P5658Incorporation of severity of left atrial enlargement in clinical risk factors improves identification of patients at risk for development of atrial fibrillation

Background

Early identification of patients at risk for atrial fibrillation (AF) is desirable to prevent its development and complications. Clinical predictors have been recognized but need refinement to improve predictability. We evaluated whether severity of left atrial enlargement (LAE) added to a scoring system (CHA2DS2VASC) in an unselected non-AF population improves risk stratification for incident AF.

Purpose

To assess the incremental benefit of LAE severity added to CHA2DS2VASc in predicting future AF in non-AF patients.

Methods

From 2012–2017, consecutive adult patients with an echocardiogram and no prior AF were identified. CHA2DS2VASc was used to define baseline AF risk, and the incremental risk of AF with addition of LAE was assessed through increased LA volume index (LAVI; moderate 42–48 ml/m2, severe >48 ml/m2). To quantify improvement in risk prediction, logistic regression model was fitted and odds ratios (OR) and ROC curves obtained.

Results

Out of 155,597 patients with no prior AF, 13.8% developed AF over 1.5±1.3 years. OR for AF with CHA2DS2VASc was 1.68 (95% CI 1.66–1.69). With addition of moderately or severely increased LAVI to the model, OR for AF increased to 2.3 (2.2–2.5) and 3.8 (3.6–4.0), respectively. ROC analysis showed c-statistics of 0.66 with CHA2DS2VASc, 0.63 with LAVI, and 0.71 with incorporation of both (Fig).

AF CHAD score

Conclusion(s)

In non-AF patients, predictability for future AF can be improved by using clinical factors (CHA2DS2VASc) and increased LAVI. This information may guide closer monitoring and initiation of therapies to prevent progression to AF or stroke.

Acknowledgement/Funding

None

Measuring and modeling the effects of drainage water management on soil greenhouse gas fluxes from corn and soybean fields

Controlled tile drainage can boost crop yields and improve water quality, but it also has the potential to increase GHG emissions. This study compared in-situ chamber-based measures of soil CH4, N2O, and CO2 fluxes for silt loam soil under corn and soybean cropping with conventional tile drainage (UTD) and controlled tile drainage (CTD). A semi-empirical model (NEMIS-NOE) was also used to predict soil N2O fluxes from soils using observed soil data. Observed N2O and CH4 fluxes between UTD and CTD fields during the farming season were not significantly different at 0.05 level. Soils were primarily a sink for CH4 but in some cases a source (sources were associated exclusively with CTD). The average N2O fluxes measured ranged between 0.003 and 0.028 kg N ha(-1) day(-1). There were some significantly higher (p ≤ 0.05) CO2 fluxes associated with CTD relative to UTD during some years of study. Correlation analyses indicated that the shallower the water table, the greater the CO2 fluxes. Higher corn plant C for CTD tended to offset estimated higher CTD CO2 C losses via soil respiration by ∼100-300 kg C ha(-1). There were good fits between observed and predicted (NEMIS-NOE) N2O fluxes for corn (R(2) = 0.70) and soybean (R(2) = 0.53). Predicted N2O fluxes were higher for CTD for approximately 70% of the paired-field study periods suggesting that soil physical factors, such as water-filled pore space, imposed by CTD have potentially strong impacts on net N fluxes. Model predictions of daily cumulative N2O fluxes for the agronomically-active study period for corn-CTD and corn-UTD, as a percentage of total N fertilizer applied, were 3.1% and 2.6%, respectively. For predicted N2O fluxes on basis of yield units, indices were 0.0005 and 0.0004 (kg N kg(-1) crop grain yield) for CTD and UTD corn fields, respectively, and 0.0011 and 0.0005 for CTD and UTD soybean fields, respectively.

Precipitation changes impact stream discharge, nitrate-nitrogen load more than agricultural management changes

Nitrate-N losses to surface waters in the Upper Midwest of the Untied States have increased in recent decades, contributing to hypoxia in the Gulf of Mexico. This paper investigates whether increasing nitrate-N export from cropland in the Upper Midwest since the late 1960s results from changes in land use or climate. The Agricultural Drainage and Pesticide Transport (ADAPT) Model simulated current and historical agricultural systems under past and recent wet climate for Seven Mile Creek in Minnesota. Simulations were run with management and climate for three distinctly different periods--namely, 1965 to 1969, 1976 to 1980, and 1999 to 2003 (wettest period). Results showed discharge and nitrate-N losses responded more to changes in climate than management. The wetter period (1999-2003) caused a simulated 70% increase in discharge under 1960s-era management compared with that period's observed climate and a simulated 51% increase in discharge under 1970s-era management compared with the 1976 to 1980 climate. The recent, wetter climate also produced a 62% increase in nitrate-N losses for 1960s-era management compared with the actual climate and a 137% increase in nitrate-N losses for 1978 management conditions compared with actual 1970s climate. Had recent climate been in place and stable since 1965, agricultural changes would have decreased discharge by 6.4% through the late 1970s and then by another 21.1% under modern management but would have increased nitrate-N losses by 184% through the late 1970s and then decreased nitrate-N losses by 13.5% between 1978 and 2001. Management changes that were important drivers included increasing N-fertilizer rates, increases in corn acreage, and increases in crop yield. But the most important factor driving increased nitrate-N losses from agriculture since the 1970s was an increasingly wetter climate.

