Quantitative evaluation of left atrial volumes and ejection fraction by 320-slice computed-tomography in comparison with three- and two-dimensional echocardiography: a single-center retrospective-study in 22 subjects

Biatrial Volumetric Assessment by Non-ECG-Gated CT Pulmonary Angiography Correlated with Transthoracic Echocardiography in Patients with Normal Diastology

Atrial size is a predictor of cardiovascular mortality. Non-ECG-gated computed tomography pulmonary angiography (CTPA) is a common test for cardiopulmonary evaluation but normative values for biatrial volumes are lacking. We derived normal CT biatrial volumes using manual and semiautomated segmentation with contemporaneous transthoracic echocardiography (TTE) to confirm normal diastology. Thirty-five consecutive cases in sinus rhythm with no history of cardio-vascular, renal, or pulmonary disease and normal diastolic function were selected. Planimetric CTPA measurements were compared to TTE volumes measured using area length method. TTE and CTPA derived normal LAVi and RAVi were 27 + 5 and 20 + 6 mL/m², and 30 + 8 and 29 + 9 mL/m², respectively. Bland-Altman analysis revealed an underestimation of biatrial volumes by TTE. TTE-CT mean biases for LAV and RAV were -5.7 + 12.0 mL and -16.2 + 14.8 mL, respectively. The CT intraclass correlation coefficients (ICC 95% CI) for LA and RA volumes were 0.99 (0.96-1.00) and 0.96 (0.76-0.99), respectively. There was excellent correlation (p < 0.001) between the semiautomated and manual measurements for LA (r 0.99, 95% CI 0.98-0.99) and RA (r 0.99, 95% CI 0.99-1.00). Atrial volumetric assessment on CTPA is easy and reproducible and can provide additional metric in cardiopulmonary assessment.

Multi-Modality Imaging for the Identification of Arrhythmogenic Substrates Prior to Electrophysiology Studies

Noninvasive cardiac imaging is crucial for the characterization of patients who are candidates for cardiac ablations, for both procedure planning and long-term management. Multimodality cardiac imaging can provide not only anatomical parameters but even more importantly functional information that may allow a better risk stratification of cardiac patients. Moreover, fusion of anatomical and functional data derived from noninvasive cardiac imaging with the results of endocavitary mapping may possibly allow a better identification of the ablation substrate and also avoid peri-procedural complications. As a result, imaging-guided electrophysiological procedures are associated with an improved outcome than traditional ablation procedures, with a consistently lower recurrence rate.

A fast and reproducible method to estimate left atrial volume using cardiac computed tomography

PURPOSE

The purpose of this study was to do better than the simple maximal axial area (MArea_ax) and to validate simple, fast and robust orthogonal methods for determining the left atrium volume (LAV) with cardiac CT (CCT).

MATERIAL AND METHODS

A total of 60 patients who underwent CTT were retrospectively included. There were 30 men and 30 women with a mean age of 59±12 (SD) years (range: 27-80 years), using four methods to assess LAV beyond the MArea_ax: two orthogonal methods requiring the measurements of axial, coronal and sagittal planes of 3 diameters LAV_3diam or 3 area LAV_3Areas; Area-length biplane method LAV_biplane; and volumetric method LAV_volumetric using a semi-automated tool that served as the reference standard. The orthogonal methods were applied on contrast-enhanced (IV+) and unenhanced (IV-) CCT images. Comparisons were performed using Pearson correlation test (r) and Bland-Altman analysis. Inter- and intra-observer variability were assessed using intraclass correlation coefficient (ICC) with a two-way mixed-effects model.

RESULTS

On IV+ CCT, LAV_biplane, LAV3diam_-IV+, LAV_3Areas-IV+ underestimated LAV (-15±1.99mL; -21±1.37mL; -15±1.98mL; all P<0.001). LAV_3diam-IV+, LAV3_Areas-IV+ better correlated with reference standard (r=0.97 and 0.98) than LAV_biplane (r=0.79) as well as MArea_ax (r=0.90). Estimating LAV on IV- further showed high correlation against the reference (r=0.93 and 0.95 for LAV3diam_-IV- and LAV_3Areass-IV-, respectively). Intra- and inter-observer ICC increased from LAV_volumetric (2.43% and 3.09%); LAV_3Areas-IV+ (3.04 and 3.30%); LAV_3Areas-IV-(3.34 and 4.23%), LAV3diam_-IV+ (3.36 and 5.11%); LAV3diam_-IV- (5.16 and 6.90%); to LAV_biplane (9.65 and 10.28%).

