Reference value of left and right atrial size and phasic function by SSFP CMR at 3.0 T in healthy Chinese adults

Atrial dimension reference values in healthy participants using the biplane/monoplane method for clinical and research use

AIM

To provide reference values of the dimensions of the left and right atrium (RA) obtained using the biplane and monoplane methods, respectively, on two- and four-chamber views, which represent the standard projections acquired in clinical practice, and correlation with body surface area (BSA), age, and gender.

MATERIALS AND METHODS

Healthy volunteers, M:F = 1:1, including five participants per gender and age decile from 20 to 70 years, who underwent cardiovascular magnetic resonance imaging (CMR) were enrolled prospectively. Normal atrial reference values were calculated for male and female subpopulations and stratified by age. Atrial areas and volumes were assessed both as absolute values and indexed to BSA. Differences among genders and correlation with age were assessed. Intra- and interobserver reproducibility were assessed in a subpopulation.

RESULTS

Fifty participants (mean age 43.3 ± 14 years, 25 men) were evaluated. Image analysis took <1 minute for each subject (mean time 30 ± 5 seconds). Intra- and interobserver reproducibility were excellent (ICC >0.85 for all datasets). RA areas were significantly higher in males (p=0.0001). The left atrial (LA) surface did not show significant differences among genders. Atrial areas normalised to BSA did not show significant gender differences. Both right and left absolute atrial volumes turned out to be significantly higher in males (p=0.0001 and p=0.0047, respectively), and normalised to BSA remained significantly different only for the RA (p=0.0006). Neither atrial volume nor areas showed significant correlation with age.

CONCLUSIONS

The monoplane method is a fast and reproducible technique to assess atrial dimensions. Absolute atrial dimensions show significant variations among genders. Gender-specific reference ranges for atrial dimensions are recommended.

Associations between 3D-based Left Atrial Volumetric and Blood Flow Parameters in a Single-Site Cohort of the Multi-Ethnic Study of Atherosclerosis

Purpose To investigate associations between left atrial volume (LAV) and function with impaired three-dimensional hemodynamics from four-dimensional flow MRI. Materials and Methods A subcohort of participants from the Multi-Ethnic Study of Atherosclerosis from Northwestern University underwent prospective 1.5-T cardiac MRI including whole-heart four-dimensional flow and short-axis cine imaging between 2019 and 2020. Four-dimensional flow MRI analysis included manual three-dimensional segmentations of the LA and LA appendage (LAA), which were used to quantify LA and LAA peak velocity and blood stasis (% voxels < 0.1 m/sec). Short-axis cine data were used to delineate LA contours on all cardiac time points, and the resulting three-dimensional-based LAVs were extracted for calculation of LA emptying fractions (LAEFtotal, LAEFactive, LAEFpassive). Stepwise multivariable linear models were calculated for each flow parameter (LA stasis, LA peak velocity, LAA stasis, LAA peak velocity) to determine associations with LAV and LAEF. Results This study included 158 participants (mean age, 73 years ± 7 [SD]; 83 [52.5%] female and 75 [47.4%] male participants). In multivariable models, a 1-unit increase of LAEFtotal was associated with decreased LA stasis (β coefficient, -0.47%; P < .001), while increased LAEFactive was associated with increased LA peak velocity (β coefficient, 0.21 cm/sec; P < .001). Furthermore, increased minimum LAV indexed was most associated with impaired LAA flow (higher LAA stasis [β coefficient, 0.65%; P < .001] and lower LAA peak velocity [β coefficient, -0.35 cm/sec; P < .001]). Conclusion Higher minimum LAV and reduced LA function were associated with impaired flow characteristics in the LA and LAA. LAV assessment might therefore be a surrogate measure for LA and LAA flow abnormalities. Keywords: Atherosclerosis, Left Atrial Volume, Left Atrial Blood Flow, 4D Flow MRI Supplemental material is available for this article. © RSNA, 2024.

