Promise of combined low-molecular-weight heparin and platelet glycoprotein IIb/IIIa inhibition: results from Platelet IIb/IIIa Antagonist for the Reduction of Acute coronary syndrome events in a Global Organization Network B (PARAGON B)

Antithrombotic Therapy for ACS in Elderly Patients

BACKGROUND

Patients over 75 account for more than one third of those presenting with myocardial infarction and more than 50% of intrahospital mortality. There are no specific guidelines for the management of acute coronary syndromes (ACS) in the elderly.

SETTING

Although antithrombotic therapy seems to be effective and safe in such patients, it requires specific precautions and treatment adjustments because of the higher bleeding risk due to comorbidities such as renal function impairment and malnutrition.

RESULTS

Scientific evidence concerning elderly patients is scarce as they are either excluded or underrepresented in most randomized trials. Overall, the antithrombotic therapy needs to be adapted to avoid complications, mainly bleeding complications, without compromising the effectiveness of the treatment in this high-risk population.

CONCLUSION

In the present paper, we review the current treatment strategies in ACS while focusing on data concerning the elderly, according to available data in pivotal trials and in both AHA/ACC and ESC guidelines.

Relationship Between Peak Troponin Values and Long-Term Ischemic Events Among Medically Managed Patients With Acute Coronary Syndromes

BACKGROUND

The relationship between troponin level and outcomes among patients with non-ST-segment elevation ACS is established, but the relationship of troponin level with long-term outcomes among medically managed non-ST-segment elevation ACS patients receiving contemporary antiplatelet therapy is inadequately defined.

METHODS AND RESULTS

In 6763 medically managed non-ST-segment elevation ACS patients randomized in TRILOGY ACS (Targeted Platelet Inhibition to Clarify the Optimal Strategy to Medically Manage Acute Coronary Syndromes) (prasugrel versus clopidogrel), we examined relationships between categories of peak troponin/upper limit of normal (ULN) ratio within 48 hours of the index ACS event (≈4.5 days before randomization) and 30-month outcomes (cardiovascular death, myocardial infarction, or stroke; cardiovascular death or myocardial infarction; and all-cause death). Patients with peak troponin levels <1×ULN were younger, were more often women, and had lower GRACE risk scores than those in other troponin groups. Those with ratios ≥5×ULN were more frequently smokers but less often had prior myocardial infarction or percutaneous coronary intervention. Diabetes mellitus prevalence, body mass index, serum creatinine, and hemoglobin were similar across groups. For all end points, statistically significant differences in 30-month event rates were observed between peak troponin categories. The relationship was linear for 30-month mortality (<1×ULN, n=1849 [6.2%]; 1 to <3×ULN, n=1203 [9.6%]; 3 to <5×ULN, n=581 [10.8%]; and ≥5×ULN, n=3405 [12.8%]) but plateaued for composite end points beyond peak troponin values ≥3×ULN. There was no statistically significant heterogeneity in treatment effect by peak troponin ratio for any end point.

CONCLUSIONS

Among medically managed non-ST-segment elevation ACS patients selected for medical management, there was a graded relationship between increasing peak troponin and long-term ischemic events but no heterogeneity of treatment effect for prasugrel versus clopidogrel according to peak troponin.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00699998.

Outcomes among non-ST-segment elevation acute coronary syndromes patients with no angiographically obstructive coronary artery disease: observations from 37,101 patients

AIMS

Limited data exist concerning outcomes of patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS) with no angiographically obstructive coronary artery disease (non-obstructive CAD). We assessed the frequency of clinical outcomes among patients with non-obstructive CAD compared with obstructive CAD.

METHODS AND RESULTS

We pooled data from eight NSTE ACS randomized clinical trials from 1994 to 2008, including 37,101 patients who underwent coronary angiography. The primary outcome was 30-day death or myocardial infarction (MI). Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for 30-day death or MI for non-obstructive versus obstructive CAD were generated for each trial. Summary ORs (95% CIs) across trials were generated using random effects models. Overall, 3550 patients (9.6%) had non-obstructive CAD. They were younger, more were female, and fewer had diabetes mellitus, previous MI or prior percutaneous coronary intervention than patients with obstructive CAD. Thirty-day death or MI was less frequent among patients with non-obstructive CAD (2.2%) versus obstructive CAD (13.3%) (OR(adj) 0.15; 95% CI, 0.11-0.20); 30-day death or spontaneous MI and six-month mortality were also less frequent among patients with non-obstructive CAD (OR(adj) 0.19 (0.14-0.25) and 0.37 (0.28-0.49), respectively).

