|Year : 2006 | Volume
| Issue : 4 | Page : 120-122
|Date of Web Publication||17-Jun-2010|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
. Cardiovascular News. Heart Views 2006;7:120-2
GDF-15: New Biomarker for Risk of Death in Patients with Non-ST-Elevation Acute Coronary Syndrome
Growth-differentiation factor-15 (GDF-15) is a member of the transforming growth factor-b cytokine superfamily that is induced in the heart after ischemia-and-reperfusion injury. Circulating levels of GDF-15 may provide prognostic information in patients with non-ST-elevation acute coronary syndrome.
Blood samples were obtained on admission from 2081 patients with acute chest pain and either ST-segment depression or troponin elevation who were included in the Global Utilization of Strategies to Open Occluded Arteries (GUSTO)-IV Non-ST-Elevation Acute Coronary Syndrome trial and from a matching cohort of 429 apparently healthy individuals. GDF-15 levels were determined by immunoradiometric assay.
Approximately two thirds of patients presented with GDF-15 levels above the upper limit of normal in healthy controls (1200 ng/L); one third presented with levels >1800 ng/L. Increasing tertiles of GDF-15 were associated with an enhanced risk of death at 1 year (1.5%, 5.0%, and 14.1%; P < 0.001). By multiple Cox regression analysis, only the levels of GDF-15 and N-terminal pro-B-type natriuretic peptide, together with age and a history of previous myocardial infarction, contributed independently to 1-year mortality risk. Receiver operating characteristic curve analyses further illustrated that GDF-15 is a strong marker of 1-year mortality risk (area under the curve, 0.757; best cutoff, 1808 ng/L). At this cutoff value, GDF-15 added significant prognostic information in patient subgroups defined by age; gender; time from symptom onset to admission; cardiovascular risk factors; previous cardiovascular disease; and the risk markers ST-segment depression, troponin T, N-terminal pro-B-type natriuretic peptide, C-reactive protein, and creatinine clearance.
GDF-15 is a new biomarker of the risk for death in patients with non-ST-elevation acute coronary syndrome that provides prognostic information beyond that provided by established clinical and biochemical markers.
Cardiac Tissue Engineering in an In Vivo Vascularized Chamber
Cardiac tissue engineering offers the prospect of a novel treatment for acquired or congenital heart defects. Researchers created vascularized pieces of beating cardiac muscle in the rat that are as thick as the adult rat right ventricle wall.
Neonatal rat cardiomyocytes in Matrigel were implanted with an arteriovenous blood vessel loop into a 0.5-mL patented tissue-engineering chamber, located subcutaneously in the groin. Chambers were harvested 1, 4, and 10 weeks after insertion. At 4 and 10 weeks, all constructs that grew in the chambers contracted spontaneously. Immunostaining for sarcomeric actin, troponin, and desmin showed that differentiated cardiomyocytes present in tissue at all time points formed a network of interconnected cells within a collagenous extracellular matrix. Constructs at 4 and 10 weeks were extensively vascularized. The maximum thickness of cardiac tissue generated was 1983 ΅m.
Cardiomyocytes increased in size from 1 to 10 weeks and were positive for the proliferation markers Ki67 and PCNA. Connexin-43 stain indicated that gap junctions were present between cardiomyocytes at 4 and 10 weeks. Echocardiograms performed between 4 and 10 weeks showed that the tissue construct contracted spontaneously in vivo. In vitro organ bath experiments showed a typical cardiac muscle length-tension relationship, the ability to be paced from electrical field pulses up to 3 Hz, positive chronotropy to norepinephrine, and positive inotropy in response to calcium.
In summary, the use of a vascularized tissue-engineering chamber allowed generation of a spontaneously beating 3-dimensional mass of cardiac tissue from neonatal rat cardiomyocytes. Further development of this vascularized model will increase the potential of cardiac tissue engineering to provide suitable replacement tissues for acquired and congenital defects.
Effect of High-Dose Atorvastatin on Hospitalizations for Heart Failure
Statins reduce the rate of major cardiovascular events in high-risk patients, but their potential benefit as treatment for heart failure (HF) is less clear.
Patients (n = 10 001) with stable coronary disease were randomized to treatment with atorvastatin 80 or 10 mg/d and followed up for a median of 4.9 years. A history of HF was present in 7.8% of patients. A known ejection fraction <30% and advanced HF were exclusion criteria for the study. A predefined secondary end point of the study was hospitalization for HF. The incidence of hospitalization for HF was 2.4% in the 80-mg arm and 3.3% in the 10-mg arm (hazard ratio, 0.74; 95% confidence interval, 0.59 to 0.94; P = 0.0116).
