Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy

The assessment of left ventricular diastolic function: guidance and recommendations from the British Society of Echocardiography

Impairment of left ventricular (LV) diastolic function is common amongst those with left heart disease and is associated with significant morbidity. Given that, in simple terms, the ventricle can only eject the volume with which it fills and that approximately one half of hospitalisations for heart failure (HF) are in those with normal/'preserved' left ventricular ejection fraction (HFpEF) (Bianco et al. in JACC Cardiovasc Imaging. 13:258-271, 2020. 10.1016/j.jcmg.2018.12.035), where abnormalities of ventricular filling are the cause of symptoms, it is clear that the assessment of left ventricular diastolic function (LVDF) is crucial for understanding global cardiac function and for identifying the wider effects of disease processes. Invasive methods of measuring LV relaxation and filling pressures are considered the gold-standard for investigating diastolic function. However, the high temporal resolution of trans-thoracic echocardiography (TTE) with widely validated and reproducible measures available at the patient's bedside and without the need for invasive procedures involving ionising radiation have established echocardiography as the primary imaging modality. The comprehensive assessment of LVDF is therefore a fundamental element of the standard TTE (Robinson et al. in Echo Res Pract7:G59-G93, 2020. 10.1530/ERP-20-0026). However, the echocardiographic assessment of diastolic function is complex. In the broadest and most basic terms, ventricular diastole comprises an early filling phase when blood is drawn, by suction, into the ventricle as it rapidly recoils and lengthens following the preceding systolic contraction and shortening. This is followed in late diastole by distension of the compliant LV when atrial contraction actively contributes to ventricular filling. When LVDF is normal, ventricular filling is achieved at low pressure both at rest and during exertion. However, this basic description merely summarises the complex physiology that enables the diastolic process and defines it according to the mechanical method by which the ventricles fill, overlooking the myocardial function, properties of chamber compliance and pressure differentials that determine the capacity for LV filling. Unlike ventricular systolic function where single parameters are utilised to define myocardial performance (LV ejection fraction (LVEF) and Global Longitudinal Strain (GLS)), the assessment of diastolic function relies on the interpretation of multiple myocardial and blood-flow velocity parameters, along with left atrial (LA) size and function, in order to diagnose the presence and degree of impairment. The echocardiographic assessment of diastolic function is therefore multifaceted and complex, requiring an algorithmic approach that incorporates parameters of myocardial relaxation/recoil, chamber compliance and function under variable loading conditions and the intra-cavity pressures under which these processes occur. This guideline outlines a structured approach to the assessment of diastolic function and includes recommendations for the assessment of LV relaxation and filling pressures. Non-routine echocardiographic measures are described alongside guidance for application in specific circumstances. Provocative methods for revealing increased filling pressure on exertion are described and novel and emerging modalities considered. For rapid access to the core recommendations of the diastolic guideline, a quick-reference guide (additional file 1) accompanies the main guideline document. This describes in very brief detail the diastolic investigation in each patient group and includes all algorithms and core reference tables.

Left atrial cardiomyopathy: Pathophysiological insights, assessment methods and clinical implications

Atrial cardiomyopathy is defined as any complex of structural, architectural, contractile or electrophysiological changes affecting atria, with the potential to produce clinically relevant manifestations. Most of our knowledge about the mechanistic aspects of atrial cardiomyopathy is derived from studies investigating animal models of atrial fibrillation and atrial tissue samples obtained from individuals who have a history of atrial fibrillation. Several noninvasive tools have been reported to characterize atrial cardiomyopathy in patients, which may be relevant for predicting the risk of incident atrial fibrillation and its related outcomes, such as stroke. Here, we provide an overview of the pathophysiological mechanisms involved in atrial cardiomyopathy, and discuss the complex interplay of these mechanisms, including aging, left atrial pressure overload, metabolic disorders and genetic factors. We discuss clinical tools currently available to characterize atrial cardiomyopathy, including electrocardiograms, cardiac imaging and serum biomarkers. Finally, we discuss the clinical impact of atrial cardiomyopathy, and its potential role for predicting atrial fibrillation, stroke, heart failure and dementia. Overall, this review aims to highlight the critical need for a clinically relevant definition of atrial cardiomyopathy to improve treatment strategies.

Left atrial functional assessment and mortality in patients with severe aortic stenosis with sinus rhythm

BACKGROUND

Aortic valve stenosis (AS) is the most common primary valvular heart disease leading to surgical or percutaneous aortic valve replacement (AVR) in Europe and its prevalence keeps growing. While other risk factors in severe AS are well documented, little is known about the prognostic value of left atrial (LA) function in AS. Our aim is to clarify the relationship between LA function measured at severe AS diagnosis (evaluated by means of volumetric assessment) and all-cause mortality during follow-up.

METHODS

We retrospectively evaluated patients diagnosed with severe AS for the first time at our echocardiography laboratory. We evaluated LA reservoir, conduit and pump function by measuring LA volumes at different timings of cardiac cycle. Treatment strategy was decided according to heart team consensus and patient decision. We divided patients into groups according to terciles of LA reservoir, conduit and pump function. Primary outcome was defined by the occurrence of all-cause mortality during follow-up.

