Reliability of left atrial strain reference values: A 3D echocardiographic study

Early detection of left atrial dysfunction in young hypertensive patients with a normal left atrial size: a comprehensive analysis using four-dimensional auto left atrial quantification echocardiography

BACKGROUND

This study aimed to detect early left atrial (LA) function abnormalities in young hypertensive patients with a normal two-dimensional LA volume index (2D-LAVI) using four-dimensional auto LA quantification technology (4D Auto LAQ) and to analyse correlations between LA strain parameters and clinical metabolic indicators.

METHODS

This study enrolled 70 young patients who underwent standard hypertension treatment or diagnosis at the Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, from October 2023 to July 2024 and 41 control volunteers enrolled during the same period. LA volume and strain parameters were evaluated with a 4D Auto LAQ. A correlation analysis was conducted between the clinical and strain parameters.

RESULTS

Compared with the control group, young hypertensive patients presented significantly greater LA minimum volume (LAVmin), LA minimum volume index (LAVImin) and LA pre-atrial volume (LAVpreA) values (all p < 0.001). The LA ejection fraction (LAEF) was reduced in young hypertensive patients (57.85%±4.47% vs. 50.44%±5.96%, p < 0.001), along with LA reservoir longitudinal strain (25.00% [20.50-29.50%] vs. 20.00% [16.00-24.25%], p < 0.001), LA conduit longitudinal strain (-16.32%±4.19% vs. -11.37%±4.65%, p < 0.001), LA contraction longitudinal strain (-12.27%±2.85% vs. -9.60 ± 4.12, p < 0.001), LA reservoir circumferential strain (34.32%±6.90% vs. 28.41%±6.95%, p < 0.001), LA conduit circumferential strain (-17.90%±4.84% vs. -11.46%±4.96%, p < 0.001), and LA contraction circumferential strain (-18.54%±4.85% vs. -16.23%±6.11%, p < 0.05). Multivariate linear regression analysis revealed that body mass index (BMI), triglyceride (TG), and uric acid (UA) were negatively and independently correlated with LA longitudinal strain.

CONCLUSIONS

In young hypertensive patients with normal 2D-LAVI, while LAVmin, LAVImin and LAVpreA are elevated, the LAEF and LA reservoir, conduit, and contraction strain are notably reduced. The application of 4D Auto LAQ technology may highlight altered values in young hypertensive patients with normal 2D-LAVI. 4D Auto LAQ may serve as a valuable tool for clinicians in the early detection and assessment of LA dysfunction in young hypertensive patients.

Diagnosis of atrial cardiomyopathy: from the electrocardiogram to the new opportunities with multimodality imaging

Atrial cardiomyopathy (AC) has been defined by the European Heart Rhythm Association as "Any complex of structural, architectural, contractile, or electrophysiologic changes in the atria with the potential to produce clinically relevant manifestations".1 The left atrium (LA) plays a key role in maintaining normal cardiac function; in fact atrial dysfunction has emerged as an essential determinant of outcomes in different clinical scenarios, such as valvular diseases, heart failure (HF), coronary artery disease (CAD) and atrial fibrillation (AF). A comprehensive evaluation, both anatomical and functional, is routinely performed in cardiac imaging laboratories. Recent advances in imaging techniques offer opportunities for evaluation of LA function, fundamental in clinical practice for early cardiovascular (CV) risk estimation, choice of therapeutic intervention and follow up. In this review we explore the concept of AC, its diagnosis through a multimodal approach, ranging from the historical electrocardiogram to the latest CV imaging techniques and its clinical implications.

Identification of atrial myopathy and atrial fibrillation recurrence after ablation using 3D left atrial phasic strain from retrospective gated computed tomography

Aims

Reduced left atrial (LA) mechanical function associates with atrial myopathy and adverse clinical endpoints in atrial fibrillation (AF) patients; however, conventional 2D imaging modalities are limited by atrial foreshortening and sub-optimally capture 3D LA motion.

Objectives

We set out to test the hypothesis that 3D LA motion features from 4D (3D + time) retrospective gated computed tomography (RGCT) associate with AF phenotypes and predict AF recurrence in patients undergoing catheter ablation.

