Predictors of recurrent ischemic events and death in unstable coronary artery disease after treatment with combination antithrombotic therapy

Relation between hemoglobin level and recurrent myocardial ischemia in acute coronary syndromes detected by continuous electrocardiographic monitoring

Anemia has been associated with adverse outcomes in patients with acute coronary syndromes (ACS). However, the underlying pathophysiologic mechanisms have not been well elucidated. We sought to determine the independent relation between the hemoglobin level and recurrent ischemia in patients with non-ST-segment elevation ACS using continuous electrocardiographic monitoring. In the Integrilin and Enoxaparin Randomized Assessment of Acute Coronary Syndrome Treatment (INTERACT) trial, 746 patients presenting with non-ST-segment elevation ACS underwent continuous ST-segment monitoring for 48 hours. The data were analyzed independently at a core laboratory. We stratified the study population according to their hemoglobin level on presentation. The primary outcome of the study was recurrent ischemia, defined as ST-segment shifts on continuous electrocardiographic monitoring. Of the 705 patients with analyzable data, 64 had a baseline hemoglobin level <120 g/L, 259 had a level of 120 to 139 g/L, 315 had a level of 140 to 159 g/L, and 67 had a level >160 g/L. The corresponding rates of recurrent ischemia were 39.1%, 22.0%, 15.6%, and 11.9% (p for trend <0.001). A lower hemoglobin level was associated with advanced age, co-morbidities, and a higher GRACE risk score. In multivariable analysis adjusting for these confounders, lower hemoglobin levels retained a significant independent association with recurrent ischemia (p for trend = 0.004). In conclusion, a lower hemoglobin level at presentation was independently associated with recurrent ischemia detected by continuous electrocardiographic monitoring in the setting of non-ST-segment elevation ACS. This suggests that anemia might predispose patients to recurrent ischemia, which could be an important underlying mediator of worse outcomes in patients with lower hemoglobin levels.

Evaluation of hospitalization and follow-up care costs among patients hospitalized with ACS treated with a stent and clopidogrel

OBJECTIVE

This retrospective claims study was performed to evaluate the initial and subsequent healthcare costs in patients with acute coronary syndrome (ACS) who had been treated with stent placement and clopidogrel following discharge from the hospital.

METHOD AND RESULTS

This was a retrospective, administrative claims-based analysis from a large, geographically diverse US managed care plan affiliated with i3 Innovus. Study subjects were commercially insured enrollees, aged > or = 18, who were hospitalized for ACS between 1 January 2000 and 31 December 2004 with a stent placed, and had at least one filled prescription for clopidogrel within 7 days of discharge from the index hospitalization. Of the 9135 subjects included in the cost analysis, 2241 subjects experienced a subsequent event. On average, subjects with a second event incurred $32,495 more in medical costs over 2 years and $39,742 more in medical costs over 3 years versus those who did not have a second event. Excluding ischemic hospitalizations, subjects with a second event incurred $7257 and $9724 more in medical costs than patients without a second event during the 2 and 3 years following discharge from the index hospitalization, respectively.

CONCLUSIONS

Significant cost increases were observed among patients who had a subsequent hospitalization for an ischemic event compared to those without a subsequent hospitalization. Cost increases were still present after excluding costs of the ischemic hospitalizations. The findings of this study must be considered within the limitations of database analysis as claims data are collected for the purpose of payment and not research.

Explicit risk in acute coronary syndrome management

At least implicitly, most clinical decisions represent an integration of disease and treatment-based risk assessments. Often, as is the case with acute coronary syndrome (ACS), these decisions need to be made quickly at a time when data elements are limited, and published risk models are very useful in clarifying time-dependent determinants of risk. The present review emphasizes the value of explicit risk assessment and reinforces the fact that patients at highest risk are often those most likely to benefit from newer and more invasive therapies. Suggested ways to incorporate published ACS risk models into clinical practice are included. In addition, the need to adopt a longer-term view of risk in ACS patients is stressed, with particular regard to the important role of heart failure prediction and treatment.

Cardiac troponin T in acute coronary syndrome with renal insufficiency

Cardiac troponin levels are frequently elevated in patients with chronic renal failure, hence diagnosis of myocardial necrosis is difficult. The prevalence of elevated serum troponin T was determined and its diagnostic value in acute coronary syndrome was assessed in patients with chronic renal insufficiency. A retrospective cross-sectional analysis was performed in 227 patients with chronic renal insufficiency and a diagnosis of unstable angina, non-ST or ST-segment elevation myocardial infarction. All patients had baseline serum troponin T levels measured at previous visits; the baseline troponin T level was raised in 53.3%. Cardiac troponin T levels did not correlate with creatinine levels, and were not affected by dialysis. Mortality after an acute coronary event was high (46.3%). Because of the elevated baseline cardiac troponin T levels, detection of acute coronary syndrome in patients with chronic renal failure requires evaluation of serial cardiac enzyme measurements and serial 12-lead electrocardiograms. Early and definitive cardiac interventions may contribute towards decreasing the mortality rate in this group of patients.