RESULTS

A total of 408 patients were included in the analysis, with a median follow-up time of 45 months (interquartile range 54 months). 57.9% of patients underwent AVR and 44.9% of patients registered the primary outcome during follow-up. Left atrial emptying fraction (LAEF) was the best LA functional parameter and the best overall parameter in discriminating primary outcome (AUC 0.845, 95%CI 0.81-0.88, P < 0.001). After adjustment for clinical, demographic and echocardiographic variables, cumulative survival of patients with LAEF < 37% and LAEF 37 to 53% relative to patients with LAEF ≥54% remained significantly lower (HR 13.91, 95%CI 6.20-31.19, P < 0.001 and HR 3.40, 95%CI 1.57-7.37, P = 0.002, respectively). After adjustment for AVR, excess risk of LAEF < 37% and LAEF 37 to 53% relative to LAEF ≥54% remained significant (HR 11.71, 95%CI 5.20-26.40, P < 0.001 and HR 3.59, 95%CI 1.65-7.78, P = 0.001, respectively).

CONCLUSIONS

In patients with a first diagnosis of severe AS, LA function, evaluated by means of volumetric assessment, is an independent predictor of all-cause mortality and a more potent predictor of death compared to classical severity parameters. These data can be useful to identify high-risk patients who might benefit of AVR.

The atrial uremic cardiomyopathy regression in patients after kidney transplantation - the prospective echocardiographic study

BACKGROUND

In patients with end stage renal disease (ESRD), left ventricular (LV) hypertrophy with impaired LV function, which is called uremic cardiomyopathy (UC) is often observed. The UC historically has been considered a contraindication for kidney transplantation (KTx). Currently, moderate LV dysfunction does not exclude the possibility of KTx. The amelioration of uremia after KTx improved cardiac function in patients with LV dysfunction. There is a little information on the function of the left atrium (LA) after the KTx procedure. There are no studies evaluating (LA) changes in patients with UC after KTx and determining the possibility of inhibiting the occurrence of LA unfavourable changes (remodelling) and even a possible LA recovery process (reverse remodelling) as a result of a successful KTx. The aim of the study was to assess the LA reverse remodelling in patients with ESRD undergoing KTx.

METHODS

The study group consisted of 42 patients, aged 43.3 ± 12.6 followed for 36 months after a deceased donor KTx. The patients were studied at five time points: 1, 3, 6, 12 and 36 months after KTx. In all patients transthoracic echocardiography was performed in order to assess the following LA planimetric parameters: LAmax, LAmin, LAwaveP. LAshortmax, LAshortmin, LAshortwaveP, LAlongmax, LAlongmin, LAlongwaveP, LAcircmax and LAareamax, volumentric parameters: LA volume (LAV), LA volume index (LAVI), and hemodynamic indices: LA ejection fraction (LAEF), LA active emptying fraction (LAAE), LA passive emptying fraction (LAPE), LA index of expansion (LAIE) and LA fractional shortening (LAFS).

RESULTS

The LAVI values were 34.63 ± 10.34 ml/m2, 32.24 ± 9.59 ml/m2 (p < 0,001), 31.36 ± 9.20 ml/m2 (p < 0,001), 28.29 ± 8.32 ml/m2 (p < 0,001) and 27.57 ± 8.40 ml/m2 (p < 0,001), after: 1, 3, 6, 12 and 36 months after KTx, respectively. The reduction of the LA size was accompanied by gradual LA contractility improvement, which was manifested as an increase of the LA hemodynamic indices such as LAEF, LAAE, LAIE, LAFS and a decrease of LAPE.

CONCLUSIONS

LA remodelling secondary to atrial uraemic cardiomyopathy is an example of complex cardiomyopathy with elements characteristic of both congestive and infiltrative cardiomyopathy. Early LAVI reduction post KTx mostly depends on changed haemodynamic conditions, whereas the main reason for further decrease of LAVI values is related to resolution of uraemic toxaemia.

Left atrial volume index in patients with heart failure and severely impaired left ventricular systolic function: the role of established echocardiographic parameters, circulating cystatin C and galectin-3

Backround: Left atrial (LA) enlargement plays an important role in the development of heart failure (HF) and is a robust prognostic factor. Fibrotic processes have also been advocated to evoke HF through finite signalling proteins.

METHODS

We examined the association of two such proteins, cystatin C (CysC) and galectin-3 (Gal-3), and other clinical, echocardiographic and biochemical parameters with LA volume index (LAVi) in patients with HF with severely impaired left ventricular ejection fraction (LVEF). Severe renal, liver, autoimmune disease and cancer were exclusion criteria.

RESULTS

A total of 40 patients with HF (31 men, age 66.6 ± 1.7) with LVEF = 25.4 ± 0.9% were divided into two groups according to the mean LAVi (51.03 ± 2.9 ml/m2) calculated by two-dimensional transthoracic echocardiography. Greater LAVi was positively associated with LV end-diastolic volume ( p = 0.017), LV end-systolic volume ( p = 0.025), mitral regurgitant volume (MRV) ( p = 0.001), right ventricular systolic pressure (RVSP) ( p < 0.001), restrictive diastolic filling pattern ( p = 0.003) and atrial fibrillation ( p = 0.005). Plasma CysC was positively correlated with LAVi ( R2 = 0.135, p = 0.019) and log-transformed plasma Gal-3 ( R2 = 0.109, p = 0.042) by simple linear regression analysis. Stepwise multiple linear regression analysis showed that only MRV ( t = 2.236, p = 0.032), CysC ( t = 2.467, p = 0.019) and RVSP ( t = 2.155, p = 0.038) were significant predictors of LAVi.

