Reproducibility of left atrial function using cardiac magnetic resonance imaging

High-Resolution Maps of Left Atrial Displacements and Strains Estimated With 3D Cine MRI Using Online Learning Neural Networks

The functional analysis of the left atrium (LA) is important for evaluating cardiac health and understanding diseases like atrial fibrillation. Cine MRI is ideally placed for the detailed 3D characterization of LA motion and deformation but is lacking appropriate acquisition and analysis tools. Here, we propose tools for the Analysis of Left Atrial Displacements and DeformatIons using online learning neural Networks (Aladdin) and present a technical feasibility study on how Aladdin can characterize 3D LA function globally and regionally. Aladdin includes an online segmentation and image registration network, and a strain calculation pipeline tailored to the LA. We create maps of LA Displacement Vector Field (DVF) magnitude and LA principal strain values from images of 10 healthy volunteers and 8 patients with cardiovascular disease (CVD), of which 2 had large left ventricular ejection fraction (LVEF) impairment. We additionally create an atlas of these biomarkers using the data from the healthy volunteers. Results showed that Aladdin can accurately track the LA wall across the cardiac cycle and characterize its motion and deformation. Global LA function markers assessed with Aladdin agree well with estimates from 2D Cine MRI. A more marked active contraction phase was observed in the healthy cohort, while the CVD $\text {LVEF}_{\downarrow } $ group showed overall reduced LA function. Aladdin is uniquely able to identify LA regions with abnormal deformation metrics that may indicate focal pathology. We expect Aladdin to have important clinical applications as it can non-invasively characterize atrial pathophysiology. All source code and data are available at: https://github.com/cgalaz01/aladdin_cmr_la.

Diagnostic value of cardiac magnetic resonance imaging-based left atrial strain analysis for identifying cardiac diseases with overlapping phenotype

BACKGROUND

The main objective of this study was to compare diagnostic accuracies of cardiac magnetic resonance (CMR)-based left atrial (LA) volumetry and function, including LA strain analysis, for the detection of myocardial impairments in diseases of different etiologies such as hypertensive heart disease, Fabry disease and acute myocarditis.

METHODS

Healthy volunteers (HV, n = 50) and patients with cardiomyopathies (n = 140), including patients with hypertensive heart disease (n = 40), Fabry disease (n = 49), and acute myocarditis (n = 51), underwent CMR at 3 T. Atrial volume and strain analysis based on long-axis cine acquisition was performed using a commercially available post-processing software.

RESULTS

Patients exhibited impaired LA reservoir (28.60 ± 9.91 % vs. 41.27 ± 7.54 %), conduit (17.35 ± 7.72 % vs. 26.89 ± 5.25 %) and booster strain (11.30 ± 4.52 % vs. 14.61 ± 4.15 %) parameters compared to HV (all p < 0.001). In contrast, the volumetric values showed no significant difference between patients and HV (p > 0.05). Passive and total emptying fractions were significantly lower in patients (p < 0.001), while active emptying fraction did not differ (p > 0.05). Superior diagnostic accuracy for the LA reservoir strain demonstrated improved prognostic performance comparing to LA volumetric and functional parameters (area under the curve [AUC] 0.85 vs. e.g. passive emptying fraction AUC 0.78, p < 0.05).

CONCLUSION

LA strain parameters effectively distinguish patients with cardiac diseases presenting overlapping phenotypes from HV and outperform volumetric and traditional functional assessments of the LA.

The value of left ventricular T1 mapping and left atrial strain for distinguishing myocardial amyloidosis and hypertrophic cardiomyopathy

PURPOSE

This study aimed to use T1 mapping and left atrial feature tracking techniques to distinguish myocardial amyloidosis (CA) from hypertrophic cardiomyopathy (HCM).

METHODS

A retrospective analysis was conducted on 130 subjects who underwent cardiac magnetic resonance examinations from January 2021 to May 2024 at 1.5 and 3.0 T systems. Measurements of global left ventricular myocardial T1 values were performed, a standardized T1 z-score used as an assessment metric to overcome the effects of various manufacturers and field strengths. Left atrial strain was measured with feature tracking techniques.

RESULTS

42 CA patients、58 HCM patients and 30 healthy subjects were analyzed. For both 1.5T and 3.0T systems, the overall T1 values of LV myocardium was significantly higher in the CA group compared with the HCM and control groups (p < 0.001). T1z-scores in the CA and HCM groups were 4.8 ± 2.2 and 3.4 ± 1.9, respectively (p < 0.001). Myocardial strain analysis showed that atrial strain was significantly lower in the CA group when compared with the HCM and healthy control groups (p < 0.05). The correlation between left atrial strain and function parameters was assessed through Spearman correlation analysis. Multivariate logistic regression analysis showed that a combination model including T1z-score and left atrial reservoir function (Es) had an improved ability to discriminate CA and HCM with a higher AUC (0.937), with a sensitivity of 95.2% and a specificity of 83.3% (P < 0.05).

CONCLUSION

T1 mapping combined with Εs could effectively distinguish CA from HCM, and provide new insights for the diagnosis of the etiology and treatment of cardiac hypertrophic diseases.

Prognostic value of left atrioventricular coupling index in heart failure

AIMS

To investigate the distribution of left atrioventricular coupling index (LACI) among patients with heart failure and left ventricular ejection fraction (LVEF) < 50% and to explore its association with the combined endpoint of all-cause death or HF hospitalization at long-term follow-up.