Quantification of left atrial function by the area-length method overestimates left atrial emptying fraction

PURPOSE

The biplane area-length method is commonly used in cardiac magnetic resonance (CMR) to assess left atrial (LA) volume (LAV) and function. Associations between left atrial emptying fraction (LAEF) and clinical outcomes have been reported. However, only limited data are available on the calculation of LAEF using the biplane method compared to 3D assessment. This study aimed to compare volumetric and functional LA parameters obtained from the biplane method with 3D assessment in a large, multiethnic cohort.

METHOD

158 participants of MESA (Multi-Ethnic Study of Atherosclerosis) underwent CMR that included standard two- and four-chamber steady-state free precession (SSFP) cine imaging for the biplane method. For 3D-based assessment, short-axis SSFP cine series covering the entire LA were obtained, followed by manual delineation of LA contours to create a time-resolved 3D LAV dataset. Paired t-tests and Bland-Altman plots were used to analyze the data.

RESULTS

Standard volumetric assessment showed that LAVmin (bias: -8.35 mL, p < 0.001), LAVmax (bias: -9.38 mL, p < 0.001) and LAVpreA (bias: -10.27 mL, p < 0.001) were significantly smaller using the biplane method compared to 3D assessment. Additionally, the biplane method reported significantly higher LAEFtotal (bias: 7.22 %, p < 0.001), LAEFactive (bias: 6.08 %, p < 0.001), and LAEFpassive (bias: 4.51 %, p < 0.001) with wide limits of agreement.

CONCLUSIONS

LA volumes were underestimated using the biplane method compared to 3D assessment, while LAEF parameters were overestimated. These findings demonstrate a lack of precision using the biplane method for LAEF assessment. Our results support the usage of 3D assessment in specific settings when LA volumetric and functional parameters are in focus.

Reference Values for Pediatric Atrial Volumes Assessed by Steady-State Free-Precession Magnetic Resonance Imaging Using Monoplane and Biplane Area-Length Methods

BACKGROUND

Measurement of atrial volumes by MRI is becoming increasingly important in pediatric cardiac disorders. However, MRI normal values for atrial volumes in children are lacking.

PURPOSE

To establish pediatric reference values for atrial volumes.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 155 healthy children from two large institutions (103 male, age 13.9 ± 2.8 years, range 4-18 years).

FIELD STRENGTH/SEQUENCE

A 1.5 T; balanced steady-state free precession (bSSFP) sequence.

ASSESSMENT

The monoplane and biplane area-length methods were used to measure minimal and maximal left and right atrial volumes (LAmin , LAmax , RAmin , and RAmax ) from four-chamber (4ch) and two-chamber (2ch) MR cine images. Centile charts and tables for atrial volumes were created.

STATISTICAL TESTS

Descriptive statistics, lambda-mu-sigma (LMS)-method of Cole and Green, univariable and multivariable linear regression models. A P value < 0.05 was considered to be statistically significant.

RESULTS

In the multivariable linear model, body surface area was significantly associated with all atrial volumes and sex was significantly associated with RA volumes, LA volumes measured in the 2ch-view as well as biplane LAmax. Average atrial volumes measured: monoplane 4ch: LAmin 13.1 ± 4.8 mL/m2 , LAmax 33.4 ± 8.8 mL/m2 , RAmin 18.5 ± 6.8 mL/m2 , RAmax 33.2 ± 9.6 mL/m2 ; monoplane 2ch: LAmin 12.7 ± 4.9 mL/m2 , LAmax 30.5 ± 9.5 mL/m2 ; biplane: LAmin 12.3 ± 4.5 mL/m2 , LAmax 30.9 ± 8.7 mL/m2 .

DATA CONCLUSION

Pediatric MRI reference values for atrial volumes have been provided.

