A Systematic Review of Scaling Left Atrial Size: Are Alternative Indexation Methods Required for an Increasingly Obese Population?

Adjusting Atrial Size Parameters for Body Surface Area: Does it Affect the Association With Pulmonary Embolism-related Adverse Events?

PURPOSE

Small left atrial (LA) volume was recently reported to be one of the best predictors of acute pulmonary embolism (PE)-related adverse events (AE). There is currently no data available regarding the impact that body surface area (BSA)-indexing of atrial measurements has on the association with PE-related adverse events. Our aim is to assess the impact of indexing atrial measurements to BSA on the association between computed tomography (CT) atrial measurements and AE.

MATERIALS AND METHODS

Retrospective study (IRB: 2015P000425). A database of hospitalized patients with acute PE diagnosed on CT pulmonary angiography (CTPA) between May 2007 and December 2014 was reviewed. Right and left atrial volume, largest axial area, and axial diameters were measured. Patients undergo both echocardiographies (from which the BSA was extracted) and CTPAs within 48 hours of the procedure. The patient's body weight was measured during each admission. LA measurements were correlated to AE (defined as the need for advanced therapy or PE-related mortality at 30 days) before and after indexing for BSA. The area under the ROC curve was calculated to determine the predictive value of the atrial measurements in predicting AE.

RESULTS

The study included 490 acute PE patients; 62 (12.7%) had AE. There was a significant association of reduced BSA-indexed and non-indexed LA volume (both <0.001), area (<0.001 and 0.001, respectively), and short-axis diameters (both <0.001), and their respective RA/LA ratios (all <0.001) with AE. The AUC values were similar for BSA-indexed and non-indexed LA volume, diameters, and area with LA volume measurements being the best predictor of adverse outcomes (BSA-indexed AUC=0.68 and non-indexed AUC=0.66), followed by non-indexed LA short-axis diameter (indexed AUC=0.65, non-indexed AUC=0.64), and LA area (indexed AUC=0.64, non-indexed AUC=0.63).

CONCLUSION

Adjusting for BSA does not substantially affect the predictive ability of atrial measurements on 30-day PE-related adverse events, and therefore, this adjustment is not necessary in clinical practice. While LA volume is the better predictor of AE, LA short-axis diameter has a similar predictive value and is more practical to perform clinically.

Characterizing the influence of cardiorespiratory fitness on left atrial size and function in the general population

Increased left atrial (LA) size and reduced LA function have been associated with heart failure and atrial fibrillation (AF) in at-risk populations. However, atrial remodeling has also been associated with exercise training and the relationship between fitness, LA size, and function has not been defined across the fitness spectrum. In a cross-sectional study of 559 ostensibly healthy participants, comprising 304 males (mean age, 46 ± 20 yr) and 255 females (mean age, 47 ± 15 yr), we sought to define the relationship between cardiorespiratory fitness (CRF), LA size, and function. We also aimed to interrogate sex differences in atrial factors influencing CRF. Echocardiographic measures included biplane measures of LA volumes indexed to body surface area (LAVi) and atrial deformation using two-dimensional speckle tracking. CRF was measured as peak oxygen consumption (V̇o2peak) during cardiopulmonary exercise testing (CPET). Using multivariable regression, age, sex, weight, and LAVi (P < 0.001 for all) predicted V̇o2peak (P < 0.001, R2 = 0.66 for combined model). After accounting for these variables, heart rate reserve added strength to the model (P < 0.001, R2 = 0.74) but LA strain parameters did not predict V̇o2peak. These findings add important nuance to the perception that LA size is a marker of cardiac pathology. LA size should be considered in the context of fitness, and it is likely that the adverse prognostic associations of increased LA size may be confined to those with LA enlargement and low fitness.NEW & NOTEWORTHY Left atrial (LA) structure better predicts cardiorespiratory fitness (CRF) than LA function. LA function adds little statistical value to predictive models of peak oxygen uptake (V̇o2peak) in healthy individuals, suggesting limited discriminatory for CRF once LA size is factored. In the wider population of ostensibly healthy individuals, the association between increased LA volume and higher CRF provides an important counter to the association between atrial enlargement and heart failure symptoms in those with cardiac pathology.

Reference Values for Indexed Echocardiographic Chamber Sizes in Older Adults: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Normalization of echocardiographic chamber measurements for body surface area may result in misclassification of individuals with obesity or sarcopenia. Normalization for alternative measures of body size may be preferable, but there remains a dearth of information on their normative values and association with cardiovascular function metrics.