CONCLUSIONS

Apart from known determinants of LAVi, circulating CysC and Gal-3 were associated with greater LA dilatation in patients with HF with reduced LVEF. Interestingly, the correlation between these two fibrotic proteins was positive.

Left Atrial Remodeling and Atrioventricular Coupling in a Canine Model of Early Heart Failure With Preserved Ejection Fraction

BACKGROUND

Left atrial (LA) compliance and contractility influence left ventricular stroke volume. We hypothesized that diminished LA compliance and contractile function occur early during the development of heart failure with preserved ejection fraction (HFpEF) and impair overall cardiac performance.

METHODS AND RESULTS

Cardiac magnetic resonance imaging, echocardiography, left ventricular and LA pressure-volume studies, and tissue analyses were performed in a model of early HFpEF (elderly dogs, renal wrap-induced hypertension, exogenous aldosterone; n=9) and young control dogs (sham surgery; n=13). Early HFpEF was associated with LA enlargement, cardiomyocyte hypertrophy, and enhanced LA contractile function (median active emptying fraction 16% [95% confidence interval, 13-24]% versus 12 [10-14]%, P=0.008; end-systolic pressure-volume relationship slope 2.4 [1.9-3.2]mm Hg/mL HFpEF versus 1.5 [1.2-2.2]mm Hg/mL controls, P=0.01). However, atrioventricular coupling was impaired and the curvilinear LA end-reservoir pressure-volume relationship was shifted upward/leftward in HFpEF (LA stiffness constant [β_LA] 0.16 [0.11-0.18]mm Hg/mL versus 0.06 [0.04-0.10]mm Hg/mL controls; P=0.002), indicating reduced LA compliance. Impaired atrioventricular coupling and lower LA compliance correlated with lower left ventricular stroke volume. Total fibrosis and titin isoform composition were similar between groups; however, titin was hyperphosphorylated in HFpEF and correlated with β_LA. LA microvascular reactivity was diminished in HFpEF versus controls. LA microvascular density tended to be lower in HFpEF and inversely correlated with β_LA.

CONCLUSIONS

In early-stage hypertensive HFpEF, LA cardiomyocyte hypertrophy, titin hyperphosphorylation, and microvascular dysfunction occur in association with increased systolic and diastolic LA chamber stiffness, impaired atrioventricular coupling, and decreased left ventricular stroke volume. These data indicate that maladaptive LA remodeling occurs early during HFpEF development, supporting a concept of global myocardial remodeling.

The differences in left atrial function between ischemic and idiopathic dilated cardiomyopathy patients: A two-dimensional speckle tracking imaging study

PURPOSE

To evaluate left atrial (LA) function in patients with ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy via two-dimensional speckle-tracking imaging.

METHODS

We measured the LA maximum volume, minimum volume, and volume before the atrial systole, and calculated total emptying volume, expansion index, active emptying volume, and fraction. We measured strain and strain rate during systole and late diastole using two-dimensional speckle-tracking imaging, and analyzed correlations between variables.

RESULTS

We found no significant differences in LA size, left ventricle (LV) end-diastole diameter, LV ejection fraction (EF), E/A, E/e', deceleration time of the E wave, and effective mitral regurgitant orifice area between the DCM and the ICM group. However, the LA expansion index, active EF, systolic and late diastolic strain, and strain rate were lower in the ICM group (p < 0.05). The expansion index and active EF were positively correlated with the systolic strain rate and the absolute value of the late diastolic strain rate, respectively.

CONCLUSIONS

LA basic echocardiographic variables did not reflect the differences between ICM and DCM patients, but the systolic and late diastolic strain, as well as the strain rate, were lower in DCM patients. Two-dimensional speckle-tracking imaging is a promising method to differentiate these patients. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:437-445, 2016.

The mitral annular displacement by two-dimensional speckle tracking: a new tool in evaluating the left atrial function

BACKGROUND

The methods used to characterize the volume change and the deformation of the left atrium are highly dependent on technical factors and difficult to use in a clinical environment. The aim of this study was to demonstrate that mitral annular displacement by speckle tracking can be an alternative method to studying the longitudinal left atrial function.

METHODS

Ninety study participants (54% men), with a mean age of 53(±15) years, underwent a complete echocardiographic examination, comprising two-dimensional, three-dimensional and tissue Doppler imaging (TDI). They were divided into normal individuals (35) and patients having an abnormal echocardiography (55).

RESULTS

There was a very strong correlation between three-dimensional volumetric function and mitral annular displacement, both for the reservoir (r = 0.78; P < 0.0001) and contractile (r = 0.76; P < 0.0001) functions. The correlation with the longitudinal strain displayed an r = 0.87, P > 0.0001 for the reservoir and r = 0.81, P < 0.0001 for the contractile function. The systolic speed in pulsed TDI and the systolic displacement had an r = 0.83, P < 0.0001. Mitral annular displacement was a very good discriminator for normal versus abnormal participants [area under the curve (AUC) for reservoir = 0.872 and for contractile = 0.843; P < 0.0001], performing less well than three-dimensional (AUC reservoir = 0.892 and contractile = 0.915; P < 0.0001) or deformation (AUC = 0.921 and 0.903 respectively; P < 0.0001), but better than pulsed TDI (AUC = 0.807; P < 0.0001). The percentage error was ±15% for interobserver and ±12% for intraobserver variability. The time taken for displacement analysis was 9 ± 3 s for an experienced cardiologist and 12 ± 4 s for a beginner.