TECHNICAL EFFICACY

2 EVIDENCE LEVEL: 4.

Predictive value of left atrial strain analysis in adverse clinical events in patients with hypertrophic cardiomyopathy: a CMR study

BACKGROUND

A subset of patients with hypertrophic cardiomyopathy (HCM) will experience adverse clinical events such as heart failure (HF), cardiovascular death, and new-onset atrial fibrillation (AF). Current risk stratification methods are imperfect and limit the identification of patients at high risk for HCM. This study aimed to evaluate the role of cardiac magnetic resonance (CMR)-derived left atrial strain parameters in the occurrence of adverse clinical events in patients with HCM.

METHODS

Left atrial (LA) structural, functional, and strain parameters were evaluated in 99 patients with HCM and compared with 89 age-, sex-, and BMI-matched control subjects. LA strain parameters were derived from CMR two- and four-chamber cine images by a semiautomatic method. LA strain parameters include global longitudinal strain (GLS) and global circumferential strain (GCS). The LA GLS includes reservoir strain (GLS reservoir), conduit strain (GLS conduit), and booster strain (GLS booster). Three LA GLS strain rate (SR) parameters were derived: SR reservoir, SR conduit, and SR booster. The primary endpoint was set as a composite of adverse clinical events, including SCD, new-onset or worsening to hospitalized HF, new-onset AF, thromboembolic events, and fatal ventricular arrhythmias.

RESULTS

LA GLS, GLS SR and GCS were impaired in HCM patients compared to control subjects (all p < 0.001). After a mean follow-up of 37.94 ± 23.69 months, 18 HCM patients reached the primary endpoint. LA GLS, GLS SR, and GCS were significantly lower in HCM patients with adverse clinical events than in those without adverse clinical events (all p < 0.05). In stepwise multiple Cox regression analysis, LV SV, LA diameter, pre-contraction LAV (LAV pre-ac), passive LA ejection fraction (EF), and LA GLS booster were all independent determinants of adverse clinical events. LA GLS booster ≤ 8.9% was the strongest determinant (HR = 8.9 [95%CI (1.951, 40.933)], p = 0.005). Finally, LA GLS booster provided predictive adverse clinical events value (AUC = 0.86 [95%CI 0.77-0.98]) that exceeded traditional outcome predictors.

CONCLUSION

LA strain assessment, a measure of LA function, provides additional predictive information for established predictors of HCM patients. LA GLS booster was independently associated with adverse clinical events in patients with HCM.

Prognostic value of right atrial strain derived from cardiovascular magnetic resonance in non-ischemic dilated cardiomyopathy

BACKGROUND

The value of right atrial (RA) function in cardiovascular diseases is currently limited. This study was to explore the prognostic value of RA strain derived from fast long axis method by cardiovascular magnetic resonance (CMR) in patients with non-ischemic dilated cardiomyopathy (DCM).

METHODS

We prospectively enrolled patients with DCM who underwent CMR from June 2012 to March 2019 and 120 age- and sex-matched healthy subjects. Fast long-axis strain method was performed to assess the RA phasic function including RA reservoir strain, conduit strain, and booster strain. The predefined primary endpoint was all-cause mortality. The composite heart failure (HF) endpoint included HF death, HF readmission, and heart transplantation. Cox regression analysis and Kaplan-Meier survival curve were performed to describe the association between RA strain and outcomes.

RESULTS

A total of 624 patients (444 men, mean 48 years) were studied. After a median follow-up of 32.5 months, 116 patients (18.6%) experienced all-cause mortality and 205 patients (32.9%) reached composite HF endpoint. RA function was impaired in DCM patients compared with healthy subjects (all P < 0.001). After adjustment for covariates, RA reservoir strain [hazard ratio (HR) (per 5% decrease) 1.19, 95% confidence interval (CI) 1.03-1.37, P = 0.022] and conduit strain [HR (per 5% decrease) 1.37, 95% CI 1.03-1.84, P = 0.033] were independent predictors of all-cause mortality. Moreover, RA strain added incremental prognostic value for the prediction of adverse cardiac events over baseline clinical and CMR predictors (all P < 0.05).