METHODS AND RESULTS

A total of 3032 individuals underwent comprehensive 2-dimensional echocardiography at Exam 6 in MESA (Multi-Ethnic Study of Atherosclerosis). In the subgroup of 608 individuals free of cardiopulmonary disease (69.5±7.0 years, 46% male, 48% White, 17% Chinese, 15% Black, 21% Hispanic), normative values were derived for left and right cardiac chamber measurements across a variety of ratiometric (body surface area, body mass index, height) and allometric (height1.6, height2.7) scaling parameters. Normative upper and lower reference values were provided for each scaling parameter stratified across age groups, sex, and race or ethnicity. Among scaling parameters, body surface area and height were associated with the least variability across race and ethnicity categories and height2.7 was associated with the least variability across sex categories.

CONCLUSIONS

In this diverse cohort of community-dwelling older adults, we provide normative values for common echocardiographic parameters across a variety of indexation methods.

Indexing of Left Atrial Volume by various body size parameters in the Indian non-obese normal subjects: Is there an incremental value ?

BACKGROUND

Left atrial (LA) volume indexing for body surface area (BSA) is the common practice. Since LA volume index is of cardiovascular pathophysiologic significance, it is suggested that indexing for other body size parameters be explored to evaluate a more appropriate alternative method. The aims of this study were to find normal and the best cutoff values for LA volume indexed for multiple body size parameters in normal Indian subjects.

METHODS

Data from the multicentric prospective INDEA study conducted through 2018 to 2020 was reviewed and subjects without known cardiac disease and completely normal echocardiograms that had the left atrial volume (LAV) measured by biplane Simpson's method were included. LAV was indexed by BSA (ml/m2), by height (LAV/m), by height raised to exponent 1.72 (mL/m 1.72 and 2.7 (ml/m2.7), by body weight, by ideal body weight (IBW), by ideal body surface area (IBSA) and by height squared (ml/h2).

RESULTS

A total of 1046 healthy volunteers (382 female, 38%), mean age 38 ± 10.4 years (range 30-48 years) and body mass index 23.6 kg/m2 (22-25 kg/m2) were analyzed. Mean and normal values were: LAV/BSA 18.7 + 3.15 ml/m2 (range 15-21 ml/m2), LAV/ht 26.0 ± 4.5 ml/m, (range 17-35 ml/m), LAV/ht2 16 ± 2.8 ml/m2 (range 10.4-21.6 ml/m2) and LAV/ht2.7 8.71 ± 2.2 ml/m2.7 (range 6.98-13.58 ml/m2.7). Using ROC curve analysis, LAV/h 1.72 had the highest AUC and the best predictive value to identify LA enlargement but not very different from LAV/BSA. Ideal BSA and ideal body weight as a denominator did not provide any incremental value.

CONCLUSION

Normal values for LAV indexed for height, weight, body surface area by three different methods of height as an allometric parameter are described in normal Indian individuals. We reinforce that LA volume indexation for BSA is an acceptable and robust method in non-obese Indian subjects. Indexing for height 1.72 is probably slightly superior method to evaluate LAV.

Improved identification of left atrial enlargement in patients with obesity

Accurate standardization of left atrium volume (LAV) in patients with obesity is challenging. The aim of this study was to investigate and to examine the relation between LAV indexed to height2 and left atrial function in patients with moderate to severe obesity. Echocardiograms of patients with moderate to severe obesity (body mass index (BMI) ≥ 35 kg/m2) without known cardiac disease were analyzed. LAV was indexed to body surface area (BSA) and height2, and patients were divided into those with or without left atrial enlargement (LAE) based on normalization using either BSA (LAEbsa) or height2 (LAEh2). Using speckle tracking echocardiography, LA reservoir strain (LASr), LA conduit strain (LAScd), and LA contractile strain (LASct) were assessed as a measure of LA function. LA dysfunction was defined as LASct < 14%. A total of 142 patients were included in the analysis of whom 54.2% had LAEh2 and 18.3% LAEBSA. The LAEh2 group had significantly lower LASct (12.2% ± 3.2% vs. 13.6% ± 4.5%, p = 0.019) as compared to the patients without LAEh2. Significantly more patients with LA dysfunction would be correctly identified by LAEh2 than by LAEBSA (41.5% vs. 15.0%, p < 0.001). In patients with moderate to severe obesity, the use of LAEh2 identified significantly more patients with decreased LA function. LAVh2 should be preferred over LAVBSA in patients with moderate to severe obesity.

