Clinical epidemiology of acute myocardial infarction

The Future of Anticoagulation

Anticoagulant agents, such as unfractionated heparin and warfarin, have been in use for roughly 50 years. Over the past decade, injectable agents such as low-molecular-weight heparins, pentasaccharide, and direct thrombin inhibitors have been major advances in preventing and treating thrombosis. Despite these somewhat recent additions, there is still enormous potential to improve on the pharmacokinetic and pharmacodynamic properties of these agents, as well as improve patient outcomes. There are currently a large number of anticoagulant agents (injectable and oral) that could be available for use in the next several years. Many of these new agents have unique mechanisms that may provide practitioners with anticoagulant alternatives. This review gives a detailed analysis of the anticoagulant agents that may add to our armamentarium in the management of thrombosis.

Baicalin inhibits inflammation and attenuates myocardial ischaemic injury by aryl hydrocarbon receptor

OBJECTIVES

Recent evidence indicates that suppressing inflammation by specific drug target and treatment measures contributes to attenuate ischaemic injury and the related heart diseases. This study aimed to investigate the potential effect of baicalin on myocardial ischaemic injury through inhibition of inflammation by inactivating the aryl hydrocarbon receptor (AhR).

METHODS

The mouse model with myocardial ischaemic injury was prepared by the left anterior descending coronary artery-amputation and then treated using baicalin. After observing the expression of AhR by immunohistochemical staining, the AhR and inflammatory mediators in circulation and myocardial tissues, including high-sensitive C-reactive protein (hsCRP), interleukin (IL)-1β and IL-6, were detected based on enzyme-linked immunosorbent assay, real-time polymerase chain reaction and Western blot methods.

KEY FINDINGS

The results showed that (1) substantial expression of AhR was observed in myocardial tissues; (2) ischaemic injury caused myocardial necrosis and remodelling, and stimulated hsCRP, IL-1β and IL-6 by activation of AhR; and (3) baicalin alleviated the myocardial injury and inflammatory response by inhibiting the expression of AhR.

CONCLUSION

Our findings extend the list of AhR ligands beyond exogenous toxins and endogenous molecules to cardiac immunological factors, and moreover it could be considered potential drug targets due to its pathological modulatory properties, while baicalin demonstrated promise as a novel vehicle for ischaemic heart disease.

Endurance exercise accelerates myocardial tissue oxygenation recovery and reduces ischemia reperfusion injury in mice

Exercise training offers cardioprotection against ischemia and reperfusion (I/R) injury. However, few essential signals have been identified to underscore the protection from injury. In the present study, we hypothesized that exercise-induced acceleration of myocardial tissue oxygenation recovery contributes to this protection. C57BL/6 mice (4 weeks old) were trained on treadmills for 45 min/day at a treading rate of 15 m/min for 8 weeks. At the end of 8-week exercise training, mice underwent 30-min left anterior descending coronary artery occlusion followed by 60-min or 24-h reperfusion. Electron paramagnetic resonance oximetry was performed to measure myocardial tissue oxygenation. Western immunoblotting analyses, gene transfection, and myography were examined. The oximetry study demonstrated that exercise markedly shortened myocardial tissue oxygenation recovery time following reperfusion. Exercise training up-regulated Kir6.1 protein expression (a subunit of ATP-sensitive K(+)channel on vascular smooth muscle cells, VSMC sarc-K(ATP)) and protected the heart from I/R injury. In vivo gene transfer of dominant negative Kir6.1AAA prolonged the recovery time and enlarged infarct size. In addition, transfection of Kir6.1AAA increased the stiffness and reduced the relaxation capacity in the vasculature. Together, our study demonstrated that exercise training up-regulated Kir6.1, improved tissue oxygenation recovery, and protected the heart against I/R injury. This exercise-induced cardioprotective mechanism may provide a potential therapeutic intervention targeting VSMC sarc-K(ATP) channels and reperfusion recovery.

Interleukin-13 deficiency aggravates healing and remodeling in male mice after experimental myocardial infarction

BACKGROUND

Activation of innate immunity, especially infiltration of monocytes, is critical for proper wound healing and scar formation after myocardial infarction (MI). Therefore, we tested the hypothesis that interleukin-13 (IL-13), which influences the differentiation of monocytes/macrophages and has profibrotic properties, modulates wound healing and remodeling after MI.