CONCLUSION

RA strain by fast long-axis analysis is independently associated with adverse clinical outcomes in patients with DCM.

TRIAL REGISTRATION

Trial registration number: ChiCTR1800017058; Date of registration: 2018-07-10 (Retrospective registration); URL: https://www.

CLINICALTRIALS

gov.

Imaging assessment of the right atrium: anatomy and function

The right atrium (RA) is the cardiac chamber that has been least well studied. Due to recent advances in interventional cardiology, the need for greater understanding of the RA anatomy and physiology has garnered significant attention. In this article, we review how a comprehensive assessment of RA dimensions and function using either echocardiography, cardiac computed tomography, and magnetic resonance imaging may be used as a first step towards a better understanding of RA pathophysiology. The recently published normative data on RA size and function will likely shed light on RA atrial remodelling in atrial fibrillation (AF), which is a complex phenomenon that occurs in both atria but has only been studied in depth in the left atrium. Changes in RA structure and function have prognostic implications in pulmonary hypertension (PH), where the increased right ventricular (RV) afterload first induces RV remodelling, predominantly characterized by hypertrophy. As PH progresses, RV dysfunction and dilatation may begin and eventually lead to RV failure. Thereafter, RV overload and increased RV stiffness may lead to a proportional increase in RA pressure. This manuscript provides an in-depth review of RA anatomy, function, and haemodynamics with particular emphasis on the changes in structure and function that occur in AF, tricuspid regurgitation, and PH.

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.

Right atrial function is associated with RV diastolic stiffness: RA-RV interaction in pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) patients have altered right atrial (RA) function and right ventricular (RV) diastolic stiffness. This study assessed the impact of RV diastolic stiffness on RA-RV interaction.

METHODS

Low or high end-diastolic elastance (E_ed) PAH patients (n=94) were compared to controls (n=31). Treatment response was evaluated in n=62 patients. RV and RA longitudinal strain, RA emptying and RV filling were determined and diastole was divided in a passive and active phase. Vena cava backflow was calculated as RV active filling-RA active emptying; RA stroke work as RA active emptying*RV end-diastolic pressure.

RESULTS

With increased E_ed, RA and RV passive strain were reduced while active strain was preserved. In comparison to controls, patients had lower RV passive filling, but higher RA active emptying and RA stroke work. RV active filling was lower in high E_ed patients, resulting in higher vena cava backflow. Upon treatment, E_ed reduced in half of high E_edpatients, which coincided with larger reductions in afterload, RV mass and vena cava backflow and greater improvements in RV active filling and stroke volume in comparison to patients in whom E_ed remained high.

CONCLUSIONS

In PAH, RA function is associated with changes in RV function. Despite increased RA stroke work, severe RV diastolic stiffness is associated with reduced RV active filling and increased vena cava backflow. In 50% of high baseline E_ed patients, diastolic stiffness remains high, despite treatment. E_ed reduction coincided with a large reduction in afterload, increased RV active filling and decreased vena cava backflow.

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.

Prognostic value of fast semi-automated left atrial long-axis strain analysis in hypertrophic cardiomyopathy

BACKGROUND

The prognostic value of left atrial (LA) size and function in hypertrophic cardiomyopathy (HCM) is well recognized, but LA function is difficult to routinely analyze. Fast LA long-axis strain (LA-LAS) analysis is a novel technique to assess LA function on cine cardiovascular magnetic resonance (CMR). We aimed to assess the association between fast LA-LAS and adverse clinical outcomes in patients with HCM.

METHODS

359 HCM patients and 100 healthy controls underwent routine CMR imaging. Fast LA-LAS was analyzed by automatically tracking the length between the midpoint of posterior LA wall and the left atrioventricular junction based on standard 2- and 4-chamber balanced steady-state free precession cine-CMR. Three strain parameters including reservoir strain (εs), conduit strain (εe), and active strain (εa) were assessed. The endpoint was set as composite adverse events including cardiovascular death, resuscitated cardiac arrest, sudden cardiac death aborted by appropriate implantable cardioverter-defibrillator discharge, and hospital admission related to heart failure.