METHODS AND RESULTS

Patients with HF and LVEF < 50% undergoing cardiac magnetic resonance were evaluated. Patients with atrial fibrillation or flutter were excluded. Left atrioventricular coupling index was measured as the ratio between the left atrial (LA) and the LV end-diastolic volumes. Patient population was divided according to LACI tertiles and followed up. Total of 478 patients (mean age 62 ± 12 years, 78% male) were included. The median value of LACI was 27.1% (interquartile range 19.9-34.5). Patients within the worst LACI tertile (≥30.9%) showed smaller LV volumes and larger LA volumes as compared with patients in the first or second tertile (LACI 6.2-22.2 and LACI 22.3-30.9, respectively). Left atrioventricular coupling index was significantly associated with the combined endpoint [hazard ratio (HR) 1.87, P = 0.01]. After adjusting for sex, age, ischaemic HF aetiology, LVEF, LA reservoir strain, diabetes mellitus, LV scar, mitral regurgitation, and LVEDVi, LACI remained significantly associated with the combined endpoint (HR 1.77, P = 0.02). Patients with the highest LACI values had worse outcomes compared with patients in first and second tertiles (HR 1.69, P = 0.02 and HR 1.77, P = 0.02, respectively).

CONCLUSION

In patients with HF and LVEF <50%, LACI is independently associated with adverse events. Patients with most impaired left atrioventricular coupling have the worst clinical outcomes.

Left atrioventricular coupling and left atrial abnormality in patients with acute myocardial infarction with and without hyperglycemia assessed with 3.0T cardiac magnetic resonance imaging feature tracking

Background

The relationship between stress hyperglycemia and left atrial (LA) abnormality and left atrioventricular coupling in patients with acute myocardial infarction (AMI) has not been fully explored. This study aimed to assess the additive effect of hyperglycemia on LA phasic function and to investigate the atrioventricular interaction in patients with AMI via cardiac magnetic resonance imaging (MRI).

Methods

This study comprised 120 patients with AMI with admission normoglycemia (aNGL), 88 patients with AMI and admission hyperglycemia (aHGL), and 70 age- and sex-matched controls. LA volume (LAV), LA ejection fraction (LAEF), and LA reservoir/conduit/contraction strain (εs/εe/εa) were measured and compared. Subgroup analysis was performed according to the presence of LA enlargement [LAE; defined as a maximum LAV index (LAVImax) >55 mL/m2]. Univariate and multivariate linear regression analyses were employed to identify the independent factors related to LA phasic strains.

Results

Compared with controls, patients with AMI had increased LAVI and decreased LAEF and LA strains (all P values <0.05), and the LA reservoir [LA total ejection fraction (LATEF) and εs] and conduit [LA passive ejection fraction (LAPEF) and εe] dysfunction was also present in those without LAE (all P values <0.05). Furthermore, εs and εe were significantly reduced in the aHGL group as compared with the aNGL group (both P values <0.001). After adjustments were made for confounding clinical factors, admission blood glucose level (aBGL) was independently and significantly associated with εs (β=-0.211; P=0.002) and εe (β=-0.215; P=0.001) in patients with AMI. After the introduction of left ventricular (LV) indicators into multivariable regression models, LV global longitudinal strain (GLS) was significantly associated with εs (β=-0.467; P<0.001) and εe (β=-0.455; P<0.001).

Conclusions

Hyperglycemia was found to exacerbate LA reservoir and conduit dysfunction in patients with AMI. aBGL and LV GLS were independent determinants of the εs and the εe, suggesting that attention should be paid not only to glucose monitoring but also to cardiac function indicators.

The prognostic value of CMR diastolic parameters in patients with cardiac light-chain amyloidosis: a retrospective analysis

Cardiac light-chain amyloidosis (AL-CA), characterized by the accumulation of amyloid fibers in the myocardium, often results in progressive diastolic dysfunction and adverse clinical outcomes. This study aimed to explore the diastolic characteristics of AL-CA using feature tracking cardiac magnetic resonance (CMR) and determine the prognostic parameters for all-cause mortality in such patients. A total of 102 AL-CA patients who underwent CMR between January 2014 and September 2018 were retrospectively reviewed, participations were follow-up until 2021. According to the inclusion and exclusion criteria, 60 patients were ultimately included. All-cause mortality was set as the primary endpoint. Healthy subjects were selected as controls. AL-CA patients were classified as the non-survival and survival group. The baseline characteristics, as well as the CMR-derived LV diastolic strain rate and LA diastolic parameters (LA volume, phasic EF, phasic strain, and strain rate), of survivors, non-survivors, and controls were compared. The associations of diastolic parameters with clinical outcomes were assessed via Cox regression and Kaplan‒Meier analyses. At a median follow-up of 7 months (interquartile range, 2-28 months), 43 (71.6%) cases of all-cause mortality were observed. Compared with controls, non-survivors presented significantly variation for all diastolic parameters (all P < 0.05), with LA volume indexes, LSRconduit and LSRpump value significantly increased and the remaining diastolic functional values significantly decreased. Compared with survivors, non-survivors presented significantly lower LV eGLSR, eGCSR, aGLSR, and selected LA diastolic parameters, including the LA phasic ejection fraction, LA phasic longitudinal strain, and LA longitudinal reservoir strain rate (all P < 0.05); moreover, LA volume indices and LA longitudinal conduit and booster‒pump strain rate values were significantly higher in the non-survival group. Multivariate Cox regression identified LA LSR as a significant predictor of all-cause mortality (hazard ratio, 14.35; 95% CI: 1.44-142.85, p < 0.05), with an optimal cutoff of -0.28 s-1 according to Kaplan‒Meier analysis. LA LSRconduit further demonstrated additive prognostic value over conventional systolic parameters, including LVEF, the LVGCS, and LV-LGE (p < 0.05). CMR-derived diastolic parameters, particularly the LA LSRconduit, have potential as predictive biomarkers for all-cause mortality in patients with AL-CA.