CONCLUSION

Among patients with NSTE ACS, one in 10 had non-obstructive CAD. Death or MI occurred in 2.2% of these patients by 30 days. Compared with patients with obstructive CAD, the rate of major cardiac events was lower in patients with non-obstructive CAD but was not negligible, prompting the need to better understand management strategies for this group.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Safety and efficacy of bivalirudin monotherapy in patients with diabetes mellitus and acute coronary syndromes: a report from the ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) trial

OBJECTIVES

We sought to evaluate clinical outcomes of patients with diabetes mellitus in the ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) trial, overall and by treatment arm.

BACKGROUND

In the ACUITY trial, 13,819 patients with moderate- or high-risk acute coronary syndromes (ACS) were randomized to heparin (unfractionated or enoxaparin) plus glycoprotein IIb/IIIa inhibition (GPI), bivalirudin plus GPI, or bivalirudin monotherapy. Compared with heparin plus GPI, bivalirudin monotherapy resulted in similar protection from ischemic events with less major bleeding. Whether these results apply to patients with diabetes is unknown.

METHODS

We evaluated the impact of diabetes on 30-day net adverse clinical outcomes (composite ischemia [death, myocardial infarction, or unplanned ischemic revascularization] or major bleeding), overall and by antithrombotic strategy.

RESULTS

Diabetes was present in 3,852 randomized patients (27.9%). Compared with nondiabetic patients, diabetic patients had higher 30-day rates of net adverse clinical outcomes (12.9% vs. 10.6%; p < 0.001), composite ischemia (8.7% vs. 7.2%; p = 0.003), and major bleeding (5.7% vs. 4.2%; p < 0.001). Among diabetic patients, compared with heparin plus GPI, bivalirudin plus GPI resulted in similar rates of net adverse clinical outcomes (14.0% vs. 13.8%; p = 0.89), while bivalirudin monotherapy resulted in a similar rate of composite ischemia (7.9% vs. 8.9%; p = 0.39) and less major bleeding (3.7% vs. 7.1%; p < 0.001), yielding fewer net adverse clinical outcomes (10.9% vs. 13.8%; p = 0.02).

CONCLUSIONS

Diabetic patients with ACS managed invasively have higher rates of composite ischemia and major bleeding. Compared with treatment with heparin plus GPI, bivalirudin monotherapy provides similar protection from ischemic events with less major bleeding, resulting in a significant reduction in net adverse clinical outcomes.

[Mean length of stay and prognosis in unstable angina. Results from the ARIAM database]

BACKGROUND AND OBJECTIVE

The objective of this project is to investigate the factors predicting mortality and mean length of stay in patients diagnosed with unstable angina (UA) during admission to the Intensive Care Unit or Critical Care Unit (ICU/CCU).

PATIENTS AND METHOD

A retrospective cohort study including all the UA patients listed in the Spanish ARIAM register. The study period comprised from June, 1996 to December, 2003. The follow-up period is limited to the stay in the ICU/CCU. One univariate analysis was performed between deceased and live patients; and another between prolonged and non-prolonged stay patients. Three multivariate analyses were also performed; one to evaluate the factors related to mortality, another to evaluate the variables associated to percutaneous coronary intervention (PCI) and another to evaluate the factors associated to the prolonged mean stay in ICU/CCU.

RESULTS

14,096 patients with UA were included in the study. The UA mortality rate during ICU/CCU admission was 1.1%. Mortality was associated to Killip classification, age, the need for CPR, development of cardiogenic shock, development of arrhythmia (such as VF, sinus tachycardia or high-degree atrioventricular block) and diabetes; whereas patients who smoke were associated to a lower mortality rate. PCI was only performed in 1,226 patients (8.9%), increasing over the years. The PCI-predicting variables were: age, being referred from another hospital, smoking, presenting prior acute myocardial infarction (AMI), complications consisting of cardiogenic shock or high-degree atrioventricular block and being treated with oral beta blockers. The mean length of stay in ICU/CCU was 3.15 (18.65) days (median, 2 days), depending on age, a coronariography having previously been performed, the Killip classification, having required coronariography and PCI or echocardiography or mechanical ventilation, and presenting complications such as angina that is difficult to control, arrhythmia, right ventricular failure or death.

