Stavros Konstantinides

Highly sensitive troponin T assay in normotensive patients with acute pulmonary embolism

AIMS To assess the role of cardiac troponin T (cTnT) levels on admission using a new, highly sensitive assay (hsTnT) in the risk assessment of normotensive patients with acute pulmonary embolism (PE). METHODS AND RESULTS We prospectively studied 156 consecutive normotensive patients with confirmed PE. The prognostic value of hsTnT at baseline was compared with the conventional cTnT troponin assay and with N-terminal pro-brain natriuretic peptide concentrations. Long-term follow-up was available for 153 patients (98.1%). Highly sensitive troponin T values ranged from 0.001 to 357.2 pg/mL [median 27.2 (25th-75th percentile 9.4-69.4) pg/mL]. Overall, 100 patients (64%) had hsTnT > or =14 pg/mL. Baseline hsTnT was higher in patients with an adverse 30-day outcome (> or =1: death, need for catecholamines, endotracheal intubation, or cardiopulmonary resuscitation) compared with an uncomplicated course [71.7 (35.5-117.9) vs. 26.4 (9.2-68.2) pg/mL; P = 0.027]. The cut-off value of 14 pg/mL showed an excellent prognostic sensitivity and negative predictive value (both 100%). In comparison, as many as 50% of the patients with an adverse early outcome would have been misclassified as low risk by cTnT (cut-off 0.03 ng/mL). Logistic regression indicated a two-fold increase in the risk of an adverse outcome for each increase of hsTnT by 1SD of the natural logarithm (P = 0.037). Patients with elevated hsTnT levels had a reduced probability of long-term survival (P = 0.029 by log-rank); by Coxs regression analysis, hsTnT was the only laboratory biomarker predicting an elevated risk of death over the long term. CONCLUSION Highly sensitive troponin T assays may be capable of improving risk stratification of non-high-risk PE.

Elevated heart-type fatty acid-binding protein levels on admission predict an adverse outcome in normotensive patients with acute pulmonary embolism.

OBJECTIVES We assessed the predictive value of heart-type fatty acid-binding protein (H-FABP) in normotensive patients with acute pulmonary embolism (PE). BACKGROUND Risk stratification of initially normotensive patients with PE on the basis of right ventricular dysfunction or injury remains controversial. Previous studies investigating biomarkers or imaging modalities included unselected patients, some of whom presented with cardiogenic shock. METHODS We included 126 consecutive normotensive patients with confirmed PE. Complicated 30-day outcome was defined as death, resuscitation, intubation, or use of catecholamines. Long-term survival was assessed by follow-up clinical examination. RESULTS During the first 30 days, 9 (7%) patients suffered complications. These patients had higher baseline H-FABP values (median, 11.2 ng/ml [interquartile range: 8.0 to 36.8 ng/ml]) compared with patients with an uncomplicated course (3.4 ng/ml [2.1 to 4.9 ng/ml]; p < 0.001). H-FABP values were above the calculated (by receiver operating characteristic curve analysis) cutoff value of 6 ng/ml in 29 patients. Eight (28%) of them suffered complications versus 1 of 97 patients with low H-FABP (negative predictive value, 99%; p < 0.001). By logistic regression, elevated (> or =6 ng/ml) H-FABP was associated with a 36.6-fold increase in the death or complication risk. The combination of H-FABP with tachycardia was a particularly useful prognostic indicator. H-FABP also predicted long-term mortality over 499 (interquartile range: 204 to 1,166) days (hazard ratio: 3.6; 95% confidence interval: 1.6 to 8.2; p = 0.003). CONCLUSIONS The H-FABP might be a useful biomarker for risk stratification of normotensive patients with acute PE.

A Strategy Combining Imaging and Laboratory Biomarkers in Comparison With a Simplified Clinical Score for Risk Stratification of Patients With Acute Pulmonary Embolism