A comprehensive evaluation of the left atrium using cardiovascular magnetic resonance

Atrial disease or myopathy is a growing concept in cardiovascular medicine, particularly in the context of atrial fibrillation, as well as amyloidosis and heart failure. Among cardiac imaging modalities, cardiovascular magnetic resonance (CMR) is particularly well suited for a comprehensive assessment of atrial myopathy, including tissue characterization and hemodynamics. The goal of this review article is to describe clinical applications and make recommendations on pulse sequences as well as imaging parameters to assess the left atrium and left atrial appendage. Furthermore, we aimed to create an overview of current and promising future emerging applications of left atrium-specific CMR pulse sequences focusing on both electrophysiologic (EP) and non-EP applications.

Normal Values for Atrial Deformation Measured by Feature-Tracking Cardiac MRI: A Meta-Analysis

BACKGROUND

A consensus on normal atrial deformation measurements by feature-tracking cardiac MRI remained absent.

PURPOSE

Provide reference ranges for atrial strain parameters in normal subjects, evaluating the influence of field strength and analysis software on the measurements.

STUDY TYPE

Meta-analysis.

POPULATION

2708 subjects from 42 studies undergoing cardiac MRI.

ASSESSMENT

A systematic search was conducted from database (PubMed, Web of Science, ScienceDirect, and EMBASE) inception through August 2023. The random-effects model was used to pool the means of biatrial strain parameters. Heterogeneity and clinical variable effects were assessed. Strain measurements among different field strengths and analysis software were compared.

STATISTICAL TESTS

The inverse-variance method, Cochrane Q statistic, and I2 value, meta-regression analysis, and ANOVA were used; P < 0.05 was considered statistically significant.

RESULTS

The pooled means of left atrial (LA) total strain (εs), passive strain (εe), and active strain (εa) were 37.46%, 22.73%, and 16.24%, respectively, and the pooled means of LA total strain rate (SRs), passive strain rate (SRe), and active strain rate (SRa) were 1.66, -1.95, and -1.83, indicating significant heterogeneity. The pooled means of right atrial (RA) εs, εe, and εa were 44.87%, 26.05%, and 18.83%. RA SRs, SRe, and SRa were 1.66, -1.95, and -1.83, respectively. The meta-regression identified age as significantly associated with LA εs, εe and SRe, field strength was associated with LA SRa (all P < 0.05). ANOVA revealed differences in LA εa and SRa among different analysis software and in LA εs and all LA strain rates (all P < 0.05) among field strengths. No significant differences were identified in RA strain across analysis software (RA strain: P = 0.145-0.749; RA strain rates: P = 0.073-0.744) and field strengths (RA strain: P = 0.641-0.794; RA strain rates: P = 0.204-0.458).

DATA CONCLUSION

This study demonstrated the pooled reference values of biatrial strain. Age, analysis software, and field strength were attributed to differences in LA strain, whereas RA strain showed consistency across different field strengths and analysis software. Limited study subjects may account for the absence of influence on RA strain.

LEVEL OF EVIDENCE: 1

TECHNICAL EFFICACY

Stage 5.

The prognostic and diagnostic significance of echocardiographic parameters on acute ischemic stroke

OBJECTIVE

To comprehensively explore the prognostic significance of transthoracic echocardiography (TTE) and three-dimensional speckle-tracking echocardiography (3D STE) parameters in AIS and their role in distinguishing cardioembolic stroke.

METHODS

301 acute ischemic stroke (AIS) patients were enrolled. TTE and 3D STE were employed to evaluate cardiac function and structure, also left atrial strain. Patients were categorized into two groups based on functional outcome at discharge and 3 months post-stroke, respectively. Models combining variables related to unfavorable outcome were established, and their predictive efficacy was assessed using receiver operating characteristic (ROC) curves. Additionally, AIS patients were stratified into cardioembolic and non-cardioembolic stroke groups. Logistic regression identified predictors for cardioembolic stroke, and ROC curves assessed their diagnostic performance.

RESULTS

We found that a decrease in early diastolic peak velocity of the mitral valve (E value) was independently associated with adverse outcomes at both discharge (P = 0.014, OR = 0.126, 95% CI 0.024-0.657) and 3 months post-stroke in AIS patients (P = 0.004, OR = 0.054, 95% CI 0.007-0.403). Adding E value significantly improved predictive ability for adverse outcome at discharge and 3 months post-onset (0.807 vs. 0.794; 0.834 vs. 0.815). Moreover, left atrial diameter (LAD) [area under the curve (AUC) = 0.705] was the most valuable TTE parameter, and left atrial reservoir circumferential strain (LASr-c) (AUC = 0.766) was the most valuable STE parameter, even among all echocardiographic parameters for prediction of cardioembolic stroke.

CONCLUSIONS

This study indicates reduced E value was associated with unfavorable outcome at discharge and 3 months post-onset of AIS patients. LAD, especially LASr-c exhibited optimal diagnostic performance on cardioembolic stroke.