RESULTS

During an average follow-up of 40.9 months, 59 patients (19.7%) reached endpoints. LA strains were correlated with LA diameter, LA volume index (LAVI) and LA empty fraction (LAEF) (all p < 0.05). In the stepwise multivariate Cox regression analysis, εs and εe (hazard ratio, 0.94 and 0.89; p = 0.019 and 0.006, respectively) emerged as independent predictors of the composite adverse events. Fast LA εs and LA εe are stronger prognostic factors than LA size, LAVI and the presence of left ventricular late gadolinium enhancement.

CONCLUSIONS

Fast LA reservoir and conduit strains are independently associated with adverse outcomes in HCM.

Reference ranges ("normal values") for cardiovascular magnetic resonance (CMR) in adults and children: 2020 update

Cardiovascular magnetic resonance (CMR) enables assessment and quantification of morphological and functional parameters of the heart, including chamber size and function, diameters of the aorta and pulmonary arteries, flow and myocardial relaxation times. Knowledge of reference ranges ("normal values") for quantitative CMR is crucial to interpretation of results and to distinguish normal from disease. Compared to the previous version of this review published in 2015, we present updated and expanded reference values for morphological and functional CMR parameters of the cardiovascular system based on the peer-reviewed literature and current CMR techniques. Further, databases and references for deep learning methods are included.

Fractal Analysis: Prognostic Value of Left Ventricular Trabecular Complexity Cardiovascular MRI in Participants with Hypertrophic Cardiomyopathy

Background The prognostic value of myocardial trabecular complexity in patients with hypertrophic cardiomyopathy (HCM) is unknown. Purpose To explore the prognostic value of myocardial trabecular complexity using fractal analysis in participants with HCM. Materials and Methods The authors prospectively enrolled participants with HCM who underwent 3.0-T cardiovascular MRI from August 2011 to October 2017. The authors also enrolled 100 age- and sex-matched healthy participants to form a comparison group. Trabeculae were quantified with fractal analysis of cine slices to estimate the fractal dimension (FD). Participants with HCM were divided into normal and high FD groups according to the upper limit of normal reference value from the healthy group. The primary end point was defined as all-cause mortality and aborted sudden cardiac death. The secondary end point was the composite of the primary end point and readmission to the hospital owing to heart failure. Internal validation was performed using the bootstrapping method. Results A total of 378 participants with HCM (median age, 50 years; age range, 40-61 years; 207 men) and 100 healthy participants (median age, 46 years; age range, 36-59 years; 55 women) were included in this study. During the median follow-up of 33 months ± 18 (standard deviation), the increased maximal apical FD (≥1.325) had a higher risk of the primary and secondary end points than those with a normal FD (<1.325) (P = .01 and P = .04, respectively). Furthermore, Cox analysis revealed that left ventricular maximal apical FD (hazard ratio range, 1.001-1.008; all P < .05) provided significant prognostic value to predict the primary and secondary end points after adjustment for the European Society of Cardiology predictors and late gadolinium enhancement. Internal validation showed that left ventricular maximal apical FD retained a good performance in predicting the primary end points with an area under the curve of 0.70 ± 0.03. Conclusion Left ventricular apical fractal dimension, which reflects myocardial trabecular complexity, was an independent predictor of the primary and secondary end points in patients with hypertrophic cardiomyopathy. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Captur and Moon in this issue.

Balloon pulmonary angioplasty improves right atrial reservoir and conduit functions in chronic thromboembolic pulmonary hypertension

AIMS

Right atrial (RA) function largely contributes to the maintenance of right ventricular (RV) function. This study investigated the effect of balloon pulmonary angioplasty (BPA) on RA functions in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) using cardiac magnetic resonance imaging (CMRI).

