Left atrial size is the major predictor of cardiac death and overall clinical outcome in patients with dilated cardiomyopathy: a long-term follow-up study

Comparison of echocardiographic single-plane versus biplane method in the assessment of left atrial volume and validation by real time three-dimensional echocardiography

BACKGROUND

The American Society of Echocardiography recommends calculating left atrial (LA) biplane volume because of its greater accuracy and prognostic value over LA diameter. However, biplane methods are not always feasible. The aim of this study was to assess the correlation between the echocardiographic LA biplane and single-plane volumes and their agreement in the classification of LA size when American Society of Echocardiography cutoffs are applied.

METHODS

Two-dimensional echocardiography was performed on the participants of the population-based Cardiovascular Abnormalities and Brain Lesions study. LA volume was calculated by the biplane area-length and single-plane modified Simpson's methods and validated against three-dimensional echocardiography.

RESULTS

The study sample consisted of 527 participants (mean age 69.6 +/- 9.7 years; 61.9% women). Both single-plane and biplane LA volumes correlated well with three-dimensional echocardiography (r = 0.93, P < .001). The correlation between the single-plane and biplane methods was excellent (r = 0.95, P < .001; intraclass correlation coefficient, 0.92; 95% confidence interval, 0.80-0.96). Categorical agreement between the single-plane and biplane methods was modest (kappa = 0.51; 95% confidence interval, 0.45-0.57; disagreement rate, 26.0%), mainly because of overestimation by the single-plane method. The correction of the single-plane volume by a regression equation improved the agreement (kappa = 0.70; 95% confidence interval, 0.64-0.76), but misclassifications remained in 14.0% of cases.

CONCLUSIONS

Single-plane and biplane LA volume measurements have strong correlations, but their agreement for categorical classification is suboptimal. Specific cutoff points should be developed for the single-plane method.

Independent relationship of left atrial size and mortality in patients with heart failure: an individual patient meta-analysis of longitudinal data (MeRGE Heart Failure)

AIMS

Left atrial (LA) size is considered a marker of poor prognosis in heart failure (HF) patients. Prior studies have recruited relatively few subjects limiting their power to adequately analyse the interaction between LA size, left ventricular (LV) systolic and diastolic function, and prognosis.

METHOD AND RESULTS

The MeRGE collaboration combines prospective data from 18 studies in HF patients. In this analysis of data from 1157 patients, the primary endpoint was death or hospitalization for worsening HF. In multivariate analysis (Cox proportion hazard model), LA area was associated with prognosis (HR 1.03 per cm(2), 95% CI 1.02, 1.05; P < 0.0001) independently of age, NYHA class, LV ejection fraction, and restrictive filling pattern (RFP). When LA area was used as a categorical variable, the HR associated with larger LA area (above median) was 1.4 (95% CI 1.13, 1.74) and when LA area index was used, the HR was 2.36 (95% CI 1.80, 3.08). When the patients with and without RFP were divided on the basis of either LA area or LA area index, significantly higher event rates were observed in those with larger LA area.

CONCLUSION

Left atrial area is a powerful predictor of outcome among HF patients with predominantly impaired systolic function, and is independent of, and provides additional prognostic information beyond LV systolic and diastolic function.

Axial area and anteroposterior diameter as estimates of left atrial size using computed tomography of the chest: comparison with 3-dimensional volume

BACKGROUND

Left atrial (LA) size has incremental value in risk stratification.

OBJECTIVES

We aimed to assess feasibility and reproducibility of 2 quick measures of LA size by chest CT (axial LA area and LA anteroposterior [AP] diameter) by using contrast-enhanced and CT scans.

METHODS

We measured LA size in 100 contrast-enhanced 64-slice multidetector CT (MDCT) scans (randomly selected from the ROMICAT collective) by (1) axial LA area at the level of the left ventricular outflow tract and the mitral valve leaflets, (2) AP diameter in 3-chamber view, and (3) 3-dimensional (3D) LA volume by Simpson's methods. We assessed interobserver and intraobserver intraclass correlation coefficient (ICC) for axial LA area and AP diameter as well as their correlation to 3D LA volume. For axial area, feasibility and reproducibility were also determined in 100 non-contrast MDCT scans, randomly selected from the Framingham Heart Offspring collective.