METHODS AND RESULTS

MI was induced by permanent ligation of the left coronary artery in both male and female wild-type (WT)/IL-13(-/-) mice. Real-time polymerase chain reaction demonstrated that expression of IL-13 was induced in left and right ventricular myocardium of WT mice within days in response to MI. Fifty-six-day survival was significantly impaired (65% in WT versus 34% in IL-13(-/-)) in male but not female IL-13(-/-) (55% in WT versus 54% in IL-13(-/-)) mice. Serial echocardiography showed significantly increased left ventricular dilation in male IL-13(-/-) compared with WT mice starting from day 1 after MI, despite comparable infarct size. Fluorescence-activated cell sorter analysis revealed less leukocyte infiltration in male IL-13(-/-) mice on day 3. Real-time polymerase chain reaction analysis demonstrated reduced expression of marker genes of alternative activation in monocytes sorted from the infarct zone of male IL-13(-/-) in comparison with WT mice on day 3 after MI.

CONCLUSIONS

Genetic deficiency of IL-13 worsens outcome after MI in male mice. Our data indicate that IL-13 regulates leukocyte recruitment and induces M2-like monocyte/macrophage differentiation, which modifies wound healing within the infarct zone.

Evaluation of Aggregometery Parameters and Efficacy of Plavix versus Clopidex in Patients Suffering from Ischemic Heart Disease: A Randomized Double Blind Clinical Trial

BACKGROUND

Ischemic heart disease is the leading cause of death in most societies. In a pathophysiologic point of view, it chiefly results from the formation of thrombus in coronary arteries which could not be only prevented by aspirin. Many of clinical trials have shown the long-term benefits of antiplatelet drugs in reducing the risk of thrombotic accidents.

OBJECTIVES

Clopidogrel is a thienopyridine derivative used to prevent platelets from adhering together by direct inhibition of Adenosine diphosphate (ADP), the major factor behind platelets aggregation. Sanofi-Aventis and Bristol-Myers are companies that produce Clopidogrel by the name of Clopidogrel bisulfate. Its trade name is Plavix, nonetheless in Iran it is distributed under the name of Clopidex by Exir Company. In this study we are to compare Plavix and Clopidex in terms of efficacy as well as aggregometry parameters like ADP and PRP (Platelet Rich Plasma).

PATIENTS AND METHODS

This is a double blind clinical trial in which we had two groups of patients suffering from Ischemic heart disease who were selected by inclusion criteria. Group A (36 patients) took Plavix (75 mg/d) and group B (36 patients) used clopidex (75 mg/d) both for 30 days. The aggregometry parameters also consisted of PRP and ADP that were run on the patients before and after the study. Finally, a comparison of aforementioned tests, quality of life, lab parameters and compliance in both groups was provided.

RESULTS

In groups A and B, the mean levels of PRP before the study were 348000 and 340000/µL respectively. The ADPs were also 73/76 and 68/07 µM that showed no significant difference (P > 0.05).The Means of ADP5 in group A before and after the study were 66.40 and 43.84 µM respectively that there was significant difference (P = 0.001). The Means of ADP5 in group B before and after the study were 58.04 and 40.16 µM respectively that there was significant difference (P < 0.001).The Means of ADP20 in group A before and after the study were 73.76 and 54.97 µM respectively which showed significant difference (P < 0.001). The Means of ADP20 in group B before and after the study were 68.07 and 52.49 µM respectively which showed significant difference (P = 0.001). Difference of ADP5 between group A and B was not significant (P = 0.495). Difference of ADP20 between group A and B was not significant (P = 0.721). The Means of PRP in group A before and after the study were 348000 and 335000/ µL respectively that there was no significant difference (P = 0.66). The Means of PRP in group B before and after the study were 340000 and 336000/ µL respectively that indicated no significant difference (P = 0.81). Difference of PRP between group A and B was not significant (P = 0.563).

CONCLUSIONS

Our findings suggested that both drugs significantly lessen the ADP level; even so there was no significant difference between two groups in PRP and ADP factors.