Methods and results

Sixty-nine AF patients (60.8 ± 12.2 years, 39% female, 30% non-paroxysmal AF) who were indicated for CT coronary angiography including a RGCT protocol in sinus rhythm prior to ablation were included. We measured 3D LA endocardial motion by optimized 3D feature tracking and calculated 3D global and regional phasic strain and peak strain rates (SRs). AF recurrence was observed in 18 patients (26%) at 1-year. Global reservoir strain (P < 0.05) and contractile strain and SR (both P < 0.01) were reduced in patients with vs. those without recurrent AF. Global and anterior wall contractile SR were more predictive of recurrent AF than LA volume index (area under the curve, AUC: 0.74, 0.77, and 0.68, respectively). Reduced global conduit SR and septal reservoir strain were more strongly associated with non-paroxysmal AF than CHADS2-VASc (AUCs: 0.74, 0.75, and 0.59, respectively).

Conclusion

Reduced passive and active 3D LA motion from 4D RGCT associates with more advanced AF and AF recurrence post-ablation, respectively. Future work should extend this approach to larger populations, with new low-radiation CT technologies to widen its applicability.

High volume-rate echocardiography for simultaneous imaging of electromechanical activation and cardiac strain of the whole heart in a single heartbeat in humans

BACKGROUND

Imaging both electrical and mechanical cardiac function can better characterize cardiac disease and improve patient care. Currently, there is no noninvasive technique that can simultaneously image both electrical and mechanical function of the whole heart at the point of care. Here, our aim is to demonstrate that high volume-rate echocardiography can simultaneously map cardiac electromechanical activation and end-systolic cardiac strain of the whole heart in a single heartbeat.

METHOD

A 32x32 ultrasound matrix array connected to four synchronized ultrasound scanners were used for transthoracic high volume-rate imaging (840 volumes/s) in sixteen young volunteers (28.1±4.2 y.o.). An electromechanical activation map of the whole heart and volumetric end-systolic atrial and ventricular strain images were obtained.

RESULTS

The whole heart activation sequence was found to be consistent across volunteers and in agreement with previously reported normal electrical activation sequences. The mean electromechanical activation time was 72.6±15.2 ms in the atria, 132.4±19.7 ms in the ventricles and 154.5±19.6 ms in the whole heart. Volumetric right and left atrial as well as right and left ventricular strains were also consistent across all volunteers, with a mean end-systolic global longitudinal strain of 26.8±6.5% in the atria and -16.6±3.4% in the ventricles.

CONCLUSIONS

This initial feasibility study demonstrates that noninvasive high-volume rate imaging of the heart in a single heartbeat is feasible and can provide electromechanical activation and systolic strains simultaneously in all four cardiac chambers. This technique can be further developed and used at the point of care to assist for screening, diagnosis, therapy guidance and follow-up of heart disease patients.

Evaluation of left atrial function and the relationship between left atrial stiffness index and exercise capacity in hypertension-related heart failure with preserved ejection fraction

Objective

The left atrial stiffness index (LASI) holds significance in the atrioventricular coupling function and heart failure progression. To assess left atrial function and evaluate the relationship between LASI and exercise capacity in hypertension-related heart failure with preserved ejection fraction (HT-HFpEF).

Methods

The study involved 62 healthy subjects and 163 patients with HT (112 patients in simple HT group and 51 patients in HT-HFpEF group). Each patient performed exercise stress test and standard ultrasonic images were evaluated. A comprehensive evaluation of atrioventricular function, along with investigation into the correlation between these functional parameters and exercise capacity. And further to investigate the feasibility of predicting exercise intolerance using three-dimensional derived left atrial strain index (LASI) (E/e'/LASr and E/e'/LASr-c).

Results

Compared to healthy subjects, HT group demonstrated the elevation in left atrial volume accompanied by decrease in strain value (P < 0.05). In HT-HFpEF group, further significant reductions were observed in both longitudinal (LASr) and circumferential strain (LASr-c, LASct-c) (P < 0.05). Univariate regression demonstrated that both E/e'/LASr and E/e'/LASr-c were significantly correlated with metabolic equivalents (METs) (r = -0.462, P < 0.001; r = -0.381, P < 0.001). The E/e'/LASr demonstrates comparable diagnostic efficacy to exercise-E/e' in assessing exercise intolerance in HT-HFpEF patients (AUC: 0.836 vs. 0.867, P = 0.239).

Conclusion

Progressive LA remodeling contributes to decreased atrioventricular compliance in HT and HT-HFpEF patients.E/e'/LASr serves as an independent indicator of exercise intolerance in patients with HT-HFpEF.