Left atrial and ventricular longitudinal strain by cardiac magnetic resonance feature tracking improves prognostic stratification of patients with ST-segment elevation myocardial infarction

We aimed to investigate the predictive value of left atrium (LA) and left ventricle (LV) longitudinal strain derived by CMR-FT early after ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI). Patients with STEMI who received pPCI and completed CMR within the following week were enrolled. LA and LV longitudinal strain parameters were derived from cine CMR by FT; conventional CMR indexes were also performed. The primary endpoint was the occurrence of major cardiovascular adverse events (MACE), defined as a composite of death, reinfarction, and congestive heart failure (HF). 276 participants (median age, 57 years, IQR, 48-66 years; 85% men) were included in this study. CMR was usually completed on the 5 (IQR,4-7) days after pPCI. During a median follow-up of 16 months, MACE occurred in 35 (12.7%) participants. Multivariable Cox regression analysis showed that LA conduit strain (HR 0.91, 95%CI: 0.84, 0.98, p = 0.013) and LV global longitudinal strain (HR 1.17, 95%CI: 1.03, 1.34, p = 0.016) remained independently associated with MACE. Participants with impaired LA conduit strain (≤ 12.8%) and LV global longitudinal strain (> -13.1%) had a higher risk of MACE than those with preserved. Longitudinal strain of LA and LV could provide independent prognostic information in STEMI patients, and comprehensive assessment of Left atrial and ventricular longitudinal strain significantly improved the prognosis.

MRI Quantification of Left Atrial Circumferential Strain in Mitral Regurgitation: A Feasibility and Reproducibility Study

BACKGROUND

MRI-derived left atrial (LA) longitudinal strain has been shown to be a marker for mitral regurgitation, but the utility of LA circumferential strain remains unclear.

PURPOSE

To assess feasibility and reproducibility of LA circumferential strain, identify changes in mitral regurgitation patients compared to healthy volunteers, and determine strain's association with mitral regurgitation severity and cardiac function.

STUDY TYPE

Retrospective.

POPULATION

52 mitral regurgitation patients, 12 healthy volunteers.

FIELD STRENGTH/SEQUENCE

Steady-state free precession cine and 2D phase contrast sequences at 1.5T.

ASSESSMENT

Peak LA circumferential strain was computed in each of three short-axis slices (superior, mid, and inferior) and longitudinal strain computed from long-axis slices using MRI feature-tracking software. Strain test-retest reproducibility was determined from two repeat studies in healthy volunteers.

STATISTICAL TESTS

LA circumferential strain test-retest reproducibility was assessed by intra-class correlation coefficient (ICC). Strain was compared between cohorts using Student's t-test or Mann-Whitney U. Mitral regurgitation severity association with strain and LV function was assessed using Spearman correlation and multivariable regression. Significance was defined as P < 0.05.

RESULTS

LA circumferential strain assessment was feasible in all subjects with moderate reproducibility in the superior (ICC = 0.74), mid LA (ICC = 0.71), and inferior LA (ICC = 0.63). In mitral regurgitation patients, LA circumferential strain was significantly lower in the superior (11.86% [6.5%,19.2%] vs. 18.73% ± 6.7%) and mid LA slices (18.41% ± 9.5% vs. 28.7% ± 10.4%) compared to healthy volunteers. Mitral regurgitation severity significantly associated with mid LA circumferential strain (β = -0.03) and LAV significantly associated with superior LA circumferential strain (β = -2.09), both independent of LA longitudinal strain and CO.

DATA CONCLUSION

LA circumferential strain assessment is feasible with moderate reproducibility. Compared to healthy volunteers, patients had significantly lower LA circumferential strain. Mitral regurgitation severity and LAV were significantly associated with LA circumferential strain independent of LA longitudinal strain.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Validation of Left Atrial Volume Correction for Single Plane Method on Four-Chamber Cine Cardiac MRI

BACKGROUND

Left atrial (LA) assessment is an important marker of adverse cardiovascular outcomes. Cardiovascular magnetic resonance (CMR) accurately quantifies LA volume and function based on biplane long-axis imaging. We aimed to validate single-plane-derived LA indices against the biplane method to simplify the post-processing of cine CMR.

METHODS

In this study, 100 patients from Leeds Teaching Hospitals were used as the derivation cohort. Bias correction for the single plane method was applied and subsequently validated in 79 subjects.

RESULTS

There were significant differences between the biplane and single plane mean LA maximum and minimum volumes and LA ejection fraction (EF) (all p < 0.01). After correcting for biases in the validation cohort, significant correlations in all LA indices were observed (0.89 to 0.98). The area under the curve (AUC) for the single plane to predict biplane cutoffs of LA maximum volume ≥ 112 mL was 0.97, LA minimum volume ≥ 44 mL was 0.99, LA stroke volume (SV) ≤ 21 mL was 1, and LA EF ≤ 46% was 1, (all p < 0.001).

CONCLUSIONS

LA volumetric and functional assessment by the single plane method has a systematic bias compared to the biplane method. After bias correction, single plane LA volume and function are comparable to the biplane method.

Impact of temporal and spatial resolution on atrial feature tracking cardiovascular magnetic resonance imaging

BACKGROUND

Myocardial deformation assessment by cardiovascular magnetic resonance-feature tracking (CMR-FT) has incremental prognostic value over volumetric analyses. Recently, atrial functional analyses have come to the fore. However, to date recommendations for optimal resolution parameters for accurate atrial functional analyses are still lacking.

METHODS

CMR-FT was performed in 12 healthy volunteers and 9 ischemic heart failure (HF) patients. Cine sequences were acquired using different temporal (20, 30, 40 and 50 frames/cardiac cycle) and spatial resolution parameters (high 1.5 × 1.5 mm in plane and 5 mm slice thickness, standard 1.8 × 1.8 × 8 mm and low 3.0 × 3.0 × 10 mm). Inter- and intra-observer reproducibility were calculated.

