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

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.

Atrial cardiomyopathy revisited-evolution of a concept: a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS)

AIMS

The concept of "atrial cardiomyopathy" (AtCM) had been percolating through the literature since its first mention in 1972. Since then, publications using the term were sporadic until the decision was made to convene an expert working group with representation from four multinational arrhythmia organizations to prepare a consensus document on atrial cardiomyopathy in 2016 (EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication). Subsequently, publications on AtCM have increased progressively.

METHODS AND RESULTS

The present consensus document elaborates the 2016 AtCM document further to implement a simple AtCM staging system (AtCM stages 1-3) by integrating biomarkers, atrial geometry, and electrophysiological changes. However, the proposed AtCM staging needs clinical validation. Importantly, it is clearly stated that the presence of AtCM might serve as a substrate for the development of atrial fibrillation (AF) and AF may accelerates AtCM substantially, but AtCM per se needs to be viewed as a separate entity.

CONCLUSION

Thus, the present document serves as a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS) to contribute to the evolution of the AtCM concept.

MRI Assessment of Diastolic Dysfunction in People Living With the Human Immunodeficiency Virus: Correlation With Markers of Disease Activity

BACKGROUND

Despite the advent of combination antiretroviral therapy, people living with human immunodeficiency virus (PLWH) are at an increased risk for cardiac disease.

PURPOSE

To explore the presence and extent of diastolic atrial and left ventricular dysfunction in PLWH using cardiac MRI in correlation with clinical markers of disease activity.

STUDY TYPE

Prospective.

POPULATION

A total of 163 participants comprising 101 HIV-infected individuals (age: 52 years [42-62 years]; 92% male) and 62 age- and sex-matched healthy volunteers (age: 51 years [30-72 years]; 85% male).

FIELD STRENGTH/SEQUENCE

3.0 T, cardiac MRI including balanced steady-state free precession (SSFP) for the short-axis, two-, three-, and four-chamber views were performed.

ASSESSMENT

Assessment of cardiac function and strain analysis were accomplished by CVI42 software. Blood samples for CD4+ T cells and cardiac risk factors were also collected before MRI.

STATISTICAL TESTS

Independent t tests, Mann-Whitney U test, Pearson's correlation analysis, and multivariate linear analyses (significance level: P < 0.05).

RESULTS

PLWH had a significantly larger left atrial volume maximum index (LAVImax: 32.6 ± 8.7 vs. 28.7 ± 8.1 mL/m2), minimum (LAVImin: 14.8 ± 5.5 vs. 11.5 ± 5.4 mL/m2,), and prior to atrial contraction (LAVIpre-a: 23.4 ± 6.7 vs. 19.7 ± 7.2 mL/m2) as compared to healthy volunteers. The LA reservoir (LAtEF: 55.0 ± 10.2 vs. 61.4 ± 10.4; Sls: 29.0 ± 8.1 vs. 33.8 ± 11.8), conduit (LApEF: 28.4 ± 8.2 vs. 32.3 ± 11.3, P = 0.01; Sle: 16.3 ± 6.5 vs. 18.9 ± 8.2), and booster pump function (LAaEF: 37.4 ± 12.4 vs. 42.7 ± 13.1, P = 0.01, Sla: 12.7 ± 5.1 vs. 14.9 ± 5.7) were all significant impaired in PLWH. Global circumferential left ventricular diastolic strain rate (LVGCS-d) was significantly lower in the HIV patients. Multivariate analysis results showed that Nadir CD4+ T cells had a significant adverse association with LVGCS-d (β = 0.51).

CONCLUSION

LA structure abnormalities and LV diastolic dysfunction were manifested in PLWH, with Nadir CD4+ T cell counts potentially serving as a risk factor for early cardiac diastolic dysfunction.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 3.

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.

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.

Prognostic value of a left atrioventricular coupling index in pre- and post-menopausal women from the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Sex hormones associated with both the left atrial (LA) and left ventricular (LV) structures in women, but the association of menopause status with left atrioventricular coupling is not established.

AIM

To assess the prognostic value of a left atrioventricular coupling index (LACI) in peri-menopausal women without a history of cardiovascular disease (CVD).

MATERIALS AND METHODS

In all women participating in MESA study with baseline cardiovascular MRI, the LACI was measured as the ratio of the LA end-diastolic volume to the LV end-diastolic volume. Cox models were used to assess the association between the LACI and the outcomes of atrial fibrillation (AF), heart failure (HF), coronary heart disease (CHD) death, and hard CVD.