Left atrial strain measured by three-dimensional echocardiography predicts atrial fibrillation in the general population

BACKGROUND

Left atrial (LA) strain by three-dimensional echocardiography (3DE), has been proposed as a more accurate measure of LA function, providing incremental prognostic benefits over traditional two-dimensional approaches.

OBJECTIVES

Our aim was to evaluate the prognostic value of LA strain by 3DE in predicting incident atrial fibrillation (AF) in the general population.

METHODS

The study included 4466 participants from a prospective longitudinal cohort study in the general population, among these 3DE LA strain was analysed in 1935 participants. The endpoint was incident AF. Adjustments were made for the CHARGE-AF clinical risk score.

RESULTS

Mean age was 54 ± 17 years, 43 % were male. During a median follow-up time of 4.8 years (interquartile range 4.3-5.5 years) 59 participants (3.0 %) developed AF. In univariable analysis, all three parameters were associated with incident AF (p value for all <0.01). After multivariable adjustments, only LA reservoir strain (LASr) and LA contractile strain (LASct) were associated with incident AF (LASr: HR 1.12 (1.07-1.17), p < 0.001, per 1 % decrease; LASct: HR 1.16 (1.09-1.24), p < 0.001, per 1 % decrease), whereas LA conduit strain (LAScd) was not (HR 1.04 (0.98-1.10), p = 0.17, per 1 % decrease). Both LASr (continuous net reclassification index 0.37 ± 0.14; p = 0.003) and LASct (continuous net reclassification index 0.41 ± 0.14; p = 0.002) provided incremental prognostic information beyond the CHARGE-AF risk score.

CONCLUSION

LASr and LASct measured by 3DE are independently associated with incident AF and provided incremental prognostic information beyond existing risk scores.

Left Atrial Strain: State of the Art and Clinical Implications

The assessment of left atrial strain (LAS) has emerged as an essential component in the evaluation of cardiac function, especially in pathologies such as heart failure and atrial fibrillation. This narrative review aims to outline the available methods for assessing LAS with a major emphasis on speckle-tracking echocardiography techniques. Other imaging modalities, including cardiac magnetic resonance and cardiac computed tomography, also provide important information on LA dynamics but have disadvantages with respect to cost and availability. The current narrative review underlines basic concepts such as the accurate assessment of LAS and discusses the clinical relevance of LAS by pointing out its significant diagnostic and prognostic role in several cardiovascular conditions. The aim of this article is to discuss the current integration of LAS into clinical practice with a view to further improving patient management and treatment strategies.

Prognostic value of left ventricular and left atrial strain imaging in moderate to severe aortic stenosis: Insights from an Asian population

BACKGROUND

Data regarding the prognostic value of left atrial (LA) strain in aortic stenosis (AS) is scarce, especially in Asian population and moderate AS.

METHOD

Left ventricular global longitudinal strain (LVGLS), LA reservoir strain (LASr), conduit strain (LAScd), and contractile strain (LASct) were measured using automated speckle-tracking echocardiography in consecutive patients with moderate or severe AS. The primary endpoint was a composite of all-cause death (ACD) and major adverse cardiovascular events (MACE; myocardial infarction, syncope, and heart failure hospitalization).

RESULTS

Of 712 patients (mean age, 78 ± 12 years; 370 [52%] moderate AS; 342 [48%] severe AS), average LV ejection fraction (LVEF) was 68 with SD of 12%. At a median follow-up of 18 months (interquartile range, 11-26 months), the primary endpoint occurred in 93 patients (60 deaths and 35 MACEs) and 221 patients underwent surgical or transcatheter aortic valve replacement (AVR). In the entire cohort, separate multivariable models adjusted for age, Charlson index, symptomatic status, time-dependent AVR, AS-severity, LA volume index and LVEF demonstrated that only LASr was associated with MACE+ACD (Hazard ratio, 0.97; P = 0.014). Subgroup analysis for MACE+ACD demonstrated consistent prognostication for LASr in moderate and severe AS; LVGLS was prognostic only in severe AS (all P ≤ 0.023). The optimal MACE+ACD cutoff for LASr from spline curves was 21.3%. Adjusted Kaplan-Meier curves demonstrated better event-free survival in patients with LASr >21.3% versus those with LASr ≤21.3% (P = 0.04).

CONCLUSIONS

In both moderate and severe AS, only LASr robustly predicted outcomes; thus, including LASr in the AS staging algorithm should be considered.