BACKGROUND This study aimed to assess the performance of two prognostic models-the European Society of Cardiology (ESC) model and the simplified Pulmonary Embolism Severity Index (sPESI)-in predicting short-term mortality in patients with pulmonary embolism (PE). METHODS We compared the test characteristics of the ESC model and the sPESI for predicting 30-day outcomes in a cohort of 526 patients with objectively confirmed PE. The primary end point of the study was all-cause mortality. The secondary end point included all-cause mortality, nonfatal symptomatic recurrent VTE, or nonfatal major bleeding. RESULTS Overall, 40 of 526 patients died (7.6%; 95% CI, 5.3%-9.9%) during the first month of follow-up. The sPESI classified fewer patients as low risk (31% [165 of 526], 95% CI, 27%-35%) compared with the ESC model (39% [207 of 526], 95% CI, 35% to 44%; P < .01). Importantly however, low-risk patients based on the sPESI had no 30-day mortality compared with 3.4% (95% CI, 0.9-5.8) in low-risk patients by the ESC model. The secondary end point occurred in 1.8% of patients in the sPESI low-risk and 5.8% in the ESC low-risk group (difference, 4.0 percentage points; 95% CI, 0.2-7.8). The prognostic ability of the ESC model remained significant in the subgroup of patients at high-risk according to the sPESI model (OR 1.95, 95% CI, 1.41 to 2.71, P < .001). CONCLUSIONS Both the sPESI and the ESC model successfully predict 30-day mortality after acute symptomatic PE, but exclusion of an adverse early outcome does not appear to require routine imaging procedures or laboratory biomarker testing.

Exercise Training Reduces Neointimal Growth and Stabilizes Vascular Lesions Developing After Injury in Apolipoprotein E–Deficient Mice

Background—Population-based studies have shown that exercise reduces cardiovascular morbidity and mortality. However, it is unknown whether these effects are solely a result of risk factor modification or whether exercise directly affects the homeostasis of the vessel wall. Methods and Results—We subjected 19-week-old apolipoprotein E (apoE)–knockout mice (apoE−/−; n=25) to a 6-week training program on a motorized treadmill. The control group consisted of 17 sedentary mice. After 3 weeks in the program, training and sedentary mice underwent carotid artery injury with ferric chloride. Training was then resumed for another 3 weeks. Exercise did not change body weight or lipid levels in apoE−/− mice but resulted in upregulated expression of nitric oxide synthase in the endothelium. Physical training did not significantly affect the thrombotic response to injury. However, morphometric analysis of vessels harvested 3 weeks after injury showed that neointima formation was reduced in the exercising group. This resulted in a lower intima/media ratio (0.29±0.03 versus 0.41±0.03 in sedentary mice; P =0.008) and less luminal stenosis (21±2.7% versus 33±2.3%; P =0.003). Importantly, exercise reduced the number of Mac-3–positive, oxidized LDL-containing macrophages in the vessel wall while increasing the content in collagen fibers (14.1±0.9% versus 4.8±0.8%; P <0.001). Plasminogen activator inhibitor-1, tissue factor, and fibrinogen were all significantly reduced in the lesions of trained mice. Conclusions—In the apoE−/− mouse, exercise training reduces neointimal growth and stabilizes vascular lesions after injury. These effects appear to be at least partly independent of changes in lipid levels or the initial thrombotic response to injury.

Effects of Obesity and Weight Loss on the Functional Properties of Early Outgrowth Endothelial Progenitor Cells

OBJECTIVES The purpose of this study was to examine the impact of obesity and weight loss on the angiogenic and regenerative capacity of endothelial progenitor cells (EPCs). BACKGROUND EPCs participate in angiogenesis and tissue repair. Several cardiovascular risk factors are associated with EPC dysfunction. METHODS Early outgrowth EPCs were isolated from 49 obese (age 42 +/- 14 years; body mass index 42 +/- 7 kg/m(2)) normoglycemic participants in a professional weight reduction program and compared with those from 49 age-matched lean controls. EPC function was tested both in vitro and in vivo. RESULTS EPCs expanded from the obese possessed reduced adhesive, migratory, and angiogenic capacity, and mice treated with obese EPCs exhibited reduced EPC homing in ischemic hind limbs in vivo. EPCs from the obese subjects failed to respond to conditioned medium of lean controls or to potent angiogenic factors such as vascular endothelial growth factor. Although no differences existed between lean and obese EPCs regarding the surface expression of vascular endothelial growth factor or chemokine receptors, basal p38 mitogen-activated protein kinase (MAPK) phosphorylation was elevated in obese EPCs (3.7 +/- 2.1-fold increase; p = 0.006). These cells also showed reduced secretion of the angiogenic chemokines interleukin-8 (p = 0.047) and monocyte chemoattractant protein-1 (p = 0.012). By inhibiting p38 MAPK, we could restore chemokine levels to those of lean control EPCs and also improve the angiogenic properties of obese EPCs. Accordingly, 6-month follow-up of 26 obese persons who achieved significant weight reduction revealed normalization of p38 MAPK phosphorylation levels and improved EPC function. CONCLUSIONS Obesity is associated with a reversible functional impairment of EPCs. This involves reduced secretion of angiogenic chemokines and increased basal phosphorylation of signaling molecules, notably p38 MAPK.