METHODS AND RESULTS

CMRI and RV catheterization were performed before BPA sessions and at the follow-up periods in 29 CTEPH patients. Reservoir [RA longitudinal strain (RA-LS)], passive conduit [RA early LS rate (LSR)], and active (RA late LSR) phases were assessed by using cine CMRI and a feature-tracking algorithm. The relationships between the changes in RA functions and in brain natriuretic peptide (BNP) were evaluated in both the dilated and non-dilated RA groups. RA-LS (32.4% vs. 42.7%), RA LSR (6.3% vs. 8.3%), and RA early LSR (-2.3% vs. -4.3%) were improved after BPA, whereas no significant change was seen in RA late LSR. The changes in RA peak LS and in RA early LSR were significantly correlated with the changes in BNP (ΔRA-LS: r = -0.63, ΔRA-early LSR: r = 0.65) and pulmonary vascular resistance (PVR) (ΔRA-LS: r = -0.69, ΔRA-early LSR: r = 0.66) in the nondilated RA group.

CONCLUSION

The RA reservoir and passive conduit functions were impaired in inoperable CTEPH, whereas RA active function was preserved. BPA markedly reversed these impaired functions. The improvements in RA reservoir and conduit functions were significantly correlated with the changes in BNP levels and PVR in CTEPH patients with normal RA sizes.

Prognostic value of left ventricular remodelling index in idiopathic dilated cardiomyopathy

AIMS

To evaluate the prognostic value of left ventricular (LV) remodelling index (RI) in idiopathic dilated cardiomyopathy (DCM) patients.

METHODS AND RESULTS

We prospectively enrolled 412 idiopathic DCM patients and 130 age- and sex-matched healthy volunteers who underwent cardiovascular magnetic resonance imaging between September 2013 and March 2018. RI was defined as the cubic root of the LV end-diastolic volume divided by the mean LV wall thickness on basal short-axis slice. The primary endpoint included all-cause mortality and heart transplantation. The secondary endpoint included the primary endpoint and heart failure (HF) readmission. During the median follow-up of 28.1 months (interquartile range: 19.3-43.0 months), 62 (15.0%) and 143 (34.7%) patients reached the primary and secondary endpoints, respectively. Stepwise multivariate Cox regression showed that RI [hazard ratio (HR) 1.20, 95% confidence interval (CI) 1.11-1.30, P < 0.001], late gadolinium enhancement (LGE) presence and log (N-terminal pro-B-type natriuretic peptide) were independent predictors of the primary endpoint, while RI (HR 1.15, 95% CI 1.08-1.23, P < 0.001) and extracellular volume were independent predictors of the secondary endpoint. The addition of RI to LV ejection fraction (EF) and LGE presence showed significantly improved global χ2 for predicting primary and secondary endpoints (both P < 0.001). Furthermore, RI derived from echocardiography also showed independent prognostic value for primary and secondary endpoints with clinical risk factors.

CONCLUSIONS

RI is an independent predictor of all-cause mortality, heart transplantation, and HF readmission in DCM patients and provides incremental prognostic value to LVEF and LGE presence.

Association of left atrial deformation indices with left atrial appendage thrombus in patients with non valvular atrial fibrillation

Aim

Assessment of the value of left atrial deformation indices for prediction of left atrial appendage functioning patients with non-valvular atrial fibrillation.

Method

The study included 250 patients with non-valvular atrial fibrillation and normal left atrial dimension. Trans-thoracic and trans-esophageal echocardiography were performed. Patients were divided into two groups; patients with LAA thrombus (group I) and patients without LAA thrombus (group II), a correlation between trans-esophageal and trans-thoracic data was analyzed.

