Reference values of left atrial size and function according to age: should we redefine the normal upper limits?

Effect of sex, age and body measurements on heart weight, atrial, ventricular, valvular and sub-epicardial fat measurements of the normal heart

AIMS

Descriptive morphological studies of the normal heart are lacking. Previous autopsy studies have focused mainly on heart weight. We characterize the normal heart by providing normal dimensions of the atria, ventricles, valves and sub-epicardial fat, comparing the findings in terms of sex, age and body measurements.

METHODS

From 3602 referrals to our cardiovascular pathology unit, pathological criteria used for the classification of a morphologically normal heart were a weight of below 500 grams in males, and below 400 grams in females. Diseased hearts were excluded on anatomical and histological evaluation.

RESULTS

We diagnosed 1062 morphologically normal hearts. Mean age at death was 34±12, with a male predominance (701, 66%). Age was similar in females and males (35±13 vs 34±12). Females had a significantly lower heart weight (285±55 vs 374±64). Sex was an independent predictor of most measurements. The atrial and ventricular cavities were significantly larger in males. All ventricular measurements of muscle thickness were larger in males. All valvular circumferences were larger in males. In contrast, sub-epicardial fat was significantly thicker in females in 6 of 7 regions. This is the first study to provide a calculator to give expected values according to sex, age, height and weight.

CONCLUSIONS

Major differences between the sexes exist in the morphologically normal heart. These variations should be considered when assessing cardiac structure in imaging for risk stratification and diagnosis in the cardiomyopathies, as well as in treatment outcomes.

Reference Values for Point-of-Care Echocardiographic Measurements of Preterm Infants in China

BACKGROUND

Few studies have examined the reference value of the left ventricular structure and function in preterm infants. This study was designed to establish a point-of-care echocardiographic reference range of left ventricular structure and function based on different gestational age, weight, and body surface area (BSA) for preterm infants within 7 days after birth.

METHODS

We retrospectively studied 489 patients with traditional echocardiographic data of left ventricular (LV) M-mode: LV end diastolic dimensions (LVED), LV end systolic dimension (LVES), end-diastolic interventricular septal thickness (IVSd), end diastolic LV posterior wall thickness (LVPWd), left atrial (LA) and aortic root (AO) diameters, and index of LA/AO, LV ejection fraction (LVEF), LV fractional shortening (LVFS), and pulsed wave Doppler: aortic valve flow rate (AV), peak mitral valve flow rate E(MV-E), peak mitral valve flow rate A(MV-A), and MV-E/A. The LV dimensions and the maximum blood flow velocities of the aortic valves and mitral valves according to gestational age, birth weight, and body surface area (BSA) are presented in percentiles tables. Percentile curves of aforesaid four cardiac measurements (LVED, LA diameter (LAD), MV-E, MV-E/A) using the R language Generalized Additive Models for Location, Scale and Shape (GAMLSS) method were developed according to different gestational ages and weights.

RESULTS

Measurements of all cardiac dimensions and Doppler maximum velocities of AV, MV-E, and MV-E/A showed a correlation with gestational age, weight, and BSA. LVED, LAD, MV-E, and MV-E/A showed a trend of increasing values with gestational age and weight on the percentile curves.

CONCLUSION

The percentile tables and graphs of these point-of-care echocardiographic data can provide reliable reference data for Chinese neonates. Normative values are recommended as a source of reference data for the identification of potentially abnormal echocardiography.

Human immunodeficiency viral infection and differences in interstitial ventricular fibrosis and left atrial size

AIMS

The extent to which human immunodeficiency viral (HIV) infection is independently associated with myocardial disease in the era of combination antiretroviral therapy (cART) remains understudied. We assessed differences in cardiovascular magnetic resonance imaging (CMR) metrics among people living with HIV (PLWH) and without HIV (PWOH).