Hyperoxia and transforming growth factor β1 signaling in the post-ischemic mouse heart

AIMS

Following ischemic injury, myocardial healing and remodeling occur with characteristic myofibroblast trans-differentiation and scar formation. The current study tests the hypothesis that hyperoxia and nitric oxide (NO) regulate TGF-β1 signaling in the post-ischemic myocardium.

MAIN METHODS

C57BL/6 wild-type (WT), endothelial and inducible nitric oxide synthase knockout (eNOS(-/-) and iNOS(-/-)) mice were subjected to 30-min left anterior descending coronary artery occlusion followed by reperfusion. Myocardial tissue oxygenation was monitored with electron paramagnetic resonance oximetry. Protein expressions of TGF-β1, receptor-activated small mothers against decapentaplegic homolog (Smad), p21 and α-smooth muscle actin (α-SMA) were measured with enzyme-linked immunosorbent assay (ELISA), Western immunoblotting, and immunohistochemical staining.

KEY FINDINGS

There was a hyperoxic state in the post-ischemic myocardial tissue. Protein expressions of total and active TGF-β1, p-Smad2/3 over t-Smad2/3 ratio, p21, and α-SMA were significantly increased in WT mice compared to Sham control. Knockout of eNOS or iNOS further increased protein expression of these signals. The expression of α-SMA was more abundant in the infarct of eNOS(-/-) and iNOS(-/-) mice than WT mice. A protein band indicating nitration of TGF-β type-II receptor (TGFβRII) was observed from WT heart. Carbogen (95% O2 plus 5% CO2) treatment increased the ratio of p-Smad2/t-Smad2, which was inhibited by 10006329 EUK (EUK134) and sodium nitroprusside (SNP). In conclusion, hyperoxia up-regulated and NO/ONOO(-) inhibited cardiac TGF-β1 signaling and myofibroblast trans-differentiation.

SIGNIFICANCE

These findings may provide new insights in myocardial infarct healing and repair.

Cognitive and emotional factors affecting avoidable decision-making delay in acute myocardial infarction male adults

BACKGROUND

To study the potentially avoidable decision-making delay in acute myocardial infarction (AMI) adults male with different psychological characteristics a nationwide multicentre study was conducted in Italy by the 118 Coronary Care Units (CCUs).

METHOD

929 AMI patients consecutively presented to the CCU in a conscious condition less than two hours, 2-6 hours, 6-12 hours, and more than 12 hours after symptom onset and completing the Disease Distress Questionnaire (DDQ) were enrolled in a multicentre case-control study. The DDQ collects information regarding the decision time to seek help, and includes a set of items assessing psychological factors and pain-related symptoms. The relationship between the perceived threat and the delay due to decision-making was evaluated by means of a multivariate model using LISREL 8 structural equation modelling.

RESULTS

The delay significantly correlated with perceived threat, which was mainly related to somatic awareness. It was only slightly related to pain and was not associated with any of the other variables. Perceived threat was also related to psychological upset, fear and health worries, the first of which was considerably influenced by emotional instability.

CONCLUSION

Somatic awareness is the main dimension affecting perceived threat, but subjective pain intensity affects the delay both directly and indirectly. The core of the model is the relationship between perceived threat and the delay due to decision-making. The importance of subjective pain intensity is well documented, but it is still not clear how subjective and objective pain interact.

Characterization of circulating endothelial cells in acute myocardial infarction

Acute myocardial infarction (MI), which involves the rupture of existing atheromatous plaque, remains highly unpredictable despite recent advances in the diagnosis and treatment of coronary artery disease. Accordingly, a clinical measurement that can predict an impending MI is desperately needed. Here, we characterize circulating endothelial cells (CECs) using an automated and clinically feasible CEC three-channel fluorescence microscopy assay in 50 consecutive patients with ST-segment elevation MI and 44 consecutive healthy controls. CEC counts were significantly elevated in MI cases versus controls, with median numbers of 19 and 4 cells/ml, respectively (P = 1.1 × 10(-10)). A receiver-operating characteristic (ROC) curve analysis demonstrated an area under the ROC curve of 0.95, suggesting near-dichotomization of MI cases versus controls. We observed no correlation between CECs and typical markers of myocardial necrosis (ρ = 0.02, creatine kinase-myocardial band; ρ = -0.03, troponin). Morphological analysis of the microscopy images of CECs revealed a 2.5-fold increase (P < 0.0001) in cellular area and a twofold increase (P < 0.0001) in nuclear area of MI CECs versus healthy controls, age-matched CECs, as well as CECs obtained from patients with preexisting peripheral vascular disease. The distribution of CEC images that contained from 2 to 10 nuclei demonstrates that MI patients were the only subject group to contain more than 3 nuclei per image, indicating that multicellular and multinuclear clusters are specific for acute MI. These data indicate that CEC counts may serve as a promising clinical measure for the prediction of atherosclerotic plaque rupture events.