CONCLUSIONS

The factors are associated to mortality were; greater age, diabetes, Killip classification, arrhythmia, cardiogenic shock and the need for CPR, whereas smoking is associated to a lower mortality rate. The patients on whom PCI was performed represent a less severe population. Management has changed over the years, with an increase in PCI. A prolonged mean length of stay is associated to the appearance of arrhythmia, right or left heart failure, angina that is difficult to control, age and PCI.

Acute coronary care in the elderly, part I: Non-ST-segment-elevation acute coronary syndromes: a scientific statement for healthcare professionals from the American Heart Association Council on Clinical Cardiology: in collaboration with the Society of Geriatric Cardiology

BACKGROUND

Age is an important determinant of outcomes for patients with acute coronary syndromes (ACS); however, community practice reveals a disproportionately lower use of cardiovascular medications and invasive treatment even among elderly patients with ACS who would stand to benefit. Reasons include limited trial data to guide the care of older adults and uncertainty about benefits and risks, particularly with newer medications or invasive treatments and in the setting of advanced age or complex health status.

METHODS AND RESULTS

This 2-part American Heart Association scientific statement summarizes evidence on patient heterogeneity, clinical presentation, and treatment of non-ST-elevation ACS in relation to age (< 65, 65 to 74, 75 to 84, and > or = 85 years). In addition, we review methodological issues that influence the acquisition and application of evidence to the elderly patients treated in community practice. A writing group combining international cardiovascular and geriatric perspectives convened to summarize available data from trials (5 combined Virtual Coordinating Center for Global Collaborative Cardiovascular Research [VIGOUR] trials) and 3 registries (Global Registry of Acute Coronary Events, National Registry of Myocardial Infarction, and the Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the American College of Cardiology/American Heart Association guidelines national quality improvement initiative [CRUSADE]) to provide a conceptual framework for future work in the care of the elderly with acute cardiac disease. Treatment for non-ST-segment-elevation ACS (Part I) and ST-segment-elevation myocardial infarction (Part II) are reviewed. In addition, ethical considerations pertaining to acute care and secondary prevention are considered (Part II). The primary goal is to identify the areas in which sufficient evidence is available to guide practice, as well as to determine areas that warrant further study. Although treatment-related benefits should rise in an elderly population with high disease risk, data to assess these benefits are limited, outcomes of importance vary, and heterogeneity among the elderly increases treatment-related risks. Although a uniform approach to care in the oldest of the old is unlikely, understanding the major contributors to benefits and risks from treatment will advance the ability to apply guideline-based care in this subset of patients.

CONCLUSIONS

Although a few recent trials have described treatment effects in older patients, others continue to exclude patients on the basis of age. Going forward, prospective trials should enroll elderly subjects proportionate to their prevalence among the treated population to define risk and benefit. Findings from age subgroup analyses should be reported in a consistent manner across trials, including absolute and relative risks for efficacy and safety. Outcomes of particular relevance to the elderly, such as quality of life, physical function, and independence, should also be considered. Creatinine clearance should be calculated for every elderly patient to enable appropriate dosing. In addition, physicians need an understanding of conditions unique to older patients (eg, frailty, cognitive impairment) that influence treatment goals and outcomes. With these efforts, treatment risks can be minimized, and benefits can be placed in the health context of the elderly patient with ACS.

Discordant Cardiac Biomarkers: Frequency and Outcomes in Emergency Department Patients With Chest Pain

STUDY OBJECTIVE

We evaluate associations between pairs of discordant cardiac biomarkers (positive MB band of creatine kinase [CKMB] with negative creatine kinase, positive CKMB with negative cardiac troponin, and positive troponin with negative CKMB) and the presence of acute coronary syndromes in emergency department (ED) chest pain patients.

METHODS

This was a secondary analysis of a prospective registry. Data were obtained from the multicenter Internet Tracking Registry of Acute Coronary Syndromes, which included 17,713 ED visits for possible acute coronary syndrome between June 1999 and August 2001. First visits and first ED cardiac biomarker results from the 9 sites, 8 in the United States and 1 in Singapore, were included. Subjects were excluded for incomplete information or an initial ECG consistent with ST-segment elevation myocardial infarction. Acute coronary syndrome was defined by diagnosis-related group code indicating myocardial infarction, positive invasive or noninvasive diagnostic testing, revascularization, or death during hospitalization or within 30 days.