Insights Into the Standard Echocardiographic Views From Multimodality Imaging: Ventricles, Pericardium, Valves, and Atria

The widespread use of cardiac computed tomography and cardiac magnetic resonance imaging in patients undergoing echocardiography presents an opportunity to correlate the images side by side. Accordingly, the aim of this report is to review aspects of the standard echocardiographic examination alongside similarly oriented images from the two tomographic imaging modalities. It is hoped that this exercise will enhance understanding of the structures depicted by echocardiography as they relate to other structures in the thorax. In addition to reviewing basic cardiac anatomy, the authors take advantage of these correlations with computed tomography and cardiac magnetic resonance imaging to better understand the issue of foreshortening, a common pitfall in transthoracic echocardiography. The authors also highlight an important role that three-dimensional echocardiography can potentially play in the future, especially as advances in image processing permit higher fidelity multiplanar reconstruction images.

Normalized Echocardiographic Values From Guideline-Directed Dedicated Views for Cardiac Dimensions and Left Ventricular Function

BACKGROUND

Continuous technologic development and updated recommendations for image acquisitions creates a need to update the current normal reference ranges for echocardiography. The best method of indexing cardiac volumes is unknown.

OBJECTIVES

The authors used 2- and 3-dimensional echocardiographic data from a large cohort of healthy individuals to provide updated normal reference data for dimensions and volumes of the cardiac chambers as well as central Doppler measurements.

METHODS

In the fourth wave of the HUNT (Trøndelag Health) study in Norway 2,462 individuals underwent comprehensive echocardiography. Of these, 1,412 (55.8% women) were classified as normal and formed the basis for updated normal reference ranges. Volumetric measures were indexed to body surface area and height in powers of 1 to 3.

RESULTS

Normal reference data for echocardiographic dimensions, volumes, and Doppler measurements were presented according to sex and age. Left ventricular ejection fraction had lower normal limits of 50.8% for women and 49.6% for men. According to sex-specific age groups, the upper normal limits for left atrial end-systolic volume indexed to body surface area ranged from 44 mL/m2 to 53 mL/m2, and the corresponding upper normal limit for right ventricular basal dimension ranged from 43 mm to 53 mm. Indexing to height raised to the power of 3 accounted for more of the variation between sexes than indexing to body surface area.

CONCLUSIONS

The authors present updated normal reference values for a wide range of echocardiographic measures of both left- and right-side ventricular and atrial size and function from a large healthy population with a wide age-span. The higher upper normal limits for left atrial volume and right ventricular dimension highlight the importance of updating reference ranges accordingly following refinement of echocardiographic methods.

The impact of body mass index on cardiac structure and function in a cohort of obese patients without traditional cardiovascular risk factors

Background

Obesity has been linked with alterations in hemodynamic, autonomic, and hormonal pathways in the body, leading to a spectrum of cardiovascular changes. We sought to evaluate the effects of obesity on structural and functional changes of the heart in the absence of cardiac disease and associated risk factors.

Methods

We identified healthy outpatients without any cardiovascular disease or risk factors from our institution's echocardiography database (2017-2020). Patients were stratified by body mass index (BMI; normal: 18.5-25 kg/m2; overweight: 25-30 kg/m2; class 1 obesity: 30-35 kg/m2; class 2 obesity: 35-40 kg/m2; class 3 obesity: >40 kg/m2). Traditional and advanced echocardiographic parameters of cardiac chamber size and function including left ventricular global longitudinal strain (LV-GLS), left atrial reservoir strain (LASr), and right ventricular free wall strain (RV-FWS) were examined. The optimal cut-off BMI for discriminating LV-GLS (>-17.5%), LASr (<23%), and RV-FWS (>-23%) impairment was calculated using ROC curves.

Results

307 patients were assessed (41.5 ± 13.3yrs; 36.5%male; LVEF 61.3 ± 4.8%). No significant differences in indexed chamber volumes or LVEF were appreciated across BMI groups (p > 0.05 for all). LV-GLS, LASr, and RV-FWS were all significant on one-way ANOVA for differences from the group mean (all p < 0.01). Jonckheere-Terpstra test confirmed a significant trend of lower absolute LV-GLS, LASr and RV-FWS values across the rising BMI groups. On ROC curve analysis, a BMI value of 29.9 kg/m2, 35.1 kg/m2, and 37.3 kg/m2 were associated with LASr (AUC: 0.75), RV-FWS (AUC: 0.72), and LV-GLS (AUC: 0.75) impairment respectively.

Conclusion

Obesity is linked with subclinical reduction of cardiac function in otherwise healthy subjects without cardiovascular risk factors, with reduction of left atrial function occurring at lower BMI, followed by the right and left ventricular function.