CONCLUSIONS

Better than MArea_ax, orthogonal methods using either diameter or surface are fast and reproducible methods to assess LAV on CCT when performed with or without intravenous administration of contrast material.

Comparison of left and right atrial volumes determined by two- and three-dimensional echocardiography with those determined by multidetector computed tomography for healthy dogs

OBJECTIVE

To compare left atrial volume (LAV) and right atrial volume (RAV) determined by 2-D and 3-D echocardiographic methods with the LAV and RAV determined by ECG-gated multidetector CT (MDCT) for healthy dogs.

ANIMALS

11 healthy purpose-bred young adult hound-type dogs.

PROCEDURES

Each dog was anesthetized and underwent MDCT and a complete echocardiographic examination. Modality-specific software was used to measure the respective atrial volumes at ventricular end systole, and LAV and RAV measurements were subsequently indexed to body weight and compared among imaging modalities.

RESULTS

The LAV determined by echocardiographic methods did not differ significantly from the LAV determined by MDCT. However, the RAV determined by 3-D echocardiography and 2-D echocardiography via the left apical and left cranial windows differed significantly from the RAV determined by MDCT. Bland-Altman analyses indicated that the indexed LAV and RAV determined by echocardiographic methods were systematically underestimated, compared with MDCT measurements, but the bias was much smaller for LAV than for RAV.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that, for dogs, echocardiography might be an acceptable alternative to MDCT for measurement of LAV but not for measurement of RAV. However, the study population was small and homogenous in terms of breed, age, and weight. These findings need to be validated in a larger, more varied population of dogs with and without cardiac disease.

Left ventricular diastolic dysfunction: identifying presence by left atrial function

Objective

The left atrium (LA) is exposed to left ventricular pressure during diastole. Applying the 2016 American Society of Echocardiography left ventricular diastolic function (LVDF) guidelines, this study aims to investigate whether left atrial ejection fraction (LAEF) and left atrial active emptying fraction (LAAEF) are markers of diastolic dysfunction (LVDD).

Methods

Retrospective cohort of consecutive patients (n = 124) who underwent transthoracic echocardiography were studied. Doppler peak velocities of passive (MV E) and active filling (MV A) were measured and ratio E/A calculated. Tissue Doppler imaging parameters of peak early (e′) of the septal and lateral mitral annulus were measured, and average E/e′ ratio (E/e′) was calculated. Tricuspid regurgitation velocity, left atrial maximum volume, left atrial minimum volume and LA volume pre-contraction were measured, allowing calculation of LAEF and LAAEF. Subjects were assigned LVDF categories.

Results

Binomial logistic regression model (X²(2) = 48.924, P < 0.01) determined that LAEF and LAAEF predicted diastolic dysfunction with sensitivity 85.5% and specificity 78%. ROC curves determined good diagnostic accuracy for LAEF and LAAEF to predict LVDD, AUC 0.826 and 0.861 respectively. Logistic regression model (X²(2) = 39.525, P < 0.01) predicted those patients with E/e′ ≥14 using LAEF and LAAEF with sensitivity 51.6% and specificity 92.4%. Moderate correlations were found between E/e′ and log derivatives of LAEF and LAAEF.

Conclusions

A decline in LAAEF and LAEF is associated with worsening LVDD.

The Accuracy of Left Ventricular and Left Atrial Volumetry Using 64-Slice Computed Tomography: In Vitro Validation Study With Human Cardiac Cadaveric Casts

OBJECTIVE

We aimed to validate the accuracy of imaging of left atrial and ventricular volumes using cardiac cadaveric silicone casts.

METHODS

Left atrial (n = 14) and ventricular (n = 15) casts were imaged using 64-slice computed tomography (CT). Water displacement (WD) of cardiac casts was used as the gold standard for volume measurements.

