronary artery rethrombosis after effective systemic thrombolytic therapy in patients with ST-segment elevation myocardial infarction

The aim of the study was to evaluate the diagnostic significance of ST-segment re-elevation episodes registered with telemetric ECG monitoring in patients with ST-segment elevation myocardial infarction (STEMI) treated with thrombolytic therapy (TLT). The study included 117 patients with STEMI following effective TLT. The elective coronary angiography followed by percutaneous coronary interventions was performed in the interval from 3 to 24 hours after a successful systemic TLT. Before and after cardiac catheterization, the telemetric ECG monitoring was performed using AstroCard Telemetry system (Meditec, Russia). During the study, two groups of patients were formed. Group 1 included 85 patients (72.6%) without new ST-segment deviations on telemetry. 77 patients (90.6%) had no recurrent coronary artery thrombosis at angiography. Eight patients (9.4%) from group 1 were diagnosed with thrombosis of the infarct-related coronary artery. Group 2 included 32 patients (27.4%) who underwent TLT and then had ST-segment re-elevation episodes of 1 mV or more in the infarct-related leads, lasting for at least 1 minute. In group 2, in 27 of 32 patients (84.4%), thrombosis of the infarct-related coronary artery was confirmed (p<0.01 compared with group 1). In 71.9% cases, the recurrent ischemic episodes were asymptomatic ('painless myocardial ischemia') (p<0.01). Thus, in patients with STEMI and successful TLT, re-elevation of ST-segment during remote ECG monitoring is strongly related to angiographically documented coronary artery thrombotic reocclusion. The absence of chest pain during recurrent myocardial ischemia requires continuous ECG telemetry to select patients for the rescue percutaneous coronary interventions at an earlier stage.

Temporal trends in the pre-procedural TIMI flow grade among patients with ST- segment elevation myocardial infarction - From the ACSIS registry

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Preprocedural TIMI flow grade remains of prognostic significance.

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Patients with TIMI 0 have a poorer prognosis than their counterparts with TIMI 1-3.

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In-hospital complications have decreased among patients with TIMI 0 over time.

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30-d MACE and 1-year mortality remained unchanged in those with TIMI 0 or 1-3.

Background

Pre-procedural TIMI coronary flow grade in patients with ST segment elevation myocardial infarction (STEMI) is associated with adverse clinical outcomes. There have been great advances in pharmacologic and invasive treatment of STEMI patients in the current era. We aimed to assess the temporal trends in clinical outcomes according to the TIMI flow grade amongst these patients.

Methods

Data of patients with STEMI from the acute coronary syndrome Israeli Survey (ACSIS) registry. A time-dependent analysis stratifying patient by TIMI flow grade 0 and TIMI flow grade 1–3 was performed. Survey years were divided to early (2008–2010) and late period (2013–2018). Clinical outcomes included in-hospital complications, 30d MACE (death, myocardial infarction, stroke, unstable angina, stent thrombosis, urgent revascularization) and 1-year mortality.

Results and Conclusions: Included were 2453 patients. The majority of patients had pre-procedural TIMI flow 0 (58.9% in the early period and 58.7% in the late period, P = 0.97). In-hospital complications of patients with TIMI flow 0 has significantly decreased over time (36.1% vs 26.8%, P < 0.001) but not amongst patients with TIMI flow 1–3. Compared with TIMI flow 1–3, patients with TIMI flow 0 had worse 30d MACE and 1-year mortality. There was no temporal change of these outcomes in either TIMI flow grade group. TIMI flow grade 0 is still more common among patients with STEMI and is associated with poorer prognosis. Nevertheless, over time, in-hospital complications have decreased among patients with TIMI 0, while 30d MACE and 1-year mortality has remained unchanged.

Adapting Clinical Practice of Thrombolysis for Acute Ischemic Stroke Beyond 4.5 Hours: A Review of the Literature

Several clinical trials have demonstrated that advanced neuroimaging can select patients for recanalization therapy in an extended time window. The favorable functional outcomes and safety profile of these studies have led to the incorporation of neuroimaging in endovascular treatment guidelines, and most recently, also extended to decision making on thrombolysis. Two randomized clinical trials have demonstrated that patients who are not amenable to endovascular thrombectomy within 4.5 hours from symptoms discovery or beyond 4.5 hours from the last-known-well time may also be safely treated with intravenous thrombolysis and have a clinical benefit above the risk of safety concerns. With the growing aging population, increased stroke incidence in the young, and the impact of evolving medical practice, healthcare and stroke systems of care need to adapt continuously to provide evidence-based care efficiently. Therefore, understanding and incorporating appropriate screening strategies is critical for the prompt recognition of potentially eligible patients for extended-window intravenous thrombolysis. Here we review the clinical trial evidence for thrombolysis for acute ischemic stroke in the extended time window and provide a review of new enrolling clinical trials that include thrombolysis intervention beyond the 4.5 hour window.

Thrombolysis In Myocardial Infarction (TIMI) Study Group: JACC Focus Seminar 2/8

In 1984, the National Heart, Lung, and Blood Institute (NHLBI) decided to study the efficacy and safety of the treatment of acute myocardial infarction with an emerging therapy, coronary thrombolysis, and thus the TIMI (Thrombolysis In Myocardial Infarction) Study Group was born. Following completion of 3 clinical trials of thrombolytic therapy supported by the NHLBI, TIMI became an academic research organization headquartered at Brigham and Women's Hospital and subsequently branched out to study a wide range of patients, including those with stable coronary, cerebrovascular, and peripheral arterial disease; dyslipidemia; heart failure; atrial fibrillation; diabetes; and obesity. TIMI also began to study a wide range of interventions including thrombolytic, antithrombotic, lipid-modifying, anti-inflammatory, heart failure, glucose-lowering, and weight loss agents. TIMI, now in its 37th year, has completed >70 trials. This review describes the origins of the TIMI Study Group, summarizes several of its completed trials and the major lessons learned from them, and discusses ongoing trials and future directions.