Left atrial reservoir strain is a marker of atrial fibrotic remodeling in patients undergoing cardiovascular surgery: Analysis of gene expression

Left atrial strain (LAS) measured by two-dimensional speckle tracking echocardiography (2DSTE) is considered to be a marker of LA structural remodeling, but it remains unsettled. We investigated the potential usefulness and clinical relevance of LAS to detect atrial remodeling including fibrosis by analyzing gene expression in cardiovascular surgery patients. Preoperative 2DSTE was performed in 131 patients (92 patients with sinus rhythm [SR] patients including paroxysmal AF [PAF], 39 atrial fibrillation [AF]) undergoing cardiovascular surgery. Atrial samples were obtained from the left atrial appendages, and mRNA expression level was analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) in 59 cases (24 PAF, 35 AF). Mean value of left atrial reservoir strain (mLASr) correlated with left atrial volume index (LAVI), and left atrial conduit strain (mLAScd). mLASr also correlated with left atrial contractile strain (mLASct) in SR patients including PAF. mLASr was significantly lower, and LAVI was higher, in the AF group, compared with SR patients including PAF. The expression of COL1A1 mRNA encoding collagen type I α1 significantly increased in AF patients (p = 0.031). mLASr negatively correlated with COL1A1 expression level, and multivariate regression analysis showed that mLASr was an independent predictor of atrial COL1A1 expression level, even after adjusting for age, sex, and BMI. But, neither mLAScd / mLASct nor LAVI (bp) correlated with COL1A1 gene expression. The expression level of COL1A1 mRNA strongly correlated with ECM-related genes (COL3A1, FN1). It also correlated ECM degradation-related genes (MMP2, TIMP1, and TIMP2), pro-fibrogenic cytokines (TGFB1 encoding TGFβ1, END1, PDGFD, CTGF), oxidant stress-related genes (NOX2, NOX4), ACE, inflammation-related genes (NLRP, IL1B, MCP-1), and apoptosis (BAX). Among the fibrosis-related genes examined, univariable regression analysis showed that log (COL1A1) was associated with log (TGFB1) (adjusted R2 = 0.685, p<0.001), log (NOX4) (adjusted R2 = 0.622, p<0.001), log (NOX2) (adjusted R2 = 0.611, p<0.001), suggesting that TGFB1 and NOX4 was the potent independent determinants of COL1A1 expression level. mLASr negatively correlated with the ECM-related genes, and fibrosis-related gene expression level including TGFB1, NOX2, and NLRP3 in PAF patients. PAF patients with low mLASr had higher expression of the fibrosis-related gene expression, compared with those with high mLASr. These results suggest that LASr correlates with atrial COL1A1 gene expression associated with fibrosis-related gene expression. Patients with low LASr exhibit increased atrial fibrosis-related gene expression, even those with PAF, highlighting the utility of LAS as a marker for LA fibrosis in cardiovascular surgery patients.

Patient-specific left atrium contraction quantification associated with atrial fibrillation: A region-based approach

BACKGROUND AND OBJECTIVES

Atrial fibrillation (AF) is a widespread cardiac arrhythmia that significantly impacts heart function. AF disrupts atrial mechanical contraction, leading to irregular, uncoordinated, and slow blood flow inside the atria which favors the formation of clots, primarily within the left atrium (LA). A standardized region-based analysis of the LA is missing, and there is not even any consensus about how to define the LA regions. In this study we propose an automatic approach for regionalizing the LA into segments to provide a comprehensive 3D region-based LA contraction assessment. LA global and regional contraction were quantified in control subjects and in AF patients to describe mechanical abnormalities associated with AF.

METHODS

The proposed automatic approach for LA regionalization was tested in thirteen control subjects and seventeen AF patients. After dividing LA into standard regions, we evaluated the global and regional mechanical function by measuring LA contraction parameters, such as regional volume, global and regional strains, regional wall motion and regional shortening fraction.

RESULTS

LA regionalization was successful in all study subjects. In the AF group compared with control subjects, results showed: a global impairment of LA contraction which appeared more pronounced along radial and circumferential direction; a regional impairment of radial strain which was more pronounced in septal, inferior, and lateral regions suggesting a greater reduction in mechanical efficiency in these regions in comparison to the posterior and anterior ones.