RESULTS

In contrast-enhanced CT, both LA axial area and AP diameter had excellent reproducibility (interobserver: axial area: ICC, 0.96, mean relative difference, 2.4% +/- 7.4%; AP diameter: ICC, 0.91, 3.6% +/- 7.2%; intraobserver: axial area: ICC, 0.99, 0.4% +/- 5.2%; AP diameter: ICC, 0.94, 1.7% +/- 5.5%). Correlations with 3D volume were better for axial area (r=0.88) than for AP diameter (r=0.67). In non-contrast images, axial area could be assessed with excellent reproducibility (interobserver: ICC, 0.96, 0.5% +/- 8.3%; intraobserver: ICC, 0.99, 0.01% +/- 4.4%).

CONCLUSION

Both AP diameter and axial LA area permit quick and reproducible estimates of LA volume in contrast-enhanced and non-contrast electrocardiographic-gated chest CT. However, LA area should be used preferably over AP diameter because of its better agreement to 3D LA volume.

Echocardiographic assessments of left atrial strain and volume in healthy patients and patients with mitral valvular heart disease by tissue Doppler imaging and 3-dimensional echocardiography

Background and Objectives

The purpose of the current study was to assess left atrial (LA) physiology in relation to associations between LA volume change and regional tissue velocities and strains, and to extend this information to patients with mitral stenosis (MS) or mitral regurgitation (MR).

Subjects and Methods

Twenty-two healthy persons, 22 patients with moderate-to-severe MS, and 22 patients with moderate-to-severe MR were studied. Tissue velocities, strains, and time-volume curves of the LA were acquired using tissue Doppler imaging and 3-dimensional echocardiography.

Results

In healthy controls, the maximal LA volume was negatively correlated with the posterior wall longitudinal systolic strain (r=-0.45, p=0.03). The time-to-maximal LA volume was positively correlated with the time-to-posterior wall longitudinal peak strain (r=0.46, p=0.03) and the time-to-circumferential peak strain (r=0.59, p=0.004). The LA active emptying fraction (LAactEF) was positively correlated with the posterior wall longitudinal peak systolic and late diastolic tissue velocities. In patients with MS, the maximal LA volume was negatively correlated with the posterior wall radial peak systolic velocity and the longitudinal late diastolic velocity. In patients with MS, the LAactEF had an additional positive correlation with the anterior wall longitudinal and circumferential systolic velocities, whereas the patients with MR had an additional positive correlation between the LAactEF and the lateral wall longitudinal peak strain as compared with the healthy cantrols.

Conclusion

LA longitudinal and circumferential deformations are more related than radial deformation to determining LA volume and function. The LA of patients with MS revealed a greater pathologic physiology than those of patients with MR.

The effects of short time right ventricular pacing on left atrial mechanical functions

OBJECTIVES

Left atrium (LA) plays an important role in left ventricular filling. It is well known that right ventricular apical pacing has unfavorable effects on ventricular systolic and diastolic performance. The aim of this study is to evaluate the LA mechanical functions with 2D echocardiography in patients with a permanent pacemaker after short time ventricular pacing.

DESIGN

Echocardiographic examination was performed in 38 patients (mean age 63.0+/- 10.9, 18 female) with dual chamber pacemakers or defibrillators (< 20% ventricular pacing within previous 6 months, all of them on sinus rhythm) before and after 4 hours > 90% ventricular pacing at 70 beats per minute in DDD mode with an optimal AV interval. Left atrial volumes (LAV) including at the time of mitral valve opening (Vmax), at closure (Vmin), and at the onset of atrial systole (Volp) were measured. The passive emptying, conduit, active emptying and total emptying volume, stroke volumes were also calculated.

RESULTS

No significant differences were noted at baseline and after pacing for absolute Vmax, Volp, passive emptying, conduit, active emptying, total emptying volumes as well as the volumes indexed to body surface area (p >0.05).

CONCLUSIONS

Short - time RV pacing seems to have no acute effects on left atrial mechanical functions.