RESULTS

Increasing temporal resolution is associated with higher absolute strain and strain rate (SR) values. Significant changes in strain assessment for left atrial (LA) total strain occurred between 20 and 30 frames/cycle amounting to 2,5-4,4% in absolute changes depending on spatial resolution settings. From 30 frames/cycle onward, absolute strain values remained unchanged. Significant changes of LA strain rate assessment were observed up to the highest temporal resolution of 50 frames/cycle. Effects of spatial resolution on strain assessment were smaller. For LA total strain a general trend emerged for a mild decrease in strain values obtained comparing the lowest to the highest spatial resolution at temporal resolutions of 20, 40 and 50 frames/cycle (p = 0.006-0.046) but not at 30 frames/cycle (p = 0.140).

CONCLUSION

Temporal and to a smaller extent spatial resolution affect atrial functional assessment. Consistent strain assessment requires a standard spatial resolution and a temporal resolution of 30 frames/cycle, whilst SR assessment requires even higher settings of at least 50 frames/cycle.

Analysis of bi-atrial function using CMR feature tracking and long-axis shortening approaches in patients with diastolic dysfunction and atrial fibrillation

OBJECTIVES

Atrial function can be assessed using advancing cardiovascular magnetic resonance (CMR) post-processing methods: atrial feature tracking (FT) strain analysis or a long-axis shortening (LAS) technique. This study aimed to first compare the two FT and LAS techniques in healthy individuals and cardiovascular patients and then investigated how left (LA) and right atrial (RA) measurements are related to the severity of diastolic dysfunction or atrial fibrillation.

METHODS

Sixty healthy controls and 90 cardiovascular disease patients with coronary artery disease, heart failure, or atrial fibrillation, underwent CMR. LA and RA were analyzed for standard volumetry as well as for myocardial deformation using FT and LAS for the different functional phases (reservoir, conduit, booster). Additionally, ventricular shortening and valve excursion measurements were assessed with the LAS module.

RESULTS

The measurements for each of the LA and RA phases were correlated (p < 0.05) between the two approaches, with the highest correlation coefficients occurring in the reservoir phase (LA: r = 0.83, p < 0.01, RA: r = 0.66, p < 0.01). Both methods demonstrated reduced LA (FT: 26 ± 13% vs 48 ± 12%, LAS: 25 ± 11% vs 42 ± 8%, p < 0.01) and RA reservoir function (FT: 28 ± 15% vs 42 ± 15%, LAS: 27 ± 12% vs 42 ± 10%, p < 0.01) in patients compared to controls. Atrial LAS and FT decreased with diastolic dysfunction and atrial fibrillation. This mirrored ventricular dysfunction measurements.

CONCLUSION

Similar results were generated for bi-atrial function measurements between two CMR post-processing approaches of FT and LAS. Moreover, these methods allowed for the assessment of incremental deterioration of LA and RA function with increasing left ventricular diastolic dysfunction and atrial fibrillation. A CMR-based analysis of bi-atrial strain or shortening discriminates patients with early-stage diastolic dysfunction prior to the presence of compromised atrial and ventricular ejection fractions that occur with late-stage diastolic dysfunction and atrial fibrillation.

KEY POINTS

• Assessing right and left atrial function with CMR feature tracking or long-axis shortening techniques yields similar measurements and could potentially be used interchangeably based on the software capabilities of individual sites. • Atrial deformation and/or long-axis shortening allow for early detection of subtle atrial myopathy in diastolic dysfunction, even when atrial enlargement is not yet apparent. • Using a CMR-based analysis to understand the individual atrial-ventricular interaction in addition to tissue characteristics allows for a comprehensive interrogation of all four heart chambers. In patients, this could add clinically meaningful information and potentially allow for optimal therapies to be chosen to better target the dysfunction.

Compressed sensing cine imaging with higher temporal resolution for analysis of left atrial strain and strain rate by cardiac magnetic resonance feature tracking

PURPOSE

Cardiac magnetic resonance (CMR) feature tracking (FT) is more widely used in the measurement of left atrial (LA) strain and strain rate (SR). However, in recent years, researchers have attempted to improve the low temporal resolution of CMR-FT to better capture the subtle deformations of the myocardium. The technique of compressed sensing (CS) has been applied clinically, reducing scan time while increasing temporal resolution. The purpose of this study was to explore the effect of the increased temporal resolution of CS cine sequences on the analysis of LA longitudinal strain and SR.

MATERIALS AND METHODS

Twenty-nine healthy subjects were included in the study. They underwent CMR with a reference steady-state free precession cine sequence of conventional temporal resolution (standard SSFP sequence), a cine sequence of higher temporal resolution (HT sequence), and an HT cine sequence with CS (CS HT sequence) (temporal resolution: 22.1-44.3/24.9-47.1 ms, 11.1-19.4 ms, and 8.3-19.4 ms, respectively). The standard SSFP sequence, HT sequence, and CS HT sequence were acquired in all subjects during the same scanning session. LA longitudinal strain and SR, reflecting LA reservoir, conduit, and contraction booster-pump function, were measured by CMR-FT and compared among the three sequences.

RESULTS

The measurements of LASR reservoir, conduit, and booster-pump were significantly higher on the HT and CS HT sequences than on the standard SSFP sequence. The standard SSFP sequence was correlated significantly with the HT and CS HT sequences in terms of LA strain and SR analysis, respectively. The LA strain and SR measurements also showed excellent agreement between the HT and CS HT sequences.

CONCLUSION

Higher temporal resolution led to significantly higher measured LASR values in CMR-FT. Furthermore, the addition of CS reduced scan time and did not affect LA longitudinal strain or SR analysis.

An acute increase in Left Atrial volume and left ventricular filling pressure during Adenosine administered myocardial hyperaemia: CMR First-Pass Perfusion Study

OBJECTIVE

To investigate whether left atrial (LA) volume and left ventricular filling pressure (LVFP) assessed by cardiovascular magnetic resonance (CMR) change during adenosine delivered myocardial hyperaemia as part of a first-pass stress perfusion study.