CONCLUSION

An automatic approach for LA regionalization was proposed. The regionalization method was proved to be robust with several LA anatomical variations and able to characterize contraction changes associated with AF.

Incremental diagnostic and prognostic utility of left atrial deformation in heart failure using speckle tracking echocardiography

Left atrium (LA) is a very important component of cardiovascular performance. The assessment of LA function has gathered the interest with expanding research supporting the utility as a biomarker for outcomes in heart failure (HF). Echocardiography is the main imaging modality which helps in a qualitative and quantitative assessment of the LA size and function. Recent advances in probe technology and software analysis have provided a better understanding of LA anatomy, physiology, pathology, and function. A variety of parameters have been defined as markers of LA function but there is no single parameter that best defines LA function. Speckle tracking echocardiography-derived analysis of LA deformation provides a window on all phases of LA function (reservoir, conduit, and booster pump). There is accumulative published data that supported the diagnostic and prognostic values of LA deformation integration during echo assessment of LA in HF. This review article summarized the clinical utility of LA deformation that may help in prediction, diagnosis, categorization, risk stratification, and guiding the proper selection of therapy in HF patients in daily practice.

Normal values for left atrial strain, volume, and function derived from 3D echocardiography: the Copenhagen City Heart Study

AIMS

3D echocardiographic (3DE) assessment of the left atrium (LA) is a new modality of potential clinical value. Age- and sex-based normative values are needed to benchmark these parameters for clinical use.

METHODS AND RESULTS

Of 4466 participants in the 5th Copenhagen City Heart Study, a prospective longitudinal cohort study on the general population, 2082 participants underwent 3DE of the LA. Healthy participants were included to establish normative values for LA strain, volume, and function by 3DE. The effects of age and sex were also evaluated. After excluding participants with comorbidities, 979 healthy participants (median age 44 years, 39.6% males) remained. The median and limits of normality (2.5th and 97.5th percentiles) for functional and volumetric measures were as follows: LA reservoir strain (LASr) 30.8% (18.4-44.2%), LA conduit strain (LAScd) 19.1% (6.8-32.0%), LA contractile strain 11.7% (4.3-22.2%), total LA emptying fraction (LAEF) 61.4% (47.8-71.0%), passive LAEF 37.7% (17.4-53.9%), active LAEF 37.4% (22.2-52.5%), LA minimum volume index (LAVimin) 10.2 (5.9-18.5) mL/m2, and LA maximum volume index (LAVimax) 26.8 (16.5-40.1) mL/m2. All parameters changed significantly with increasing age (P value for all <0.001). Significant sex-specific differences were observed for all parameters except active LAEF and LAVimax. Sex significantly modified the association between age and LASr (P for interaction < 0.001), LAScd (P for interaction < 0.001), LAVimin (P for interaction = 0.037), and total LAEF (P for interaction = 0.034) such that these parameters deteriorated faster with age in females than males.

CONCLUSION

We present age- and sex-specific reference material including limits of normality for LA strain, volume, and function by 3DE.

A method for measuring the angle between left atrial and left ventricular long axes using 3D echocardiography

BACKGROUND

Left ventricle (LV) optimized views are routinely used for left atrial (LA) volume and strain measurements on 2D echocardiography. This might be a source of the error because of the variation of the angle between the left atrial and left ventricle long axes (LA-LV angle), leading to foreshortening of the LA.

METHODS

We investigated two novel parameters: the angle between the left atrial and left ventricle long axes (LA-LV angle) and its deviation from the 4-chamber plane. To accurately measure the angles in 3D space, these measurements were performed using 3D echocardiography. We developed a method for the measurement based on marking anatomic points of reference in the 3D echocardiogram and measuring the angles between these points. We used three types of phantoms made of wood and agar-agar to investigate the repeatability and reproducibility of these measurements and performed measurements on human subjects.

RESULTS

The ultrasound measurements were in excellent agreement with the true angles of the phantoms: LA-LV angle bias was .5 degrees (95% CI -1.8 to +2.7) in the wooden phantoms and 1.2 degrees (-.7 to +3.1) in the agar-agar phantoms, while the angle deviation from the 4-chamber plane was -.9 degrees (-4.3 to +4.1) in the wooden phantoms and .0 degrees (-3.3 to +3.3) in the agar-agar phantoms. The measurements demonstrated good repeatability and reproducibility (Pearson correlation coefficients ranging from .91 to .99). The measurements from human hearts showed good repeatability (Pearson correlation was .81 for repeated LA-LV angle measurements and .97 for repeated measurements of the deviation from the 4-chamber plane).