Risk stratification following acute myocardial infarction

This article reviews the current risk assessment models available for patients presenting with myocardial infarction (MI). These practical tools enhance the health care provider's ability to rapidly and accurately assess patient risk from the event or revascularization therapy, and are of paramount importance in managing patients presenting with MI. This article highlights the models used for ST-elevation MI (STEMI) and non-ST elevation MI (NSTEMI) and provides an additional description of models used to assess risks after primary angioplasty (ie, angioplasty performed for STEMI).

Risk stratification of patients with acute chest pain and normal troponin concentrations

OBJECTIVE

To investigate the outcome of patients with acute chest pain and normal troponin concentrations.

DESIGN

Prospective cohort design.

SETTING

Single centre study in a teaching hospital in Spain.

PATIENTS

609 consecutive patients with chest pain evaluated in the emergency department by clinical history (risk factors and a chest pain score according to pain characteristics), ECG, and early (< 24 hours) exercise testing for low risk patients with physical capacity (n = 283, 46%). All had normal troponin concentrations after serial determination.

MAIN OUTCOME MEASURES

Myocardial infarction or cardiac death during six months of follow up.

RESULTS

29 events were detected (4.8%). No patient with a negative early exercise test (n = 161) had events versus the 6.9% event rate in the remaining patients (p = 0.0001). Four independent predictors were found: chest pain score > or = 11 points (odds ratio (OR) 2.4, 95% confidence interval (CI) 1.1 to 5.5, p = 0.04), diabetes mellitus (OR 2.3, 95% CI 1.1 to 4.7, p = 0.03), previous coronary surgery (OR 3.1, 95% CI 1.3 to 7.6, p = 0.01), and ST segment depression (OR 2.8, 95% CI 1.3 to 6.3, p = 0.003). A risk score proved useful for patient stratification according to the presence of 0-1 (2.7% event rate), 2 (10.2%, p = 0.008), and 3-4 predictors (29.2%, p = 0.0001).

CONCLUSIONS

A negative troponin result does not assure a good prognosis for patients coming to the emergency room with chest pain. Early exercise testing and clinical data should be carefully evaluated for risk stratification.

Impact of contemporary guideline compliance on risk stratification models for acute coronary syndromes in The Registry of Acute Coronary Syndromes

We compared the predictive value of the Rush score with the Thrombolysis In Myocardial Infarction (TIMI) risk score in unselected patients with an acute coronary syndrome and evaluated the effect of compliance with established guidelines on the accuracy of these models. The Registry of Acute Coronary Syndromes is a retrospective registry of 3,754 consecutive patients (38% women; mean age 67 years) who presented with acute coronary syndrome to the emergency department between April 1, 1999, and December 31, 2000, at 9 hospitals. The primary end point was death, myocardial infarction, or urgent revascularization during hospitalization. Rush classification was based on quartiles of predicted risk of cardiac complication (<2% for class I vs >15% for class IV). The TIMI score was implemented as published. Compliance with guidelines for acute coronary syndrome was assessed with a 4-point scale based on the aggregate use of aspirin, beta blockers, heparin, and glycoprotein IIb/IIIa inhibitors. Fifteen percent of patients met the primary end point. The primary end point rates for TIMI scores 0/1, 2, 3, 4, 5, and 6/7 were 11%, 14%, 13%, 11%, 14%, and 12%, respectively (p = NS). The primary end point rates for Rush classes I, II, III, and IV were 6%, 8%, 9%, and 17%, respectively (p <0.001). After controlling for compliance with established guidelines, the odds ratio of an event increased by 46% for each unit increase in Rush score (p <0.001). After adjusting for the Rush score, the odds ratio decreased by 54% for each unit increase in compliance (p <0.001). Thus, compliance with current American College of Cardiology/American Heart Association guidelines significantly improves prognosis, regardless of the risk score. The use of established risk scores may overestimate event rates in unselected populations.