RESULTS

Compared with WD, CT resulted in slightly higher left atrial and ventricular volumes (54 ± 25 vs 56 ± 26 mL [P = 0.003] and 57 ± 47 vs 66 ± 47 mL [P = 0.0001]). Variability between left atrial and ventricular volumes by CT and WD was low (coefficients of variation [CVs], 4% [intraclass correlation coefficient {ICC}, 0.99] and 12% [ICC, 0.97]). Intraobserver variability of CT was low for both the left atrium and the left ventricle (CVs, 1% [ICC, 1.00] and 4% [ICC, 1.00]).

CONCLUSIONS

Cardiac CT is both accurate and reproducible in assessment of left ventricular and atrial chamber volumes.

Quantitative evaluation of left atrial volume and function by one-dimensional, two-dimensional, and three-dimensional echocardiography in a population of normal dogs

OBJECTIVES

The primary goal of this study was to compare left atrial (LA) volume and functional indices in a population of normal dogs using transthoracic one-dimensional M-mode, two-dimensional (2D), and three-dimensional (3D) echocardiography.

ANIMALS

Forty clinically normal dogs of various breeds were stratified into four groups based on weight.

METHODS

Left atrial volume (LAV) was estimated by converting single linear measurements derived from M-mode and 2D images into volumes via the cube and sphere formulas. 2D echocardiography was employed to estimate LAV using linear measures and rectangular and ellipsoid formulas, as well as area-length and the monoplane method of disks. LAV was estimated using the biplane area-length method on 4- and 2-chamber 2D images. LAV was directly measured using 3D volume data obtained over four consecutive cardiac cycles. LAV estimates were compared amongst methods, correlated to body size, and evaluated for reproducibility. Functional indices derived from these various echocardiographic methods were compared to identify any systematic differences based on imaging modality. LA functional indices included LA ejection fraction (LAEF), total LA emptying volume, passive LA emptying volume/fraction, active LA emptying volume/fraction, and LA expansion index.

RESULTS

The M-mode derived estimates of LAV were significantly smaller than all 2D- and 3D-derived LAV (p<0.0001). The left-sided 3D LAV had the highest correlation with body weight (r² = 0.8806) for all phases of the LA cycle with acceptable interobserver variability (CV 11%).

CONCLUSIONS

3D echocardiography is a feasible, non-invasive method to measure LAV in a population of normal dogs.

The Role of Magnetic Resonance Imaging and Cardiac Computed Tomography in the Assessment of Left Atrial Anatomy, Size, and Function

In the last decade, there has been increasing evidence that comprehensive evaluation of the left atrium is of utmost importance. Numerous studies have clearly demonstrated the prognostic value of left atrial volume for long-term outcome. Furthermore, advances in catheter ablation procedures used for the treatment of drug-refractory atrial fibrillation require the need for detailed knowledge of left atrial and pulmonary venous morphology as well of atrial wall characteristics. This review article discusses the role of cardiac magnetic resonance and computed tomography in assessment of left atrial size, its normal and abnormal morphology, and function. Special interest is paid to the utility of these rapidly involving noninvasive imaging methods before and after atrial fibrillation ablation.

Single breath-hold 3D measurement of left atrial volume using compressed sensing cardiovascular magnetic resonance and a non-model-based reconstruction approach

BACKGROUND

Left atrial (LA) dilatation is associated with a large variety of cardiac diseases. Current cardiovascular magnetic resonance (CMR) strategies to measure LA volumes are based on multi-breath-hold multi-slice acquisitions, which are time-consuming and susceptible to misregistration.

AIM

To develop a time-efficient single breath-hold 3D CMR acquisition and reconstruction method to precisely measure LA volumes and function.

METHODS

A highly accelerated compressed-sensing multi-slice cine sequence (CS-cineCMR) was combined with a non-model-based 3D reconstruction method to measure LA volumes with high temporal and spatial resolution during a single breath-hold. This approach was validated in LA phantoms of different shapes and applied in 3 patients. In addition, the influence of slice orientations on accuracy was evaluated in the LA phantoms for the new approach in comparison with a conventional model-based biplane area-length reconstruction. As a reference in patients, a self-navigated high-resolution whole-heart 3D dataset (3D-HR-CMR) was acquired during mid-diastole to yield accurate LA volumes.