CONCLUSION

The measurement of the LA-LV angle is a feasible tool to investigate one eventual error of 2D echocardiography.

The use of dedicated long-axis views focused on the left atrium improves the accuracy of left atrial volumes and emptying fraction measured by cardiovascular magnetic resonance

BACKGROUND

The use of apical views focused on the left atrium (LA) has improved the accuracy of LA volume evaluation by two-dimensional (2D) echocardiography. However, routine cardiovascular magnetic resonance (CMR) evaluation of LA volumes still uses standard 2- and 4-chamber cine images focused on the left ventricle (LV). To investigate the potential of LA-focused CMR cine images, we compared LA maximuml (LAVmax) and minimum (LAVmin) volumes, and emptying fraction (LAEF), calculated on both standard and LA-focused long-axis cine images, with LA volumes and LAEF obtained by short-axis cine stacks covering the LA. LA strain was also calculated and compared between standard and LA-focused images.

METHODS

LA volumes and LAEF were obtained from 108 consecutive patients by applying the biplane area-length algorithm to both standard and LA-focused 2- and 4-chamber cine images. Manual segmentation of a short-axis cine stack covering the LA was used as the reference method. In addition, LA strain reservoir (εs), conduit (εe) and booster pump (εa) were calculated using CMR feature-tracking.

RESULTS

Compared to the reference method, the standard approach significantly underestimated LA volumes (LAVmax: bias - 13 ml; LOA =  + 11, - 37 ml; LAVmax i: bias - 7 ml/m2; LOA =  + 7, - 21 ml/m2; LAVmin; bias - 10 ml, LOA: + 9, - 28 ml; LAVmin i: bias - 5 ml/m2, LOA: + 5, - 16 ml/m2), and overestimated LA-EF (bias 5%, LOA: + 23, - 14%). Conversely, LA volumes (LAVmax: bias 0 ml; LOA: + 10, - 10 ml; LAVmax i: bias 0 ml/m2; LOA: + 5, - 6 ml/m2; LAVmin: bias - 2 ml; LOA: + 7, - 10 ml; LAVmin i: bias - 1 ml/m2; LOA: + 3, - 5 ml/m2) and LAEF (bias 2%, LOA: + 11, - 7%) by LA-focused cine images were similar to those measured using the reference method. LA volumes by LA-focused images were obtained faster than using the reference method (1.2 vs 4.5 min, p < 0.001). LA strain (εs: bias 7%, LOA = 25, - 11%; εe: bias 4%, LOA = 15, - 8%; εa: bias 3%, LOA = 14, - 8%) was significantly higher in standard vs. LA-focused images (p < 0.001).

CONCLUSION

LA volumes and LAEF measured using dedicated LA-focused long-axis cine images are more accurate than using standard LV-focused cine images. Moreover, LA strain is significantly lower in LA-focused vs. standard images.

Normal ranges of left atrial volumes and ejection fraction by 3D echocardiography in adults: a systematic review and meta-analysis

Increased sizes and dysfunction of the left atrium have been related to adverse outcomes. 3D-echocardiography is more accurate than 2D-echocardiography in estimating LA volumes and ejection fraction. However, the use of 3DE for LA analysis is limited by the absence of established reference values. We performed a systematic review and meta-analysis to provide reference ranges of LA maximum and minimum volumes indexed for body surface area (LAVi max and LAVi min, respectively), and LA-EF assessed by 3DE in healthy adults. Data search was conducted from inception through September 15, 2021, using the following Medical Subject Heading terms: left atrial/atrium, three-dimensional/3D echocardiography. The study protocol was registered in the PROSPERO database (CRD42021252428). 15 studies including 4,226 healthy adults (51% males) and reporting 3DE values of LAVi max, LAVi min and LA-EF were selected. LAVi max, LAVi min and LA-EF mean and reference values were equal to 25.18 ml/m2 (95% CI 23.10, 27.26), 11.10 ml/m2 (10.01, 12.18) and 55.94% (51.92, 59.96), respectively. No influential studies were identified. Pooled estimates per age group- and sex were also estimated. By meta-regression analyses, we identified variability in LA volumes and LA-EF depending on participants' age, ethnicity and number of heart cycles at 3D multi-beat acquisition. At individual patient data analysis conducted on 374 subjects, a software effect on LA-EF was shown. This systematic review and meta-analysis provides reference values of LAVi max, LAVi min and LA-EF assessed by 3DE in healthy adults, encouraging 3DE evaluation of the LA evaluation in daily practice.