RESULTS

Among the 2,087 women participants (61 ± 10 years), 485 cardiovascular events occurred (mean follow-up: 13.2 ± 3.3 years). A higher LACI was independently associated with AF (HR 1.70; 95%CI [1.51-1.90]), HF (HR 1.62; [1.33-1.97]), CHD death (HR 1.36; [1.10-1.68]), and hard CVD (HR 1.30; [1.13-1.51], all p < 0.001). Adjusted models with the LACI showed significant improvement in model discrimination and reclassification when compared to traditional models to predict: incident AF (C-statistic: 0.82 vs. 0.79; NRI = 0.325; IDI = 0.036), HF (C-statistic: 0.84 vs. 0.81; NRI = 0.571; IDI = 0.023), CHD death (C-statistic: 0.87 vs. 0.85; NRI = 0.506; IDI = 0.012), hard CVD (C-statistic: 0.78 vs. 0.76; NRI = 0.229; IDI = 0.012). The prognostic value of the LACI had a better discrimination and reclassification than individual LA or LV parameters.

CONCLUSION

In a multi-ethnic population of pre- and post-menopausal women, the LACI is an independent predictor of HF, AF, CHD death, and hard CVD.

CLINICAL TRIAL REGISTRATION

[https://clinicaltrials.gov/], identifier [NCT00005487].

Determinants of left atrioventricular coupling index: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Recent studies have described a novel left atrioventricular coupling index (LACI), which had a better prognostic value in predicting cardiovascular events than individual left atrial (LA) or left ventricular (LV) variables.

AIMS

To identify determinants of LACI and its 10-year annual change (ΔLACI), measured by cardiac magnetic resonance (CMR), and to better understand the variables governing this left atrioventricular coupling.

METHODS

In the Multi-Ethnic Study of Atherosclerosis, 2112 study participants, free from cardiovascular disease at baseline, had LACI assessed by CMR imaging at baseline (LACI_Baseline; 2000-2002) and 10 years later (2010-2012). The LACI was defined as the ratio of LA to LV end-diastolic volumes. Linear regression analyses were performed to identify independent determinants of LACI_Baseline and ΔLACI.

RESULTS

In the 2112 participants (mean age 58.8±9.1 years; 46.6% male), after adjustment for all covariates, age was independently associated with LACI_Baseline (R²=0.10, slope=0.16) and ΔLACI (R²=0.15, slope=0.008; both P<0.001). African Americans had the highest LACI_Baseline value (18.0±7.7%). Although there was no difference in LACI_Baseline between women and men (P=0.19), ΔLACI was higher in women (1.0±1.1 vs 0.8±1.1%/year; P<0.001). Diabetes and higher body mass index (BMI) were independently associated with LACI_Baseline (both P<0.001). LACI_Baseline was independently associated with LV myocardial fibrosis markers (native T1: R²=0.11, slope=0.09 [P=0.038]; extracellular volume: R²=0.08, slope=0.28 [P=0.035]) and N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) concentration (R²=0.10, slope=-1.11; P<0.001), but was not associated with interleukin 6 or high-sensitivity C-reactive protein.

CONCLUSIONS

Age, sex, ethnicity, diabetes and BMI were independent determinants of LACI. LACI was independently associated with myocardial fibrosis markers and NT-proBNP concentration.

Early Echocardiographic Predictors for Atrial Fibrillation Propensity: The Left Atrium Oracle

Atrial fibrillation (AF) results from structural and electrical remodeling of the atria, primarily of the left atrium (LA); therefore, LA changes, both anatomical and functional are recognized as proarrhythmic markers with a powerful prognostic value. Being widely available and noninvasive, echocardiography is used to monitor LA form and function in clinical practice. Early functional (electrical) remodeling of the LA precedes anatomical alterations. Impaired LA functions and reduced atrial compliance due to atrial fibrosis may be evaluated using novel echocardiographic techniques, such as tissue Doppler analysis and speckle tracking. Functional evaluation of the LA conveys prognostic information about the risk of AF, as the severity of the impairment is an independent predictor of new-onset AF and AF recurrence. However, specific parameters are still investigated for incorporation into algorithms to predict future AF occurrence. The aim of the review is to summarize echocardiographic parameters, their predicting value and applicability in practice.

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.

Left Atrioventricular Coupling Index to Predict Incident Heart Failure: The Multi-Ethnic Study of Atherosclerosis