RESULTS

Phantom studies. LA volumes were accurately measured by CS-cineCMR with a mean difference of -4.73 ± 1.75 ml (-8.67 ± 3.54%, r2 = 0.94). For the new method the calculated volumes were not significantly different when different orientations of the CS-cineCMR slices were applied to cover the LA phantoms. Long-axis "aligned" vs "not aligned" with the phantom long-axis yielded similar differences vs the reference volume (-4.87 ± 1.73 ml vs. -4.45 ± 1.97 ml, p = 0.67) and short-axis "perpendicular" vs. "not-perpendicular" with the LA long-axis (-4.72 ± 1.66 ml vs. -4.75 ± 2.13 ml; p = 0.98). The conventional bi-plane area-length method was susceptible for slice orientations (p = 0.0085 for the interaction of "slice orientation" and "reconstruction technique", 2-way ANOVA for repeated measures). To use the 3D-HR-CMR as the reference for LA volumes in patients, it was validated in the LA phantoms (mean difference: -1.37 ± 1.35 ml, -2.38 ± 2.44%, r2 = 0.97). Patient study: The CS-cineCMR LA volumes of the mid-diastolic frame matched closely with the reference LA volume (measured by 3D-HR-CMR) with a difference of -2.66 ± 6.5 ml (3.0% underestimation; true LA volumes: 63 ml, 62 ml, and 395 ml). Finally, a high intra- and inter-observer agreement for maximal and minimal LA volume measurement is also shown.

CONCLUSIONS

The proposed method combines a highly accelerated single-breathhold compressed-sensing multi-slice CMR technique with a non-model-based 3D reconstruction to accurately and reproducibly measure LA volumes and function.

Left atrial volumes: two-dimensional, three-dimensional, cardiac magnetic resonance and computed tomography measurements

PURPOSE OF REVIEW

Evaluation of left atrial volume is important, as it is a biomarker of cardiovascular disease and outcomes and correlates with diastolic dysfunction severity. Left atrial volume measurements by different imaging modalities, including 2D and 3D echocardiography (2DE and 3DE), cardiac magnetic resonance (CMR) and computed tomography (CT), are reviewed in regard to recent advances, methodology, prognostic value and limitations.

RECENT FINDINGS

Left atrial volume assessments correlate well between the different imaging modalities; however, 2DE significantly underestimates left atrial measurements. Assessment of the left atrial minimum volume and left atrial phasic function derived volumetrically have reported superior predictive value for major adverse cardiovascular events and elevated left ventricular diastolic pressure compared with the left atrial maximum volume.

SUMMARY

The different imaging modalities used to assess left atrial volumes are not interchangeable, particularly for serial measurements. Although 2DE underestimates left atrial volumes, most normative as well as predictive data have been obtained using this modality. Standardization, with established normative data and classification criteria, needs to be established for other imaging modalities, additionally incorporating assessment of left atrial minimum and phasic volumes. Despite the limitations of the more simplistic 2DE, its measurements are well defined with significant prognostic value. The incremental prognostic value of the more complex imaging techniques needs to be further validated.

Left atrial function following surgical ablation of atrial fibrillation: prospective evaluation using dual-source cardiac computed tomography

PURPOSE

The Maze procedure has shown excellent efficacy in the elimination of atrial fibrillation (AF); however, little is known about the quality of functional recovery in the left atrium (LA) following successful sinus rhythm conversion by the Maze procedure.

MATERIALS AND METHODS

We prospectively enrolled 12 patients (aged 52.5±10.1 years, 1 female) with valvular AF undergoing mitral valve surgery combined with the Maze procedure. Parameters of LA function in three anatomic compartments [anterior, posterior, and LA appendage (LAA)] were evaluated using electrocardiography-gated dual-source cardiac CT at one month and at six months after surgery. Twelve subjects matched by age, gender, and body surface area served as controls.

RESULTS

At one month after surgery, ejection fraction (EF) and emptying volume (EV) of the LA were 14.9±7.4% and 21.3±9.7 mL, respectively, and they were significantly lower than those of the control group (EF, 47.9±11.2%; EV, 46.0±10.7%; p<0001). These values did not significantly change throughout late periods (p=0.22 and 0.21, respectively). Functional contributions of the anterior, posterior, and appendage compartments (EV of each compartment/overall EV) were 80.4%, -0.9%, and 20.5%, respectively, for those with LAA preservation (n=6); 100.1%, -0.1%, and 0% for those with LAA resection (n=6; p<0.05); and 62.2%, 28.2%, and 9.7% in the control subjects (p<0.001).