Prognostic association supports indexing size measures in echocardiography by body surface area

Body surface area (BSA) is the most commonly used metric for body size indexation of echocardiographic measures, but its use in patients who are underweight or obese is questioned (body mass index (BMI) < 18.5 kg/m2 or ≥ 30 kg/m2, respectively). We aim to use survival analysis to identify an optimal body size indexation metric for echocardiographic measures that would be a better predictor of survival than BSA regardless of BMI. Adult patients with no prior valve replacement were selected from the National Echocardiography Database Australia. Survival analysis was performed for echocardiographic measures both unindexed and indexed to different body size metrics, with 5-year cardiovascular mortality as the primary endpoint. Indexation of echocardiographic measures (left ventricular end-diastolic diameter [n = 230,109] and mass [n = 224,244], left atrial volume [n = 150,540], aortic sinus diameter [n = 90,805], right atrial area [n = 59,516]) by BSA had better prognostic performance vs unindexed measures (underweight: C-statistic 0.655 vs 0.647; normal weight/overweight: average C-statistic 0.666 vs 0.625; obese: C-statistic 0.627 vs 0.613). Indexation by other body size metrics (lean body mass, height, and/or weight raised to different powers) did not improve prognostic performance versus BSA by a clinically relevant magnitude (average C-statistic increase ≤ 0.02), with smaller differences in other BMI subgroups. Indexing measures of cardiac and aortic size by BSA improves prognostic performance regardless of BMI, and no other body size metric has a clinically meaningful better performance.

Variations in indexation of left atrial volume across different races

Background

Left atrial volume (LAV) has prognostic value. Guidelines propose indexation to body surface area (BSA), however studies demonstrate this can overcorrect for body size. Limited studies investigate indexation across different ethnicities. We sought to evaluate the effect of ethnicity on indexation.

Methods

Using data from the World Alliance of Societies of Echocardiography (WASE) cohort, healthy subjects were classified by race as White, Black, Asian, or Other. Biplane LAV was indexed to traditional isometric measurements (BSA, height, weight, ideal body weight (IBW) and IBW derived BSA (IBSA)), as well as previously-derived allometric height exponents (2.7 and 1.72). Additionally, an allometric height exponent for our cohort was derived (linear regression of the logarithmic transformation of LAV = a(height)b) as 1.87. All indices were then assessed using Spearman correlation, with a good index retaining correlation of LAV/index to raw LAV (r∼1), while avoiding overcorrection by the index (r∼0).

Results

There were 1366 subjects (White: 524, Black: 149, Asian: 523, Other: 170; median age 44 years, 653 females (47.8%)). In the entire group, BSA, IBSA, height1.87 and height1.72 performed well with retaining correlation to raw LAV (r > 0.9 for all), and minimising overcorrection to body size (r < 0.1 for all). On race-specific analysis, BSA overcorrected for body size in the White population (r = 0.128). Height1.72 minimised overcorrection for body size in all populations (r ≤ 0.1 for all races).

Conclusion

Despite a cohort with normal BMI, there was still disparity in LAV indexation with BSA across races. Allometric height indexation, particularly using height1.72, is a possible solution, although further validation studies in BMI extremes are required.

Cryoballoon pulmonary vein isolation for atrial fibrillation in obese patients: A non-inferiority analysis

Background

Patients with obesity are at higher risk of developing atrial fibrillation (AF) and benefit from radiofrequency ablation. Potentially, cryoballoon ablation (CBA) may be equally effective and safe in such patients.

Methods

We conducted a prospective, single-center study to investigate whether CBA for pulmonary vein isolation is as effective and safe in obese patients as it is in non-obese controls. Primary efficacy endpoint was recurrence of AF, atrial flutter or atrial tachycardia after a 90-day blanking period. Safety endpoints were death, stroke or procedure-associated complications. Conduction of a subgroup analysis regarding the impact of additional diabetes was predefined in case the primary efficacy endpoint was met. The study was event driven and powered for noninferiority.

Results

A total of 949 patients underwent CBA (251 obese with mean body-mass-index 33.5 ± 3 kg/m2 and 698 non-obese with mean body-mass-index 25.3 ± 3 kg/m2) during a 5-year recruitment period. Median follow-up was 15 months. The primary efficacy endpoint occurred in 78/251 obese and 247/698 non-obese patients (12-months Kaplan-Meier event-rate estimates, hazard ratio 0.79; 95% confidence interval [CI], 0.58 to 1.07; log-rank P = 0.0002 for noninferiority). No differences were observed in safety end point occurrence (P = 0.78). The occurrence of primary efficacy end point was found to be unaffected by the presence of diabetes in the prespecified subgroup analysis (log-rank P = 0.57).

Conclusion

CBA is effective and safe in obese and DM patients. Weighing the high cardiovascular risk of obese patients against a reduction of cardiovascular events by early rhythm control, CBA should be offered to this patient population.