Leptin induces the expression of functional tissue factor in human neutrophils and peripheral blood mononuclear cells through JAK2-dependent mechanisms and TNFα involvement

INTRODUCTION Leptin is an adipocyte-derived cytokine primarily involved in the regulation of body weight and energy balance. In vivo studies suggest that leptin promotes platelet aggregation and thrombosis. Neutrophils are involved in the crosstalk between inflammation and thrombosis in clinical disorders. Leptin is also involved in the regulation of inflammation. AIM We examined the in vitro effects of leptin on the expression of tissue factor (TF), the primary initiator of coagulation, in healthy neutrophils. MATERIALS AND METHODS/RESULTS The effects on TF expression were assayed functionally using a modified prothrombin time (mPT), as well as at mRNA and protein levels. The same experiments were performed in parallel with PBMC. Leptin induced functional TF and increased TF mRNA and protein expression in both cell types, as determined by mPT, real-time RT-PCR, western blot, flow cytometry, immunocytochemistry. Inhibition studies revealed that the effect of leptin on TF expression is mediated, at least in part, by JAK2 and PI3K. Our findings, after neutralising TNFalpha in supernatants of leptin-treated cells, also suggest the involvement of TNFalpha in the leptin-induced TF expression in leukocytes. CONCLUSIONS This study indicates a novel link between inflammation, obesity and thrombosis by showing that leptin is able to trigger the extrinsic coagulation cascade. This work suggests a possible mechanism of the thrombotic effects of hyperleptinemic-associated clinical disorders.

The Diagnosis and Treatment of Acute Pulmonary Embolism

BACKGROUND Pulmonary embolism (PE) is a cardiovascular emergency with high morbidity and mortality. METHODS Review of relevant literature retrieved by a selective Medline search, including current guidelines. RESULTS Hemodynamically unstable patients are considered to have high-risk PE, whereas hemodynamically stable patients are considered to have non-high-risk PE. After classification into one of these two risk groups, patients undergo further diagnostic evaluation for PE according to the appropriate risk-adapted algorithm. Patients who are in cardiogenic shock or have persistent arterial hypotension (high-risk PE) should undergo multidetector computed tomography (MDCT) or echocardiography at once, so that a PE, if present, can be treated immediately by thrombolysis. For hemodynamically stable patients with non-high-risk PE the proper diagnostic strategy is determined by the clinical probability of PE, which can be calculated with the aid of validated scoring systems and is based on both MDCT and D-dimer levels. For further risk stratification in hemodynamically stable patients, tests are performed to detect right ventricular dysfunction or myocardial injury, either of which indicates intermediate-risk PE. In addition to specific therapy, patients with high-risk PE, patients at high risk for hemorrhage and these with severe renal insufficiency should be anticoagulated with unfractionated heparin. All other patients should be treated with low-molecular-weight heparin or fondaparinux. Thereafter, long-term oral anticoagulation with vitamin K antagonists is recommended. CONCLUSION Modern algorithms have considerably simplified the diagnosis and treatment of acute PE. It would be desirable for these algorithms to be rapidly implemented in routine practice, because speedy diagnosis and immediate treatment can lower the morbidity and mortality associated with PE.

Leptin promotes the mobilization of vascular progenitor cells and neovascularization by NOX2-mediated activation of MMP9

AIMS Bone marrow (BM) progenitors participate in new vessel formation and endothelial repair. The leptin receptor (ObR) is expressed on hematopoietic cells; however, the effects of leptin on BM progenitor cells and their angiogenic potential are unknown. METHODS AND RESULTS In the present study, we show that the short-term administration of leptin (over five consecutive days) into wild-type mice increased the number of circulating, BM-derived sca-1(+), flk-1(+) vascular progenitors, 95 ± 1.7% of which also expressed ObR. Ex vivo stimulation of BM cells with leptin enhanced the expression of NADPH oxidase isoform 2 (NOX2), and the leptin-induced increase in reactive oxygen species production, matrix metalloproteinase-9 (MMP9) expression and circulating soluble KitL levels was absent in mice lacking NOX2. Furthermore, intraperitoneal injections of leptin improved perfusion and increased the number of BM-derived, CD31-positive endothelial cells in ischaemic hindlimbs after femoral artery ligation. The effects of leptin on the mobilization of sca-1(+), flk-1(+) cells and neovascularization were abolished in mice transplanted with BM from ObR-deficient and in NOX2(-/-) mice. CONCLUSION Our findings suggest that the angiogenic effects of leptin involve sca-1(+), flk-1(+) vascular progenitor cells mobilized from the BM in response to ObR-mediated activation of NOX2, increased MMP9 expression, and sKitL release.