Learning on the Web. Case 3: acute chest pain

A 49 year old Afro-Caribbean woman presents to A&E after a 30 minute episode of severe, burning central chest pain radiating to the throat. When she had the pain she felt cold and sweaty but is now symptom-free. Episodes of a similar but less severe pain had occurred daily for the previous 10 days, predominantly at rest but also when climbing the stairs at home. The patient has multiple risk factors for coronary disease (including type II diabetes, hypertension, and being a smoker), but the clinical presentation is not absolutely typical for coronary artery disease and the initial ECG is normal. There is also a history from the patient of an exercise stress test one week before, which she believed to be normal. The significance of these signs and symptoms, the diagnosis, and the short and long term treatment of these problems are discussed in an interactive case presentation.

The problem of decompensated heart failure: nomenclature, classification, and risk stratification

Despite its high prevalence and significant rates of associated morbidity and mortality, the syndrome of decompensated heart failure remains poorly defined and vastly understudied. Few high-quality epidemiologic studies, randomized controlled trials, or published guidelines are available to guide the management of this complex disease. In addition, there is no consensus definition of the clinical problem that it presents, no agreed upon nomenclature to describe its clinical features, and no recognized classification scheme for its patient population; all of which has contributed to the lack of therapeutic development in this critical arena of cardiovascular disease. This review outlines the scope of the problem and proposes a system of nomenclature and classification sufficiently simple for general acceptance among clinicians while still encompassing the heterogeneity of the patient population. It also defines the current understanding of strategies for risk stratification in the setting of decompensated heart failure.

A review of the GUARDIAN trial results: clinical implications and the significance of elevated perioperative CK-MB on 6-month survival

BACKGROUND

The Guard During Ischemia Against Necrosis (GUARDIAN) trial was designed to determine whether cariporide, a selective sodium-hydrogen exchanger inhibitor, reduces the combined incidence of all-cause mortality and myocardial infarction (MI) in patients at risk of myocardial necrosis and to assess the safety and tolerability of this drug.

METHODS AND RESULTS

The study population consisted of 11,590 patients who were hospitalized for an acute coronary syndrome or were undergoing high-risk percutaneous coronary intervention or coronary artery bypass grafting (CABG). Patients were enrolled and randomized to one of three doses of cariporide (20, 80, or 120 mg), or placebo, administered as a 60-minute infusion every 8 hours for two to seven days. At day 36, patients treated with cariporide 120 mg demonstrated a 10% risk reduction in death or MI compared with placebo (p = 0.12). At this dose, patients undergoing CABG experienced a 25% risk reduction in death or MI (p = 0.03), which was sustained through six months (p = 0.033). The improvement resulted primarily from a 32% risk reduction in nonfatal MI (p = 0.007). Cariporide was well tolerated; most adverse events were mild and transient. Data from the GUARDIAN trial indicate that myocardial muscle creatine kinase isoenzyme (CK-MB) values of >10 times the upper limit of normal during the initial 48 hours after CABG are associated with significantly increased six-month mortality (p < 0.001); the six-month mortality risk is similar to that observed in acute coronary syndrome patients, even after adjustment for baseline variables known to impact long-term prognosis.

CONCLUSIONS

Although the results of the GUARDIAN trial failed to demonstrate overall clinical benefit, cariporide 120 mg reduced the rate of death and MI in patients undergoing CABG. Cariporide may provide a cardioprotective benefit in CABG patients at high-risk of myocardial necrosis.

[Prognostic factors in unstable angina with dynamic electrocardiographic changes. Value of fibrinogen]

INTRODUCTION AND OBJECTIVES

The prognosis of unstable angina varies between series depending on the inclusion criteria and management protocol used. The aim of this study was to analyze in-hospital events and their predictors in a homogeneous single-center series of patients with unstable angina.

MATERIAL AND METHODS

A total of 246 patients with the following inclusion criteria were studied: 1) resting anginal pain, 2) transient electrocardiographic changes during anginal pain, 3) normal CK-MB levels and 4) exclusion of postinfarction angina. All patients were treated with aspirin and enoxaparin (1 mg/kg/12 h). Coronary angiography was performed in the case of recurrent angina or ischemia in Bruce I-II stage during the predischarge effort stress test. The variables recorded were risk factors, history of ischemic heart disease, history of coronary surgery, ECG upon admission, and fibrinogen.

RESULTS

During the hospital stay the following events were recorded: 36% recurrent angina, 58% cardiac catheterization, and 5,7% major events (infarction or death). Multivariate analysis found recurrent angina to be more frequent in patients with a history of coronary bypass surgery (p = 0.004. OR = 22; CI 95%, 3-182), ST-segment changes (p = 0.01. OR = 4.7, CI 95%; 1.4-15.9) and higher fibrinogen (p = 0.002. OR = 1,4, CI 95%; 1.1-1.7). Fibrinogen was the only variable related to cardiac catheterization (p = 0,009. OR = 1.3. CI 95%, 1.1-1.6) and major events (p = 0.001. OR = 2.0. CI 95%, 1.4-3.1).