Risk Factors in first presentation acute coronary syndromes (ACS): how do we move from population to individualized risk prediction?

Patients with acute coronary syndromes (ACS) have a poor short- and long-term prognosis. We sought to examine the presence of established coronary risk factors in contemporary patients presenting with an ACS for the first time and no known coronary artery disease (CAD) in the past. The study was conducted in 3171 consecutive patients admitted with the diagnosis of ACS. Of these, 941 patients (30%) had the admission as the first occurrence of ACS and no prior history of CAD. We studied the degree to which these first presenters with ACS had 1 or more established risk factors. We found that 98% of patients presenting with an ACS for the first time and no previous CAD had at least 1 established risk factor. Current population-based screening efforts must be improved to allow more effective prevention strategies and more individualized risk prediction.

The impact of platelet function or C-reactive protein, on cardiovascular events after an acute myocardial infarction

Background

Recurrent cardiovascular events following acute myocardial infarction (AMI) are common. The purpose of this study was to evaluate the impact of platelet aggregation, PFA-100 closure times and peak C-reactive protein (CRP), respectively, on the occurrence of death, myocardial infarction and ischemic cerebral events after an AMI. Furthermore, to examine the relationship between the platelet function tests and peak CRP.

Methods

Three hundred and thirty-four patients with AMI were included in the study. Platelet aggregation was analyzed by an aggregometer using laser light (PA-200). The state of high residual platelet reactivity was defined as normal closure times (PFA-100) during treatment with aspirin.

Results

The fourth quartile of peak CRP was associated with poorer outcome as compared to the first quartile in a multivariate Cox-regression analysis, with a hazard ratio of 2.0 (95% CI 1.1–3.7) for the occurrence of death, myocardial infarction and ischemic cerebral events. The fourth quartile of peak CRP (>64.6 mg/l) was associated with platelet aggregation (p < 0.001, adjusted R² = 0.13) and high residual platelet reactivity, in a multivariate model, with an odds ratio of 2.9 (CI 95% 1.3–6.8), as compared to the first quartile. Neither the highest quartile of platelet aggregation nor the state of high residual platelet reactivity predicted new cardiovascular events.

Conclusion

In patients with myocardial infarction, measured peak CRP is associated with new cardiovascular events. Despite an association with peak CRP neither more pronounced platelet aggregation nor PFA-100 closure times independently predict new cardiovascular events.

The role of IL-1 in the pathogenesis of heart disease

Interleukin (IL)-1 consists of two distinct ligands, IL-1alpha and IL-1beta, with indistinguishable biological activities that signal through the IL-1 type I receptor (IL-1RI). A naturally occurring IL-1 receptor antagonist (IL-1Ra) binds to IL-1RI without initiating signal transduction and prevents IL-1 signaling, competitively inhibiting IL-1-mediated responses. Emerging evidence suggests that the balance between IL-1 agonists and antagonists plays an essential role in a variety of cardiovascular conditions. IL-1 may play a role in atherothrombotic disease by promoting the formation of atheromatous lesions, enhancing vascular inflammation, and triggering plaque destabilization. Following myocardial infarction, IL-1 critically regulates the inflammatory response and is involved in the development of adverse remodeling by enhancing expression of matrix metalloproteinases. IL-1 signaling may also be an essential mediator in the pathogenesis of heart failure by suppressing cardiac contractility, promoting myocardial hypertrophy, and inducing cardiomyocyte apoptosis. The present review summarizes current available data showing the significant role of IL-1 signaling in heart disease and raising the possibility that IL-1 inhibitors (such as anakinra, a nonglycosylated recombinant human IL-1Ra) may be clinically useful agents in patients with certain cardiovascular conditions.