CONCLUSION

Contractile functions of the LA significantly decreased after the Maze procedure. Functional contributions of three compartments of the LA were also altered. The influence of LAA preservation on postoperative LA functions needs to be evaluated through studies of larger populations.

The influence of type 2 diabetes on left atrial remodeling

The influence of type 2 diabetes mellitus on cardiac remodeling has been evaluated for decades; however, the majority of investigations were focused only on the left ventricle. The impact of diabetes on the left atrial (LA) function is less researched. LA enlargement has been shown as an independent predictor of cardiovascular morbidity and mortality in the general and diabetic population; however, LA dysfunction has been proven to be an independent predictor only in the general population. There are not much follow-up data about the influence of diabetes on LA function. New echocardiographic techniques, such as 2-dimensional speckle tracking imaging, provide more accurate, sensitive, and reliable information about LA function than traditional, volumetric methods. The aim of this review was to summarize the most recent reports about the influence of diabetes on LA function, as well as to discuss the possible mechanisms and potential clinical implications of the relationship between diabetes and LA remodeling.

Left atrial passive emptying function is preserved in patients with permanent atrial fibrillation--a 320-slice multidetector computed tomography study

OBJECTIVE

Left atrial (LA) mechanical function is thought to be virtually inexistent in patients with permanent atrial fibrillation (AF). Due to recent advances in multidetector computed tomography (MDCT) technology, it is now possible to acquire images of the entire heart in a single heartbeat. The objective of this study was to compare individual components of LA function assessed by MDCT in patients with permanent AF and patients in sinus rhythm (SR).

METHODS

320-slice MDCT was performed in 30 patients with permanent AF. Measurements of LA volumes during the cardiac cycle were compared to 30 patients in SR, who were matched with respect to age, sex, left ventricular ejection fraction and body surface area.

RESULTS

LA volumes were significantly larger in patients with AF than SR patients at all times during the cardiac cycle (LA maximal volume; 82 vs. 55 ml/m(2), p < 0.0001, LA minimal volume; 71 vs. 30 ml/m(2), p < 0.0001). However, except for the absence of active LA emptying, the overall trend of the LA time-volume curve was similar in patients with AF and SR.

CONCLUSION

Compared to SR patients, patients with permanent AF have significantly increased LA volumes throughout the cardiac cycle. Yet, a residual hemodynamic role of LA function may be maintained during permanent AF.

Morphological and volumetric analysis of left atrial appendage and left atrium: cardiac computed tomography-based reproducibility assessment

OBJECTIVES

Left atrial appendage (LAA) dilatation and morphology may influence an individual's risk for intracardiac thrombi and ischemic stroke. LAA size and morphology can be evaluated using cardiac computed tomography (cCT). The present study evaluated the reproducibility of LAA volume and morphology assessments.

METHODS

A total of 149 patients (47 females; mean age 60.9±10.6 years) with suspected cardioembolic stroke/transient ischemic attack underwent cCT. Image quality was rated based on four categories. Ten patients were selected from each image quality category (N = 40) for volumetric reproducibility analysis by two individual readers. LAA and left atrium (LA) volume were measured in both two-chamber (2CV) and transversal view (TV) orientation. Intertechnique reproducibility was assessed between 2CV and TV (200 measurement pairs). LAA morphology (A = Cactus, B = ChickenWing, C = WindSock, D = CauliFlower), LAA opening height, number of LAA lobes, trabeculation, and orientation of the LAA tip was analysed in all study subjects by three individual readers (447 interobserver measurement pairs). The reproducibility of volume measurements was assessed by intra-class correlation (ICC) and the reproducibility of LAA morphology assessments by Cohen's kappa.

RESULTS

The intra-observer and interobserver reproducibility of LAA and LA volume measurements was excellent (ICCs>0.9). The LAA (ICC = 0.954) and LA (ICC = 0.945) volume measurements were comparable between 2CV and TV. Morphological classification (ĸ = 0.24) and assessments of LAA opening height (ĸ = 0.1), number of LAA lobes (ĸ = 0.16), trabeculation (ĸ = 0.15), and orientation of the LAA tip (ĸ = 0.37) was only slightly to fairly reproducible.

CONCLUSIONS

LA and LAA volume measurements on cCT provide excellent reproducibility, whereas visual assessment of LAA morphological features is challenging and results in unsatisfactory agreement between readers.