RESULTS

Of 8,769 eligible patients, 1,614 (18.4%) had acute coronary syndrome. The CKMB and cardiac troponin results were discordant in 7% of patients (CKMB+/cardiac troponin-, 4.9%, CKMB-/cardiac troponin+ 2.1%), whereas increased CKMB with normal creatine kinase levels occurred in 239 (3.1%) patients. The unadjusted odds ratios with 95% confidence intervals for acute coronary syndrome in patients with and without discordant markers were: CKMB+/CK- 5.7 (4.4-7.4), CKMB+/CK+ 4.4 (3.6-5.2), CKMB-/cTn+ 4.8 (3.4-6.8), CKMB+/cTn- 2.2 (1.7-2.8), CKMB+/cTn+ 26.6 (18.0-39.3). For the group with cardiac troponin, the reference category was negative troponin and negative CKMB; for the group with creatine kinase, the reference category was negative CKMB but either a positive or negative creatine kinase.

CONCLUSION

Among the spectrum of ED patients with chest pain, an increased CKMB level with a normal creatine kinase level identifies patients at increased risk for acute coronary syndrome. Similarly, an increased troponin level regardless of CKMB level and an increased CKMB level regardless of troponin level identify patients at higher risk for acute coronary syndrome than those with uniformly normal cardiac biomarker levels. Our data suggest that discordant cardiac biomarkers may identify patients at increased risk for acute coronary syndrome.

Low-molecular-weight heparin compared with unfractionated heparin for patients with non–ST-segment elevation acute coronary syndromes treated with glycoprotein IIb/IIIa inhibitors: Results from the CRUSADE initiative

BACKGROUND

Both heparin and glycoprotein (GP) IIb/IIIa inhibitor therapy and early invasive management strategies are recommended by the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for the treatment of patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS). However, controversy exists about which form of heparin-unfractionated (UF) or low-molecular-weight (LMW)-is preferable. We sought to compare the efficacy and safety of these treatment strategies in a large contemporary population of patients with NSTE ACS.

METHODS

Using data from the CRUSADE Initiative, we evaluated LMWH and UFH in high-risk NSTE ACS patients (positive cardiac markers and/or ischemic ST-segment changes) who had received early (< 24 hours) GP IIb/IIIa inhibitor therapy and underwent early invasive management. In-hospital outcomes were compared among treatment groups.

RESULTS

From a total of 11,358 patients treated at 407 hospitals in the US from January 2002-June 2003, 6881 (60.6%) received UFH and 4477 (39.4%) received LMWH. Patients treated with UFH were more often admitted to a cardiology inpatient service (73.6% vs. 65.5%, P < 0.0001) and more frequently underwent diagnostic catheterization (91.8% vs. 85.9%, P < 0.0001) and percutaneous coronary intervention (PCI) (69.7% vs. 56.9%, P < 0.0001) than patients treated with LMWH. The point estimate of the adjusted risk of in-hospital death or reinfarction was slightly lower among patients treated with LMWH (odds ratio [OR] 0.81, 95% confidence interval [CI] 0.67-0.99) and the risk of red blood cell transfusion was similar (OR 1.01, 95% CI 0.89-1.15). Among patients who underwent PCI within 48 hours, adjusted rates of death (OR 1.14, 95% CI 0.71-1.85), death or reinfarction (OR 0.93, 0.67-1.31), and transfusion (OR 1.16, 0.89-1.50) were similar. Patients who underwent PCI more than 48 hours into hospitalization had reduced rates of death (OR 0.64, 0.46-0.88), death or reinfarction (OR 0.57, 0.44-0.73), and transfusion (OR 0.66, 0.52-0.84).