A systematic review and meta-analysis of the normal reference value of the longitudinal left atrial strain by three dimensional speckle tracking echocardiography

The normal reference value of the global longitudinal left atrial strain during the reservoir phase (LASr) by 3D speckle-tracking echocardiography (3DSTE) is needed to define the abnormal and normal spectra and to compare and interpret the obtained values. The present study is a meta-analysis of 3DSTE-derived normal reference value of the longitudinal LASr and an attempt to determine probable contributing factors in the variations of reported ranges. The databases of PubMed, Scopus, and Embase were searched for the following keywordS: "Left atrial/left atrium" and "strain/speckle/deformation" and "three-dimensional/3-dimensional/three dimensional/3 dimensional/three dimension/3 dimension/three-dimension/3-dimension/3D/3-D". The studies selected included those on adult healthy subjects without cardiovascular risk factors. A random-effect model was used to calculate the global 3DSTE-derived longitudinal LASr, and meta-regression was applied to determine inter-study heterogeneity. Our search yielded 316 adult subjects from 5 studies. The mean value of the global 3DSTE-derived longitudinal LASr was 27.5% (95% CI, 25.2-29.8%). There was significant heterogeneity between the studies. The meta-regression analysis revealed the publication year, the heart rate, and systolic and diastolic blood pressure as the sources of heterogeneity. The current meta-analysis determined a normal reference value of the global 3DSTE-derived longitudinal LASr of 27.5% (95% CI, 25.2-29.8%). The heterogeneity between studies may be explained by the publication year, the heart rate, and systolic and diastolic blood pressure.

Left Atrial Function Post Radiofrequency and Cryoballoon Ablation Assessed by Volume-Pressure Loops

BACKGROUND

Left atrial (LA) function is linked to atrial fibrillation (AF) pathogenesis. AF catheter ablation decreases disease burden with potentially favorable effects on cardiac function. Atrial volume-pressure loops can optimally assess the LA function.

OBJECTIVE

To investigate changes in LA function by volume-pressure loops after paroxysmal AF ablation and explored potential differences between the radiofrequency and cryoballoon ablation.

METHODS

We analyzed 44 patients undergoing paroxysmal AF ablation from 2 centers, 22 treated with radiofrequency and 22 with cryoablation. Pre- and post-procedure, all patients underwent a real-time three-dimensional transthoracic ECG to evaluate LA volume, while simultaneously recording LA pressure following transseptal puncture. Volume-pressure loops pre- and post-procedure were created by paired data. Areas of A-loop (LA booster pump function) and V-loop (LA reservoir function), and the stiffness constant determining the slope of the exponential curve during LA filling were calculated.

RESULTS

Average LA pressure, A-wave amplitude, and V-wave amplitude were increased post-procedurally (p < 0.001). Overall, A-loop area decreased (p = 0.001) and V-loop area tended to increase (p = 0.07). The change in both A-loop and V-loop areas was similar between radiofrequency- and cryoballoon-treated patients (p = 0.18 and p = 0.52, respectively). However, compared with cryoballoon-treated patients, radiofrequency-treated patients had higher increase in the stiffness constant (b = 0.059; 95% CI: 0.022-0.096; p = 0.006).

CONCLUSION

AF catheter ablation by the radiofrequency or cryoballoon is associated with the decrease of the booster pump function and increase of the reservoir function. Moreover, there is a post-procedural increase of LA pressure which is associated with an acute increase in LA stiffness in radiofrequency ablation, but not in cryoablation.