Results

Group I included110 patients (44%) and Group II 140 patients (56%). By TDI mean LA strain and strain rate were lower in group I (21.89 ± 7.75% vs 35.14 ± 9.28%; p < 0.001) and (1.15/sec, IQR 0.12–3/sec versus 2.1/sec, IQR 0.21–3/sec, p < 0.001) respectively. By speckle tracking PALS and strain rate were lower in group I (24.79 ± 7.78% vs 37.63 ± 8.64%; p value < 0.001) and (0.95 ± 0.32/sec. Vs 1.27 ± 0.32/sec p, value < 0.001) respectively. By TEE; group I had lower LAA EF (39.2 ± 13.55% vs 53.86 ± 12.7%); p < 0.001, and lower LAA emptying velocity (17.53 cm/s, IQR 9.54–77.4 vs 63.5 cm/s, IQR 7.89–86.4; p < 0.001). There was a good correlation between LA TDI and speckle tracking PALS and PALSR and LAA EF% and velocity p < 0.001. TDI and PALS and PALSR were found to be significant predictors for LAA thrombus (P < 0.05) with good sensitivity and specificity.

Conclusion

Left atrium deformation indices are predictors of LAA thrombus or SEC in patients with non-valvular AF with accepted sensitivity and specificity.

Computational Simulation of Cardiac Function and Blood Flow in the Circulatory System under Continuous Flow Left Ventricular Assist Device Support during Atrial Fibrillation

Prevalence of atrial fibrillation (AF) is high in heart failure patients supported by a continuous flow left ventricular assist device (CF-LVAD); however, the long term effects remain unclear. In this study, a computational model simulating effects of AF on cardiac function and blood flow for heart failure and CF-LVAD support is presented. The computational model describes left and right heart, systemic and pulmonary circulations and cerebral circulation, and utilises patient-derived RR interval series for normal sinus rhythm (SR). Moreover, AF was simulated using patient-derived unimodal and bimodal distributed RR interval series and patient specific left ventricular systolic functions. The cardiovascular system model simulated clinically-observed haemodynamic outcomes under CF-LVAD support during AF, such as reduced right ventricular ejection fraction and elevated systolic pulmonary arterial pressure. Moreover, relatively high aortic peak pressures and middle arterial peak flow rates during AF with bimodal RR interval distribution, reduced to similar levels as during normal SR and AF with unimodal RR interval distribution under CF-LVAD support. The simulation results suggest that factors such as distribution of RR intervals and systolic left ventricular function may influence haemodynamic outcome of CF-LVAD support during AF.

The prognostic value of biventricular long axis strain using standard cardiovascular magnetic resonance imaging in patients with hypertrophic cardiomyopathy

BACKGROUND

Long axis strain (LAS) is a parameter derived from standard cardiovascular magnetic resonance imaging. However, the prognostic value of biventricular LAS in hypertrophic cardiomyopathy (HCM) is unknown.

METHODS

Patients with HCM (n = 384) and healthy volunteers (n = 150) were included in the study. Left ventricular (LV)-LAS was defined as the percentage change in the length measured from the epicardial border of the LV apex to the midpoint of a line connecting the mitral annulus at end-systole and end-diastole. Right ventricular (RV)-LAS represented the percentage change of length between epicardial border of the LV apex to the midpoint of a line connecting the tricuspid annulus at end-systole and end-diastole. The primary endpoint was a combination of all-cause death and sudden cardiac death aborted by appropriate implantable cardioverter-defibrillator discharge and cardiopulmonary resuscitation after syncope. The secondary endpoint was a combination of the primary endpoint and hospitalization for congestive heart failure.

RESULTS

Twenty-nine patients (7.6%) achieved the primary endpoint, and the secondary endpoint occurred in 66 (17.2%) patients. In multivariate Cox regression analysis, RV-LAS was an independent prognostic factor for the primary (hazard ratio (HR), 1.13) and secondary (HR, 1.11) endpoints. In the subgroup of patients with a normal RV ejection fraction (EF) (>45.0%, n = 345), impaired RV-LAS was associated with adverse outcomes and might add incremental prognostic value to RVEF and tricuspid annular plane systolic excursion (TAPSE) (p < 0.01).