CONCLUSION

Mitral annular displacement by speckle tracking is a reliable and fast method to evaluate left atrial function. Given the strength of the correlations with strain parameters, it could be used as a surrogate measure of the deformation of left atrium.

Left atrial function in heart failure with impaired and preserved ejection fraction

PURPOSE OF REVIEW

Left atrial structural and functional changes in heart failure are relatively ignored parts of cardiac assessment. This review illustrates the pathophysiological and functional changes in left atrium in heart failure as well as their prognostic value.

RECENT FINDINGS

Heart failure can be divided into those with systolic dysfunction and heart failure with preserved ejection fraction (HFPEF). Left atrial enlargement and dysfunction commonly occur in systolic heart failure, in particular, in idiopathic dilated cardiomyopathy. Atrial enlargement and dysfunction also carry important prognostic value in systolic heart failure, independently of known parameters such as left ventricular ejection fraction. In HFPEF, there is evidence of left atrial enlargement, impaired atrial compliance, and reduction of atrial pump function. This occurs not only at rest but also during exercise, indicating significant impairment of atrial contractile reserve. Furthermore, atrial dyssynchrony is common in HFPEF. These factors further contribute to the development of new onset or progression of atrial arrhythmias, in particular, atrial fibrillation.

SUMMARY

Left atrial function is an integral part of cardiac function and its structural and functional changes in heart failure are common. As changes of left atrial structure and function have different clinical implications in systolic heart failure and HFPEF, routine assessment is warranted.

Left atrial geometry and pump function in ischemic cardiomyopathy

Background

Many of the factors that are known to alter left atrial (LA) contractility are present in patients with ischemic cardiomyopathy (ICM). Nevertheless, preservation of LA contractile function in this group of patients was reported in previous studies. The aim of this study was to assess the changes in LA size, geometry and contractile function in ICM.

Methods and results

60 subjects (age: 49 ± 12 years, 53% males) in sinus rhythm undergoing coronary angiography (CA), were enrolled in this study; 15 subjects as a control group, 30 patients with reduced ejection fraction (EF) and significant coronary artery disease; as the ICM group, and 15 with reduced EF and normal CA; as the dilated cardiomyopathy (DCM) group.

LA dimensions, volume, active emptying fraction (ACTEF) and eccentricity index (LAEi) as well as late diastolic velocities of the mitral annulus (a′) and LA free wall (A₃) were measured.

Compared with the control group, ICM patients had larger LA volume and reduced ACTEF, a′ and A₃, with no significant difference between patients with ICM and DCM in any of these parameters. LA eccentricity was, non-significantly, higher in both cardiomyopathy groups than in the control group.

Conclusions

Patients with ICM have increased LA volume and reduced LA contractile function in comparison with normal controls. LA enlargement, LA contractile dysfunction and LA geometric changes in ICM are similar to that occurring in DCM. LA size, contractile function and eccentricity may not be reliable in differentiating ischemic from idiopathic dilated cardiomyopathy.

Hemodynamic pressure waveform analysis in predicting fluid responsiveness

OBJECTIVE

To assess the usefulness of central venous pressure (CVP), diastolic right ventricular pressure, and pulmonary capillary wedge pressure (PCWP) waveform analysis in predicting fluid responsiveness.

DESIGN

A prospective observational study.

SETTING

Tertiary care university hospital.

PATIENTS

Forty-four patients undergoing coronary artery bypass grafting.

INTERVENTIONS

Analysis of the a/v wave ratio of the PCWP, CVP, and right ventricular dP/dt to predict an increase in stroke volume >15% after the administration of 500 mL of colloid.

MEASUREMENTS AND MAIN RESULTS

Forty-four patients were enrolled in this study and 7 were excluded. There were 24 responders and 13 nonresponders. No differences in mean CVP and PCWP values between the responders and the nonresponders were found. The only parameter associated with a significant response to volume infusion was the ratio of the a/v waves of the PCWP tracing (p = 0.0001). The performance of the a/v wave ratio>1 of the PCWP tracing in predicting fluid responsiveness was evaluated by constructing a receiver operating characteristic curve. The area under the receiver operating characteristic curve was 0.89 (95% confidence interval, 0.79-0.99; p<0.05).

CONCLUSIONS

The a/v ratio measured on the PCWP tracing is a predictor of fluid responsiveness in patients with preserved left ventricular function undergoing coronary artery bypass grafting.

Changes in left ventricular diastolic function of asymptomatic hereditary hemochromatosis subjects during five years of follow-up

We have previously reported that left ventricular (LV) diastolic function in those with cardiac asymptomatic hereditary hemochromatosis (HH) is similar to that of volunteer control (VC) subjects, despite a presence of augmented left atrial contractile function. However, concern still exists that those with HH might gradually develop LV diastolic dysfunction despite receiving conventional phlebotomy treatment. To address this concern, we prospectively monitored the LV diastolic function of those with HH and VCs during a 5-year period. A total of 14 subjects with newly diagnosed HH (age 51 ± 12 years, 4 women, group A), 20 with chronic HH (age 51 ± 9 years, 7 women, group B), and 18 VCs (age 50 ± 8 years, 6 women, group C) successfully completed both the baseline evaluation of LV diastolic function, including tissue Doppler imaging, strain rate analysis with color-coded tissue Doppler, and the same studies repeated at 5 years of follow-up. All those with HH were New York Heart Association functional class I, were positive for the C282Y homozygote, and received conventional phlebotomy therapy. No VC had HH genetic mutations. The measures of LV diastolic function were comparable among the groups at 5 years of follow-up by analysis of variance. The echocardiographic measures of active left atrial contraction tended to decrease in the HH groups at 5 years of follow-up from baseline. In conclusion, LV diastolic function does not significantly deteriorate statistically during a 5-year period in subjects with cardiac asymptomatic HH after conventional phlebotomy treatment, regardless of their treatment history.