Mouse models of myocardial infarction: comparing permanent ligation and ischaemia-reperfusion

Myocardial infarction (MI) is a disease of major consequence in the modern world, causing permanent, irreversible damage to the heart. Survivors are at risk for developing further cardiovascular pathologies such as heart failure. Further study of MI injury is crucial to improve the understanding and treatment of the post-MI heart. The most commonly used model for MI in vivo is surgical ligation of the left anterior descending coronary artery (LAD). There are two predominant approaches: permanent ligation (PL), where the LAD is permanently occluded with a suture, or ischaemia-reperfusion (IR), where the LAD is temporarily occluded before removing the suture to restore blood flow and tissue reperfusion. PL results in the majority of the area at risk becoming infarcted, leading to significant apoptotic cell death and a large scar. Conversely, IR salvages some of the area at risk; thus, the scar is smaller and includes reperfusion injury, an additional, albeit smaller, second wave of necrotic damage. PL may be a more appropriate model choice for studies of heart tissue injury and wound healing, owing to the larger, more consistent infarcts, while IR enables the study of reperfusion injury. Both are clinically relevant, and the choice of model depends upon the precise pre-clinical research questions to be addressed.

Summary: Permanent ligation and ischaemia-reperfusion are common models for studying myocardial infarction. Here, we summarise the differences between them and outline the strengths of each in addressing distinct questions related to the human condition.

Current Status of Novel Biomarkers for the Diagnosis of Acute Kidney Injury: A Historical Perspective

Acute kidney injury (AKI) is a common and serious medical condition associated with significant increases in morbidity, mortality, and cost of care. Because of the high incidence and poor outcomes associated with AKI, there has been significant interest in the development of new therapies for the prevention and treatment of the disease. A lack of efficacy in drug trials led to the concern that AKI was not being diagnosed early enough for an effective intervention and that a rise in serum creatinine itself is not a sensitive-enough marker. Researchers have been searching for novel biomarkers that can not only assess a decline in kidney function but also demonstrate structural damage to the kidney and at time points earlier than increases in serum creatinine measurements allow. Over the past 10 years, there have been 3300 new publications and hundreds of new biomarkers investigated, yet concern still remains regarding AKI biomarker performance. The AKI biomarkers are yet to be widely utilized in clinical practice, leading some to question whether AKI biomarkers will ever reach their initial promise. However, we believe that biomarkers are an important part of current and future AKI research and clinical management. In this review, we compare the historical contexts of acute myocardial ischemia and AKI biomarker development to illustrate the progress that has been made within AKI biomarker research in a relatively short period of time and also to point out key differences between the disease processes that have been barriers to widespread AKI biomarker adoption. Finally, we discuss potential paths by which biomarkers can lead to appropriate AKI treatment responses that lower morbidity and mortality.

The treatment of acute myocardial infarction: the Past, the Present, and the Future

Since Herrick's description of the clinical picture of acute myocardial infarction exactly one century ago (1912), there have been three phases of therapy: Phase 1 (1912-1961, bed rest and 'expectant' treatment); Phase 2 (1961-1974, the coronary care unit); and Phase 3 (1975-present, myocardial reperfusion). We are now on the cusp of Phase 4, which comprises efforts to reduce myocardial perfusion injury as well as regenerative medicine.

Adventures in cardiovascular research

This article, derived from an invited Distinguished Scientist lecture presented at the American Heart Association Scientific Sessions in 2007, reviews 4 themes (adventures) in clinical cardiovascular research carried out over a period of 58 years. It begins with the author's introduction to cardiovascular hemodynamics during a medical school elective in 1951. The 4 adventures include valvular heart disease, hypertrophic cardiomyopathy, heart failure (HF), and myocardial ischemia. In each of these adventures, the author describes briefly what was known when he entered each field, followed by the author's contribution to the field (the adventure), and ends with comments about the current status of the field. Of particular interest are the changes in the technologies used in clinical cardiovascular research over the past half century, commencing with pressure tracings in left heart chambers with the use of needle puncture in the operating room to genetic technologies designed to understand differences between drugs that inhibit platelet activation. The article ends with some general comments on conducting research and the rewards that can come with this activity.

Resolution of late potentials with improvement in left ventricular systolic function in patients with first acute myocardial infarction

BACKGROUND

Ventricular late potentials predict subsequent arrhythmic events and sudden death in postinfarction patients. Late potentials are recorded in the infarcted area, but it should be pointed out that they probably represent micropotentials in the area of delayed conduction found among isolated areas of scar tissue and normal myocardium.

HYPOTHESIS

The study was undertaken to investigate the relationship between chronic reversible myocardial ischemia, such as stunned or hibernating myocardium, and late potentials in 38 patients with a first myocardial infarction.

METHODS

The patients were divided into two groups, one with (Group 1) and one without (Group 2) resolution of late potentials recorded by signal-averaged electrocardiogram at 6 months after onset of myocardial infarction. We investigated the clinical, echocardiographic, and signal-averaged electrocardiographic characteristics of Groups 1 and 2.

RESULTS

In the chronic phase of myocardial infarction, a higher incidence of patency of the infarct-related artery and an improvement of wall motion score were found in Group 1, and left ventricular ejection fraction was better preserved in Group 1 than in Group 2.

CONCLUSIONS

These results suggest that the resolution of late potentials was influenced by the improvement of left ventricular systolic function and patency of the infarct-related artery. We concluded that chronic reversible myocardial ischemia, such as stunned or hibernating myocardium, might be the substrate that generated late potentials.

Prehospital thrombolysis: an idea whose time has come

Aggressive reperfusion therapy for myocardial infarction (MI) characterized by acute ST-segment elevation leads to improved patient outcome. Furthermore, use of thrombolytic therapy is highly time-dependent: reperfusion therapy is beneficial within 12 h, but the earlier it is administered, the more beneficial it is. Thus, the focus of both prehospital and emergency department management of patients with acute MI is on rapid identification and treatment. There are many components to the time delays between the onset of symptoms of acute MI and the achievement of reperfusion in the occluded infarct-related artery. Time delays occur with both the patient and the prehospital emergency medical system, although patient delays are more significant. This article focuses on the prehospital management of acute MI, including (1) the rationale for rapid reperfusion in patients with acute MI, (2) the factors related to time delays in patient presentation to the hospital, and (3) strategies for reducing time delays, both patient- and medical system-based.

Do patients with acute myocardial infarction benefit from treatment with clopidogrel?

Clopidogrel (Plavix), a platelet aggregation inhibitor, has been shown to be effective in certain patients undergoing percutaneous coronary interventions, but its use in patients with acute myocardial infarction who receive a fibrinolytic strategy instead has been controversial. The aim of the Evidence-Based Medicine (EBM) Section is to bring the readership clinically relevant and practical evidence-based medicine principles and topic reviews. This EBM - Therapy review focuses on a relatively new therapy option for Emergency Department patients with acute myocardial infarction.