Background: Although left atrial (LA) and left ventricular (LV) structural and functional parameters have independent prognostic value as predictors of heart failure (HF), the close physiological relationship between the LA and LV suggest that the assessment of LA/LV coupling could better reflect left atrioventricular dysfunction and be a better predictor of HF. Aim: We investigated the prognostic value of a left atrioventricular coupling index (LACI), measured by cardiovascular magnetic resonance (CMR), as well as change in LACI to predict incident HF in the Multi-Ethnic Study of Atherosclerosis (MESA). Materials and Methods: In the MESA, 2,250 study participants, free of clinically recognized HF and cardiovascular disease (CVD) at baseline, had LACI assessed by CMR imaging at baseline (Exam 1, 2000-2002), and 10 years later (Exam 5, 2010-2012). Left atrioventricular coupling index was defined as the ratio of LA to LV end-diastolic volumes. Univariable and multivariable Cox proportional hazard models were used to evaluate the associations of LACI and average annualized change in LACI (ΔLACI) with incident HF after adjustment for traditional MESA-HF risk factors. The incremental risk prediction was calculated using C-statistic, categorical net reclassification index (NRI) and integrative discrimination index (IDI). Results: Among the 2,250 participants (mean age 59.3 ± 9.3 years and 47.6% male participants), 50 incident HF events occurred over 6.8 ± 1.3 years after the second CMR exam. After adjustment, greater LACI and ΔLACI were independently associated with HF (adjusted HR 1.44, 95% CI [1.25-1.66] and adjusted HR 1.55, 95% CI [1.30-1.85], respectively; both p < 0.0001). Adjusted models for LACI showed significant improvement in model discrimination and reclassification compared to currently used HF risk score model for predicting HF incidence (C-statistic: 0.81 vs. 0.77; NRI = 0.411; IDI = 0.043). After adjustment, ΔLACI showed also significant improvement in model discrimination compared to the multivariable model with traditional MESA-HF risk factors for predicting incident HF (C-statistic: 0.82 vs. 0.77; NRI = 0.491; IDI = 0.058). Conclusions: In a multi-ethnic population, atrioventricular coupling (LACI), and coupling change (ΔLACI) are independently associated with incident HF. Both have incremental prognostic value for predicting HF events over traditional HF risk factors.

Left Atrioventricular Coupling Index as a Prognostic Marker of Cardiovascular Events: The MESA Study

[Figure: see text].

Multi-modality assessment and role of left atrial function as an imaging biomarker in cardiovascular disease

The left atrium (LA) plays a vital role in maintaining normal cardiac function. LA volume and function have been utilised as important imaging biomarkers, with their prognostic value demonstrated in multiple cardiac conditions. More recently, there has been a sharp increase in the number of publications utilising LA strain by echocardiography and cardiac magnetic resonance (CMR) imaging. However, little is known about its prognostic value or reproducibility as a technique. In this review, we aim to highlight the conventional and novel imaging techniques available for LA assessment, using echocardiography and CMR, their role as an imaging biomarker in cardiovascular disease, the reproducibility of the techniques and the current limitations to their clinical application. We identify a need for further standardisation of techniques, with establishment of ‘normal’ cut-offs before routine clinical application can be made.

Reference Values for Left Atrial Strain and Strain Rate Based on a Large Sample of Healthy Chinese Adults: An MR-Feature Tracking Study

BACKGROUND

While reference values of left atrial (LA) deformation parameters in Western populations have been established, reference data in healthy Asian populations are limited.

PURPOSE

To establish age- and sex-specific reference values for LA strain and strain rate (SR) based on a large sample of healthy Chinese adults using magnetic resonance-feature tracking (MR-FT).

STUDY TYPE

Retrospective.

POPULATION

Four hundred and eight healthy Chinese adults (220 males, aged 43.5 ± 11.5 years; 188 females, aged 45.3 ± 12.8 years).

FIELD STRENGTH/SEQUENCE

1.5 T/balanced steady-state free precession.

ASSESSMENT

Reservoir strain (ε_s ), conduit strain (ε_e ), booster strain (ε_a ), peak positive SR (SRs), peak early negative SR (SRe), and peak late negative SR (SRa) were obtained by MR-FT.

STATISTICAL TESTS

We used Shapiro-Wilk test, Student's t-test, Mann-Whitney U-test, linear regression, and coefficient of determination (r² ).

RESULTS

Women demonstrated significantly greater LA strain (ε_s [%]: 44.0 ± 9.9 vs. 38.3 ± 8.7; ε_e [%]: 26.7 ± 8.0 vs. 22.3 ± 6.8; ε_a [%]: 17.3 ± 4.4 vs. 16.0 ± 3.8) and SR (SRs [/second]: 1.8 ± 0.5 vs. 1.6 ± 0.4; SRe [/second]: -2.5 ± 0.9 vs. -2.1 ± 0.7; SRa [/second]: -1.9 ± 0.6 vs. -1.8 ± 0.5) than men. For both sexes, aging was significantly associated with decreased ε_s , SRs, ε_e , and SRe (r²  = 0.07, r²  = 0.05, r²  = 0.19, and r²  = 0.24 for men; r²  = 0.13, r²  = 0.11, r²  = 0.31, and r²  = 0.46 for women), and significantly increased ε_a (r²  = 0.03 and r²  = 0.05 for men and women). There was no significant correlation between age and SRa in both sexes (P = 0.057 and P = 0.377 for men and women, respectively).

DATA CONCLUSION

We provide age- and sex-specific reference values for LA strain and SR based on a large sample of healthy Chinese adults using MR-FT.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 5.