The immune system and cardiac repair

Myocardial infarction is the most common cause of cardiac injury and results in acute loss of a large number of myocardial cells. Because the heart has negligible regenerative capacity, cardiomyocyte death triggers a reparative response that ultimately results in formation of a scar and is associated with dilative remodeling of the ventricle. Cardiac injury activates innate immune mechanisms initiating an inflammatory reaction. Toll-like receptor-mediated pathways, the complement cascade and reactive oxygen generation induce nuclear factor (NF)-kappaB activation and upregulate chemokine and cytokine synthesis in the infarcted heart. Chemokines stimulate the chemotactic recruitment of inflammatory leukocytes into the infarct, while cytokines promote adhesive interactions between leukocytes and endothelial cells, resulting in transmigration of inflammatory cells into the site of injury. Monocyte subsets play distinct roles in phagocytosis of dead cardiomyocytes and in granulation tissue formation through the release of growth factors. Clearance of dead cells and matrix debris may be essential for resolution of inflammation and transition into the reparative phase. Transforming growth factor (TGF)-beta plays a crucial role in cardiac repair by suppressing inflammation while promoting myofibroblast phenotypic modulation and extracellular matrix deposition. Myofibroblast proliferation and angiogenesis result in formation of highly vascularized granulation tissue. As the healing infarct matures, fibroblasts become apoptotic and a collagen-based matrix is formed, while many infarct neovessels acquire a muscular coat and uncoated vessels regress. Timely resolution of the inflammatory infiltrate and spatial containment of the inflammatory and reparative response into the infarcted area are essential for optimal infarct healing. Targeting inflammatory pathways following infarction may reduce cardiomyocyte injury and attenuate adverse remodeling. In addition, understanding the role of the immune system in cardiac repair is necessary in order to design optimal strategies for cardiac regeneration.

Trends in Mortality from Acute Myocardial Infarction in the Coronary Care Unit

Introduction: The treatment and outcome of acute myocardial infarction (AMI) has evolved greatly over the past few decades. We compared the mortality and complication rates of patients with AMI admitted to the Coronary Care Unit (CCU) in 2002 to previously reported data. Materials and Methods: All data for AMI patients admitted to National Heart Centre CCU in 2002 were collected through the Singapore Cardiac Data Bank, including demographics, inhospital complications and mortality. These were compared to previous reports from the same institution in 1988, 1975 and 1967. Results: A total of 516 cases with AMI were identified. A higher proportion of patients were aged ≥70 years in 2002 (31.8%) compared to 1988 (25%), 1975 (11%) and 1967 (5.6%). Acute percutaneous transluminal coronary angioplasty (PTCA) was performed in 250 of 516 (48%) patients in 2002. The overall in-patient and age-standardised mortality was 14.7% and 10% respectively, compared to 20.6% and 17% respectively in 1988 (P = 0.06). For the 250 patients who underwent acute PTCA, overall mortality was 5.2% compared to 24% in those who did not (P <0.001). Common in-hospital complications included heart failure (38%), non-sustained ventricular tachycardia (8%), atrial fibrillation (8%) and complete heart block (6%). Age, heart failure, bundle branch block and sustained ventricular tachycardia were associated with higher mortality by univariate analysis. On multivariate analysis, older age, heart failure and the absence of percutaneous intervention were independently associated with higher mortality. Conclusion: In-hospital mortality for AMI patients admitted to the CCU declined from 1988 to 2002 despite a higher proportion of elderly patients. The introduction of new therapies including drugs and percutaneous intervention may have contributed to this decline. Key words: Primary percutaneous transluminal coronary angioplasty

Potential demographic and baselines variables for risk stratification of high-risk post-myocardial infarction patients in the era of implantable cardioverter-defibrillator--a prognostic indicator

BACKGROUND

Risk stratification after myocardial infarction (MI) remains expensive and disappointing. We designed a prognostic indicator using demographic information to select patients at risk of dying after MI.