Ventricular stiffening and chamber contracture in heart failure with higher ejection fraction

AIMS

Ancillary analyses from clinical trials have suggested reduced efficacy for neurohormonal antagonists among patients with heart failure and preserved ejection fraction (HFpEF) and higher ranges of ejection fraction (EF).

METHODS AND RESULTS

A total of 621 patients with HFpEF were grouped into those with low-normal left ventricular EF (LVEF) (HFpEF<65% , n = 319, 50% ≤ LVEF <65%) or HFpEF≥65% (n = 302, LVEF ≥65%), and compared with 149 age-matched controls undergoing comprehensive echocardiography and invasive cardiopulmonary exercise testing. A sensitivity analysis was performed in a second non-invasive community-based cohort of patients with HFpEF (n = 244) and healthy controls without cardiovascular disease (n = 617). Patients with HFpEF≥65% had smaller left ventricular (LV) end-diastolic volume than HFpEF<65% , but LV systolic function assessed by preload recruitable stroke work and stroke work/end-diastolic volume was similarly impaired. Patients with HFpEF≥65% displayed an end-diastolic pressure-volume relationship (EDPVR) that was shifted leftward, with increased LV diastolic stiffness constant β, in both invasive and community-based cohorts. Cardiac filling pressures and pulmonary artery pressures at rest and during exercise were similarly abnormal in all EF subgroups. While patients HFpEF≥57% displayed leftward shifted EDPVR, those with HFpEF<57% had a rightward shifted EDPVR more typical of heart failure with reduced EF.

CONCLUSION

Most pathophysiologic differences in patients with HFpEF and higher EF are related to smaller heart size, increased LV diastolic stiffness, and leftward shift in the EDPVR. These findings may help to explain the absence of efficacy for neurohormonal antagonists in this group and raise a new hypothesis, that interventions to stimulate eccentric LV remodelling and enhance diastolic capacitance may be beneficial for patients with HFpEF and EF in the higher range.

Dilated sinuses of Valsalva subsequent to type A dissection surgery: Is reoperation inevitable?

Background

This study aims to investigate the dilation of sinus valsalva in patients who underwent aortic repair due to type A aortic dissection and to evaluate its progression.

Methods

Between January 2004 and December 2019, a total of 68 patients (50 males, 18 females; mean age: 54.2±10.1 years; range, 30 to 82 years) who underwent root-preserving surgery and followed for at least one year in the outpatient setting were retrospectively analyzed. The patients were divided into two groups according to dilatation during follow-up. Group 1 (n=32) included patients with dilatation and Group 2 (n=36) included patients without dilatation. The sinus of Valsalva diameters were measured using pre- and postoperative computed tomography angiography.

Results

The mean follow-up was 4.9±3.1 (range, 1 to 4) years. Sinus of Valsalva dilatation was observed in 47% of the patients during follow-up. Preoperative sinus of Valsalva diameter was a risk factor for aneurysmatic dilatation. A diameter of ≥4.05 cm was calculated as a cut-off value for developing dilatation requiring reoperation.

Conclusion

Follow-up using postoperative echocardiography or computed tomography angiography is of utmost importance for the assessment of development of sinus of Valsalva dilatation which requires reoperation in patients without intervention to the aortic root.

Decreased left atrial function in obesity patients without known cardiovascular disease

Obesity is a risk factor for heart failure with preserved ejection fraction (HFpEF). We hypothesized that assessment of left atrial (LA) strain may be useful to reveal precursors of HFpEF in obesity patients. Echocardiograms of obesity patients without known cardiovascular disease who underwent bariatric surgery, and echocardiograms of age- and gender matched controls were analyzed. The echocardiogram was repeated 1 year after bariatric surgery. LA reservoir strain (LASr), LA conduit strain (LAScd), and LA contractile strain (LASct) were measured. 77 Obesity patients were compared with 46 non-obese controls. Obesity patients showed a significantly decreased LA function compared with non-obese individuals (LASr 32.2% ± 8.8% vs. 39.6% ± 10.8%, p < 0.001; LAScd 20.1% ± 7.5% vs. 24.9% ± 8.3%, p = 0.001; LASct 12.1% ± 3.6% vs. 14.5% ± 5.5%, p = 0.005). There was no difference in prevalence of diastolic dysfunction between the obesity group and controls (9.1% vs. 2.2%, p = 0.139). One year after bariatric surgery, LASr improved (32.1% ± 8.9% vs. 34.2% ± 8.7%, p = 0.048). In the multivariable linear regression analysis, BMI was associated with LASr, LAScd, and LASct (β =  - 0.34, CI - 0.54 to - 0.13; β =  - 0.22, CI - 0.38 to - 0.06; β =  - 0.10, CI - 0.20 to - 0.004). Obesity patients without known cardiovascular disease have impairment in all phases of LA function. LA dysfunction in obesity may be an early sign of cardiac disease and may be a predictor for developing HFpEF. LASr improved 1 year after bariatric surgery, indicating potential reversibility of LA function in obesity.