The treatment effect of the higher dose was more marked in patients with a history of HF: 17.3% versus 10.6% in the 10- and 80-mg arms, respectively (hazard ratio, 0.59; 95% confidence interval, 0.4 to 0.88; P = 0.009). Among patients without a history of HF, the rates of hospitalization for HF were much lower: 1.8% in the 80-mg group and 2.0% in the 10-mg group (hazard ratio, 0.87; 95% confidence interval, 0.64 to 1.16; P = 0.34). Only one third of patients hospitalized for HF had evidence of preceding angina or myocardial infarction during the study period. Blood pressure was almost identical during follow-up in the treatment groups.
Compared with a lower dose, intensive treatment with atorvastatin in patients with stable coronary disease significantly reduces hospitalizations for HF. In a post hoc analysis, this benefit was observed only in patients with a history of HF. The mechanism accounting for this benefit is unlikely to be due primarily to a reduction in interim coronary events or differences in blood pressure.
Prehypertension Increases Cardiovascular Disease Risk in the Women's Health Initiative
Prehypertension is common and is associated with increased vascular mortality. The extent to which it increases risk of nonfatal myocardial infarction, stroke, and congestive heart failure is less clear.
Investigators determined the prevalence of prehypertension, its association with other coronary risk factors, and the risk for incident cardiovascular disease events in 60 785 postmenopausal women during 7.7 years of follow-up using Cox regression models that included covariates as time-dependent variables. Prehypertension was present at baseline in 39.5%, 32.1%, 42.6%, 38.7%, and 40.3% of white, black, Hispanic, American Indian, and Asian women, respectively (P < 0.0001 across ethnic groups). Age, body mass index, and prevalence of diabetes mellitus and hypercholesterolemia increased across blood pressure categories, whereas smoking decreased (all P < 0.0001).
Compared with normotensive women (referent), adjusted hazard ratios for women with prehypertension were 1.58 (95% confidence interval [CI], 1.12 to 2.21) for cardiovascular death, 1.76 (95% CI, 1.40 to 2.22) for myocardial infarction, 1.93 (95% CI, 1.49 to 2.50) for stroke, 1.36 (95% CI, 1.05 to 1.77) for hospitalized heart failure, and 1.66 (95% CI, 1.44 to 1.92) for any cardiovascular event. Hazard ratios for the composite outcome with prehypertension did not differ between ethnic groups (P = 0.71 for interaction), although the numbers of events among Hispanic and Asian women were small.
Prehypertension is common and was associated with increased risk of myocardial infarction, stroke, heart failure, and cardiovascular death in white and nonwhite postmenopausal women. Risk factor clustering was conspicuous, emphasizing the need for trials evaluating the efficacy of global cardiovascular risk reduction through primordial prevention.
High Clopidogrel Maintenance Dose in Patients WithDiabetes Mellitus and Coronary Artery Disease
After treatment with clopidogrel, patients with type 2 diabetes mellitus (T2DM) have reduced platelet inhibition compared with patients who are not diabetic. Whether platelet inhibition can be enhanced by increasing clopidogrel maintenance dosage in T2DM patients is unknown.
Investigators performed a pilot study was to assess the functional impact of a high maintenance dose in T2DM patients with suboptimal clopidogrel-induced antiplatelet effects.
T2DM patients on chronic dual antiplatelet therapy were screened to identify suboptimal clopidogrel responders. The latter were randomized to 30-day treatment with a standard (75 mg; n = 20) or high (150 mg; n = 20) daily maintenance dose. Platelet function was assessed at 3 time points: baseline, 30 days after randomization, and 30 days after resuming standard dosing. Platelet function parameters included adenosine diphosphate-induced (20 and 5 ΅mol/L) maximal and late platelet aggregation, inhibition of platelet aggregation, platelet disaggregation, and P2Y12 reactivity index.
A total of 64 T2DM patients were screened to identify 40 suboptimal responders. After randomization, maximal adenosine diphosphate-induced (20 ΅mol/L) platelet aggregation was significantly reduced in the 150-mg group compared with the 75-mg group (P = 0.002; primary end point). However, suboptimal clopidogrel response was still present in 60% of patients on the 150-mg regimen. All other platelet function parameters showed enhanced clopidogrel-induced antiplatelet effects with 150 mg, which returned to baseline values after resumption of standard dosing.
A 150-mg maintenance dose of clopidogrel is associated with enhanced antiplatelet effects compared with 75 mg in high-risk T2DM patients. However, enhanced ex vivo platelet reactivity continues to persist, the clinical implications of which are unknown and need to be evaluated in large-scale clinical trials.