METHOD AND RESULTS

We combined individual patient data from the placebo arms of EMIAT, CAMIAT, TRACE and DIAMOND-MI with LVEF <or=40% or ventricular arrhythmias (i.e. >10 ventricular premature beats/hour or a run of ventricular tachycardia). Risk factors for mortality beginning at day 45 post-MI up to 2 years were examined using Cox regression analysis. Risk scores were derived from the equation of a Cox regression model containing only significant variables. The prognostic index was the sum of the individual contribution from the risk factors. 2707 patients were pooled (age: 66 (23-92) years, 78.8% M) with 480 deaths at 2-years (44% arrhythmic and 35.6% non-arrhythmic cardiac deaths). Variables predicting mortality were age, sex, previous MI or angina, hypertension, diabetes, systolic blood pressure, heart rate, NYHA functional class and non-Q wave infarct on electrocardiogram. Distinct survival curves were obtained for 3 risk groups based on the median and inter-quartile range for the prognostic index. In the high-risk group, up to 40% of patients died (all-cause mortality), 19.1% died of arrhythmic and 18.2% died of non-arrhythmic cardiac causes at 2-years.

CONCLUSION

In post-MI patients with LVEF <or=40% or frequent ventricular premature beats, the additional use of a simple prognostic indicator based on demographic information was able to provide clinically meaningful risk stratification on patients that were at high risk of dying and may be used to identify patients for prophylactic implantable cardioverter-defibrillator therapy.

The mechanistic basis of infarct healing

Myocardial infarction triggers an inflammatory cascade that results in healing and replacement of the damaged tissue with scar. Cardiomyocyte necrosis triggers innate immune mechanisms eliciting Toll-like receptor- mediated responses, activating the complement cascade and generating reactive oxygen species. Subsequent activation of NF-kappaB is a critical element in the regulation of cytokine, chemokine, and adhesion molecule expression in the ischemic myocardium. Chemokine induction mediates leukocyte recruitment in the myocardium. Pleiotropic proinflammatory cytokines, such as TNF-alpha, IL-1, and IL-6, are also upregulated in the infarct and exert a wide range of effects on a variety of cell types. Timely repression of proinflammatory gene synthesis is crucial for optimal healing; IL-10 and TGF-beta-mediated pathways may be important for suppression of chemokine and cytokine expression and for resolution of the leukocytic infiltrate. In addition, TGF-beta may be critically involved in inducing myofibroblast differentiation and activation, promoting extracellular matrix protein deposition in the infarcted area. The composition of the extracellular matrix plays an important role in regulating cell behavior. Both structural and matricellular proteins modulate cell signaling through interactions with specific surface receptors. The molecular and cellular changes associated with infarct healing directly influence ventricular remodeling and affect prognosis in patients with myocardial infarction.

Bêta-bloquants et syndromes coronariens : les réponses d’hier s’appliquent-elles aux stratégies d’aujourd’hui ?

This paper shows the eventual benefits of treatment with beta-blockers in post-myocardial infarction. An overview of main clinical trials that have been conducted to test this therapeutic in acute coronary syndrome. In patients presenting with acute myocardial infarction, the early use of intravenous beta-blockers had shown a modest and non significant reduction in mortality. Substantial reductions in mortality and reinfarction have been demonstrated when beta-blockers have been used soon after an acute myocardial infarction and continued long-term. However, these benefits were observed in randomised clinical trials conducted in the 1970s and 1980s, prior to the widespread use of reperfusion therapies and antiplatelet agents. It appears obvious that the long-term use of beta-blockers may be questionable after any acute coronary syndrome especially if complete reperfusion has been achieved and left ventricular function is preserved.

The effect of select nutrients on serum high-density lipoprotein cholesterol and apolipoprotein A-I levels

One of the factors contributing to the increased risk of developing premature atherosclerosis is low plasma concentrations of high-density lipoprotein (HDL) cholesterol (HDLc). Multiple potential mechanisms account for the cardioprotective effects of HDL and its main protein apolipoprotein A-I (apo A-I). The low plasma concentrations of HDL could be the result of increased fractional clearance and reduced expression of apo A-I. To this end, nutrients play an important role in modulating the fractional clearance rate, as well as the rate of apo A-I gene expression. Because medical nutrition therapy constitutes the cornerstone of management of dyslipidemias, it is essential to understand the mechanisms underlying the changes in HDL level in response to alterations in dietary intake. In this review, we will discuss the effect of select nutrients on serum HDLc and apo A-I levels. Specifically, we will review the literature on the effect of carbohydrates, fatty acids, and ketones, as well as some of the nutrient-related metabolites, such as glucosamine and the prostanoids, on apo A-I gene expression. Because there are multiple mechanisms involved in the regulation of serum HDLc levels, changes in gene transcription do not necessarily correlate with clinical observations on serum levels of HDLc.