Clinical update on the therapeutic use of clopidogrel: treatment of acute ST-segment elevation myocardial infarction (STEMI)

The pathogenesis of ST-elevation myocardial infarction (STEMI) involves plaque disruption, platelet aggregation and intracoronary artery thrombus formation. Aspirin is the cornerstone of antiplatelet therapy in patients with STEMI, reducing the risk of recurrent myocardial infarction or death during the acute phase and long term by about one-quarter. Recent large randomized trials have demonstrated that the addition of clopidogrel to aspirin reduces the risk of major ischemic events by up to a further one-third in patients with STEMI treated with fibrinolytic therapy and undergoing percutaneous coronary intervention, with no significant increase in bleeding. Thus, dual antiplatelet therapy with the combination of clopidogrel and aspirin is becoming the new standard of care for the management of patients with STEMI.

Adding clopidogrel to aspirin improves outcome in ST-elevation myocardial infarction patients receiving fibrinolytic therapy

Acute coronary syndromes result from the rupture of an atherosclerotic plaque with superimposed thrombosis. In an ST-elevation myocardial infarction, the thrombus occludes the coronary vessel, leading to an abrupt decrease in myocardial perfusion. The focus of initial management is the timely restoration of flow in the infarct-related artery via fibrinolytic therapy or percutaneous coronary intervention. Adjunctive therapy aimed at inhibition of platelets and the coagulation cascade is critical to establish and maintain vessel patency. Clopidogrel, an oral antiplatelet agent, has recently been shown to offer significant clinical benefit in STEMI (ST-elevation myocardial infarction) and is a welcome addition to standard fibrinolytic therapy.

Addition of clopidogrel to aspirin and fibrinolytic therapy for myocardial infarction with ST-segment elevation

BACKGROUND

A substantial proportion of patients receiving fibrinolytic therapy for myocardial infarction with ST-segment elevation have inadequate reperfusion or reocclusion of the infarct-related artery, leading to an increased risk of complications and death.

METHODS

We enrolled 3491 patients, 18 to 75 years of age, who presented within 12 hours after the onset of an ST-elevation myocardial infarction and randomly assigned them to receive clopidogrel (300-mg loading dose, followed by 75 mg once daily) or placebo. Patients received a fibrinolytic agent, aspirin, and when appropriate, heparin (dispensed according to body weight) and were scheduled to undergo angiography 48 to 192 hours after the start of study medication. The primary efficacy end point was a composite of an occluded infarct-related artery (defined by a Thrombolysis in Myocardial Infarction flow grade of 0 or 1) on angiography or death or recurrent myocardial infarction before angiography.

RESULTS

The rates of the primary efficacy end point were 21.7 percent in the placebo group and 15.0 percent in the clopidogrel group, representing an absolute reduction of 6.7 percentage points in the rate and a 36 percent reduction in the odds of the end point with clopidogrel therapy (95 percent confidence interval, 24 to 47 percent; P<0.001). By 30 days, clopidogrel therapy reduced the odds of the composite end point of death from cardiovascular causes, recurrent myocardial infarction, or recurrent ischemia leading to the need for urgent revascularization by 20 percent (from 14.1 to 11.6 percent, P=0.03). The rates of major bleeding and intracranial hemorrhage were similar in the two groups.

CONCLUSIONS

In patients 75 years of age or younger who have myocardial infarction with ST-segment elevation and who receive aspirin and a standard fibrinolytic regimen, the addition of clopidogrel improves the patency rate of the infarct-related artery and reduces ischemic complications.

Design and rationale of Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis in Myocardial Infarction (CLARITY-TIMI) 28 trial

BACKGROUND

Although fibrinolysis is effective in improving outcomes in ST-elevation myocardial infarction (STEMI), failure to achieve reperfusion and/or reocclusion of the infarct-related artery occur in substantial proportions of patients during their index hospitalization and are associated with a significant increase in mortality. We hypothesize that the addition of clopidogrel to standard fibrinolytic therapy in patients with acute STEMI will improve reperfusion.

STUDY DESIGN

CLARITY-TIMI 28 is a multicenter, international, randomized, double-blind, placebo-controlled trial designed to examine the efficacy and safety of clopidogrel when added to standard adjuvant therapy for fibrinolysis. The primary efficacy end point is the composite of an occluded infarct-related artery (defined as TIMI flow grade 0 or 1) on the predischarge angiogram or death or a recurrent myocardial infarction (MI) up to the start of coronary angiography. For subjects who do not undergo angiography, occurrence of death or recurrent MI by day 8 or by hospital discharge, whichever comes first, is used. The primary safety assessment is TIMI major bleeding. Secondary end points include ST resolution at 180 minutes and the clinical composite of death, MI, or recurrent ischemia. Substudies include analyses of biomarkers, DNA, continuous electrocardiogram monitoring, and initiation of treatment in the ambulance.

CONCLUSIONS

CLARITY-TIMI 28 will help to define the role of clopidogrel as part of the pharmacologic reperfusion regimen for acute STEMI.

Predictors of the rise in vWF after ST elevation myocardial infarction: implications for treatment strategies and clinical outcome

AIMS

Prior studies suggest that acute coronary syndromes (ACSs) are associated with endothelial activation and that this is of prognostic significance. We hypothesized that endothelial activation, as measured by a rise in von Willebrand Factor (DeltavWF), was influenced by the thrombolysis in myocardial infarction flow grade (TFG), the corrected TIMI frame count (CTFC) and the choice of anticoagulant therapy after fibrinolysis in ST elevation myocardial infarction (STEMI).

METHODS AND RESULTS

Data were drawn from the enoxaparin and tenecteplase tissue plasminogen activator (TNK-tpa) with or without GPIIb/IIIa inhibitor as the reperfusion strategy in the STEMI trial (ENTIRE-TIMI 23). Three hundred and fourteen patients had serial measurements of vWF (baseline and 48-72 h) and angiographic data available. TFG<3 (P=0.0042) or CTFC>/=40 at 60 min (P=0.0035) were associated with a higher DeltavWF. DeltavWF >/=75th percentile was associated with a higher incidence of death or myocardial infarction (MI) at 30 days, compared with <75th percentile (11.2 vs. 4.1%, P=0.027). Enoxaparin independently reduced the DeltavWF (P=0.019) and also the composite of death or MI (OR 0.33, 95% CI 0.12-0.91, P=0.03) compared with unfractionated heparin.