Cardiorespiratory fitness, obesity and left atrial function in patients with atrial fibrillation

Background

Low cardiorespiratory fitness (CRF) and obesity are related to the development and maintenance of atrial fibrillation (AF). The aim of this study was to determine the association between CRF, obesity and left atrial (LA) mechanical parameters in patients with AF.

Methods

A cohort of 154 consecutive paroxysmal and persistent AF patients (Age: 62 ± 10, 26% female) referred for exercise stress testing and transthoracic echocardiography were included. We included patients in sinus rhythm with preserved left ventricular ejection fraction who were able to complete a maximal exercise test. Left atrial strain in the reservoir (LASr), booster (LASb) and conduit (LASc) phases were assessed using dedicated software. LA stiffness, emptying fraction (LAEF) and LA to LV ratio were calculated using previously described formulas.

Results

CRF was positively associated with LAEF (β = 1.3, 95% CI 0.1–2.3, p = 0.02), reservoir (β = 1.5, 95% CI 0.9–2.1, p < 0.001), booster (β = 0.8, 95% CI 0.4–1.2, p < 0.001) and conduit strain (β = 0.7, 95% CI 0.3–1.1, p = 0.001). We observed an inverse association between CRF and both LA stiffness index (β = −0.02, 95% CI (−0.03)–(−0.01), p < 0.001) and LA to LV ratio (β = −0.03, 95% CI (−0.04)–(−0.01), p < 0.001). Obese patients had significantly higher indexed LA volumes compared to overweight and normal BMI patients. The association between obesity and measures of LA function and stiffness did not reach statistical significance.

Conclusion

Among AF patients, higher CRF was independently associated with greater LA function and compliance. Obesity was associated with higher LA volumes yet preserved mechanical function.

Echocardiographic measurements of the left heart chambers size in a large cohort of subjects: comparison of body surface area and height indexation to account for effects of obesity

BACKGROUND

The assessment of cardiac chamber size in the obese population is a challenging subject. Values usually indexed to body surface area (BSA) are smaller in obese subjects and prone to overcorrection. This study aimed to find reference thresholds to account for effects of obesity from a large cohort of patients and to evaluate the indexation by height as an alternative to BSA.

METHODS

The last 10-years records of our Echocardiography Unit were retrospectively analyzed and 14,007 subjects without known cardiac disease were included (45±15 years, 54% women, 20% obese). Measurements included left atrial diameter, area and volume (LAD, LAA and LAV), left ventricular (LV) end-diastolic (LVEDD) and end-systolic diameters (LVESD), aortic root diameter (ARD) and LV mass (LVM). Absolute, BSA and height indexed maximum thresholds (mean+1.96.SD) were calculated. An allometric indexation of the form variable/Height^β was tested. Correlation coefficients between indexed and absolute values were calculated to evaluate their proportional association (ideally r=1). Correlations between indexed values and body size represented residual associations to be minimized (ideally r=0).

RESULTS

The strongest association of echocardiographic measurements with body size was observed for BSA (r=0.36-0.63), whereas the isometric and allometric height models showed lower comparable values (r=0.28-0.48). Positive correlations with BMI were mostly observed for LA size (r≈0.36) and LVM (r≈0.36) measurements. Scaling exponents β for the allometric height indexation were 1.72 for LAV and 2.33 for LVM. Correlations between indexed and absolute values were higher for height than BSA (0.80-0.98 vs 0.44-0.92). Correlations between indexed values and height were closer to zero than for BSA, particularly using the allometric model. The overcorrection observed with increasing obesity class after BSA indexation was avoided after height indexation.

CONCLUSIONS

Unlike BSA, height indexing provided an adequate body size scaling of left heart chambers size avoiding overcorrection using allometric models in particular.

Sex and central obesity in heart failure with preserved ejection fraction

AIMS

Obesity is a risk factor for heart failure with preserved ejection fraction (HFpEF), particularly in women, but the mechanisms remain unclear. The present study aimed to investigate the impact of central adiposity in patients with HFpEF and explore potential sex differences.