Left atrial function: physiology, assessment, and clinical implications

The interest in the left atrium (LA) has resurged over the recent years. In the early 1980s, multiple studies were conducted to determine the normal values of LA size. Over the past decade, LA size as an imaging biomarker has been consistently shown to be a powerful predictor of outcomes, including major public health problems such as atrial fibrillation, heart failure, stroke, and death. More recently, functional assessment of the LA has been shown to be, at least as, if not more robust, a marker of cardiovascular outcomes. Current available data suggest that the combined evaluation of LA size and LA function will augment prognostication. The aim of this review is to provide a critical appraisal of current echocardiographic techniques for the assessment of LA function and the implications of such assessment for prediction and disease prevention.

Left atrial dysfunction in chagas cardiomyopathy is more severe than in idiopathic dilated cardiomyopathy: a study with real-time three-dimensional echocardiography

BACKGROUND

Although there is anatomopathologic evidence of atrial involvement in Chagas cardiomyopathy (CCM), the impact in left atrial (LA) function is unknown. The aim of this study was to evaluate LA function in patients with CCM with real-time three-dimensional echocardiography (RT3DE) and to compare it with patients with idiopathic dilated cardiomyopathy (DCM).

METHODS

A total of 30 patients with CCM, 30 patients with DCM, and 20 normal subjects used as the control group were studied. With the use of RT3DE, we measured LA maximum (maxLAV), minimum, and pre-atrial contraction volumes and calculated total and active LA emptying fractions.

RESULTS

Left ventricular ejection fraction and mitral regurgitation were similar in both groups. MaxLAV/m(2) was larger in the CCM group than in the DCM group (76.9 ± 21.9 mL vs. 59.1 ± 26.0 mL; P < .01), and both were significantly larger than in the control group (P < .01). Total LA emptying fraction was lower in the CCM group than in the DCM group (0.30 ± 0.10 vs. 0.40 ± 0.12; P < .01), and both were lower than in the control group (P = .01). Active LA emptying fraction was also lower in the CCM group than in the DCM group (0.22 ± 0.09 vs. 0.28 ± 0.11; P < .01), and both were lower than in the control group (P = .01). The E/e' ratio was higher in the CCM group than in the DCM group (21 ± 10 vs. 15 ± 6; P < .01), and both were greater than in the control group (P < .01). In a multiple regression model, the E/e' ratio was the only independent predictor of a worsening active LA emptying fraction.

CONCLUSION

LA function is more compromised in patients with CCM than in patients with DCM. This finding indicates a more diffuse and severe myocardial impairment in Chagas disease that is probably related to increased left ventricular filling pressures and atrial myopathy.

Augmentation of left atrial contractile function: a herald of iron overload in patients with beta thalassemia major

Early detection of myocardial iron overload is crucial for optimal management of patients with beta thalassemia major, which could lead to intensification of iron chelating therapy. In this study, we evaluate the conventional echocardiography and tissue Doppler imaging measurements in patients with beta thalassemia major and further introduce the assessment of atrial ejection force as a feasible price-saving approach for early detection of myocardial iron overload. During a 1-year period, 42 cases of beta thalassemia major aged <21 years and with preserved systolic function were evaluated with magnetic resonance T2* imaging (MRI T2*), conventional echocardiography, and tissue Doppler imaging techniques. Patients were classified into two groups according to their myocardial MRI T2* values, with and without critical iron loading. All patients with echocardiographic evidence of moderate and severe stages of diastolic dysfunction showed critical iron loading in their MRI T2*. After excluding those patients with severe and moderate ventricular diastolic filling abnormality, the atrial ejection force index (P = 0.002) and a number of volume indexes of the left atrium showed a significant difference between the two groups. None of the tissue Doppler imaging measurements showed a statistically significant difference between the two groups. The atrial ejection force index of 7.41, with a sensitivity of 93% and a specificity of 74%, was suggested to detect critical cardiac iron loading. These results imply that combining the atrial ejection force index with the transmitral-derived echocardiographic assessment is a feasible way to detect early stages of myocardial iron overload in patients with beta thalassemia major.

Left atrial remodelling contributes to the progression of asymptomatic left ventricular systolic dysfunction to chronic symptomatic heart failure

Systolic heart failure (HF) is a progressive disorder that often begins with asymptomatic left ventricular (LV) systolic dysfunction and culminates in symptoms from fluid overload and poor end-organ perfusion. The progression to symptomatic HF is accompanied by marked activation of neurohormonal and cytokine systems, as well as a series of adaptive LV anatomical and functional changes, collectively referred to as LV remodelling. However, the mechanisms underlying symptom appearance have not been delineated and the weight of experimental and clinical evidence suggests that the development of symptomatic HF occurs independently of the haemodynamic status of the patient. The left atrium is a muscular chamber strategically located between the left ventricle and the pulmonary circulation with important mechanical function (modulation of LV filling), which is closely coupled with its endocrine (atrial natriuretic peptide synthesis and secretion) and regulatory (contribution to the control of sympathetic activity and vasopressin release) functions. In this narrative review we provide evidence supporting the concept that left atrial dilation and systolic dysfunction (left atrial remodelling) contributes to the progression of asymptomatic LV dysfunction to chronic symptomatic systolic HF as it is a prerequisite for the development of the pulmonary congestion and marked neuronhormoral activity that characterize the symptomatic state.