CONCLUSIONS

1) Unstable angina with electrocardiographic changes was associated to a high rate of in-hospital events. 2) Fibrinogen was related to any event, and previous by-pass surgery and ST changes were related to recurrent angina.

Randomized double-blind safety study of enoxaparin versus unfractionated heparin in patients with non-ST-segment elevation acute coronary syndromes treated with tirofiban and aspirin: the ACUTE II study. The Antithrombotic Combination Using Tirofiban and Enoxaparin

BACKGROUND

In comparison with treatment with unfractionated heparin (UFH) and aspirin (ASA), both tirofiban administered with UFH and ASA, and enoxaparin plus ASA have shown superiority in reducing cardiac ischemic events in patients with unstable angina and non-ST-segment elevation myocardial infarction. Replacing UFH with enoxaparin when tirofiban is administered to patients may offer further therapeutic benefit, but could also increase bleeding.

OBJECTIVE

Our objective was to provide estimates of the frequency of bleeding complications, as defined by means of the Thrombolysis In Myocardial Infarction(TIMI) group, and collect data on clinical efficacy of the combination of tirofiban with enoxaparin plus ASA.

METHODS

Five hundred twenty-five patients with UA/NSTEMI were treated with tirofiban coadministered with ASA and randomized to receive either UFH (n = 210) or enoxaparin (n = 315). Therapy was administered for 24 to 96 hours. Bleeding incidences were assessed until 24 hours after trial therapy was discontinued; other clinical outcomes were assessed for as long as 30 days.

RESULTS

The total bleeding rate (TIMI major + minor + loss-no-site) for the UFH group versus the enoxaparin group was 4.8% vs 3.5% (odds ratio [OR] 1.4, CI 0.6-3.4). The TIMI major and minor bleeding rates for the UFH versus the enoxaparin groups were 1.0% versus 0.3% (OR 3.0, CI 0.3-33.8) and 4.3% versus 2.5% (OR 1.7, CI 0.7-4.6). There was an increase in nuisance cutaneous and oral bleeds (<50 mL of blood loss) in the enoxaparin group. Death or myocardial infarction occurred with similar frequency in the 2 groups (9.0% vs 9.2%). However, refractory ischemia requiring urgent revascularization and rehospitalization because of unstable angina occurred more frequently in the UFH group (4.3% vs 0.6% and 7.1% vs 1.6%, respectively).

CONCLUSIONS

Combination therapy with tirofiban plus enoxaparin appears safe, relative to therapy with tirofiban plus UFH.

Mode and timing of treatment failure (recurrent ischemic events) after hospital admission for non-ST segment elevation acute coronary syndromes

BACKGROUND

Clarification of the specific clinical course of non-ST-segment elevation acute coronary syndromes (NSTEMI ACS), including recurrent ischemic events and need for coronary revascularization, is important given the increasing economic pressure to shorten the length of hospitalization and therefore the duration of acute therapy. To examine the mode and timing of subsequent cardiac events, we analyzed pooled data from the ESSENCE and TIMI 11B studies of antithrombotic therapy in NSTEMI ACS.

METHODS

The daily event rates (with confidence intervals) during the first 43 days and the monthly average event rates during the first year were tabulated for 7081 patients.

RESULTS

The median antithrombotic treatment duration was 3.2 days, whereas the highest absolute frequency of recurrent angina prompting urgent revascularization, myocardial infarction, or death after hospital admission occurred on day 2, day 3, and day 8, respectively. Coronary revascularization was performed in 32% of patients, with the greatest number occurring on day 4. Only 12% of the end point events were adjudicated as being periprocedural. The median length of hospital stay was 7 days.

CONCLUSIONS

Despite aggressive antithrombotic therapy, a significant proportion of patients with NSTEMI ACS have recurrent ischemia precipitating urgent revascularization or infarction within the first few days, whereas the highest risk of death occurs later, after the first week.

Enoxaparin in unstable angina/non-ST-segment elevation myocardial infarction: treatment benefits in prespecified subgroups

BACKGROUND

Two large-scale phase III clinical trials, the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-wave Coronary Events (ESSENCE) trial and the Thrombolysis in Myocardial Infarction (TIMI) 11B study, have shown the low-molecular-weight heparin, enoxaparin, to be more effective than unfractionated heparin (UFH) in reducing the risk of death and severe cardiac events in patients with rest unstable angina and/or non-ST-segment elevation myocardial infarction (NSTEMI). However, patients with NSTEMI acute coronary syndromes are a heterogeneous group.