METHODS AND RESULTS

We enrolled 33 patients who had stress CMR. These patients had a baseline four-chamber cine and stress four-chamber cine, which was done at peak myocardial hyperaemic state after administering adenosine. The left and right atria were segmented in the end ventricular diastolic and systolic phases. Short-axis cine stack was segmented for ventricular functional assessment. At peak hyperaemic state, left atrial end ventricular systolic volume just before mitral valve opening increased significantly from baseline in all (91 ± 35ml vs. 81 ± 33ml, P = 0.0002), in males only (99 ± 35ml vs. 88 ± 33ml, P = 0.002) and females only (70 ± 26ml vs. 62 ± 22ml, P = 0.02). The right atrial end ventricular systolic volume increased less significantly from baseline (68 ± 21ml vs. 63 ± 20ml, P = 0.0448). CMR-derived LVFP (equivalent to pulmonary capillary wedge pressure) increased significantly at the peak hyperaemic state in all (15.1 ± 2.9mmHg vs. 14.4 ± 2.8mmHg, P = 0.0002), females only (12.9 ± 2.1mmHg vs. 12.3 ± 1.9mmHg, P = 0.029) and males only (15.9 ± 2.8mmHg vs. 15.2 ± 2.7mmHg, P = 0.002) cohorts.

CONCLUSION

Left atrial volume assessment by CMR can measure acute and dynamic changes in preloading conditions on the left ventricle. During adenosine administered first-pass perfusion CMR, left atrial volume and LVFP rise significantly.

Diagnostic accuracy of left atrial function and strain for differentiating between acute and chronic myocardial infarction

BACKGROUND

The cardiac magnetic resonance tissue tracking (CMR-TT) technique was used to obtain left atrial strain and strain rate in patients with myocardial infarction (MI) and to evaluate the utility of this technique in the quantitative assessment of myocardial infarction for distinguishing acute from chronic myocardial infarction.

METHODS

We retrospectively analyzed 36 consecutive patients with acute myocardial infarction (AMI) and 29 patients with chronic myocardial infarction (CMI) who underwent CMR and 30 controls. Left atrial (LA) and ventricular functions were quantified by volumetric, and CMR-TT derived strain analysis from long and short left ventricular view cines. Receiver Operating Characteristics (ROC) analysis was used to determine the diagnostic accuracy of CMR-TT strain parameters for discriminating between acute and chronic myocardial infarction.

RESULTS

AMI and CMI participants had impaired LA reservoir function, conduit function and LA booster pump dysfunction compared to the controls. LA strain was more sensitive than LV global strain for the assessment of the MI stage. Peak late-negative SR yielded the best areas under the ROC curve (AUC) of 0.879, showing differentiation between acute and chronic myocardial infarction of all the LA strain parameters obtained. The highest significant differences between chronic myocardial infarction and normal myocardium were also found in the LV strain (p < 0.001) and LA functional parameters (p < 0.001), but there was no difference between AMI and normals.

CONCLUSIONS

CMR-TT-derived LA strain is a potential and robust tool in demonstrating impaired LA mechanics and quantifying LA dynamics, which have high sensitivity and specificity in the differential diagnosis of acute versus chronic myocardial infarction. Their use is thus worth popularizing in clinical application.

Atrial cardiomyopathy: Current and future imaging methods for assessment of atrial structure and function

Changes in atrial size and function have historically been considered a surrogate marker of ventricular dysfunction. However, it is now recognized that atrial cardiomyopathy (ACM) may also occur as a primary myocardial disorder. Emerging evidence that ACM is a major risk factor for atrial fibrillation, heart failure, and thromboembolic stroke, has highlighted the significance of this disorder and the need for better assessment of atrial metrics in clinical practice. Key barriers in this regard include a lack of standardized criteria or hierarchy for the diagnosis of ACM and lack of consensus for the most accurate phenotyping methods. In this article we review existing literature on ACM, with a focus on current and future non-invasive imaging methods for detecting abnormalities of atrial structure and function. We discuss the relative advantages and disadvantages of transthoracic echocardiography and cardiac magnetic resonance imaging for assessing a range of parameters, including atrial size and contractile function, strain, tissue characteristics, and epicardial adipose tissue. We will also present the potential application of novel imaging methods such as sphericity index and four- or five-dimensional flow.

Magnetic resonance imaging reference values for cardiac morphology, function and tissue composition in adolescents

Background

Cardiovascular magnetic resonance (CMR) is a precise tool for the assessment of cardiac anatomy, function, and tissue composition. However, studies providing CMR reference values in adolescence are scarce. We aim to provide sex-specific CMR reference values for biventricular and atrial dimensions and function and myocardial relaxation times in this population.

Methods

Adolescents aged 15-18 years with no known cardiovascular disease underwent a non-contrast 3-T CMR scan between March 2021 and October 2021. The imaging protocol included a cine steady-state free-precession sequence for the analysis of chamber size and function, as well as T2-GraSE and native MOLLI T1-mapping for the characterization of myocardial tissue.