Echocardiographic assessment of left atrial ejection force and kinetic energy in chronic heart failure

BACKGROUND

There is limited information regarding left atrial (LA) systolic adaptation to chronic heart failure (HF) in humans. Therefore, the aim of our study was to determine the LA ejection force (LAEF) and kinetic energy in patients with HF.

METHODS AND RESULTS

58 HF patients (63.8% in NYHA II) and 48 controls were studied. LA volumes were echocardiographically determined using the biplane area-length method. LA systolic function was assessed with the: (a) active emptying volume (ACTEV) and fraction (ACTEF), (b) ejection force (kdynes/m2), calculated with Manning's method [LAEF = 0.5 * rho * mitral orifice area * A2; rho: blood density, Alpha: late transmitral flow velocity] and a modification incorporating parameters of LA function [LAEFm = 0.5 * rho * LA volume at onset of atrial systole * ACTEF * A2/VTl A], and (c) kinetic energy [LA-ke (kdynes.cm/m2) = 0.5 * rho * ACTEV * A2]. LA maximal volume and ACTEV were lower (42.9 +/- 14.4 vs. 59.7 +/- 14.7 cm3, P < 0.0001; 10.9 +/- 3.3 vs. 13 +/- 3.3 cm3, P = 0.0001, respectively), whereas ACTEF (%) was higher (36.3 +/- 7 vs. 29.3 +/- 7.6 cm3, P < 0.0001) in controls than HF. LAEF, LAEFm, and LA-ke were lower in controls than HF (7.68 +/- 5.1 vs. 10.16 +/- 3.7 kdynes/m2, P = 0.006; 3.63 +/- 2.05 vs. 5.02 +/- 1.74 kdynes/m2, P = 0.0004; 2.41 +/- 1.91 vs. 3.99 +/- 2.1 kdynes.cm/m2, P < 0.0004, respectively).

CONCLUSION

Despite the decreased LA systolic shortening, overall LA systolic performance is augmented in chronic HF due to LA dilation.

Significance of left atrial contractile function in asymptomatic subjects with hereditary hemochromatosis

Patients with hereditary hemochromatosis (HH) have been reported to develop diastolic functional abnormalities detectable by echocardiography, but it is unknown whether these occur in asymptomatic subjects. Thus, this study tested whether echocardiographic left ventricular (LV) relaxation abnormalities are detectable in subjects with asymptomatic HH. Forty-three asymptomatic subjects with HH (C282Y homozygosity in the HFE gene) and 21 age- and gender-matched control subjects without known HFE mutations underwent echocardiography with comprehensive diastolic functional evaluations. Subjects with HH were in New York Heart Association functional class I and consisted of 22 newly diagnosed patients (group A) and 21 chronically phlebotomized subjects with stable iron levels (group B). Group A subjects showed significant iron overload compared with group B subjects and controls (group C) (ferritin 1,164 +/- 886 [p <0.05 vs groups B and C], 128 +/- 262, and 98 +/- 76 microg/L and transferrin saturation 79 +/- 19% [p <0.05 vs groups B and C], 42 +/- 21%, and 26 +/- 10% for groups A, B, and C, respectively). Echocardiographic evaluation revealed (1) no statistically significant abnormalities of Doppler LV relaxation in HH groups; (2) significant augmentation of atrial contractile function in subjects with HH compared with controls, which was not correlated with iron levels and treatment status; and (3) the preservation of overall LV systolic function in HH groups. In conclusion, the results of this study suggest that the augmentation of atrial contraction appears to be an early detectable echocardiographic cardiac manifestation of abnormal diastolic function in asymptomatic subjects with HH, which may reflect undetectable subclinical LV relaxation abnormalities.

Is Functional Capacity Related to Left Atrial Contractile Function in Nonobstructive Hypertrophic Cardiomyopathy?

The mechanisms underlying reduced exercise capacity in patients with nonobstructive hypertrophic cardiomyopathy (NHCM) could include perturbations of ventricular relaxation, diastolic compliance, or compensatory atrial systolic function. We hypothesized that a loss of atrial contractility in NHCM patients leads to reduced functional capacity. To test this hypothesis, we compared resting noninvasive left atrial ejection phase indices in 49 consecutive patients with NHCM (ages 36+/-10 years; 41% female) and normal left ventricular ejection fraction (mean, 68%+/-8%) with objective metabolic exercise parameters. Left atrial active emptying fraction, ejection force, and kinetic energy failed to predict exercise capacity. Only left atrial total and active emptying volumes correlated weakly with minute volume/CO2 production slope (r=0.31 and r=0.33; p<0.05 for both). Furthermore, when subjects were stratified by New York Heart Association symptomatology, exercise parameters--but not atrial contractility--differed between groups. These data, obtained at rest, fail to suggest that NHCM-related heart failure symptoms are due to an atrial myopathy.

Left atrial systolic reserve in idiopathic vs. ischaemic-dilated cardiomyopathy

PURPOSE

There are studies indicating more pronounced left atrial (LA) systolic dysfunction at rest in idiopathic (IDDC) than in ischaemic-dilated cardiomyopathy (ISDC). It was hypothesized that the findings would be similar with regards LA systolic reserve.