Left atrial volume measurement with automated border detection by 3-dimensional echocardiography: comparison with Magnetic Resonance Imaging

Objective

Left atrial size is an important marker for adverse cardiovascular events. There is general consensus that left atrial volume index (LAVI) is the best measurement of size. The current LAVI measurement techniques are laborious. Semi-automated measurement with a 3-dimensional echocardiography (3DE) system may be a practical clinical alternative to measure LAVI, but it has not been adequately evaluated against Magnetic Resonance Imaging (MRI) gold standard. The aim of this study was to compare the accuracy of a commercially available 3D algorithm for measurement of LAVI against LAVI obtained from MRI and Area Length Method (ALM).

Design

In 27 consecutive subjects referred for cardiac MRI (age 54 ± 13 years, 63% male), LAVI was measured using 3 imaging modalities: 3DE, ALM, MRI and the results were correlated. ALM was measured using standard American Society of Echocardiography guidelines. The time required to measure LAVI by 3DE and ALM were compared.

Results

There was a significant correlation in systolic and diastolic LA volumes and left atrial ejection fraction between 3DE and MRI (r = 0.86 for systole, r = 0.76 for diastole, r = 0.88 for ejection fraction, P < 0.0001 for all). There was also significant correlation of diastolic volumes between 3DE and ALM (r = 0.77, P < 0.0001). The time to obtain LAVI was shorter using 3DE versus ALM (56 ± 8 vs 135 ± 55 seconds, P < 0.0001).

Conclusion

Three-dimensional echocardiography with semiautomatic border detection is a practical alternative for obtaining the left atrial volume in a time-efficient manner compared to the current standard.

The MUSIC Risk score: a simple method for predicting mortality in ambulatory patients with chronic heart failure

AIMS

The prognosis of chronic heart failure (CHF) is extremely variable, although generally poor. The purpose of this study was to develop prognostic models for CHF patients.

METHODS AND RESULTS

A cohort of 992 consecutive ambulatory CHF patients was prospectively followed for a median of 44 months. Multivariable Cox models were developed to predict all-cause mortality (n = 267), cardiac mortality (primary end-point, n = 213), pump-failure death (n = 123), and sudden death (n = 90). The four final models included several combinations of the same 10 independent predictors: prior atherosclerotic vascular event, left atrial size >26 mm/m(2), ejection fraction < or =35%, atrial fibrillation, left bundle-branch block or intraventricular conduction delay, non-sustained ventricular tachycardia and frequent ventricular premature beats, estimated glomerular filtration rate <60 mL/min/1.73 m(2), hyponatremia < or =138 mEq/L, NT-proBNP >1.000 ng/L, and troponin-positive. On the basis of Cox models, the MUSIC Risk scores were calculated. A cardiac mortality score >20 points identified a high-risk subgroup with a four-fold cardiac mortality risk.

CONCLUSION

A simple score with a limited number of non-invasive variables successfully predicted cardiac mortality in a real-life cohort of CHF patients. The use of this model in clinical practice identifies a subgroup of high-risk patients that should be closely managed.

Effects of obstructive sleep apnea treatment on left atrial volume and left atrial volume index

Obstructive sleep apnea (OSA) and increased left atrial volume (LAV) both independently increase cardiovascular mortality. We hypothesized that treatment of OSA with continuous positive airway pressure (CPAP) may decrease LAV. We retrospectively identified 47 OSA patients receiving CPAP who had echocardiograms done before and after polysomnography. Compliance was defined as CPAP use at-least five nights weekly and 5 h per night. The compliant group (n = 23) had a significant decrease in diastolic blood pressure (DBP; 4.4 +/- 8.9 mmHg, p < 0.05) and mean arterial pressure (MAP; 4.7 +/- 10.3 mmHg, p < 0.05), while no significant changes were observed in the noncompliant group (n = 24). LAV data were available in 13 compliant and 20 noncompliant patients. LAV decreased nonsignificantly (3.54 +/- 16.6 mL, n = 13, p = 0.65) in CPAP-compliant patients, while it increased (15.47 +/- 22.3 mL, n = 20, p < 0.006) in noncompliant patients. Similar changes were seen in the LAV index. Untreated OSA was associated with an increase in LAV and LAV index without significant changes in blood pressure. Treatment of OSA was associated with a decrease in DBP and MAP with a nonsignificant decrease in LAV. Treatment of OSA may prevent adverse left atrial remodeling.

