The role of low-molecular-weight heparins in cardiovascular medicine

Low-molecular-weight heparins (LMWHs) have been shown to be as effective and safe as unfractionated heparin (UFH) for acute phase treatment of acute coronary syndrome in the absence of ST-elevation [unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI)]. LMWHs have practical advantages over UFH, including usual lack of requirement for laboratory monitoring of the anticoagulant response because of their favourable pharmacokinetic properties, and thus represent a simpler and more cost-effective option in clinical practice. The LMWH dalteparin has been shown to provide extended therapy benefit to high-risk UA/NSTEMI patients and can provide a protective bridge until revascularization. While revascularization procedures are now an established intervention for patients with UA/NSTEMI, a new approach for patients who cannot undergo immediate catheter intervention is to continue with medical treatment until revascularization is possible. LMWHs are currently being investigated for use in the catheterization laboratory, in patients undergoing percutaneous coronary intervention procedures, and in conjunction with thrombolytics for treatment of acute myocardial infarction.     

ST-elevation myocardial infarction: the role of adjunctive antiplatelet therapy

Antiplatelet therapy to reduce the risks of recurrent myocardial infarction and restenosis after primary percutaneous coronary intervention is critically important to optimize the early treatment of ST-segment elevation myocardial infarction (STEMI). Traditionally, acetylsalicylic acid (ASA; aspirin) has been recommended for patients with suspected STEMI, but this agent targets only one of several pathways of platelet aggregation. Antiplatelet agents with different inhibitory mechanisms may act synergistically with ASA. Glycoprotein IIb/IIIa inhibitors are generally not used with fibrinolytic agents in acute STEMI management; indeed, glycoprotein IIb/IIIa inhibitors plus bolus fibrinolytics increase the risk of intracranial hemorrhage. Aggressive antiplatelet therapy with clopidogrel reduces mortality in STEMI patients and offers significant clinical benefits, without an associated increase in major bleeding events. Recent trials support the development of an early and aggressive approach to more complete platelet inhibition using clopidogrel, in combination with ASA, for patients with STEMI.     

Severe hypocalcemia simulating ST-elevation myocardial infarction

ST-elevation myocardial infarction (STEMI) is an emergency situation in which immediate measures for myocardial reperfusion are needed. The diagnosis is based on the recognition of ST-segment elevation in the electrocardiogram (ECG). In case of coronary artery occlusion, ST-segment elevation is caused by an injury current from the ischemic myocardium. Rarely, other mechanisms may lead to ECG changes mimicking STEMI. In our case, a 65-year-old man was presented to our institution with ECG abnormalities suggestive of STEMI. However, coronary angiography showed open arteries. Laboratory tests revealed severe hypocalcemia caused by a deficiency of vitamin D. After calcium replacement therapy, the ECG normalized, and the patient was discharged in good condition. Only a few case reports on hypocalcemia-induced ST-segment elevation exist, and the mechanism remains unknown.     

Therapeutic equivalency of low-molecular-weight heparins

OBJECTIVE: To review the recent literature on the approved uses of enoxaparin, dalteparin, ardeparin, and tinzaparin and the evidence for therapeutic equivalence. DATA SOURCES: A MEDLINE search (1993-January 2001) was conducted to identify English-language literature available on enoxaparin, dalteparin, ardeparin, and tinzaparin. STUDY SELECTION: All controlled trials evaluating low-molecular-weight heparins (LMWHs) versus standard therapy powered to detect a significant difference were reviewed. DATA EXTRACTION: Agents were reviewed with regard to safety and efficacy. DATA SYNTHESIS: As a class, LMWHs have chemical, physical, and clinical similarities. LMWHs have greater bioavailability, longer half-lives, a more predictable pharmacologic response, possible improved safety, and similar or greater efficacy compared with unfractionated heparin (UFH). Because of this, enoxaparin, dalteparin, ardeparin, and tinzaparin are being considered as alternatives to UFH or warfarin, and there is potential for therapeutic interchange. Evaluation of clinical trials is limited because of differing diagnostic methods, drug administration times, dose equivalencies, and outcome measurements. CONCLUSIONS: Only 1 trial has evaluated 2 LMWHs in a direct comparison in the same study. There is insufficient evidence for determining the therapeutic equivalence of LMWHs.     