Cardiac Imaging for the Assessment of Left Atrial Mechanics Across Heart Failure Stages

The left atrium (LA) is emerging as a key element in the pathophysiology of several cardiac diseases due to having an active role in contrasting heart failure (HF) progression. Its morphological and functional remodeling occurs progressively according to pressure or volume overload generated by the underlying disease, and its ability of adaptation contributes to avoid pulmonary circulation congestion and to postpone HF symptoms. Moreover, early signs of LA dysfunction can anticipate and predict the clinical course of HF diseases before the symptom onset which, particularly, also applies to patients with increased risk of HF with still normal cardiac structure (stage A HF). The study of LA mechanics (chamber morphology and function) is moving from a research interest to a clinical application thanks to a great clinical, prognostic, and pathophysiological significance. This process is promoted by the technological progress of cardiac imaging which increases the availability of easy-to-use tools for clinicians and HF specialists. Two-dimensional (2D) speckle tracking echocardiography and feature tracking cardiac magnetic resonance are becoming essential for daily practice. In this context, a deep understanding of LA mechanics, its prognostic significance, and the available approaches are essential to improve clinical practice. The present review will focus on LA mechanics, discussing atrial physiology and pathophysiology of main cardiac diseases across the HF stages with specific attention to the prognostic significance. Imaging techniques for LA mechanics assessment will be discussed with an overlook on the dynamic (under stress) evaluation of the chamber.

Left atrial evaluation by cardiovascular magnetic resonance: sensitive and unique biomarkers

Left atrial (LA) imaging is still not routinely used for diagnosis and risk stratification, although recent studies have emphasized its importance as an imaging biomarker. Cardiovascular magnetic resonance is able to evaluate LA structure and function, metrics that serve as early indicators of disease, and provide prognostic information, e.g. regarding diastolic dysfunction, and atrial fibrillation (AF). MR angiography defines atrial anatomy, useful for planning ablation procedures, and also for characterizing atrial shapes and sizes that might predict cardiovascular events, e.g. stroke. Long-axis cine images can be evaluated to define minimum, maximum, and pre-atrial contraction LA volumes, and ejection fractions (EFs). More modern feature tracking of these cine images provides longitudinal LA strain through the cardiac cycle, and strain rates. Strain may be a more sensitive marker than EF and can predict post-operative AF, AF recurrence after ablation, outcomes in hypertrophic cardiomyopathy, stratification of diastolic dysfunction, and strain correlates with atrial fibrosis. Using high-resolution late gadolinium enhancement (LGE), the extent of fibrosis in the LA can be estimated and post-ablation scar can be evaluated. The LA LGE method is widely available, its reproducibility is good, and validations with voltage-mapping exist, although further scan-rescan studies are needed, and consensus regarding atrial segmentation is lacking. Using LGE, scar patterns after ablation in AF subjects can be reproducibly defined. Evaluation of 'pre-existent' atrial fibrosis may have roles in predicting AF recurrence after ablation, predicting new-onset AF and diastolic dysfunction in patients without AF. LA imaging biomarkers are ready to enter into diagnostic clinical practice.

The prognostic impact of mechanical atrial dysfunction and atrial fibrillation in heart failure with preserved ejection fraction

AIMS

This study assessed the prognostic implications of mechanical atrial dysfunction in heart failure with preserved ejection fraction (HFpEF) patients with different stages of atrial fibrillation (AF) in detail.

METHODS AND RESULTS

HFpEF patients (n = 258) systemically underwent an extensive clinical characterization, including 24-h Holter monitoring and speckle-tracking echocardiography. Patients were categorized according to rhythm and stages of AF: 112 with no history of AF (no AF), 56 with paroxysmal AF (PAF), and 90 with sustained (persistent/permanent) AF (SAF). A progressive decrease in mechanical atrial function was seen: left atrial reservoir strain (LASr) 30.5 ± 10.5% (no AF), 22.3 ± 10.5% (PAF), and 13.9 ± 7.8% (SAF), P < 0.001. Independent predictors for lower LASr values were AF, absence of chronic obstructive pulmonary disease, higher N-terminal-pro hormone B-type natriuretic peptide, left atrial volume index, and relative wall thickness, lower left ventricular global longitudinal strain, and echocardiographic signs of elevated left ventricular filling pressure. LASr was an independent predictor of adverse outcome (hazard ratio per 1% decrease =1.049, 95% confidence interval 1.014-1.085, P = 0.006), whereas AF was not when the multivariable model included LASr. Moreover, LASr mediated the adverse outcome associated with AF in HFpEF (P = 0.008).

CONCLUSION

Mechanical atrial dysfunction has a possible greater prognostic role in HFpEF compared to AF status alone. Mechanical atrial dysfunction is a predictor of adverse outcome independently of AF presence or stage, and may be an underlying mechanism (mediator) for the worse outcome associated with AF in HFpEF. This may suggest mechanical atrial dysfunction plays a crucial role in disease progression in HFpEF patients with AF, and possibly also in HFpEF patients without AF.