Non-invasive imaging in the diagnosis of acute viral myocarditis

Autopsy series of consecutive cases have demonstrated an incidence of myocarditis at approximately 1–10%; on the contrary, myocarditis is seriously underdiagnosed clinically. In a traditional view, the gold standard has been myocardial biopsy. However, it is generally specific but invasive and less sensitive, mostly because of the focal nature of the disease. Thus, non-invasive approaches to detect myocarditis are necessary. The traditional diagnostic tools are electrocardiography, laboratory values, especially troponin T or I, creatine kinase and echocardiography. For a long period, nuclear technique with indium-111 antimyosin antibody has been used as a diagnostic approach. In the last years, the use of this technique has declined because of radiation exposure and 48-h delay in obtaining imaging after injection to prevent blood pool effect. Thus, a non-invasive diagnostic approach without radiation and online image availability has been awaited. Cardiac magnetic resonance imaging has these promising characteristics. With this technique, it is possible to analyse inflammation, oedema and necrosis in addition to functional parameters such as left ventricular function, regional wall motion and dimensions. Thus, cardiovascular magnetic resonance imaging has emerged as the most important imaging tool in the diagnostic procedure and the review focus on this field. But there are also advances in echocardiography and computer tomography, which are described in detail.Autopsy series of consecutive cases have demonstrated an incidence of myocarditis at approximately 1–10%; on the contrary, myocarditis is seriously underdiagnosed clinically. In a traditional view, the gold standard has been myocardial biopsy. However, it is generally specific but invasive and less sensitive, mostly because of the focal nature of the disease. Thus, non-invasive approaches to detect myocarditis are necessary. The traditional diagnostic tools are electrocardiography, laboratory values, especially troponin T or I, creatine kinase and echocardiography. For a long period, nuclear technique with indium-111 antimyosin antibody has been used as a diagnostic approach. In the last years, the use of this technique has declined because of radiation exposure and 48-h delay in obtaining imaging after injection to prevent blood pool effect. Thus, a non-invasive diagnostic approach without radiation and online image availability has been awaited. Cardiac magnetic resonance imaging has these promising characteristics. With this technique, it is possible to analyse inflammation, oedema and necrosis in addition to functional parameters such as left ventricular function, regional wall motion and dimensions. Thus, cardiovascular magnetic resonance imaging has emerged as the most important imaging tool in the diagnostic procedure and the review focus on this field. But there are also advances in echocardiography and computer tomography, which are described in detail.

Effects of exercise training on the severity and composition of atherosclerotic plaque in apoE-deficient mice.

Aim: To investigate the effects of exercise on atherosclerotic plaque composition, the concentration of matrix metalloproteinases (MMPs) in the atherosclerotic plaque and the systemic circulation. Methods: Ninety apolipoprotein E-deficient (apoE–/–) mice (45 male) were randomized to the following groups (n = 15 each): control male/female; sedentary male/female; exercise male/female. Mice were kept on a 16-week high-fat diet. Subsequently, the control groups were sacrificed, while the rest of the animals were placed on a normal diet for 6 more weeks. During the latter period, the exercise groups were trained daily on treadmill. At the end of the study, mice were euthanized, and blood samples as well as aortic root specimens were obtained. Results: Compared to control and sedentary animals, exercise training reduced atherosclerotic plaques (–30%; p < 0.01) and increased elastin and collagen content in both genders (p < 0.05). Body weight or lipid profile did not change significantly. Decreased macrophages and MMP-9 as well as increased tissue inhibitor of metalloproteinases 1 (TIMP-1) levels were observed in the atherosclerotic plaques of the exercise-treated groups (p < 0.05). Plasma concentrations of MMP-9 decreased, while plasma TIMP-1 levels increased in the exercise compared to control and sedentary groups (p < 0.05). Conclusions: Exercise training had a favorable effect on the size and composition of the atherosclerotic plaque in apoE–/– mice, associated with suppressed MMP activity.