CONCLUSIONS

In routine clinical practice, patients treated with GP IIb/IIIa inhibitors have slightly improved outcomes and similar bleeding risks with LMWH than with UFH. These findings are consistent with current ACC/AHA guidelines but raise important questions about the safety and effectiveness of antithrombotic therapy in real-world clinical practice. Using data from the CRUSADE Initiative, we evaluated low-molecular-weight heparin (LMWH) and unfractionated heparin (UFH) in high-risk patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS) who received early (<24 hours) glycoprotein (GP) IIb/IIIa inhibitors and early invasive management. In-hospital outcomes were compared among treatment groups. LMWH was associated with slightly improved clinical outcomes and similar rates of transfusion compared with UFH. Our results support the current ACC/AHA guidelines recommendations but raise concerns about the safety and efficacy of UFH in the setting of background use of upstream GP IIb/IIIa inhibitors for patients with NSTE ACS in routine clinical practice.

A review of the application of propensity score methods yielded increasing use, advantages in specific settings, but not substantially different estimates compared with conventional multivariable methods

OBJECTIVE

Propensity score (PS) analyses attempt to control for confounding in nonexperimental studies by adjusting for the likelihood that a given patient is exposed. Such analyses have been proposed to address confounding by indication, but there is little empirical evidence that they achieve better control than conventional multivariate outcome modeling.

STUDY DESIGN AND METHODS

Using PubMed and Science Citation Index, we assessed the use of propensity scores over time and critically evaluated studies published through 2003.

RESULTS

Use of propensity scores increased from a total of 8 reports before 1998 to 71 in 2003. Most of the 177 published studies abstracted assessed medications (N=60) or surgical interventions (N=51), mainly in cardiology and cardiac surgery (N=90). Whether PS methods or conventional outcome models were used to control for confounding had little effect on results in those studies in which such comparison was possible. Only 9 of 69 studies (13%) had an effect estimate that differed by more than 20% from that obtained with a conventional outcome model in all PS analyses presented.

CONCLUSIONS

Publication of results based on propensity score methods has increased dramatically, but there is little evidence that these methods yield substantially different estimates compared with conventional multivariable methods.

Elevated creatine kinase-MB with normal creatine kinase predicts worse outcomes in patients with acute coronary syndromes: results from 4 large clinical trials

BACKGROUND

The degree to which elevated creatine kinase (CK)-MB in the presence of normal CK is predictive of outcome is not well understood despite having been studied for decades. This analysis examined whether normal CK with elevated CK-MB in patients with non-ST-segment elevation acute coronary syndrome (NSTE ACS) is an independent predictor of worse outcomes. A concomitant goal was to contribute insight to the debate over how patients with NSTE ACS should be managed.

METHODS

Data for 25,960 patients from the GUSTO IIb, PARAGON A and B, and PURSUIT trials were analyzed. Of these patients, 6402 were excluded from primary analysis because of missing (unmeasured) biomarkers. Patients with complete laboratory data (n = 19,558) were grouped by CK and CK-MB results. To confirm the primary analysis results, data from patients with missing biomarkers were used in an imputation model.

RESULTS

Patients were categorized in 1 of 4 groups: normal CK + normal CK-MB; normal CK + elevated CK-MB; elevated CK + normal CK-MB; or elevated CK + elevated CK-MB. For the primary outcome, 180-day death, or myocardial infarction, Kaplan-Meier estimates were 14.9%, 20.8%, 14.5%, and 18.2%, respectively. Regardless of total CK, elevated CK-MB was associated with a 25% to 49% increased relative risk of worse outcomes. Findings from the analyses were verified by the multivariable model.

CONCLUSIONS

CK-MB remains a reliable marker for myocardial necrosis and a strong predictor of worse prognosis. All patients with ACS should have CK-MB measurement to search for cardiac ischemia. Patients with elevated CK-MB should receive aggressive management commensurate with their increased risks.

Low-molecular-weight heparins in ischemic heart disease

PURPOSE OF REVIEW

The objective of this review was to summarize the recent developments regarding the use of low-molecular-weight heparins in the management of acute coronary syndromes.

RECENT FINDINGS

In the setting of unstable angina and non-ST-elevation myocardial infarction, enoxaparin is superior to unfractionated heparin in reducing death, myocardial infarction, and recurrent ischemia both in the short-term and to 1 year. However, this does not necessarily imply a class effect of low-molecular-weight heparins in general. When combined with glycoprotein IIb/IIIa inhibitors, enoxaparin appears to be effective and safe even for patients treated according to an early invasive strategy. In patients receiving fibrinolytics for ST-elevation myocardial infarction, low-molecular-weight heparins are as effective as unfractionated heparin in maintaining patency of the infarct-related artery and in reducing the composite endpoint of death and reinfarction. However, serious bleeding is more common, especially among the elderly, and the optimal dosing regimen in ST-elevation myocardial infarction remains to be defined.