Accuracy of electrocardiographic criteria for atrial enlargement: validation with cardiovascular magnetic resonance

BACKGROUND

Anatomic atrial enlargement is associated with significant morbidity and mortality. However, atrial enlargement may not correlate with clinical measures such as electrocardiographic (ECG) criteria. Past studies correlating ECG criteria with anatomic measures mainly used inferior M-mode or two-dimensional echocardiographic data. We sought to determine the accuracy of the ECG to predict anatomic atrial enlargement as determined by volumetric cardiovascular magnetic resonance (CMR).

METHODS

ECG criteria for left (LAE) and right atrial enlargement (RAE) were compared to CMR atrial volume index measurements for 275 consecutive subjects referred for CMR (67% males, 51 +/- 14 years). ECG criteria for LAE and RAE were assessed by an expert observer blinded to CMR data. Atrial volume index was computed using the biplane area-length method.

RESULTS

The prevalence of CMR LAE and RAE was 28% and 11%, respectively, and by any ECG criteria was 82% and 5%, respectively. Though nonspecific, the presence of at least one ECG criteria for LAE was 90% sensitive for CMR LAE. The individual criteria P mitrale, P wave axis < 30 degrees , and negative P terminal force in V1 (NPTF-V1) > 0.04s.mm were 88-99% specific although not sensitive for CMR LAE. ECG was insensitive but 96-100% specific for CMR RAE.

CONCLUSION

The presence of at least one ECG criteria for LAE is sensitive but not specific for anatomic LAE. Individual criteria for LAE, including P mitrale, P wave axis < 30 degrees , or NPTF-V1 > 0.04s.mm are highly specific, though not sensitive. ECG is highly specific but insensitive for RAE. Individual ECG P wave changes do not reliably both detect and predict anatomic atrial enlargement.

Contrast enhanced echocardiographic follow-up of cardiac remodeling and function after myocardial infarction in rats

Echocardiography is a reliable and commonly used method to examine cardiac diseases. Recent employment of modern technologies provides new opportunities to study left ventricular (LV) remodeling after myocardial infarction (MI) also in small rodents. LV volumes as most important prognostic parameters can be estimated by noncontrast enhanced echocardiography in rats from M-mode or single cross sections only. In this study, contrast enhanced echocardiography and volume measurements by the biplane method of discs (Simpson's rule) were applied in rats to monitor remodeling and function after MI. MI was induced in female Sprague-Dawley rats (n = 26 for MI, and n = 16 for sham). LV remodeling and heart function were serially studied by contrast enhanced echocardiography for 12 to 16 wk. At the end of the observation periods hemodynamic data were additionally measured by left and right heart catheterization. LV end systolic volume (LVESV) measured by biplane method of discs correlated best with LV developed pressure as indicator for severely impaired heart function. Interestingly, LV end systolic area (LVESA) from native short axis view correlated well with LVESV (R(2) = 0.93) and was the second best predictor for depressed heart function. Moreover, left atrial size was a powerful indicator of severely impaired heart function whereas ejection fraction or fractional area change were primarily related to infarct size. In conclusion, contrast enhanced echocardiography in rats is feasible and an economical method to study time-dependent LV remodeling and deterioration of contractile function after MI.

Evaluation of Left Atrial Size in Patients with Atrial Arrhythmias: Comparison of Standard 2D Versus Real Time 3D Echocardiography

AIM

Two-dimensional echocardiography may not correctly indicate size in nonspherical atria. The present study compares different parameters of left atrial size evaluated by standard two-dimensional echocardiography with left atrial volume measured using three-dimensional echocardiography (3DE).