CONCLUSIONS

RV-LAS is an independent predictor of adverse prognosis in HCM in addition to RVEF and TAPSE.

Left atrial size and function in a South Asian population and their potential influence on the risk of atrial fibrillation

BACKGROUND

South Asians have a low prevalence of atrial fibrillation (AF) compared with Caucasians despite having a higher prevalence of conventional risk factors for the arrhythmia. The reason for this disparity is uncertain but may be due to ethnic differences in atrial morphology. This study examines the association between ethnicity and left atrial (LA) size and function in South Asian and Caucasian subjects using the reference technique of cardiovascular magnetic resonance imaging (MRI).

HYPOTHESIS

South Asians have smaller LA size and therefore increased LA function.

METHODS

Retrospective case-control study of 60 South Asian and 60 Caucasian patients who had undergone a clinically indicated MRI between April 2010 and October 2017 and had been found to have a structurally normal heart. LA and left ventricular (LV) volume and function were assessed and compared between the ethnicities.

RESULTS

In comparison with Caucasians, South Asians had significantly lower minimum (27.7 ± 11.1 mL vs 34.9 ± 12.3 mL, P = 0.002) and maximum LA volumes (64.7 ± 21.1 mL vs 80.9 ± 22.5 mL, P < 0.001), lower LV end-diastolic volume (P < 0.001), lower LV stroke volume (P < 0.001), and lower LV mass (P = 0.022) and these values remained significant after correcting for body surface area. Further analysis revealed that LA volume was independently associated with South Asian ethnicity. There was no difference in LA function between the ethnic groups.

CONCLUSIONS

South Asians have reduced LA volumes and a proportionally smaller heart size in comparison to Caucasians. Smaller LA size may protect against the development of AF by reducing the risk of reentrant circuit formation and atrial fibrosis development.

Age and Gender Impact the Measurement of Myocardial Interstitial Fibrosis in a Healthy Adult Chinese Population: A Cardiac Magnetic Resonance Study

Background: Diffuse myocardial fibrosis is a common pathological process in many cardiovascular diseases. In order to determine disease, we must have standard normal imaging values. We investigated myocardial interstitial fibrosis of the left ventricle (LV) in a healthy population of Chinese adults and explored the impact of gender, age, and other physiological factors using a T1 mapping technique of cardiac magnetic resonance imaging (CMR).

Materials and Methods: We recruited 69 healthy adult Chinese subjects (35 males; age 18–76). LV function and global strain were obtained from functional imaging. T1 mapping was performed using a modified look-locker sequence. Global and segmental native T1 and extracellular volume (ECV) were calculated using dedicated software. Gender, age, and segmental variation of both native myocardial T1 and ECV of the LV were analyzed.

Results: The global myocardial native T1 and ECV of the LV in this Chinese adult healthy population was 1,202 ± 45 ms and 27 ± 3% at 3T field strength, respectively. Females had a higher myocardial native T1 and ECV of the LV compared to males [1,210 (1,188–1,264) ms vs. 1,182 (1,150–1,211) ms, P < 0.001; 28 ± 3 vs. 26 ± 3%, P = 0.027, respectively]. ECV in older group was higher than younger group [27 (26–29)% vs. 25 (24–29), P = 0.019]. The multi-variate linear regression analysis showed that only gender (Beta = −0.512, P < 0.001) was independently related with global native T1 of LV while gender (Beta = −0.278, P = 0.017) and age (Beta = 0.303, P = 0.010) were independently related with global ECV of LV. From the base to apex of the LV, myocardial native T1 (P = 0.020) and ECV (P < 0.001) significantly increased. Within the same slice of the LV, there were significant segmental variations of both myocardial native T1 (P < 0.001) and ECV (P < 0.001) values.

Conclusion: Gender and age have significant impacts on the imaging markers of myocardial interstitial fibrosis in healthy adult Chinese volunteers. Segmental variation of myocardial interstitial fibrosis was also observed.