METHODS AND RESULTS

Among 436 participants (aged 54.7 ± 6.0 years, 29% women) from three cohorts, we acquired CMR cines, late gadolinium enhancement (LGE), and T1 mapping. Multivariable linear regressions were used to evaluate associations between HIV serostatus and CMR metrics. Baseline characteristics were similar by HIV serostatus; 63% were PLWH of whom 88% received cART and 73% were virally suppressed. Median left ventricular ejection fraction was normal and similar by HIV serostatus (73%, PWOH vs. 72%, PLWH, P = 0.43) as were right ventricular function, biventricular volumes, and masses. LGE prevalence was similar (32%, PWOH vs. 36%, PLWH, P = 0.46) with low scar extents (4.1, PWOH vs. 4.9 g, PLWH, P = 0.51) and few ischaemic scars (3%, PWOH vs. 4%, PLWH, P = 0.70). Extracellular volume fraction (ECV) was higher among PLWH (29.2 ± 4.1% vs. 28.3 ± 3.7%, P = 0.04) as was indexed maximum left atrial (LA) volume (LAVI, 29.7 ± 10.3 vs. 27.8 ± 8.7 mL/m2, P = 0.05). After multivariate adjustment, ECV was 0.84% higher among PLWH (P = 0.05) and LAVI was 2.45 mL/m2 larger (P = 0.01). HIV seropositivity and higher ECV contributed to higher LAVI (P < 0.02). There were no associations between HIV disease severity and CMR metrics among PLWH.

CONCLUSION

HIV seropositivity was independently associated with greater diffuse non-ischaemic fibrosis and larger LA volume but no other differences in CMR metrics.

Echocardiographic Measurement of Left Atrial Strain - A Key Requirement in Clinical Practice

Unlike the left ventricle (LV), the left atrium (LA) has a thin-walled structure and has been regarded as a simple conduit chamber. However, the unique function of the LA to modulate LV filling has recently drawn much attention. Because LA structure and function are directly influenced by the LV filling pressure, LA assessment is an essential step in the diagnosis of diastolic dysfunction that can help predict new-onset atrial fibrillation, assess the risk of further embolic events, and identify high-risk patients for adverse cardiovascular events. Even in the recent era of multimodality imaging, 2-dimensional (2D) echocardiography is the most common imaging method and the central modality for evaluation of LA function. LA strain derived from 2D echocardiography can help assess LA function objectively and demonstrates the 3 distinct phasic motions of the LA cycle. Further, LA strain provides invaluable pathophysiologic information and helps to predict clinical prognosis in various cardiovascular diseases. In this review article, we focus on LA strain: basic concepts, advantages over conventional parameters, and some unresolved issues. Additionally, we present a brief history of the clinical evidence for LA strain. Through this review, we suggest echocardiography for LA strain assessment in clinical practice.

References Values for Left Atrial Volumes, Emptying Fractions, Strains, and Strain Rates and Their Determinants by Age, Gender, and Ethnicity: The Multiethnic Study of Atherosclerosis (MESA)

RATIONALE AND OBJECTIVES

Left Atrial (LA) adverse remodeling is an important predictor of morbidity and mortality in several cardiovascular (CV) diseases. Our goals were to quantify and provide reference ranges for LA structure and function using feature tracking cine cardiac magnetic resonance.

MATERIALS AND METHODS

2526 participants of the Multiethnic Study of Atherosclerosis study who had feature tracking cine cardiac magnetic resonance derived LA data and were free of atrial fibrillation/flutter and prior CV events at year five follow-up examination (2010-2012) were included in this study. LA phasic indexed volumes: maximum (LAVi max), minimum (LAVi min), and preatrial contraction (LAVi preA); LA empty fractions: total, passive, and active (LAtEF, LApEF, and LAaEF); LA longitudinal strain: maximum and preatrial contraction (S max and S preA); and LA longitudinal strain rate: systolic (SR max) and early/late diastolic (SR e and SR a) were measured. Age, gender, and race/ethnicity-specific reference ranges were identified. Also, reference values in a select subgroup of healthy participants free of traditional CV risk factors at the time of exam date were reported.