Findings

CMR scans were performed in 123 adolescents (mean age 16 ± 0.5 years, 52% girls). Mean left and right ventricular end-diastolic indexed volumes were higher in boys than in girls (91.7 ± 11.6 vs 78.1 ± 8.3 ml/m², p < 0.001; and 101.3 ± 14.1 vs 84.1 ± 10.5 ml/m², p < 0.001), as was the indexed left ventricular mass (48.5 ± 9.6 vs 36.6 ± 6.0 g/m², p < 0.001). Left ventricular ejection fraction showed no significant difference by sex (62.2 ± 4.1 vs 62.8 ± 4.2%, p = 0.412), whereas right ventricular ejection fraction trended slightly lower in boys (55.4 ± 4.7 vs. 56.8 ± 4.4%, p = 0.085). Indexed atrial size and function parameters did not differ significantly between sexes. Global myocardial native T1 relaxation time was lower in boys than in girls (1215 ± 23 vs 1252 ± 28 ms, p < 0.001), whereas global myocardial T2 relaxation time did not differ by sex (44.4 ± 2.0 vs 44.1 ± 2.4 ms, p = 0.384). Sex-stratified comprehensive percentile tables are provided for most relevant cardiac parameters.

Interpretation

This cross-sectional study provides overall and sex-stratified CMR reference values for cardiac dimensions and function, and myocardial tissue properties, in adolescents. This information is useful for clinical practice and may help in the differential diagnosis of cardiac diseases, such as cardiomyopathies and myocarditis, in this population.

Funding

Instituto de Salud Carlos III (PI19/01704).

Reverse remodeling of left atrium assessed by cardiovascular magnetic resonance feature tracking in hypertrophic obstructive cardiomyopathy after septal myectomy

BACKGROUND

Assessing the structure and function of left atrium (LA) is crucial in hypertrophic obstructive cardiomyopathy (HOCM) because LA remodeling correlates with atrial fibrillation. However, few studies have investigated the potential effect of myomectomy on LA phasic remodeling in HOCM after myectomy using cardiovascular magnetic resonance (CMR) feature tracking (FT). This study aims to evaluate the LA structural and functional remodeling with HOCM after myectomy by CMR-FT and to further investigate the determinants of LA reverse remodeling.

METHODS

In this single-center study, we retrospectively studied 88 patients with HOCM who received CMR before and after myectomy between January 2011 and June 2021. Preoperative and postoperative LA parameters derived from CMR-FT were compared, including LA reservoir function (total ejection fraction [EF], total strain [εs], peak positive strain rate [SRs]), conduit function (passive EF, passive strain [εe], peak early negative strain rate [SRe]) and booster function (booster EF, active strain [εa], late peak negative strain rate [SRa]). Eighty-six healthy participants were collected for comparison. Univariate and multivariate linear regression identified variables associated with the rate of change of εa.

RESULTS

Compared with preoperative parameters, LA reservoir function (total EF, εs, SRs), booster function (booster EF, εa, SRa), and SRe were significantly improved after myectomy (all P < 0.05), while no significant differences were observed in passive EF and εe. Postoperative patients with HOCM still had larger LA and worse LA function than healthy controls (all P < 0.05). After analyzing the rates of change in LA parameters, LA boost function, especially εa, showed the most dramatic improvement beyond the improvements in reservoir function, conduit function, and volume. In multivariable regression analysis, minimum LA volume index (adjusted β = - 0.39, P < 0.001) and Δleft ventricular outflow tract (LVOT) pressure gradient (adjusted β = - 0.29, P = 0.003) were significantly related to the rate of change of εa.

CONCLUSIONS

Patients with HOCM after septal myectomy showed LA reverse remodeling with a reduction in LA size and restoration in LA reservoir and booster function but unchanged LA conduit function. Among volumetric and functional changes, booster function had the greatest improvement postoperatively. Besides, preoperative LAVmin index and ΔLVOT might be potential factors associated with the degree of improvement in εa.

Left Atrial Dysfunction in Children with Repaired Pulmonary Artery Atresia with Ventricular Septal Defect: A Cardiovascular Magnetic Resonance Imaging Study

(1) Background: The left atrium (LA) is much more than a reservoir for left ventricular filling. The aim of this study was to assess the LA volume and function in patients with repaired pulmonary artery atresia with ventricular septal defect (rPA/VSD) using CMR. (2) Methods: 31 pediatric patients with rPA/VSD and 30 healthy controls were prospectively recruited. Left atrial ejection fraction (EF), strain and strain rate of three phases (reservoir, conduit, and pump) and left atrial volume were measured with cardiac function analysis software. (3) Results: Patients with rPA/VSD had decreased maximal volume index (p = 0.008). Compared to controls, LA reservoir strain and strain rate, conduit strain and strain rate, booster pump strain rate, total EF and passive EF were significantly lower (p = 0.001, p < 0.001, p = 0.001, p = 0.02, p = 0.03, p < 0.001, p < 0.001); the patients with preserved but lower RVEF(<50%) had lower reservoir strain, reservoir strain rate and pump strain rate (p = 0.01, p = 0.02, p = 0.04, respectively) than the patients with higher RVEF (≥50%). (4) Conclusions: In patients with rPA/VSD, LA function was altered when biventricular EF was preserved, which may provide an early indication of left ventricular diastolic dysfunction. CMR can detect LA dysfunction at an early stage, even before LA enlargement.