Cost-effectiveness of thrombolytics: a simplified model

OBJECTIVE OF THE STUDY

To construct a simple model for an internal, retrospective cost-effectiveness analysis and to calculate the incremental cost-effectiveness of tissue plasminogen activator (TPA) over streptokinase (SK) in Turkey.

SETTING

Koşuyolu Heart, Education and Research Hospital, Istanbul, Turkey.

METHOD

Among patients who were hospitalized for treatment of acute myocardial infarction (AMI), 196 were randomly selected. One-year mortality rates according to the treatment groups (TPA, SK, other) were determined. Among surviving patients, 28 from TPA and another 28 from SK group were randomly selected for the pharmacoeconomic analysis. Patient treatment data were taken from medical records while data regarding to costs were taken from hospital bills.

MAIN OUTCOME MEASURES

Incremental cost-effectiveness ratio (ICER). The cost part of the ratio was considered as 'the overall-costs', while the effectiveness part was considered as 'lives saved' per treatment group.

RESULTS

With an increased one-year survival rate of 2.37% and an increased cost of euro 1120.8 ($1165.6) per patient in the TPA group, the ICER for the use of TPA instead of SK was euro 47,289 ($49,180.6) per life saved.

CONCLUSION

This model can be a guide for similar analyses. The results of our study (the incremental cost-effectiveness of TPA over SK) will be informative for the decision-makers in Turkey, by whom the medical benefit for money spent would be assessed and judged. We believe that our results make a contribution to similar studies in the literature.

Ximelagatran: Pharmacology, Pharmacokinetics, and Pharmacodynamics

Thromboembolism is the largest cause of morbidity and mortality in the western world, yet oral anticoagulation is currently available only with vitamin K antagonists--most often, warfarin. Warfarin has been used for treatment of thrombotic disease for about 50 years. However, despite its widespread use, it is associated with several limitations, such as varied patient response, a narrow therapeutic window, numerous drug and food interactions, and need for frequent therapeutic monitoring. In addition, its full anticoagulant effect usually takes at least 4-5 days after the start of therapy or any dosage change, and it has a slow offset of therapy. A new oral anticoagulant, ximelagatran, has considerable advantages compared with warfarin. The agent requires no therapeutic monitoring, has a wide therapeutic window, and is not known to interact with food or drugs. The advantages ximelagatran brings to clinical practice should be a welcome addition to the options for management of thrombotic disease.

Pharmacokinetics and pharmacodynamics of ximelagatran, a novel oral direct thrombin inhibitor, in young healthy male subjects

OBJECTIVES

Ximelagatran is a novel, oral direct thrombin inhibitor designed to overcome the low and variable oral absorption of melagatran, its active form. The pharmacokinetics and pharmacodynamics of ximelagatran following single and repeated oral administration were investigated. The primary objectives were to determine the dose linearity and reproducibility of melagatran exposure and the influence of food intake.

METHODS

Two open-label studies were performed in healthy male subjects. Study I was a dose-escalation study, in which subjects received single oral doses of ximelagatran (1-98 mg). Study II was a randomised, two-way crossover study consisting of two 5-day treatment periods, in which subjects received a 20-mg oral dose of ximelagatran twice daily, either before breakfast and with dinner, or with breakfast and after dinner.

RESULTS

Ximelagatran was rapidly absorbed and converted to melagatran, which was the predominant compound in plasma. The mean (+/- standard deviation) bioavailability of melagatran was 22.2+/-4.3% and 17.4+/-2.8% after single and repeated dosings, respectively. The maximum plasma concentration of melagatran and the area under the melagatran plasma concentration-time curve (AUC) increased linearly with dose. Inter- and intra-subject variability in melagatran AUC was 8% and 12%, respectively, with no relevant food- or time dependence. Anticoagulation, assessed as activated partial thromboplastin time, was correlated with melagatran plasma concentration. There was virtually no increase in capillary bleeding time over the dose range studied, and ximelagatran was well tolerated.