METHODS

Twenty-six patients with IDDC, 28 with ISDC and 25 normal controls underwent low-dose dobutamine stress echocardiography (5-10 microg kg(-1) min(-1) IV). Left atrial volumes were echocardiographically determined at rest and during stress at the mitral valve opening (maximal, Vmax), electrocardiographic P wave (onset of atrial systole, Vp) and mitral valve closure (minimal, Vmin) from the apical 4- and 2-chamber views (biplane area-length method). Left atrial systolic function was assessed with the LA-active emptying volume (ACTEV) = Vp-Vmin and fraction (ACTEF) = ACTEV/Vp.

RESULTS

Vmax at rest was similar in IDDC and ISDC and greater than in the controls (54.2 +/- 12 vs. 48.5 +/- 18 vs. 27.1 +/- 6.3 cm(3) m(-2), respectively, P < 0.001) and did not change with stress (53.9 +/- 13.8 vs. 46.9 +/- 16.2 vs. 25.8 +/- 5.9 cm(3) m(-2), P < 0.001). The ACTEV at rest was similar in IDDC and ISDC and greater than in the controls (8.6 +/- 3.5 vs. 9.7 +/- 2.9 vs. 6.1 +/- 2.2 cm(3) m(-2) P < 0.01), whereas during the dobutamine infusion it remained unaltered in IDDC (10.8 +/- 4.6 cm(3) m(-2), P = NS vs. rest) and increased in ISDC (11.8 +/- 3.3 cm(3) m(-2), P < 0.05) and the controls (13.1 +/- 3.2 cm(3) m(-2), P < 0.01). The ACTEF was lower in IDDC than ISDC and the controls at rest (20 +/- 10% vs. 33 +/- 8% vs. 36 +/- 10%, P < 0.01). Dobutamine infusion was associated with no significant increase in ACTEF in IDDC (25 +/- 12%, P = NS vs. rest), and with an increase in this variable in ISDC (39 +/- 10%, P < 0.05) and the controls (49 +/- 12%, P < 0.01).

CONCLUSIONS

Dobutamine infusion is associated with an increase in LA ACTEV and fraction in ISDC and no significant change in these indices in IDDC. These findings indicate a reduced LA systolic reserve in IDDC.

Assessment of atrial regional and global electromechanical function by tissue velocity echocardiography: a feasibility study on healthy individuals

Background

The appropriate evaluation of atrial electrical function is only possible by means of invasive electrophysiology techniques, which are expensive and therefore not suitable for widespread use. Mechanical atrial function is mainly determined from atrial volumes and volume-derived indices that are load-dependent, time-consuming and difficult to reproduce because they are observer-dependent.

Aims

To assess the feasibility of tissue velocity echocardiography (TVE) to evaluate atrial electromechanical function in young, healthy volunteers.

Subjects and methods

We studied 37 healthy individuals: 28 men and nine women with a mean age of 29 years (range 20–47). Standard two-dimensional (2-D) and Doppler echocardiograms with superimposed TVE images were performed. Standard echocardiographic images were digitized during three consecutive cardiac cycles in cine-loop format for off-line analysis. Several indices of regional atrial electrical and mechanical function were derived from both 2-D and TVE modalities.

Results

Some TVE-derived variables indirectly reflected the atrial electrical activation that follows the known activation process as revealed by invasive electrophysiology. Regionally, the atrium shows an upward movement of its walls at the region near the atrio-ventricular ring with a reduction of this movement towards the upper levels of the atrial walls. The atrial mechanical function as assessed by several TVE-derived indices was quite similar in all left atrium (LA) walls. However, all such indices were higher in the right (RA) than the LA. There were no correlations between the 2-D- and TVE-derived variables expressing atrial mechanical function. Values of measurement error and repeatability were good for atrial mechanical function, but only acceptable for atrial electrical function.

Conclusion

TVE may provide a simple, easy to obtain, reproducible, repeatable and potentially clinically useful tool for quantifying atrial electromechanical function.

Left atrial systolic function in primary and familial amyloidosis: assessment from left atrial volume change

The severity of left ventricular involvement may differ between primary (PA) and familial amyloidosis (FA). This study examined whether differences in left atrial (LA) systolic function are also present. Twenty-eight patients (18 men, 10 women, aged 59 +/- 12 years) with PA, 17 (11 men, 6 women, aged 40 +/- 11 years) with FA, and 25 normal controls (18 men, 7 women, aged 56 +/- 14 years) underwent transthoracic M-mode, two-dimensional, and Doppler echocardiography. Left atrial volumes were determined at mitral valve (MV) opening (maximal, Vmax), electrocardiographic P wave (onset of atrial systole, Vp), and MV closure (minimal, Vmin) from the apical two-and four-chamber views using the biplane area-length method. Left atrial systolic function was assessed with the LA active emptying volume (ACTEV) = Vp-Vmin and fraction (ACTEF) = ACTEV/Vp. The E/A ratio was increased (1.34 +/- 0.93 vs. 0.89 +/- 0.3), whereas deceleration time was decreased (168.1 +/- 33.7 vs. 196.2 +/- 34.2 ms) in PA compared with FA (p<0.05). Vmax and Vp were similar in PA and FA and greater than in the controls (46.6 +/- 14 vs. 40 +/- 11.4 vs. 27.1 +/- 6.3 cm3/m2, p<0.01, and 33.4 +/- 11.6 vs. 29.7 +/- 10.8 vs. 16.8 +/- 3.8 cm3/m2, p<0.01, respectively). The ACTEV was lower in PA and in the controls than in FA (6.7 +/- 2 vs. 6.2 +/- 2.2 vs. 8.5 +/- 3.3, respectively, p<0.05). The ACTEF was lower in PA than in FA and both were lower than those in the controls (20 +/- 5% vs. 28 +/- 7% vs. 36 +/- 11%, respectively, p<0.01). Despite a similar increase in LA volume, LA systolic dysfunction is more pronounced in PA than in FA. This is most likely due to the restrictive left ventricular physiology possibly associated with depressed LA contractility in the former.