RESULTS

The mean ± SD for LAVi max, LAVi min, LAVi preA, S max, SR e, and SR a were in the 45-65-year-old participants: (33.8 ± 10 mL/m²), (14.5 ± 6.4 mL/m²), (24.8 ± 8.2 mL/m²), (34.6 ± 13.8 %), (-1.4 ± 0.7 s^-1), (-2.1 ± 1 s^-1) and in the ≥ 65-year-old participants: (35 ± 11.5 mL/m2), (16.6 ± 8.3 mL/m2), (27.6 ± 9.9 mL/m2), (31.2 ± 14.3 %), (-1 ± 0.6 s^-1), (-2.1 ± 1 s^-1) respectively. Younger individuals had Powered by Editorial Manager and ProduXion Manager from Aries Systems Corporation smaller LA volumes and better LA function compared to their older counterparts. Similar findings were observed in Chinese-Americans as compared to Whites.

CONCLUSION

This study provides reference values of LA structure and function parameters from a healthy multiethnic community-based population aged 53-94 years evaluated by FTMRI.

Atrial size and sports. A great training for a greater left atrium: how much is too much?

Athlete's heart results from physiological adaptations to the increased demands of exercise, and left atrial (LA) enlargement (LAE) is a fundamental component. However, LAE occurs in certain pathological conditions and it might represent a diagnostic challenge in athletes. LA volume index (LAVi) by echo is a convenient diagnostic tool for LAE identification. We hypothesized that accumulated lifetime training thousand hours (LTH) would have a main role in LAE. Therefore, our aim was to assess the association between LTH, LAVi and LAE in athletes. Young and middle-aged males with different training levels were included and grouped as recreational (REa, n = 30), competitive (COa, n = 169) and elite (ELa, n = 80) athletes for LTH calculation and echo assessment. LA dimensions resulted greater in ELa when compared to other groups (p < 0.001). LAVi correlated stronger with LTH than with age (p < 0.001). Polynomial regression analysis showed a non-linear, almost triphasic, effect of cumulative training on LA size (p < 0.02). Multivariate logistic regression, including LTH, age, body surface area, systolic blood pressure and other explanatory variables to predict LAE, showed LTH as the sole significant factor [OR 1.45 (CI 1.1-1.92), p < 0.008]. ROC analysis found an optimal cut off point of 3.6 LTH for LAE identification (AUC = 0.84, p < 0.001. RR = 5.65, p < 0.001). We conclude that LAE associates with LTH more than with other clinical parameters, and with less impact at higher amounts of LTH. Lifetime training greater than 3600 hours increases the probability of finding LAE in athletes. Future research should provide more insights and implications of these findings.

Left ventricular hypertrophy in athletes: How to differentiate between hypertensive heart disease and athlete’s heart

Athlete’s heart is typically accompanied by a remodelling of the cardiac chambers induced by exercise. However, although competitive athletes are commonly considered healthy, they can be affected by cardiac disorders characterised by an increase in left ventricular mass and wall thickness, such as hypertension. Unfortunately, training-induced increase in left ventricular mass, wall thickness, and atrial and ventricular dilatation observed in competitive athletes may mimic the pathological remodelling of pathological hypertrophy. As a consequence, distinguishing between athlete’s heart and hypertension can sometimes be challenging. The present review aimed to focus on the differential diagnosis between hypertensive heart disease and athlete’s heart, providing clinical information useful to distinguish between physiological and pathological remodelling.

Left Atrial Volume, Cardiorespiratory Fitness, and Diastolic Function in Healthy Individuals: The HUNT Study, Norway