CONCLUSION

In STEMI treated by fibrinolysis, coronary flow at 60 min and choice of adjunctive anticoagulant appear to be independent determinants of DeltavWF. Enoxaparin is independently associated with a reduction in DeltavWF and a reduction in death or MI. The clinical benefits of enoxaparin as an adjunctive treatment in STEMI may be mediated in part by a reduction in vWF release.

Combined assessment of thrombolysis in myocardial infarction flow grade, myocardial perfusion grade, and ST-segment resolution to evaluate epicardial and myocardial reperfusion

The restoration of epicardial and myocardial flow remains the primary goal of reperfusion therapy in patients with ST-segment elevation myocardial infarction, but the optimal method to assess this goal has not been defined. Thrombolysis In Myocardial Infarction flow grade (TFG), myocardial perfusion grade (MPG), and ST-segment resolution (STRes) were combined to formulate a new measure of successful reperfusion in 649 patients who received pharmacologic reperfusion therapy in 3 recent phase II clinical trials of ST-segment elevation myocardial infarction. Coronary angiograms and electrocardiograms were analyzed at 60 minutes (before any intervention) after the initiation of reperfusion therapy. The complete restoration of perfusion, or the "trifecta," defined as the presence of TFG 3, MPG 3, and complete (> or =70%) STRes, occurred in 117 patients (18%). The achievement of this trifecta was associated with low rates of 30-day mortality (0% vs 3.9%, p = 0.02), congestive heart failure (CHF) (0.9% vs 7.1%, p = 0.01), and the combination of death or CHF (0.9% vs 10.7%, p = 0.001). When the results were stratified with respect to subsequent percutaneous coronary intervention (PCI) from 60 to 120 minutes, attainment of the trifecta at 60 minutes remained a strong predictor of better clinical outcomes, particularly in those patients who underwent early PCI. The achievement of TFG 3, MPG 3, and complete STRes at 60 minutes after fibrinolytic therapy and before PCI occurred in only 18% of patients but was associated with very low rates of death and CHF at 30 days. This new end point is proposed to evaluate the success of reperfusion therapy in patients who undergo early angiography.

Adaptive remodeling of the infarct-related artery is associated with recurrent ischemic events after thrombolysis in acute myocardial infarction

BACKGROUND

Recurrent ischemic events occur during the hospital stay of 7-32% of patients after successful thrombolytic treatment of acute myocardial infarction (AMI).

OBJECTIVE

To define the association between postinfarction angina pectoris and the clinical, angiographic, and intravascular ultrasound (IVUS) parameters of the infarct-related artery for consecutive prospectively included patients.

METHODS

Clinical, qualitative, and quantitative angiographic and IVUS data for 64 patients (56 men, aged 53+/-12 years) with thrombolysis of AMI were analyzed. All patients underwent coronary angiography and pre-interventional IVUS measurement electively within 1 month of AMI or at the time of the occurrence of postinfarction angina pectoris. Classification as adaptive or constrictive remodeling was according to whether the cross-sectional area of a vessel was larger or smaller than that of the proximal or distal reference segment.

RESULTS

Nineteen of the 64 patients (29.7%) suffered from recurrence of ischemic events (group 1), whereas 45 patients (60.3%, group 2) remained free from symptoms. In univariate analyses, multivessel disease (42 versus 24%, P= 0.0236) and adaptive remodeling (63 versus 24%, P= 0.0032) were found to occur more commonly among patients in group 1. The patients in group 1 exhibited larger total vessel cross-sectional areas than did the patients in group 2 (17.5+/-4.2 versus 14.9+/-6.1 mm2, P = 0.0556). In multivariate regression analysis, adaptive remodeling proved to be a significant predictor (P = 0.0145) of the recurrence of ischemic events after thrombolysis of AMI.

CONCLUSIONS

Adaptive remodeling of the infarct-related artery is associated with early postinfarction angina pectoris after thrombolysis of AMI.

Effect of the stenosis location and severity on left ventricular function after single-vessel anterior wall myocardial infarction

BACKGROUND

The purpose of the current study was to determine how the location of the infarct-related lesion (IRL) and the degree of stenosis during the acute and chronic phases of infarction might affect left ventricular (LV) function in patients with acute anterior wall myocardial infarction.

METHODS

Ninety consecutive patients with a first single-vessel anterior wall myocardial infarction (male/female ratio 75:15, mean age 60+/-9 years) underwent coronary angiography (CAG) immediately and 1 month after infarction. Patients were grouped according to IRL location (proximal [Coronary Artery Surgery Study (CASS) No. 12] or distal [CASS No. 13] to the first diagonal branch of the left anterior descending artery) and according to the severity of stenosis at 1 month (severe stenosis [IRL >75%] and mild stenosis [IRL < or =75%]). At the time of infarction and 1 month and 1 year after infarction, total wall motion index (TWMI), left ventricular end-diastolic dimension (LVDd), left ventricular end-systolic dimension (LVDs), and fractional shortening (FS) were determined.

RESULTS

TWMI was greater and FS was lower for CASS No. 12 lesions than for CASS No. 13 lesions. CASS No. 12 lesions were associated with a greater LVDd at 1 year and a greater LVDs throughout 1 year of observation. The patients with mild stenoses had significant improvements in TWMI and FS over time, whereas those with severe stenoses showed no improvement. Multivariate analysis showed that the independent factors predicting left ventricular function were IRL location at CASS No. 12, initial TIMI 0-1 flow in the IRL at emergency coronary artery graft, and the presence of a severe stenosis at 1 month.

CONCLUSIONS

In patients with severe stenoses at 1 month at CASS No. 12, left ventricular functional recovery is delayed and the left ventricular chamber is enlarged. In patients with CASS No. 13 lesions, left ventricular function is preserved well, regardless of the severity of residual stenosis.

The impact of time to thrombolytic treatment on outcome in patients with acute myocardial infarction. For the CORE investigators (Collaborative Organisation for RheothRx Evaluation)

OBJECTIVES

To examine the impact of time to thrombolytic treatment on multiple acute outcome variables in a single trial of thrombolysis in acute myocardial infarction.

DESIGN AND PATIENTS

Mortality and reinfarction rate were measured in 2770 patients with acute myocardial infarction who received thrombolysis within 12 hours in CORE, an international, dose ranging trial of poloxamer 188. Tc-99m sestamibi infarct size and radionuclide angiographic ejection fraction substudies included 1099 and 1074 patients, respectively.