Primary angioplasty for acute ST-elevation myocardial infarction

This article examines primary percutaneous coronary intervention as a reperfusion treatment for acute ST-segment elevation myocardial infarction. It discusses the nursing care of patients undergoing this procedure.     

Recommendations on biosimilar low-molecular-weight heparins

Summary.  Based on the results of large clinical trials, several low-molecular-weight heparins (LMWHs) have been approved for prophylaxis and the treatment of venous and arterial thromboembolism. As a result of expiration or pending expiration of patent protection of the originator LMWHs, many generic or biosimilar LMWHs have been approved in some countries and more are likely to be approved elsewhere. Their greater availability may reduce the treatment costs. The Working Party on Requirements for Development of Biosimilar LMWHs of the Subcommittee on Control of Anticoagulation, Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis has reached a consensus on recommendations to ensure the quality of biosimilar LMWHs as compared with the originator LMWHs.     

Fibrinolytic therapy in patients with ST-elevation myocardial infarction

ST-elevation myocardial infarction (STEMI) is related to acute occlusion of a coronary artery by a fibrin-rich thrombus. Early reperfusion in STEMI reduces infarct size and improves prognosis. Acute reperfusion may be achieved with percutaneous coronary intervention (PCI) and/or fibrinolytic agents. When performed in a timely manner, primary PCI is the preferred method of reperfusion; however, due to logistic reasons, including lack of PCI-capable hospitals and delay in the first medical contact-to-balloon time, this simplified approach lacks universal applicability. Due to clinical efficacy and the ease of administration, fibrinolysis is still an important reperfusion modality in patients with STEMI who cannot have primary PCI within guideline-recommended time. This review focuses on the role of fibrinolysis in patients with STEMI.     

The role of fibrinolytics in the prehospital treatment of ST-elevation myocardial infarction (STEMI)

The efficacy of fibrinolytics in the treatment of ST-elevation myocardial infarction is directly related to the time of administration, with the first 2 h after symptom onset seen as a critical period for greatest improvement in cardiovascular parameters and mortality. The American College of Cardiology/American Heart Association recommends a medical contact to treatment time of 30 min for fibrinolysis in patients with ST-elevation myocardial infarction. In selected patients, reperfusion goals may be expedited with prehospital administration of fibrinolytics. In clinical trials, prehospital fibrinolysis markedly reduced the time from symptom onset to treatment, allowed earlier ST-segment resolution, and reduced short- and long-term mortality compared with in-hospital treatment. Prehospital fibrinolysis has become more feasible with the introduction of prehospital 12-lead electrocardiography, improved skills of emergency medical services personnel, improved communication with the Emergency Department, and the advent of bolus fibrinolysis. Rapid and accurate administration of a fibrinolytic is vital for the success of prehospital fibrinolysis.     

Acute ST-elevation myocardial infarction after successful cardiopulmonary resuscitation

After successful cardiopulmonary resuscitation, acute ST-elevation myocardial infarction (STEMI) may be documented. We investigated the incidence and prognosis of patients admitted to our department between 1 January 2000 and 31 December 2004. Among 2393 consecutive patients with STEMI, 135 (5.7%) presented after a return of spontaneous circulation (ROSC). Forty-nine patients (36%) regained consciousness and 86 patients (64%) remained unconscious during initial evaluation. The delay from collapse to advanced cardiac life support (ACLS) was longer in comatose patients (5.8 min versus 0.5 min; p<0.01) in those with a lower proportion of shockable rhythm (76% versus 96%; p<0.01) and in those with a less favourable course of ACLS were also documented. Primary percutaneous coronary intervention (PCI) was performed in all but one conscious patient with success rate (96% versus 94%; p=0.63) and hospital survival without neurological deficit (100% versus 94.8%; p=0.20) comparable to patients without cardiac arrest. In comatose patients, primary PCI was performed in 79% with a somewhat lower success rate (82%, p=0.21). Mechanical ventilation, haemodynamic support, haemodialysis and antimicrobial agents were used more frequently in comatose patients. Hospital survival among comatose patients was 51% and hospital survival with cerebral performance category (CPC) 1 or 2 was 29%. Accordingly, outcome of patients with STEMI who regain consciousness after ROSC and undergo primary PCI is comparable to patients without cardiac arrest. This is in contrast with comatose survivors who, despite aggressive reperfusion treatment, had a significantly worse outcome.     