METHODS

A meta-analysis using pooled data from ESSENCE and TIMI 11B was performed to examine the efficacy of enoxaparin in different patient subgroups. In addition, a statistical model was developed to test which factors best predicted an enhanced treatment effect.

RESULTS

Enoxaparin was more effective than intravenous dose-adjusted UFH in reducing the incidence of the composite endpoint (including death, myocardial infarction or recurrent angina prompting urgent revascularization) in the majority of subgroups at 43 days after randomization. Univariate analyses revealed that there was a greater benefit with enoxaparin in patients with ST-segment deviation or elevated cardiac enzyme markers on admission, women, nonsmokers and patients with characteristics indicative of higher cardiac risk, including prior percutaneous coronary interventions, being at least 65 years old, prior angina and prior aspirin use. Multivariate statistical modelling of treatment effect revealed that ST-segment depression and electrocardiographic changes were the best predictors of an enhanced treatment effect.

CONCLUSIONS

These data reinforce previous evidence suggesting that enoxaparin administered subcutaneously twice daily may be considered as an alternative to intravenous UFH in the acute treatment of a broad range of patients with unstable coronary artery disease.

2000 ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: a practical summary for emergency physicians

There have been numerous significant clinical advances in both the diagnosis and therapy of acute coronary syndrome during the past several years. Even the term "acute coronary syndrome" is a recent creation meant to expand clinical attention in patients with chest pain of coronary origin beyond identification of ST-segment elevation myocardial infarction and prompt initiation of reperfusion therapy and to include the evaluation and management of those patients with unstable angina (UA) or myocardial injury that does not cause ST-segment elevation. Many of these advances have been studied and first implemented outside the emergency department, leading some emergency physicians to be slow to embrace them, and leaving others without a viable practical option to use them outside of the cardiac catheterization laboratory or the coronary care unit. In September 2000, the American College of Cardiology and the American Heart Association issued practice guidelines for the care of patients with UA and non-ST-segment elevation myocardial infarction. The guidelines specifically address the diagnosis and management of UA and non-ST-segment elevation myocardial infarction in the ED, suggesting evidence-based standards for risk stratification, for the use of biologic markers of myocardial damage and other adjunctive diagnostic tests, and for the appropriate use of antiplatelet and antithrombin therapeutic agents. This article provides an overview of the ED-pertinent analyses and recommendations from the 93-page document. A commentary on the implementation of these recommendations in the ED follows in a separate article.

Risk stratification in non-ST segment elevation acute coronary syndromes with special focus on recent guidelines

Patients with unstable angina or non-ST segment elevation (non-Q-wave) myocardial infarction are a heterogeneous group with respect to their risk of developing clinically significant adverse events such as subsequent myocardial infarction and death. Recent guidelines promote risk stratification of these patients, targeting high-risk patients for maximal antithrombotic and antiischemic therapy and low-risk patients for early discharge. We reviewed current and future modalities for risk stratification of patients and the predictive value of these methods in context with available pharmacologic agents. Unfortunately, most of the data identifying a particular pharmacologic regimen as beneficial in high-risk patients are retrospectively derived from large trials. Until prospective studies that use markers to guide therapy are available, clinicians should be familiar with the use of these risk markers and their application to the role of a given management strategy, including pharmacologic therapy.

Update on the management of acute coronary syndromes

At present there is debate as to whether an invasive or a conservative strategy should form the basis of an optimal management strategy for unstable angina/non-Q wave myocardial infarction (UA/NQMI). However, these approaches are complementary, not necessarily mutually exclusive. On the basis of current evidence, all patients should receive optimized medical therapy, with surgical interventions targeted at high-risk patients, to improve both clinical outcomes and cost effectiveness. While standard antithrombotic combinations have improved short-term outcomes, they do not fully eliminate the risk of recurrent ischemic episodes. The recent introduction of direct thrombin inhibitors, platelet fibrinogen receptor antagonists and low-molecular-weight heparins (LMWHs) has offered an opportunity to develop more aggressive antithrombotic regimens. Enoxaparin, an LMWH, has demonstrated improved efficacy compared with standard heparin in both the acute and chronic phases of UA/NQMI, without an increase in major complications caused by bleeding. Further studies are justified to investigate the potential of combined antithrombotic regimens containing enoxaparin as an alternative to heparin in conservative strategies and as adjuncts to interventional procedures. Recommendations for the management of UA/NQMI should be continually reviewed in response to the impact of novel treatment modalities.