RESULTS

Time to thrombolysis, subgrouped by intervals (< 2, 2-4, > or = 4-6, and > or = 6 hours), was significantly associated with infarct size (median 15.0%, 18.5%, 22.0%, 18.5% of left ventricle; p = 0.033), mean (SD) ejection fraction (51.5 (12.0)%, 48. 3 (13.9)%, 48.2 (13.3)%, 48.2 (15.0)%; p = 0.006), 35 day mortality (5.7%, 7.1%, 7.9%, 12.5%; p = 0.0004), six month mortality (7.3%, 8. 6%, 10.4%, 15.5%; p < 0.0001), and 35 day reinfarction rate (6.1%, 3. 2%, 4.0%, 0.9%; p = 0.0001).

CONCLUSIONS

In this single large trial, the beneficial effect of time to thrombolysis on infarct size and ejection fraction was restricted to treatment given within two hours of symptom onset, while the effect on mortality was evident over all time intervals. Reinfarction rate was higher in patients treated with earlier thrombolysis.

Microvascular dysfunction in acute myocardial infarction: focus on the roles of platelet and inflammatory mediators in the no-reflow phenomenon

Recent interest has shifted from infarct artery patency to microvascular perfusion in the evaluation of patients with acute myocardial infarction (AMI). Microvascular dysfunction occurs in a substantial proportion of patients, despite aggressive therapy with thrombolytic agents and/or percutaneous mechanical revascularization techniques. Patients with impaired microvascular perfusion after immediate reperfusion therapy have an adverse clinical prognosis. Recent studies have extended our understanding of the pathophysiology of this so-called no-reflow phenomenon, focusing on the critical roles of platelet and inflammatory mediators leading to microvascular obstruction and reperfusion injury. Moving beyond the Thrombolysis in Myocardial Infarction (TIMI) flow grade system, new techniques have been developed to assess microvascular perfusion, including TIMI frame counting, angiographic myocardial perfusion grading, myocardial contrast echocardiography, Doppler flow wire studies, nuclear scintigraphy, and magnetic resonance imaging. Armed with a greater understanding of the primary mediators of microvascular dysfunction, these tools may identify improved therapy directed at optimizing myocardial perfusion in patients with AMI.

Early, Complete Infarct Vessel Patency: Arriving at a Gold Standard for Future Clinical Investigation in Myocardial Reperfusion

Early clinical trials of thrombolytic therapy in the setting of acute myocardial infarction (AMI) demonstrated that early angiographic reperfusion correlated with improved survival. This supported the open-artery hypothesis that early reperfusion decreases infarct size, improves left ventricular function, and improves survival. Two subsequent comparative thrombolytic trials showed no difference in left ventricular function or survival between agents with different rates of reperfusion. Additionally, reduction in mortality was demonstrated without improvement in left ventricular function and with the late administration of thrombolytic therapy. Therefore, there was a real question as to the importance of infarct vessel patency, and its relation to clinical outcome. This article discusses the various markers of coronary artery patency, their relation to clinical outcome, and how they reflect perfusion at the tissue level. The coronary angiogram gives a snapshot view of the infarct-related artery (IRA) that does not reflect the dynamic process of vessel reocclusion and recanalization. The patent artery is therefore "open" at only a given time frame, and may undergo cyclic or complete reocclusion. Angiographically characterized flow has been demonstrated to be more clinically meaningful. The GUSTO-I trial was designed to test the open-artery hypothesis. This trial confirmed that improved early IRA patency and optimal (TIMI-3) flow correlated with improved survival. The presence of TIMI-3 flow in the IRA has consistently demonstrated significant improvement in patient morbidity and mortality, and conversely, less than optimal, but still "patent" (TIMI-2) flow in the IRA correlates with clinical outcomes observed in patients with occluded infarct vessels. Even TIMI-3 flow in the IRA does not always confirm perfusion of the myocardium at risk. Therefore, the "patent" IRA can be subsequently compromised by intermittent patency, reocclusion, less than TIMI-3 flow, and a "no-reflow" effect at the tissue level. The development of accurate, reliable non-invasive markers of IRA patency is crucial. This would allow a more selective application of invasive and interventional techniques to restore patency to the IRA. The merits and faults of these noninvasive markers are discussed. The ideal gold standard for establishing the adequacy of therapy in AMI is one that could detect rapid, complete, and sustained coronary reperfusion with adequate myocardial perfusion. Current technologic achievements allow an approach to this ideal; however, as of 1997, the coronary angiogram demonstrating TIMI-3 flow represents the clinically proven standard of optimal therapeutic efficacy.

Time to Treatment: A Crucial Factor in Thrombolysis and Primary Angioplasty

Time to treatment with thrombolytic therapy has been recognized as an important factor in the treatment of patients with acute myocardial infarction: By restoring infarct-related artery patency earlier, clinical outcome is improved. Of the several components of time delay between the onset of pain to opening of the artery, in-hospital time delay (i.e., the door-to-needle time) is one that physicians can control the most, with improvements being reported with the use of a myocardial infarction (MI) protocol like the one advocated by the National Heart Attack Alert Program. These same principles apply to the alternate reperfusion strategy, primary angioplasty. Indeed, while primary angioplasty has been shown to be beneficial in early clinical trials, it appears that the "door-to-balloon" time is a crucial component of the overall strategy. Thus, a growing body of evidence demonstrates that time to treatment is a crucial factor in both thrombolysis and primary angioplasty.

Hirudin in Acute Myocardial Infarction

The central role of thrombosis in the pathogenesis of acute myocardial infarction has led to intense interest in developing more effective thrombolytic-antithrombotic regimens. Hirudin is 65 amino acid polypeptide that binds in a 1:1 relationship with thrombin, thereby inhibiting the final step in the coagulation cascade. Hirudin has several potential advantages over the current antithrombin agent heparin: It is a direct inhibitor that does not require a cofactor, it has no known inhibitors that would attentuate its anticoagulant effects, and it can inhibit clot-bound thrombin, thereby achieving an antithrombotic effect at the site of potential rethrombosis. Initial clinical trials have shown promising results: Hirudin, as compared with heparin, provided a more consistent level of anticoagulation, as gauged by the activated partial thromboplastin time. As an adjunct to thrombolytic therapy in acute myocardial infarction, hirudin improved indices of coronary reperfusion and patency. Initial results with clinical end points, including death or myocardial infarction, also have shown favorable results for hirudin compared with heparin. In the first phases of the larger phase III trials, the rate of hemorrhagic events, including intracranial hemorrhage, was higher than expected in both the hirudin and heparin arms, indicating that a safety ceiling had been reached. The TIMI 9B and GUSTO IIb trials are using lower doses of intravenous hirudin and heparin, which should allow testing of the "thrombin hypothesis": that more potent inhibition of thrombin will translate into improved clinical outcome for patients with acute MI.