CONCLUSION

After oral administration of ximelagatran to healthy male subjects, the pharmacokinetic and pharmacodynamic profile of melagatran is predictable and reproducible.

Review of the Current ACS Practice Guideline to Develop an Ischemic Chest Pain Protocol

This review covers the major recommendations to the 2000 American College of Cardiology/American Heart Association (ACC/AHA) Acute Coronary Syndromes (ACS) Practice Guidelines. This review describes the evidence-based medicine that rationalizes the recommended pharmacotherapy for ST elevation myocardial infarction (STEMI) and non- STEMI (NSTEMI) ACS. To ensure conformity, an Ischemic Chest Pain Protocol (ICPP) order form was developed. The ICPP is like a menu that includes orders for all the recommended therapies in an easy-to-use checklist format. The ICPP has facilitated the implementation, acceptance, and understanding of the 2002 ACC/AHA ACS practice guidelines. Hence with improved conformity, it is hoped that the improved outcomes that were intended will result. A description of the ICPP and a mechanism for implementation is provided in this article.

Therapeutic Angiogenesis for Coronary Artery Disease

Angiogenesis is a promising new therapy for the treatment of patients with coronary artery disease who are not candidates for standard revascularization techniques. The concept of therapeutic angiogenesis is based upon improving myocardial function by increasing blood flow to ischemic areas of the heart. Angiogenic growth factors, including fibroblast growth factor and vascular endothelial growth factor, have been shown to induce functionally significant angiogenesis in preclinical studies. Both protein and gene formulations are under investigation; currently, protein-based therapy is considered the more practical form of therapy. The delivery of these growth factors is another aspect of angiogenic therapy under development, with several techniques used in clinical trials. However, the optimal method of delivery with regard to tissue specificity and duration of exposure is not yet defined. Despite encouraging preclinical data, the results of clinical trials so far have shown only, if any, modest improvements in cardiac function and clinical outcome. Further randomized, double-blind, placebo-controlled trials are necessary to support angiogenesis as a therapy for ischemic cardiac disease.

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.

Gene transfer to induce angiogenesis in myocardial and limb ischaemia

Stimulation of angiogenesis/arteriogenesis by gene transfer methods offers hope for treating patients with myocardial and peripheral limb ischaemia who are not candidates for standard revascularisation procedures. Preclinical studies showed that adenoviral and plasmid vectors encoding various angiogenic cytokines were capable of inducing functionally significant angiogenesis in vitro and in animal models of chronic myocardial ischaemia. Early clinical studies using VEGF121-, FGF-4- and VEGF165-encoding vectors showed a reasonable safety profile with promising results. However, significant advances in vector technology including regulatable and longer-term expression, delivery strategies (local and organ/tissue specific), clinical trial design, and outcome measure development are needed before this investigational treatment becomes reality.

PITFALLS IN THE EMERGENCY DEPARTMENT DIAGNOSIS OF ACUTE MYOCARDIAL INFARCTION

The accurate assessment and triage of patients with potential ACS is a complex decision-making process based on information that is not entirely reliable. The knowledgeable EP recognizes that assessment of patients with chest pain requires an understanding of the various clinical presentations of ACS and high-risk patient types, as well as careful use of the available modalities to diagnose these syndromes efficiently while incurring minimal risk to the patients safety. The busy EP is faced with sick patients with chest pain daily, so that it behoove anyone in emergency medicine to familiarize themselves with these diagnostic pitfalls.

Gene transfer for angiogenesis in coronary artery disease

Angiogenesis is a promising novel therapeutic strategy to provide new venues for blood flow in patients with severe ischemic heart and peripheral vascular disease, who are not candidates for standard revascularization strategies. We describe the underlying mechanisms involved in physiologic and therapeutic angiogenesis, underscoring the relative importance of vasculogenesis, angiogenesis, and arteriogenesis. We then present the various gene transfer vectors including plasmid, viral, and cell-based vectors, and various delivery modalities. The available preclinical data are presented, followed by a description of preliminary clinical experience, with an emphasis on the preliminary nature of these results, which address safety and not efficacy. Finally, we discuss the promises and pitfalls of clinical angiogenesis and gene transfer studies, stressing the importance of proper design of clinical trials and adequate protection of research subjects.