METHODS AND RESULTS

A total of 124 women and 105 men with HFpEF underwent invasive haemodynamic exercise testing and rest echocardiography. Central obesity was defined as a waist circumference (WC) ≥88 cm for women and ≥102 cm for men. Exercise-normalized pulmonary capillary wedge pressure (PCWP) responses were evaluated by the ratio of PCWP to workload (PCWP/W) and after normalizing to body weight (PCWL). The prevalence of central obesity (77%) exceeded that of general obesity (62%) defined by body mass index ≥30 kg/m² . Compared to patients without central adiposity, patients with HFpEF and central obesity displayed greater prevalence of diabetes and dyslipidaemia, higher right and left heart filling pressures and pulmonary artery pressures during exertion, and more severely reduced aerobic capacity. Associations between WC and fasting glucose, low-density lipoprotein (LDL) cholesterol, peak workload, and pulmonary artery pressures were observed in women but not in men with HFpEF. Although increased WC was associated with elevated PCWP in both sexes, the association with PCWP/W was observed in women but not in men. The strength of correlation between PCWP/W and WC was more robust in women with HFpEF as compared to men (Meng's test p = 0.0008), and a significant sex interaction was observed in the relationship between PCWL and WC (p for interaction = 0.02).

CONCLUSIONS

Central obesity is even more common than general obesity in HFpEF, and there appear to be important sexual dimorphisms in its relationships with metabolic abnormalities and haemodynamic perturbations, with greater impact in women.

Measures of left atrial function predict incident heart failure in a low-risk general population: the Copenhagen City Heart Study

AIMS

This study investigated left atrial (LA) parameters as measured on transthoracic echocardiography as predictors of incident heart failure (HF) in a community cohort.

METHODS AND RESULTS

In a large general population study (n = 2221), participants underwent a health examination with echocardiography. The maximum and minimum LA volumes indexed to body surface area (LAVImax and LAVImin) were measured and the LA emptying fraction (LAEF) and LA expansion index (LAEI) were calculated. Among 1951 participants without atrial fibrillation or significant valve disease, the mean age was 59 ± 16 years and 58% were women. At baseline, 1% (n = 16) had a left ventricular ejection fraction of <50%, 44% had hypertension, and 10% had diabetes. During follow-up (median 15.8 years, interquartile range: 11.3-16.2 years), 187 (10%) participants were diagnosed with incident HF. Participants who were diagnosed with HF during follow-up had a larger LAVImax and LAVImin and a lower LAEF and LAEI compared to participants without HF. In unadjusted analysis, LAVImax, LAVImin, LAEF and LAEI were predictors of incident HF. After multivariable adjustment for clinical and echocardiographic parameters, only LAVImin remained an independent predictor of incident HF (hazard ratio per 1 standard deviation increase: 1.22 [95% confidence interval 1.01-1.47], p = 0.038).

CONCLUSION

In the general population, LAVImin is an independent predictor of incident HF. LAVImax, currently the only LA measure in a routine echocardiographic examination, was not an independent predictor of incident HF.

Standardization of normal values for cardiac chamber size in echocardiography

Echocardiography is used worldwide to evaluate cardiac size and function. To determine what values are abnormal, it is essential to establish normal reference values for echocardiography. The current guidelines for chamber quantification specify normative values for cardiac chambers and recommend that gender and body size be taken into account. However, these normative data were established using databases for which a variety of measurement methods were used and the majority of subjects consisted of Whites in Europe and the United States. However, several regional studies from other countries suggest that cardiac size varies globally. To overcome these limitations, the Normal Reference Ranges for Echocardiography study and the World Alliance of Societies of Echocardiography Normal Values study have recently been conducted to examine similarities and differences in cardiac chamber size and to establish normal reference values while taking worldwide diversity into account. The results from these studies have demonstrated that standardization of normal reference values for cardiac size is important. This review article aims to summarize the current status of normative echocardiographic values for cardiac chamber size.

How to standardize measurement of global longitudinal strain

Global longitudinal strain (GLS) is a robust and sensitive marker of left-ventricular systolic function, reflecting longitudinal shortening of the ventricle. A growing body of evidence indicates its superiority in identifying subclinical, early alterations in cardiac function compared to traditional markers, such as ejection fraction. Therefore, there is a growing demand to assess GLS in clinical settings, but limited availability on how to obtain GLS accurately and appropriately in the current literature. This review summarizes key aspects of GLS measurement, including image acquisition, post-processing, and training/experience needed to facilitate the clinical implication with standardization.