Time as an Adjunctive Agent to Thrombolytic Therapy

Thrombolytic therapy has dramatically reduced mortality following acute myocardial infarction (MI) with the major effect coming from early achievement of infarct-related artery patency. A major factor in achieving rapid reperfusion is early treatment with thrombolytic therapy. Recent trials have shown that mortality can be reduced if time to treatment is shortened: In the Thrombolysis in Myocardial Infarction (TIMI) 2 trial, for each hour earlier that thrombolytic therapy was started, approximately 10 lives were saved per 1000 patients treated. Thus, one must consider time as an adjunctive agent to thrombolytic therapy. There are four components of the time delay between the onset of MI and achievement of reperfusion: (1) patient delays in seeking medical attention; (2) transport delays; (3) the so-called door to needle time, the interval between the patient's arrival at the medical facility and the initiation of thrombolytic therapy; and (4) thrombolytic reperfusion time, the time between the administration of thrombolytic therapy and the achievement of roperfusion, Efforts to reduce each of these components will lead to additive benefits in improving time to reperfusion and survival of patients with acute MI.

Time to Reperfusion: The Critical Modulator in Thrombolysis and Primary Angioplasty

Rapid achievement of reperfusion with thrombolytic therapy or primary angioplasty has made a dramatic impact an improving the survival of patients with acute myocardial infarction (MI). Restoring infarct-related artery patency early after the onset of MI minimizes infarct size, reduces the degree of left ventricular dysfunction, and improves survival. Several recent studies have confirmed the benefit of reducing time to treatment with thrombolysis (between the onset of pain to initiation of thrombolysis), and that of more rapid drug reperfusion time with more aggressive thrombolytic regimens (between initiation of thrombolytic therapy and actual achievement of reperfusion). Furthermore, these effects are additive, confirming the benefit of rapid reperfusion. For primary angioplasty, the same relationship has been observed-more rapid treatment appears to be associated with improved outcome. The "door-to-balloon" time is a major determinant of overall time to reperfusion, and as such is a crucial component of the overall strategy. Integrating the experience in trials of thrombolytic therapy and primary angioplasty, a clear relationship exists between higher rates of early reperfusion and lower mortality. Thus, time to reperfusion appears to be the critical modulator in both thrombolysis and primary angioplasty.

Effects of Late Coronary Artery Reperfusion on Left Ventricular Remodeling Persist for 10 Weeks After Experimental Rat Myocardial Infarction and Are Associated with Improved Survival

Objective: To test the hypothesis that coronary artery reperfusion performed too late to reduce infarct size improves survival by altering left ventricular remodeling and preventing progressive left ventricular dilation. Background: Several clinical trials have suggested that late coronary artery reperfusion without infaret size reduction is associated with a survival benefit. Although the mechanism is not known, survival benefits could be related to decreased infarct expansion associated with late coronary artery reperfusion. Decreased infarct expansion results in decreased left ventricular volume, and the resulting decreased wall stress could prevent or attenuate progressive left ventricular dilation and improve survival. Methods: Rats (n = 84) were randomized to undergo sham operation, permanent left coronary artery ligation, or 2 hours of left coronary artery ligation followed by reperfusion. Ten weeks later, hemodynandic measurements were made before and after volume loading. The rats were killed, the hearts were removed, and passive pressure-volume curves were obtained. The hearts were fixed at a constant pressure and analyzed morphometrically. Results: When examined 10 weeks after experimental myocardial infarction late eperfusion's effects on left ventricular remodeling resulted in reduced left ventricular volume when compared to hearts with infarcts supplied by a permanently occluded coronary artery (1.9 +/- 0.1 ml/kg vs. 2.1 +/- 0.2 ml/kg; p < 0.01). Although there was a trend toward less thinning along (0.95 +/- 0.13 mm vs. 1.00 +/- 0.10 mm; p = NS) and less expansion (2.3 +/- 0.4 vs. 2.8 +/- 0.9; p = NS) in reperfused hearts compared to hearts with a permanently occluded coronary artery, changes in infarct shape 10 weeks after infarction were not significantly different. Reperfusion's beneficial effects on remodeling of noninfarcted myocardiurn were associated with improved survival. Mortality was higher in the permanently occluded rats than in the reperfused rats (35% vs. 12%; p < 0.05). Conclusion: Late coronary artery reperfusion has a beneficial effect on remodeling of noninfarcted myocardum that results in reduced left ventricular volume in rat hearts examined 10 weeks after infarction. These beneficial effects on left ventricular remodeling are associated with improved survival.

Myocardial infarction and remodeling in mice: effect of reperfusion

Anatomic and functional changes after either a permanent left anterior descending coronary artery occlusion (PO) or 2 h of occlusion followed by reperfusion (OR) in C57BL/6 mice were examined and compared with those in sham-operated mice. Both interventions generated infarcts comprising 30% of the left ventricle (LV) measured at 24 h and equivalent suppression of LV ejection velocity and filling velocity measured by Doppler ultrasound at 1 wk. Serial follow-up revealed that the ventricular ejection velocity and filling velocity returned to the levels of the sham-operated controls in the OR group at 2 wk and remained there; in contrast, PO animals continued to display suppression of both systolic and diastolic function. In contrast, ejection fractions of PO and OR animals were depressed equivalently (50% from sham-operated controls). Anatomic reconstruction of serial cross sections revealed that the percentage of the LV endocardial area overlying the ventricular scar (expansion ratio) was significantly larger in the PO group vs. the OR group (18 +/- 1.7% vs. 12 +/- 0.9%, P < 0.05). The septum that was never involved in the infarction had a significantly (P < 0.002) increased mass in PO animals (22.5 +/- 1.08 mg) vs. OR (17.8 +/- 1.10 mg) or sham control (14.8 +/- 0.99 mg) animals. Regression analysis demonstrated that the extent of septal hypertrophy correlated with LV expansion ratio. Thus late reperfusion appears to reduce the degree of infarct expansion even under circumstances in which it no longer can alter infarct size. We suggest that reperfusion promoted more effective ventricular repair, less infarct expansion, and significant recovery or preservation of ventricular function.

ST-segment elevation on Q leads at rest and during exercise: relation with myocardial viability and left ventricular remodeling within the first 6 months after infarction

BACKGROUND

Resting ST-segment elevation on Q leads after an acute myocardial infarction has been related to a greater infarct size. Otherwise, the relation between exercise-induced ST-segment elevation and myocardial viability is controversial. We investigated the relation between ST-segment elevation on Q leads at rest and during exercise and regional dysfunction and its evolution, contractile reserve, left ventricular dilation, and coronary patency.