Water quality modeling of fertilizer management impacts on nitrate losses in tile drains at the field scale

Nitrate losses from subsurface tile drained row cropland in the Upper Midwest U.S. contribute to hypoxia in the Gulf of Mexico. Strategies are needed to reduce nitrate losses to the Mississippi River. This paper evaluates the effect of fertilizer rate and timing on nitrate losses in two (East and West) commercial row crop fields located in south-central Minnesota. The Agricultural Drainage and Pesticide Transport (ADAPT) model was calibrated and validated for monthly subsurface tile drain flow and nitrate losses for a period of 1999-2003. Good agreement was found between observed and predicted tile drain flow and nitrate losses during the calibration period, with Nash-Sutcliffe modeling efficiencies of 0.75 and 0.56, respectively. Better agreements were observed for the validation period. The calibrated model was then used to evaluate the effects of rate and timing of fertilizer application on nitrate losses with a 50-yr climatic record (1954-2003). Significant reductions in nitrate losses were predicted by reducing fertilizer application rates and changing timing. A 13% reduction in nitrate losses was predicted when fall fertilizer application rate was reduced from 180 to 123 kg/ha. A further 9% reduction in nitrate losses can be achieved when switching from fall to spring application. Larger reductions in nitrate losses would require changes in fertilizer rate and timing, as well as other practices such as changing tile drain spacings and/or depths, fall cover cropping, or conversion of crop land to pasture.

Emotional arousal and activation of the visual cortex: an fMRI analysis

Functional activity in the visual cortex was assessed using functional magnetic resonance imaging technology while participants viewed a series of pleasant, neutral, or unpleasant pictures. Coronal images at four different locations in the occipital cortex were acquired during each of eight 12-s picture presentation periods (on) and 12-s interpicture interval (off). The extent of functional activation was larger in the right than the left hemisphere and larger in the occipital than in the occipitoparietal regions during processing of all picture contents compared with the interpicture intervals. More importantly, functional activity was significantly greater in all sampled brain regions when processing emotional (pleasant or unpleasant) pictures than when processing neutral stimuli. In Experiment 2, a hypothesis that these differences were an artifact of differential eye movements was ruled out. Whereas both emotional and neutral pictures produced activity centered on the calcarine fissure (Area 17), only emotional pictures also produced sizable clusters bilaterally in the occipital gyrus, in the right fusiform gyrus, and in the right inferior and superior parietal lobules.

Optic nerve head circulation in untreated ocular hypertension

AIMS

The laser Doppler technique was used to compare the capillary blood speed measured at localised sites of the optic nerve head in stable, untreated ocular hypertensive patients with that measured in healthy normal subjects. The stereophotogrammetric technique was also used to measure the retinal nerve fibre layer thickness at the disc margin in the eyes of the patients.

METHODS

Doppler broadening measurements were made at superior and inferior temporal disc sites in 18 eyes of 10 ocular hypertensive patients and in 12 eyes of seven age and sex-matched normal subjects.

RESULTS

On average, Doppler broadening and, hence, capillary blood speed were significantly higher (p = 0.018) in the patients than in the normal subjects. The largest values of Doppler broadening in the patients were measured at sites adjacent to the thinnest retinal nerve fibre layer. Linear regression analysis showed a significant inverse relation (p = 0.0004) between Doppler broadening and nerve fibre layer thickness in left eyes, and a nearly significant relation (p = 0.06) in right eyes. At temporal sites of the optic nerve head there is a compensatory relation between a thinning nerve fibre layer and a locally increasing blood supply to the optic nerve head.

CONCLUSION

Together with previous observations of fluorescein filling defects in similar patients, these results indicate that there is spatial heterogeneity of blood flow in the optic nerve head in stable, untreated ocular hypertensive patients.

Standardised echography in the differential diagnosis of extraocular muscle enlargement

Standardised echography is well documented for its use in the evaluation of enlarged extraocular muscles in orbital disease, but is still a largely underdeveloped imaging method in Britain. This paper demonstrates the technique of muscle ultrasound scanning and the characteristic echographic findings in a variety of extraocular muscle diseases, as illustrated by five case reports. The role of echography in the management of such cases is discussed.

Metastatic endophthalmitis caused by Clostridium perfringens

A case of metastatic endophthalmitis due to Clostridium perfringens originating from the biliary tract is reported. The grave visual prognosis and the importance of early detection and treatment of the primary source of infection are emphasised.

Changes in respiratory function tests during pregnancy

Anatomical, physiological and biochemical adaptations that occur during pregnancy are profound. Changes in respiratory physiology are a part of the same process. In the present study of 70 selected women, 50 pregnant and nonpregnant control, it was found that out of seven parameters studied five showed changes. There were changes in respiratory frequency, tidal volume, vital capacity, inspiratory capacity and expiratory reserve volume. Maximum voluntary ventilation and timed vital capacity did not change. RF, VT, VC and IC rose significantly while ERV had a significant fall. These changes may be affecting ante-intranatal behaviour of pregnant women and their pregnancy outcome.