Diagnostic accuracy of plasma NT-proBNP levels for excluding cardiac abnormalities in the very elderly

<p>Abstract</p> <p>Background</p> <p>In the elderly the diagnosis of chronic heart failure is often challenging and the availability of echocardiography can be limited. Plasma levels of NT-proBNP are valuable tools to diagnose patients with heart failure. However, the performance of this biomarker to detect cardiac abnormalities in the very elderly remains unclear. The aims of this study were to investigate the relation between NT-proBNP and cardiac abnormalities and to evaluate the use of NT-proBNP to exclude structural and functional cardiac abnormalities in a community-based sample of "well-functioning" nonagenarians.</p> <p>Methods</p> <p>A diagnostic cross-sectional study embedded within the Leiden 85-plus Study in the municipality of Leiden, the Netherlands. Plasma NT-proBNP levels were measured and 2-dimensional echocardiography was performed in a subgroup of 80 well-functioning nonagenarians. Linear regression analysis was used to explore the relation between NT-proBNP and cardiac abnormalities and ROC curve analysis was used to assess the performance of NT-proBNP to exclude cardiac abnormalities. The upper limit of the lowest tertile of NT-proBNP was used as a cut-off value.</p> <p>Results</p> <p>NT-proBNP levels were associated with abnormal left ventricular (LV) dimensions, LV systolic and diastolic function, left atrial enlargement and valvular heart disease. LV mass, E/A ratio and degree of aortic regurgitation were identified as independent predictors of NT-proBNP. NT-proBNP levels were higher with greater number of echocardiographic abnormalities (P < 0.001). A cut-off level of 269.5 pg/mL identified patients with abnormal LV dimensions or depressed LV systolic function (sensitivity 85%, negative predictive value (NPV) 77%, area under the curve 0.75 (95% CI 0.64-0.85)). In addition, high NPV were found for LV systolic dysfunction, left atrial enlargement, severe valvular heart disease and pulmonary hypertension. The test performance of NT-proBNP to exclude any echocardiographic abnormality showed a sensitivity of 82% and a NPV of 65%.</p> <p>Conclusions</p> <p>In this convenience sample of well-functioning nonagenarians NT-proBNP was related to a wide variety of functional and structural echocardiographic abnormalities. Moreover, NT-proBNP could be used to exclude echocardiographic abnormalities in well-functioning nonagenarians and might be used to indicate who needs to be referred for further cardiovascular examination.</p

Predicting Cetacean Habitats from Their Energetic Needs and the Distribution of Their Prey in Two Contrasted Tropical Regions

International audienceTo date, most habitat models of cetaceans have relied on static and oceanographic covariates, and very few have relatedcetaceans directly to the distribution of their prey, as a result of the limited availability of prey data. By simulating thedistribution of six functional micronekton groups between the surface and .1,000 m deep, the SEAPODYM model providesvaluable insights into prey distributions. We used SEAPODYM outputs to investigate the habitat of three cetacean guildswith increasing energy requirements: sperm and beaked whales, Globicephalinae and Delphininae. We expected HighEnergy Requirements cetaceans to preferentially forage in habitats of high prey biomass and/or production, where theymight easily meet their high energetic needs, and Low Energy Requirements cetaceans to forage in habitats of either highor low prey biomass and/or production. Cetacean sightings were collected from dedicated aerial surveys in the South WestIndian Ocean (SWIO) and French Polynesia (FP). We examined cetacean densities in relation to simulated distributions oftheir potential prey using Generalised Additive Models and predicted their habitats in both regions. Results supported theirknown diving abilities, with Delphininae mostly related to prey present in the upper layers of the water column, andGlobicephalinae and sperm and beaked whales also related to prey present in deeper layers. Explained deviances rangedfrom 9% for sperm and beaked whales in the SWIO to 47% for Globicephalinae in FP. Delphininae and Globicephalinaeappeared to select areas where high prey biomass and/or production were available at shallow depths. In contrast, spermand beaked whales showed less clear habitat selection. Using simulated prey distributions as predictors in cetacean habitatmodels is crucial to understand their strategies of habitat selection in the three dimensions of the ocean