METHODS AND RESULTS

Exercise testing and cardiac catheterization were performed at the first week after infarction in 51 patients. The study group was divided according to the existence (in 2 or more Q leads; n = 36) or not (n = 15) of resting ST-segment elevation and according to the existence (n = 28) or not (n = 23) of exercise-induced ST-segment elevation. Left ventricular end-diastolic and end-systolic volumes (mL/m2), regional wall motion (SD/chord), contractile reserve (wall motion percentage improvement with low-dose dobutamine), and coronary patency in the culprit artery were analyzed. Cardiac catheterization was repeated at the sixth month in 35 patients; systolic recovery (wall motion percentage improvement), left ventricular volumes, and coronary patency were again evaluated. Patients with resting ST-segment elevation showed poorer wall motion (2.1 +/- 0.8 SD/chord vs 1.2 +/- 1 SD/chord, P =.002), lesser contractile reserve (17% [0% to 39%] vs 41% [4% to 92%], P =.04), greater end-systolic volume (32 +/- 15 mL/m2 vs 23 +/- 11 mL/m2, P =.04), and higher percentage of occlusion (36% vs 7%, P =.04) than did patients without ST-segment elevation. Likewise, patients with exercise-induced ST-segment elevation showed lesser contractile reserve (8% [0% to 40%] vs 35% [12% to 86%], P =.03) than did patients without exercise-induced ST-segment elevation. The only independent predictors of contractile reserve were wall motion <2 SD/chord (odds ratio [OR] 7.1, confidence interval [CI] 6.3 to 7.9, P =.01) and the absence of exercise-induced ST-segment elevation (OR 5.7, CI 4.9 to 6.5, P =. 02). There were no significant differences between patients with and those without ST-segment elevation (at rest or during exercise) in systolic recovery or left ventricular volumes at the sixth month.

CONCLUSIONS

ST-segment elevation on Q leads at rest is related to a poorer systolic function (more severe regional dysfunction, greater end-systolic volume, and less response to dobutamine). ST-segment elevation during exercise is independently related to a lesser contractile reserve. ST-segment elevation (at rest or during exercise) is not related to the evolution of volumes or regional dysfunction during the first 6 months after infarction.

Long-term follow-up after direct percutaneous transluminal coronary angioplasty for acute myocardial infarction

OBJECTIVES

The purpose of this study was to analyze long-term follow-up information over several years from consecutive, unselected patients treated with direct percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction (MI).

BACKGROUND

Direct PTCA is often used in patients with acute MI. Short-term results are favorable. However, there is less information available on long-term observations over several years in these patients.

METHODS

A total of 416 consecutive and unselected patients with acute MI underwent direct PTCA. Survival of the acute infarct phase was 94.2%; the remaining 392 patients--the study population-were discharged and followed for 3.3+/-1.4 years. Mortality as well as cardiac events and reinterventions are reported. Clinical variables assessed at the time of discharge are submitted to statistical analysis to detect potential risk factors.

RESULTS

Total cumulative mortality in the first year was 10% for the entire group and 6% for patients not presenting in cardiogenic shock. Mortality after discharge was 4.6% in the first year and dropped to <4% per year thereafter. Reinterventions after discharge were required in 16% in the first year and in <4% per year in years 2 to 4. Poor left ventricular ejection fraction (<35%), three-vessel disease and advanced age (> or =75 years) were long-term risk factors for total mortality after direct PTCA.

CONCLUSIONS

The clinical benefit of direct PTCA for acute MI is maintained during follow-up with respect to mortality. However, reinterventions for restenosis or de novo stenosis are often required (10% to 20%). Although few in number (<10%), patients with severely impaired left ventricular function continue to have a poor prognosis.

Prognostic value of myocardial viability and ischemia detected by dobutamine stress echocardiography early after acute myocardial infarction treated with thrombolysis

OBJECTIVES

The aim of the study was to assess the prognostic value of myocardial viability and ischemia detected by dobutamine stress echocardiography (DSE) in patients with acute myocardial infarction (AMI) treated with thrombolysis.

BACKGROUND

DSE can detect myocardial viability and ischemia early after AMI, but the prognostic importance of viability and ischemia in these patients has yet to be assessed.

METHODS

DSE was performed in 152 patients at a mean of 9 +/- 5 days after a first AMI treated with thrombolysis to evaluate myocardial viability and ischemia. The patients were followed up for 15 +/- 19 months.

RESULTS

On the basis of DSE results three groups of patients were identified: group 1 (95 patients, 62.5%) with myocardial viability and ischemia, group 2 with myocardial viability without ischemia (32 patients, 21%) and group 3 (25 patients, 16.5%) with no myocardial viability. During follow-up 10 patients (6.5%) had hard events, 53 (35%) developed unstable angina and 67 (44%) underwent myocardial revascularization. The rate of hard events was 10% in group 1 and 0% in group 2 and 3 patients (p < 0.05 group 1 versus group 2); group 1 patients with viability and ischemia showed a significantly higher rate of recurrence of unstable angina and myocardial revascularization procedures (40% and 60%) compared to group 2 (22% and 16%) and group 3 patients (20% and 20%). Using the Cox multivariate stepwise model, only the extent of ischemic myocardium (hazard ratio (HR) = 21.7, p = 0.02) and angina during DSE (HR = 4.45, p = 0.03) were significant predictors of hard events; an ischemic response to DSE (HR = 2.92, p = 0.001) was the most important predictor of spontaneous events, followed by ST-segment depression during DSE (HR = 1.71, p = 0.04), angina during DSE (HR = 1.53, p = 0.19) and age (HR = 0.96, p = 0.05).

CONCLUSIONS

In patients with a first AMI treated with thrombolysis the presence and extent of myocardial ischemia during DSE is the most important predictor of both hard and spontaneous cardiac events, whereas myocardial viability does not have an independent prognostic value.

Routine Coronary Arteriography Following Thrombolytic Therapy for Acute Myocardial Infarction: An Unsettled Controversy

Although coronary artery disease remains the leading cause of death in industrialized countries, the management of patients recovering from acute myocardial infarction varies significantly. The issue of routine arteriography and revascularization following thrombolytic therapy remains controversial despite substantial evidence associating infarct-related artery patency with improved cardiac function and survival. Randomized trials of routine intervention after myocardial infarction have generally failed to demonstrate advantages of this invasive approach but methodological problems limit their application to current practice. High-risk patients should be referred for arteriography. While awaiting definitive trials addressing the influence of routine arteriography on patient survival and its cost effectiveness, the management of other patient groups must be individualized.