Left atrial function preserves pulmonary circulatory pressure during pacing-tachycardia and contributes to exercise capacity in patients with idiopathic dilated cardiomyopathy in sinus rhythm, whose exercise is limited by dyspnea

The aim of this study was to determine whether left atrial (LA) function contributes to pulmonary circulatory pressure during pacing-tachycardia and exercise capacity in patients with idiopathic dilated cardiomyopathy (DCM). Thirty-two patients with DCM and in sinus rhythm had limited exercise capacity because of dyspnea. The correlation between peak oxygen consumption (VO2) and the variables of cardiac function by cardiac catheterization and 2-dimensional, Doppler echocardiography, and plasma neurohumoral factor levels was tested, as was the correlation between non-invasive LA functional parameters and pulmonary circulatory pressure during pacing-tachycardia. A significant correlation was observed between VO2 and LA dimension (r = -0.45, p < 0.01), the peak velocities of LA appendage empty flow during atrial systole (r = 0.63, p < 0.0001) and the pulmonary venous forward flow in early ventricular systole (PVS1; r = 0.74, p < 0.0001), as well as plasma brain natriuretic peptide (BNP) concentrations. The predictable equation to VO2 with the multiple regression analysis was: VO2 = -0.01 BNP+0.21 PVS1+15.4 (r = 0.81, p < 0.0001). Furthermore, LA functional variables derived from pulmonary venous flow, especially PVS1, but not plasma BNP concentration, were useful for predicting the degree of the increase in pulmonary circulatory pressure during pacing-tachycardia. Therefore, it is suggested that LA function contributes to exercise capacity through its influence on pulmonary hemodynamic reserve in patients with DCM with sinus rhythm whose exercise is limited by dyspnea.

Cardiac adaptation to intensive training in prepubertal swimmers

BACKGROUND

Despite the increasing involvement of child athletes in intensive training regimens, little is known about the influence of such training on autonomic regulation and cardiac structure and function.

PATIENTS AND METHODS

Twenty-five highly trained (12-14 h weekly for at least 4 years) swimmers (aged 11.9 +/- 1.6 years; 15 males, 10 females) and 20 non-training normal children who served as controls (aged 11.3 +/- 0.6 years; 14 males, 6 females) were studied. Heart rate variability analysis in the time and frequency domains was performed on 15 min resting heart rate acquisitions. Left ventricular morphology and systolic function was studied with two-dimensional guided M-mode echocardiography. The transmitral flow velocity profile was assessed with pulsed Doppler. Parameters measured included the peak early (E) and peak late (A) transmitral flow velocity and their ratio (E/A). Left atrial (LA) volumes were determined at mitral valve (MV) opening (maximal, Vmax), at onset of atrial systole (P wave of the ECG, Vp), and at MV closure (minimal, Vmin) from the apical 2- and 4-chamber views, using the biplane area-length method. LA systolic function was assessed with the LA active emptying volume (ACTEV) = Vp-Vmin and the LA active emptying fraction (ACTEF) = ACTEV/Vp.

RESULTS

Average NN (967.1 +/- 141.8 vs. 768.4 +/-85.6 ms, P < 0.0001), logSDNN (1.89 +/- 0.14 vs. 1.80 +/- 0.17 ms, P < 0.05), logPNN 50% (1.66 +/- 0.23 vs. 1.46 +/- 0.35, p < 0.05), and logHF power (3.13 +/- 0.32 vs. 2.95 +/- 0.26 ms2, p < 0.05) were greater in swimmers than in controls. Left ventricular end-diastolic diameter was greater (32.3 +/- 3.3 vs. 29.5 +/- 3.3 mm m(-2), P < 0.02) in swimmers than in controls, whereas the left ventricular septal (5.9 +/- 1 vs. 5.6 +/- 0.8 mm m(-2), P = NS) and posterior wall thickness (5.7 +/-0.9 vs. 5.4 +/- 0.8 mm m(-2), P = NS) were similar in the two groups. The E/A ratio was greater (2.2 +/- 0.49 vs. 1.78 +/- 0.36, P < 0.003) whereas the A velocity was lower (0.41 +/- 0.09 vs. 0.50 +/- 0.13 m s(-1), P < or = 0.02) in swimmers than in controls. Vmax was greater (18.6 +/-4.8 vs. 14.9 +/-5.3 cm m(-2), P < 0.03), whereas ACTEF was lower (36 +/- 12% vs. 44.2 +/- 12%, P < 0.04) in swimmers than in controls.

CONCLUSION

Cardiac adaptation to intensive training in prepubertal swimmers includes vagal predominance, a mild increase in left ventricular dimensions without significant changes in septal or posterior wall thickness, and increased LA size associated with depressed LA systolic function. Evaluation of LA size and systolic function may contribute to a better understanding of the characteristics of the 'athlete's heart' in children and to the differential diagnosis between left ventricular adaptive and pathologic changes.