SUMMARY

Low-molecular-weight heparins are safe and effective in the management of unstable angina and non-ST-elevation myocardial infarction, with or without concurrent administration of glycoprotein IIb/IIIa inhibitors. Ongoing studies will clarify the role of low-molecular-weight heparins as adjunctive therapy for fibrinolysis.

Long-Term Clinical Outcomes of Platelet Glycoprotein IIb/IIIa Inhibitor Combined With Low Molecular Weight Heparin in Patients With Acute Coronary Syndrome

BACKGROUND

Platelet activation and aggregation with resultant arterial thrombus formation play a pivotal role in the pathophysiology of acute coronary syndrome (ACS). In the present study the efficacy of tirofiban, a specific inhibitor of the platelet glycoprotein IIb/IIIa receptor, combined with heparin or low-molecular-weight heparin (dalteparin), was evaluated for the management of ACS.

METHODS AND RESULTS

One hundred and sixty patients (60.9+/-11.1 years, 104 male) with unstable angina or non-ST elevation myocardial infarction and who had ST-T changes and elevated troponin were randomly assigned to 4 groups: group I (n=40: heparin alone), group II (n=40: dalteparin alone), group III (n=40: tirofiban + heparin) and group IV (n=40: tirofiban + dalteparin). The occurrence of major adverse cardiac events (MACE) was compared prospectively during a 6-month clinical follow-up. Percutaneous coronary intervention or coronary artery bypass graft was performed in 32 cases in group I, 29 in group II, 28 in group III and 31 in group IV (p=0.72). Minor bleeding complication developed in 2 patients (5.0%) in group I, 2 (5.0%) in group II, 4 (10.0%) in group III and 3 (7.5%) in group IV (p=0.78). During the follow-up MACE occurred in 10 patients (31.3%) in group I, 9 (31.0%) in group II, 4 (14.3%) in group III and 4 (12.9%) in group IV (p=0.02: Group I and II vs Group III and IV).

CONCLUSIONS

Tirofiban combined with dalteparin was associated with relatively more bleeding complications in the short term, but was effective in reducing the incidence of MACE during long-term clinical follow-up in patients with ACS.

Antithrombotic therapy for coronary artery disease: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This chapter about antithrombotic therapy for coronary artery disease (CAD) is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following: For patients presenting with non-ST-segment elevation (NSTE) acute coronary syndrome (ACS), we recommend immediate and then daily oral aspirin (Grade 1A). For patients with an aspirin allergy, we recommend immediate treatment with clopidogrel, 300-mg bolus po, followed by 75 mg/d indefinitely (Grade 1A). In all NSTE ACS patients in whom diagnostic catheterization will be delayed or when coronary bypass surgery will not occur until > 5 days, we recommend clopidogrel as bolus therapy (300 mg), followed by 75 mg/d for 9 to 12 months in addition to aspirin (Grade 1A). In NSTE ACS patients in whom angiography will take place within 24 h, we suggest beginning clopidogrel after the coronary anatomy has been determined (Grade 2A). For patients who have received clopidogrel and are scheduled for coronary bypass surgery, we recommend discontinuing clopidogrel for 5 days prior to the scheduled surgery (Grade 2A). In moderate- to high-risk patients presenting with NSTE ACS, we recommend either eptifibatide or tirofiban for initial (early) treatment in addition to treatment with aspirin and heparin (Grade 1A). For the acute treatment of NSTE ACS, we recommend low molecular weight heparins over unfractionated heparin (UFH) [Grade 1B] and UFH over no heparin therapy use with antiplatelet therapies (Grade 1A). We recommend against the direct thrombin inhibitors as routine initial antithrombin therapy (Grade 1B). For patients after myocardial infarction, after ACS, and with stable CAD, we recommend aspirin in doses from 75 to 325 mg as initial therapy and in doses of 75 to 162 mg as indefinite therapy (Grade 1A). For patients with contraindications to aspirin, we recommend long-term clopidogrel (Grade 1A). For primary prevention in patients with at least moderate risk for a coronary event, we recommend aspirin, 75 to 162 mg/d, over either no antithrombotic therapy or vitamin K antagonist (VKA) [Grade 2A]; for patients at particularly high risk of events in whom the international normalized ratio (INR) can be monitored without difficulty, we suggest low-dose VKA (target INR, 1.5) [Grade 2A].