Thrombolytic Therapy in Acute Myocardial Infarction Part II: 1997 Update

Thrombolytic therapy has become an established treatment for acute myocardial infarction. Streptokinase was first demonstrated in 1988 to reduce mortality rates. In 1993, tissue plasminogen activator was shown to have a slight superiority over streptokinase in reducing mortality rates (approximately 1%). Reteplase is a second generation thrombolytic agent that is given in two bolus injections intravenously over 30 minutes. Studies demonstrated slightly better and more rapid improvement in myocardial perfusion with reteplase compared to tissue plasminogen activator. However, recent studies showed 30-day mortality rates in patients treated with reteplase were similar as those treated with tissue plasminogen activator. The use of angioplasty, aspirin, beta blockers, angiotensin converting enzyme inhibitors, and lipid lowering agents also contribute to the reduction of mortality from acute myocardial infarction.

Detection of perfusion defects during coronary occlusion and myocardial reperfusion after thrombolysis by intravenous administration of the echo-enhancing agent BR1

The purpose of this study was to detect myocardial perfusion defects as a result of coronary occlusion and myocardial reperfusion after thrombolysis with intravenous (i.v.) administration of the echo contrast agent BR1 (Bracco Research, Switzerland), which consists of microbubbles (median diameter 2.5 microm) containing sulfur exafluoride in a phospholipidic shell. To generate a coronary thrombosis, a copper coil was advanced into the left circumflex coronary artery in eight anesthetized dogs with opened chest cavities. Coronary occlusion occurred 18 +/- 10 minutes after the insertion of the coil and was documented both by an electromagnetic flow meter (as zero blood flow) and by radiolabeled microspheres (as myocardial perfusion defect). After 2 hours of occlusion, streptokinase was infused i.v.; reperfusion was documented by both the flow-meter and microspheres. Left ventricular cavity enhancement was apparent after all contrast injections. Peak cavity intensity did not increase with dose and was not affected by signal processing (suggesting signal saturation), whereas the duration of contrast effect significantly increased with the dose (from 26 +/- 16 to 147 +/- 74 seconds). Myocardial contrast intensity also increased after contrast (from 15 +/- 12 to 21 +/- 18 gray level/pixel, p < 0.001). Contrast echo detected myocardial perfusion defects (corresponding to 17% +/- 11% of LV cross-sectional area) in all the injections performed during coronary occlusion and detected myocardial reperfusion with a sensitivity of 50% versus microspheres. The extent of perfusion defects by contrast echo showed a good correlation with microspheres (r = 0.73). Myocardial reperfusion was not detected by changes in heart rate, aortic pressure, pulmonary arterial pressure, cardiac output, left ventricular fractional area change, or wall-motion score index. Hemodynamic parameters were not affected by contrast injections. Thus, the i.v. administration of BR1 allows us to accurately detect myocardial perfusion defects during coronary occlusion and, to a lesser extent, myocardial reperfusion after thrombolysis.

Randomised trial of elective stenting after successful percutaneous transluminal coronary angioplasty of occluded coronary arteries

BACKGROUND

The value of angioplasty in occluded coronary arteries is limited by a restenosis/reocclusion rate of 50-70%. In patients with subtotal occlusion, stent implantation has been shown to reduce clinical and angiographic restenosis. Retrospective observational studies have suggested that stenting could reduce restenosis in total occlusions. The value of sustained coronary patency on global and regional left ventricular function in this clinical setting has not been defined clearly.

OBJECTIVES

To assess the medium term effect of elective intracoronary stent deployment after successful percutaneous transluminal coronary angioplasty (PTCA) of an occluded coronary artery.

METHODS

Sixty patients with a total coronary occlusion successfully treated by PTCA were randomised to receive an intracoronary stent or no stent. Patients underwent clinical and angiographic follow up at six months.

RESULTS

Thirty patients received a stent (group A) and 30 were treated by angioplasty alone (group B), all with initial success. One patient in group B required repeat angioplasty with stenting at 24 hours and one patient died after 10 days. Angiographic follow up was available for 57 patients. This showed a significantly reduced reocclusion rate in group A compared with group B (7% v 29%, p < 0.01) and a tendency to a reduced restenosis rate (22% v 40%, p = 0.105) in patients with no reocclusion. Left ventricular function, both global and regional, improved in group A. Only the regional left ventricular function in the area supplied by the target coronary artery improved in group B. Recurrence of symptoms and clinical events such as repeat angioplasty, coronary artery bypass grafting, death or myocardial infarction tended to be reduced in group A (4 (13%) v 9 (30%)).

CONCLUSIONS

Intracoronary stent insertion is effective in reducing the rate of reocclusion and shows a trend towards reduced restenosis after opening of a total coronary occlusion by balloon angioplasty. Sustained patency of the target coronary artery is associated with improvement in global and regional left ventricular function.

Clinical perspectives on the use of composite endpoints

Although mortality is the most important endpoint in evaluating new regimens, insistence on its use as the only endpoint in clinical trials can require that thousands of patients be studied. Accordingly, composite endpoints have been increasingly used to increase the overall event rate and thereby reduce the number of patients needed for the trial. For use as part of composite endpoint, nonfatal endpoints should be clinically meaningful, i.e., related to an adverse subsequent prognosis. In acute myocardial infarction (MI), several intermediate endpoints in the well-described pathophysiology of acute MI have been correlated with an adverse long-term outcome: recurrent MI, new onset congestive heart failure or cardiogenic shock, left ventricular dysfunction, large infarct size, and failure to achieve early patency of the infarct-related artery. Furthermore, in acute MI, new therapies that improve these nonfatal endpoints also improve mortality, thereby validating this approach. Once this link is established, such nonfatal endpoints can be validly used in evaluating new therapies. Note, however, if this link has not been made (that mortality is reduced when there is a reduction in the nonfatal endpoint), as in the case of suppression of ventricular premature complexes with antiarrhythmic therapy, the nonfatal endpoint cannot be used validly. Thus, appropriately designed and validated composite endpoints can provide a valid means of testing new treatments in a smaller trial than one using mortality alone. Their use should allow testing of a greater number of new regimens, thereby allowing more rapid progress toward improving the clinical outcome of patients.