Feature tracking cardiovascular magnetic resonance reveals recovery of atrial function after acute myocarditis

Follow-up after acute myocarditis is important to detect persisting myocardial dysfunction. However, recovery of atrial function has not been evaluated after acute myocarditis so far. Thirty-five patients with strictly defined acute myocarditis underwent cardiovascular magnetic resonance (CMR, 1.5 T) in the acute stage at baseline (BL) and at 3 months follow-up (FU). The study population included 13 patients with biopsy-proven "cardiomyopathy-like" myocarditis (CLM) and 22 patients with "infarct-like" (ILM) clinical presentation. CMR feature tracking (FT) was performed on conventional cine SSFP sequences. Median LA-GLS increased from 33.2 (14.5; 39.2) at BL to 37.0% (25.2; 44.1, P = 0.0018) at FU in the entire study population. Median LA-GLS also increased from 36.7 (26.5; 42.3) at BL to 41.3% (34.5; 44.8, P = 0.0262) at FU in the ILM subgroup and from 11.3 (6.4; 21.1) at BL to 21.4% (14.2; 30.7, P = 0.0186) at FU in the CLM subgroup. Median RA-GLS significantly increased from BL with 30.8 (22.5; 37.0) to FU with 33.7% (26.8; 45.4, P = 0.0027) in the entire study population. Median RA-GLS also significantly increased from 32.7 (25.8; 41.0) at BL to 35.8% (27.7; 48.0, P = 0.0495) at FU in the ILM subgroup and from 22.8 (13.1; 33.9) at BL to 31.0% (26.0; 40.8, P = 0.0266) at FU in the CLM subgroup. Our findings demonstrate recovery of LA and RA function by CMR-FT strain analyses in patients after acute myocarditis independent from clinical presentation. Monitoring of atrial strain could be an important tool for an individual assessment of healing after acute myocarditis.

Cardiac Computed Tomography-Derived Left Atrial Strain and Volume in Pediatric Patients With Congenital Heart Disease: A Comparative Analysis With Transthoracic Echocardiography

Purpose

This study aimed at exploring the feasibility and reproducibility of CCT for the measurement of Left Atrial (LA) strain and volume compared with transthoracic echocardiography (TTE) in pediatric patients with congenital heart disease (CHD).

Materials and Methods

The present study included 43 postoperative patients with CHD (7.39 ± 3.64 years, 56% male) who underwent clinically indicated CCT, and all patients underwent additional TTE on the same day. LA strain and volume parameters were measured by dedicated software. The correlation and agreement of LA strain and volume parameters were assessed using Pearson’s correlation coefficient and Bland-Altman analysis. Intra-class correlation coefficients (ICC) were used to assess CCT intra-observer and inter-observer reproducibility.

Results

All strain parameters of CCT were lower compared to TTE (reservoir strain: 28.37 ± 6.92 vs. 32.15 ± 8.15, respectively; conduit strain: 21.33 ± 6.46 vs. 24.23 ± 7.75, respectively; booster strain: 7.04 ± 2.74 vs. 7.92 ± 3.56). While the volume parameters of CCT were higher compared to TTE (LAV: 29.60 ± 19.01 vs. 25.66 ± 17.60, respectively; LAVi: 30.36 ± 22.31 vs. 28.63 ± 19.25, respectively). Both LA strain and volume measurements showed good correlation and agreement between the two modalities (r = 0.63–0.87, p < 0.001). CT-derived LA strain and volume measurements showed good intra- and inter-observer reproducibility using prototype software (ICC = 0.78–0.96).

Conclusions

CCT was feasible for measuring LA strain and volume with good correlation and high reproducibility as compared with TTE. As a complementary modality, CCT can regard as an accepted method in the evaluation of LA function in pediatric patients with CHD

Assessing left atrial function in patients with atrial fibrillation and valvular heart disease using cardiovascular magnetic resonance imaging

Background

Atrial fibrillation (AF) is common arrhythmia in valvular heart disease (VHD) and is associated with adverse outcomes.

Hypothesis

To evaluate the left atrial (LA) function in patients with AF‐VHD by cardiovascular magnetic resonance imaging feature tracking (CMR‐FT) using LA strain (ε_s/ε_e/ε_a) and their corresponding strain rate (SRs/SRe/SRa).

Methods

This was a retrospective cross‐sectional inter‐reader and intra‐reader reproducibility conducted from July 1, 2020, to January 31, 2021. A total of 39 patients with AF‐VHD (rheumatic heart valvular disease [RHVD] [n = 22], degenerative heart valvular disease [DHVD] [n = 17]) underwent MRI scans performed with drug‐controlled heart rate before correcting the rhythm and valves through maze procedure. Fifteen participants with normal cardiac MRI were included as healthy control. ε_s/SRs, ε_e/SRe, and ε_a/SRa, corresponding to LA reservoir, conduit, and booster‐pump function, were assessed using Feature Tracking software (CVI42 v5.12.1).

Results

Compared with healthy controls, LA global strain parameters (ε_s/ε_e/ε_a/SRs/SRe/SRa) were significantly decreased (all p < 0.001), while LA size and volume were increased in AF‐VHD group (all p < 0.001). In the subgroup, RHVD group showed lower LA total ejection fraction (LATEF) and strain data than DHVD group (12.6% ± 3.3% vs. 19.4 ± 8.6, p = 0.001). Decreased LATEF was significantly related to altered LA strain and strain rate, especially in ε_s, ε_e, and SRs (Pearson/Spearman r/ρ = 0.856/0.837/0.562, respectively; all p < 0.001). Interstudy and intrastudy reproducibility were consistent for LA volumetry and strain parameters (intraclass correlation coefficient: 0.88–0.99).

Conclusions

CMR‐FT can be used to assess the LA strain parameters, and identify LA dysfunction and deformation noninvasively, which could be a helpful functional imaging biomarker in the clinical treatment of AF‐VHD.

Imaging of the left atrium: pathophysiology insights and clinical utility

Left atrial imaging and detailed knowledge of its pathophysiology, especially in the context of heart failure, have become an increasingly important clinical and research focus. This development has been accelerated by the growth of non-invasive imaging modalities, advanced image processing techniques, such as strain imaging, and the parallel emergence of catheter-based left atrial interventions like pulmonary vein ablation, left atrial appendage occlusion, and others. In this review, we focus on novel imaging methods for the left atrium, their pathophysiological background, and their clinical relevance for various cardiac conditions and diseases.