Feasibility of sonothrombolysis in the ambulance for ST-elevation myocardial infarction

The International Journal of Cardiovascular Imaging - Patients with ST-elevation myocardial infarction (STEMI) due to coronary occlusion require immediate restoration of epicardial and...     

Overview of contemporary reperfusion strategies in acute ST-elevation myocardial infarction

The rupture of an atherosclerotic plaque in an epicardial coronary artery with subsequent occlusive coronary thrombosis has been established as the decisive event in the pathogenesis of an acute coronary syndrome, which encompasses the clinical entities of unstable angina, non-ST- and ST-elevation myocardial infarction. This article focuses on contemporary treatment strategies for patients with acute ST-elevation myocardial infarction and reviews the role of pharmacologic thrombolysis and mechanical reperfusion by percutaneous transluminal approaches. Statements of the latest guidelines for the treatment of ST-elevation myocardial infarction are included, as well as some recently distributed information not covered by the guideline publications. Finally, some future perspectives for the treatment of acute ST-elevation myocardial infarction are outlined.     

Overview of contemporary reperfusion strategies in acute ST-elevation myocardial infarction

The rupture of an atherosclerotic plaque in an epicardial coronary artery with subsequent occlusive coronary thrombosis has been established as the decisive event in the pathogenesis of an acute coronary syndrome, which encompasses the clinical entities of unstable angina, non-ST- and ST-elevation myocardial infarction. This article focuses on contemporary treatment strategies for patients with acute ST-elevation myocardial infarction and reviews the role of pharmacologic thrombolysis and mechanical reperfusion by percutaneous transluminal approaches. Statements of the latest guidelines for the treatment of ST-elevation myocardial infarction are included, as well as some recently distributed information not covered by the guideline publications. Finally, some future perspectives for the treatment of acute ST-elevation myocardial infarction are outlined.     

Hospital guidelines for use of low-molecular-weight heparins

OBJECTIVE: To describe the development of guidelines for initial use of low-molecular-weight heparins (LMWHs) and other anticoagulants in acute-care hospitals that are part of a national group purchasing organization (GPO). DATA SOURCES: A systematic literature search (1970-December 2001) was conducted to identify evidence on the efficacy of various anticoagulants for initial therapy in deep-vein thrombosis and pulmonary embolism, and in treatment of acute coronary syndrome. A group consensus method was then used to develop guidelines. Guidelines were reviewed and revised by an internal expert panel as well as an external expert panel. Final guidelines were disseminated to GPO members and assistance was provided with implementation at the local level. RESULTS: The final set of guidelines is described. The guidelines are organized based on recommended therapeutic options for each indication. For each option, consensus opinion is provided on the level of evidence that exists in the literature, comparisons of cost and convenience, and additional dosing information. The guidelines were disseminated along with supporting material to interested GPO member hospitals, and teleconferences were held to facilitate implementation at the local level. The guidelines were initially implemented at 18 hospitals across the country. CONCLUSIONS: The process by which these guidelines were developed, plus the final set of guidelines, may be useful to hospitals and healthcare systems contemplating or engaged in a similar effort with this class of drugs.     