Impact of Patient and Target-Vessel Characteristics on Arterial Venous Bypass Graft Patency
Investigators evaluated the optimal patient and target-vessel characteristics to maximize arterial and venous graft patency on the basis of data from a large clinical trial.
Angiographic data on 440 radial artery grafts and 440 saphenous vein grafts were analyzed with methodology to account for within-patient clustering. Multivariable models that incorporated patient demographic, operative, anatomic, and postdischarge medical management were constructed to determine predictors of graft occlusion. Radial artery use was strongly protective against graft occlusion at 1 year after adjustment for all covariates, with a larger protective effect seen in women (P=0.05 for a subgroup-by-treatment interaction). Among all grafts, diabetes and small target-vessel diameter were associated with an increased risk of graft occlusion, and grafting to a target vessel with more severe proximal stenosis was associated with a decreased risk of graft occlusion.
With regard to gender, radial artery graft occlusion at 1 year occurred in similar proportions of men (8.6%) and women (5.3%, P = 0.6), whereas, for saphenous vein grafts the comparable occlusion rates were 12.0% and 23.3% respectively (P =0.02). A history of peripheral vascular disease was associated with an elevated risk of radial artery occlusion but was not associated with early vein graft occlusion (P = 0.02 for a subgroup-by-treatment interaction).
Patients benefit from radial artery-coronary artery bypass conduits as opposed to saphenous vein conduits, and this effect is especially strong in women. Small target-vessel size adversely affected graft patency, and grafting to a target vessel with more severe proximal stenosis improved graft patency.
Among Postmenopausal Women (ESTHER Study)
Oral estrogen therapy increases the risk of venous thromboembolism (VTE) in postmenopausal women. Transdermal estrogen may be safer. However, currently available data have limited the ability to investigate the wide variety of types of progestogen.
Investigators performed a multicenter case-control study of VTE among postmenopausal women 45 to 70 years of age between 1999 and 2005 in France. We recruited 271 consecutive cases with a first documented episode of idiopathic VTE (208 hospital cases, 63 outpatient cases) and 610 controls (426 hospital controls, 184 community controls) matched for center, age, and admission date. After adjustment for potential confounding factors, odds ratios (ORs) for VTE in current users of oral and transdermal estrogen compared with nonusers were 4.2 (95% CI, 1.5 to 11.6) and 0.9 (95% CI, 0.4 to 2.1), respectively. There was no significant association of VTE with micronized progesterone and pregnane derivatives (OR, 0.7; 95% CI, 0.3 to 1.9 and OR, 0.9; 95% CI, 0.4 to 2.3, respectively). In contrast, norpregnane derivatives were associated with a 4-fold-increased VTE risk (OR, 3.9; 95% CI, 1.5 to 10.0).
Oral but not transdermal estrogen is associated with an increased VTE risk. In addition, our data suggest that norpregnane derivatives may be thrombogenic, whereas micronized progesterone and pregnane derivatives appear safe with respect to thrombotic risk. If confirmed, these findings could benefit women in the management of their menopausal symptoms with respect to the VTE risk associated with oral estrogen and use of progestogens.
Epidemiology and Cause-Specific Outcome of Hypertrophic Cardiomyopathy in Children
Current information on the epidemiology and outcomes of hypertrophic cardiomyopathy (HCM) in children is limited by disease diversity and small case series.
The Pediatric Cardiomyopathy Registry has collected prospective and retrospective data on children diagnosed with HCM since 1990. We identified the various causes of HCM in childhood and determined the relationship between outcomes, cause, and age at presentation. Of 855 patients <18 years of age with HCM, 8.7% (n = 74) had inborn errors of metabolism, 9.0% (n = 77) had malformation syndromes, 7.5% (n = 64) had neuromuscular disorders, and 74.2% (n = 634) had idiopathic HCM.
Children with HCM associated with inborn errors of metabolism and malformation syndromes have significantly worse survival than the other 2 groups. Patients with idiopathic HCM diagnosed before 1 year of age (n = 227) had worse survival from the time of diagnosis than those diagnosed after 1 year of age(n = 407). Patients with idiopathic HCM who survived to at least 1 year of age, however, had an annual mortality rate of 1% that was similar regardless of whether they were diagnosed before or after 1 year of age.
In children, HCM is a diverse disorder with outcomes that depend largely on cause and age. Patients presenting before 1 year of age have the broadest spectrum of causes and the poorest outcome. In those children with idiopathic HCM who survive beyond age 1, however, survival is independent of age at diagnosis, with an annual mortality rate (1%) that is much lower than previously reported in children and is not different from has been found in population-based studies in adults.
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