Low molecular weight heparin and atherosclerosis

Low molecular weight heparin (LMWH) has dramatically impacted the treatment of venous thromboembolic disease and acute coronary syndromes. Recent studies help define the role of these agents for patients undergoing percutaneous coronary interventions and for patients treated with thrombolytic agents for ST-segment elevation myocardial infarction. Recent studies also suggest potential usefulness of LMWH for patients with peripheral vascular disease and its limits of utility in stroke. This review summarizes the evidence about the use of LMWH in these clinical situations.

Low molecular weight heparins combined with platelet glycoprotein IIb/IIIa inhibitors in the management of acute coronary syndromes

Clinical trials of several platelet glycoprotein (GP) IIb/IIIa receptor inhibitors have demonstrated an unequivocal benefit of this potent antithrombotic therapy in high-risk patients with acute coronary syndromes (ACS) as well as in those undergoing percutaneous coronary intervention. In all of these major trials, however, GP IIb/IIIa inhibitors were used in combination with unfractionated (UF) heparin. Low molecular weight heparins (LMWH) have several advantages over UF heparin therapy, making them attractive alternatives for use in combination with GP IIb/IIIa inhibitors. In the INTegrelin and Enoxaparin Randomized assessment of Acute Coronary syndrome Treatment (INTERACT) study, combination therapy using the GP IIb/IIIa inhibitor eptifibatide (Integrilin) and the LMWH enoxaparin (Lovenox) in patients with high-risk non-ST-segment elevation ACS, resulted in improved outcomes compared to the currently recommended therapy of UF heparin, with better safety results. It is anticipated that the LMWHs may soon replace the traditional UF heparin for combination therapy with GP IIb/IIIa inhibitors in the medical stabilisation of patients with ACS. Results of other ongoing studies of LMWH combinations with other GP IIb/IIIa inhibitors and in the setting of percutaneous coronary intervention are awaited.

Use of low-molecular-weight heparins in the management of acute coronary artery syndromes and percutaneous coronary intervention

CONTEXT

Low-molecular-weight heparins (LMWHs) possess several potential pharmacological advantages over unfractionated heparin as an antithrombotic agent.

OBJECTIVE

To systematically summarize the clinical data on the efficacy and safety of LMWHs compared with unfractionated heparin across the spectrum of acute coronary syndromes (ACSs), and as an adjunct to percutaneous coronary intervention (PCI).

DATA SOURCES

We searched MEDLINE for articles from 1990 to 2002 using the index terms heparin, enoxaparin, dalteparin, nadroparin, tinzaparin, low molecular weight heparin, myocardial infarction, unstable angina, coronary angiography, coronary angioplasty, thrombolytic therapy, reperfusion, and drug therapy, combination. Additional data sources included bibliographies of articles identified on MEDLINE, inquiry of experts and pharmaceutical companies, and data presented at recent national and international cardiology conferences.

STUDY SELECTION

We selected for review randomized trials comparing LMWHs against either unfractionated heparin or placebo for treatment of ACS, as well as trials and registries examining clinical outcomes, pharmacokinetics, and/or phamacodynamics of LMWHs in the setting of PCI. Of 39 studies identified, 31 fulfilled criteria for analysis.

DATA EXTRACTION

Data quality was determined by publication in the peer-reviewed literature or presentation at an official cardiology society-sponsored meeting.

DATA SYNTHESIS

The LMWHs are recommended by the American Heart Association and the American College of Cardiology for treatment of unstable angina/non-ST-elevation myocardial infarction. Clinical trials have demonstrated similar safety with LMWHs compared with unfractionated heparin in the setting of PCI and in conjunction with glycoprotein IIb/IIIa inhibitors. Finally, LMWHs show promise as an antithrombotic agent for the treatment of ST-elevation myocardial infarction.

CONCLUSIONS

The LMWHs could potentially replace unfractionated heparin as the antithrombotic agent of choice across the spectrum of ACSs. In addition, they show promise as a safe and efficacious antithrombotic agent for PCI. However, further study is warranted to define the benefit of LMWHs in certain high-risk subgroups before their use can be universally recommended.