Predictors of left ventricular remodeling after ST-elevation myocardial infarction

Adverse left ventricular (LV) remodeling after acute ST-elevation myocardial infarction (STEMI) is associated with morbidity and mortality. We studied clinical, biochemical and angiographic determinants of LV end diastolic volume index (LVEDVi), end systolic volume index (LVESVi) and mass index (LVMi) as global LV remodeling parameters 4 months after STEMI, as well as end diastolic wall thickness (EDWT) and end systolic wall thickness (ESWT) of the non-infarcted myocardium, as compensatory remote LV remodeling parameters. Data was collected in 271 patients participating in the GIPS-III trial, presenting with a first STEMI. Laboratory measures were collected at baseline, 2 weeks, and 6–8 weeks. Cardiovascular magnetic resonance imaging (CMR) was performed 4 months after STEMI. Linear regression analyses were performed to determine predictors. At baseline, patients were 21% female, median age was 58 years. At 4 months, mean LV ejection fraction (LVEF) was 54?±?9%, mean infarct size was 9.0?±?7.9% of LVM. Strongest univariate predictors (all p?<?0.001) were peak Troponin T for LVEDVi (R²?=?0.26), peak CK-MB for LVESVi (R²?=?0.41), NT-proBNP at 2 weeks for LVMi (R²?=?0.24), body surface area for EDWT (R²?=?0.32), and weight for ESWT (R²?=?0.29). After multivariable analysis, cardiac biomarkers remained the strongest predictors of LVMi, LVEDVi and LVESVi. NT-proBNP but none of the acute cardiac injury biomarkers were associated with remote LV wall thickness. Our analyses illustrate the value of cardiac specific biochemical biomarkers in predicting global LV remodeling after STEMI. We found no evidence for a hypertrophic response of the non-infarcted myocardium.     

Serum uric acid in patients with acute ST-elevation myocardial infarction

BACKGROUND:

Few studies investigated serum uric acid levels in patients with acute Stelevation myocardial infarction (STEMI). The study was to assess the clinical value of serum uric acid levels in patients with acute ST-elevation myocardial infarction (STEMI).

METHODS:

Totally 502 consecutive patients with STEMI were retrospectively studied from January 2005 to December 2010. The level of serum lipid, echocardiographic data and in-hospital major adverse cardiovascular events (MACE) in patients with hyperuricemia (n=119) were compared with those in patients without hyperuricemia (n=383). The relationship between the level of serum uric acid and the degree of diseased coronary artery was analyzed. All data were analyzed with SPSS version 17.0 software for Student’s t test, the Chi-square test and Pearson’s correlation coefficient analysis.

RESULTS:

Serum uric acid level was positively correlated with serum triglyceride level. Hyperlipidemia was more common in hyperuricemia patients than in non-hyperuricemia patients (43.7% vs. 33.7%, P=0.047), and serum triglyceride level was significantly higher in hyperuricemia patients (2.11±1.24 vs. 1.78±1.38, P=0.014). But no significant association was observed between serum uric acid level and one or more diseased vessels (P>0.05). Left ventricular end-diastolic diameter (LVEDd) was larger in hyperuricemia patients than in non-hyperuricemia patients (53.52±6.19 vs. 52.18±4.89, P=0.041). The higher rate of left systolic dysfunction and diastolic dysfunction was discovered in hyperuricemia patients (36.4% vs. 15.1%, P<0.001; 68.2% vs. 55.8%, P=0.023). Also, hyperuricemia patients were more likely to have in-hospital MACE (P<0.05).

CONCLUSIONS:

Serum uric acid level is positively correlated with serum triglyceride level, but not with the severity of coronary artery disease. Hyperuricemia patients with STEMI tend to have a higher rate of left systolic dysfunction and diastolic dysfunction and more likely to have more in hospital MACE.KEY WORDS: Acute ST-elevation myocardial infarction, Serum uric acid, Triglyceride, Coronary angiography, Echocardiography, Left ventricular systolic dysfunction, Left ventricular diastolic dysfunction, Major adverse cardiovascular events