Background Left atrial (LA) size and cardiorespiratory fitness (CRF) are predictors of future cardiovascular events in high-risk populations. LA dilatation is a diagnostic criterion for left ventricular diastolic dysfunction. However, LA is dilated in endurance athletes with high CRF, but little is known about the association between CRF and LA size in healthy, free-living individuals. We hypothesized that in a healthy population, LA size was associated with CRF and leisure-time physical activity, but not with echocardiographic indexes of left ventricular diastolic dysfunction. Methods and Results In this cross-sectional study from HUNT (Nord-Trøndelag Health Study), 107 men and 138 women, aged 20 to 82 years, without hypertension, cardiovascular, pulmonary, or malignant disease participated. LA volume was assessed by echocardiography and indexed to body surface area LAVI (left atrial volume index). CRF was measured as peak oxygen uptake (VO_2peak) using ergospirometry, and percent of age- and-sex-predicted VO_2peak was calculated. Indexes of left ventricular diastolic dysfunction were assessed in accordance with latest recommendations. LAVI was >34 mL/m² in 39% of participants, and LAVI was positively associated with VO_2peak and percentage of age- and-sex-predicted VO_2peak (β [95% CI], 0.11 [0.06-0.16] and 0.18 [0.09-0.28], respectively) and weighted minutes of physical activity per week (β [95% CI], 0.01 [0.003-0.015]). LAVI was not associated with other indexes of left ventricular diastolic dysfunction. There was an effect modification between age and VO_2peak/percentage of age- and-sex-predicted VO_2peak showing higher LAVI with advanced age and higher VO_2peak/percentage of age- and-sex-predicted VO_2peak as presented in prediction diagrams. Conclusions Interpretation of LAVI as a marker of diastolic dysfunction should be done in relation to age-relative CRF. Studies on the prognostic value of LAVI in fit subpopulations are needed.

Normal Reference Values for Left Atrial Strain and Its Determinants from a Large Korean Multicenter Registry

BACKGROUND

Left atrial (LA) strain is a novel parameter of LA function. However, its reference value has not been established, and the determining factors for LA strain remain elusive. We aimed to present LA strain with reservoir, conduit, and contractile components and associated parameters in a large-sized group of healthy individuals.

METHODS

The present study was from a prospective multicenter registry in South Korea. Subjects who had no history of cardiovascular disease with adequate images were eligible for inclusion. LA reservoir, conduit, and contractile strains (LAS_RES, LAS_CD and LAS_CT, respectively) were measured. Left ventricular global longitudinal strain (LV GLS) and early and late diastolic strain rates (DSR_e and DSR_a, respectively) were also evaluated.

RESULTS

Among a total of 324 subjects (mean age: 49 ± 16 years, 167 females), the mean LAS_RES, LAS_CD, and LAS_CT values were 35.9% ± 10.6%, 21.9% ± 9.3%, and 13.9% ± 3.6%, respectively. Mean LV GLS was -20.4% ± 2.2%, and mean DSR_e and DSR_a were 1.6 ± 0.4 s^-1 and 0.8 ± 0.3 s^-1, respectively. With aging, LAS_RES and LAS_CD showed significant decreases. Factors showing independent associations with LAS_RES were age (B = -0.425, p < 0.001), DSR_e (B = 4.706, p = 0.001), and LV GLS (B = -1.081, p < 0.001). Age (B = -0.319, p < 0.001), DSR_e (B = 4.140, p = 0.002), DSR_a (B = -3.409, p = 0.018), and LV GLS (B = -0.783, p < 0.001) showed associations with LAS_CD. With LAS_CT, only DSR_a showed a correlation (R = 0.277, p < 0.001).

CONCLUSIONS

We presented LA strain in a large-sized group of healthy subjects. Age is a significant determinant of LA function. Associations of LA strain with diastolic strain rates and LV GLS reflect cardiac mechanics.

The role of the left atrial function in the surgical management of aortic and mitral valve disease

The right management of both mitral and aortic disease can be challenging, especially in asymptomatic patients. The current guidelines recommend valve repair or replacement when symptoms arise or when there is an evident left ventricular dysfunction. However, deciding the optimal surgical timing can be very difficult, since the line between the absence of symptoms and being minimally symptomatic, especially in the elderly, is blurred. Another relevant issue regards the second surgical criterion: operating on a patient with a reduced left ventricular ejection fraction or with a dilated left ventricle might jeopardize the possibility of a fully reverse remodeling of the heart after surgery. In this scenario, the left atrium might play an important role. In particular, left atrial deformation might be a very useful tool to detect early ultrastructural alterations, and help or support guiding a patient-tailored treatment at an early stage, optimizing the outcome in the long term.