Right atrium size in the general population

Echocardiography is the most common routine cardiac imaging method. Nevertheless, only few data about sex-specific reference limits for right atrium (RA) dimensions are available. Transthoracic echocardiographic RA measurements were studied in 9511 participants of the Gutenberg-Health-Study. A reference sample of 1942 cardiovascular healthy subjects without chronic obstructive pulmonary disease was defined. We assessed RA dimensions and sex-specific reference limits were defined using the 95th percentile of the reference sample. Results showed sex-specific differences with larger RA dimensions in men that were attenuated by standardization for body-height. RA-volume was 20.2 ml/m in women (5th–95th: 12.7–30.4 ml/m) and 26.1 ml/m in men (5th–95th: 16.0–40.5 ml/m). Multivariable regressions identified body-mass-index (BMI), coronary artery disease (CAD), chronic heart failure (CHF) and atrial fibrillation (AF) as independent key correlates of RA-volume in both sexes. All-cause mortality after median follow-up-period of 10.7 (9.81/11.6) years was higher in individuals who had RA volume/height outside the 95% reference limit (HR 1.70 [95%CI 1.29–2.23], P = 0.00014)). Based on a large community-based sample, we present sex-specific reference-values for RA dimensions normalized for height. RA-volume varies with BMI, CHF, CAD and AF in both sexes. Individuals with RA-volume outside the reference limit had a 1.7-fold higher mortality than those within reference limits.

Uncoupling between intravascular and distending pressures leads to underestimation of circulatory congestion in obesity

AIMS

Patients with obesity frequently present with dyspnoea. Biomarkers that reflect wall stress are often used to evaluate circulatory congestion and help determine whether dyspnoea is of cardiac causes. Patients with obesity display greater external restraint on the heart, which may alter relationships between intravascular pressures and stress markers.

METHODS AND RESULTS

Subjects with unexplained dyspnoea (n = 212) underwent cardiac catheterization with simultaneous echocardiography. Blood sampling was performed in a subset (n = 58). Relationships between echocardiographic and blood biomarkers of circulatory congestion and directly-measured haemodynamics were compared between participants with severe obesity [body mass index (BMI) ≥35 kg/m² , Group B) and those without (BMI <35 kg/m² , Group A). Circulatory congestion was assessed by pulmonary capillary wedge pressure (PCWP), and vascular distending pressure was assessed by left ventricular transmural pressure (LVTMP). As compared to Group A, participants in Group B displayed higher PCWP relative to N-terminal pro-B-type natriuretic peptide, mid-regional pro-atrial natriuretic peptide (MR-proANP), troponin T, and growth differentiation factor-15 (all p < 0.01). In contrast, the relationships between LVTMP and the biomarkers were superimposable. Echocardiographic biomarkers revealed the same pattern: PCWP was higher for any E/e' ratio in Group B compared to Group A, but the relationship between LVTMP and E/e' was similar. In contrast, levels of C-terminal pro-endothelin-1 and MR-proADM were more robustly correlated with PCWP (r = 0.67 and r = 0.62, both p < 0.0001), with no differential relationship based upon BMI.

CONCLUSIONS

Non-invasive haemodynamic markers underestimate circulatory congestion in patients with obesity, an effect that appears related to uncoupling between cardiac wall stress and intravascular pressures. This may lead to systematic under-recognition of congestion in patients with obesity.

Association between Isometric and Allometric Height-indexed Left Atrial Size and Atrial Fibrillation

BACKGROUND

Height-based indexations for evaluation of left atrial (LA) volumes have been proposed as an alternative method to account for body stature when body composition is abnormal. We sought to derive reference values for these indexation methods, and to examine their association to atrial fibrillation (AF).

METHODS

A healthy population was randomly split into a derivation and validation cohort (n=493 each). The derivation cohort was used to derive reference values for iso- and allometric height-indexed LA volumes. Echocardiography included measurement of maximal and minimal LA volume (LAV_max and LAV_min, respectively). Association between these measures and AF was investigated in the validation cohort. Cox proportional hazards regression was performed adjusting for CHARGE-AF risk score.

RESULTS

From 986 healthy subjects, allometric height-indexed exponents were determined to 1.72 and 1.56 for LAV_max and LAV_min, respectively. Upper reference values were determined to LAV_max>22.1mL/m^1.72 and LAV_min>12.7mL/m^1.56. In the validation cohort, 41 (8%) developed AF during follow-up (median: 14.7 years). In unadjusted analyses, both isometric and allometrically indexed LAV_max were associated with AF (HR=1.07 (1.03-1.11), p<0.001 and HR=1.11 (1.05-1.18), p<0.001, per 1-ml/m and 1-ml/m^1.72 increase respectively) with equal C-statistics of 0.63. Height-indexed LAV_min was also associated with AF with higher C-statistics than LAV_max. All findings were consistent after multivariable adjustment. LAV_max>22.1mL/m^1.72 posed an increased risk of AF (HR=4.65 (1.83-11.86)), however, LAV_min>12.7mL/m^1.56 carried a higher risk (HR=6.33 (2.66-15.07)).

CONCLUSION

Both Isometric and allometrically height-indexed LA volumes are associated with AF in the general population. LAV_min is more strongly associated with AF than LAV_max regardless of indexation.