METHODS AND RESULTS

One hundred seventy consecutive patients with a history of atrial arrhythmias were studied by standard two-dimensional and by real time 3DE. Of these 166 (98%) recordings were of sufficient quality for interpretation by both imaging techniques. The following parameters of left atrial size were measured: parasternal long axis diameter (PLAX), apical 4-chamber short-axis diameter (4CH short axis), apical 4-chamber (4CH long axis), and 2-chamber long-axis diameters and planimetry areas. Two-dimensional-derived left atrial volumes were calculated by using both single plane (4CH area-length) and biplane area-length methods. The 2D parameters were then correlated with left atrial volume measured by 3D echocardiography. Linear regression analysis showed moderate correlation for 4-chamber planimetry area (r = 0.76, P < 0.0001) and 2D-derived volume calculations (r of 4CH single plane area-length LA volume = 0.74 and biplane area-length LA volume = 0.78, P < 0.0001). Diameters correlated less well with 3DE volume (r of PLAX = 0.67, 4CH short axis = 0.68, 4CH long axis = 0.63, P < 0.0001 respectively).

CONCLUSION

The results demonstrate that measurements of dimensions using standard echocardiography are of limited accuracy to assess left atrial volume. If 3DE is not available, 4-chamber planimetry area is a valid simple parameter for evaluating left atrial size in clinical practice. Two-dimensional-derived volume by biplane area-length method was only slightly better correlated with 3DE volume than 4-chamber planimetry area.

Left atrial enlargement and NT-proBNP as predictors of sudden cardiac death in patients with heart failure

AIMS

The identification of valuable markers of sudden cardiac death (SCD) in patients with established HF remains a challenge. We sought to assess the value of clinical, echocardiographic and biochemical variables to predict SCD in a consecutive cohort of patients with heart failure (HF) due to systolic dysfunction.

METHODS

A cohort of 494 patients with established HF had baseline echocardiographic and NT-proBNP measurements and were followed for 942+/-323 days.

RESULTS

Fifty patients suffered SCD. Independent predictors of SCD were indexed LA size>26 mm/m2 (HR 2.8; 95% CI 1.5-5.0; p=0.0007), NT-proBNP>908 ng/L (HR 3.1; 95% CI 1.5-6.7; p=0.003), history of myocardial infarction (HR 2.3; 95% CI 1.3-4.1; p=0.007), peripheral oedema (HR 2.1; 95% CI 1.1-3.9; p=0.02), and diabetes mellitus (HR 1.9; 95% CI 1.1-3.3; p=0.03). NYHA functional class, left ventricular ejection fraction and glomerular filtration rate were not independent predictors of SCD in this cohort. Notably, the combination of both LA size>26 mm/m2 and NT-proBNP>908 ng/L increased the risk of SCD (HR 4.3; 95% CI 2.5-7.6; p<0.0001). At 36 months, risk of SCD in patients with indexed LA size<or=26 mm/m2 and NT-proBNP<or=908 ng/L was 3%, while in patients with indexed LA size>26 mm/m2 and NT-proBNP>908 ng/L reached 25% (p<0.0001).

CONCLUSIONS

Among HF patients, indexed LA size and NT-proBNP levels are more useful to stratify risk of SCD than other clinical, echocardiographic or biochemical variables. The combination of these two parameters should be considered for predicting SCD in patients with HF.

Left atrial volume provides independent and incremental information compared with exercise tolerance parameters in patients with heart failure and left ventricular systolic dysfunction

OBJECTIVE

Left atrial volume (LAV) is a powerful predictor of outcome in patients with chronic heart failure (CHF) independently of symptomatic status, age and left ventricular (LV) function. It is unknown whether LAV provides independent and incremental information compared with exercise tolerance parameters.

METHODS

273 patients with CHF (mean (SD) 62 (9) years; 13% female) prospectively underwent echocardiography and exercise testing with maximal oxygen consumption (Vo(2)). The primary end point was composite and included cardiac death, hospitalisation for worsening heart failure or cardiac transplantation.

RESULTS

At Cox proportional hazard analysis, LAV normalised for body surface area (LAV/BSA) was strongly associated with mortality (hazard ratio (HR) = 1.027 (95% CI 1.018 to 1.04), p<0.001). The predictive value of LAV/BSA was independent of Vo(2) and LV ejection fraction (EF) (HR = 1.014 (1.002 to 1.025), p = 0.02; HR = 0.95 (0.91 to 0.99), p = 0.02; HR = 0.89 (0.82 to 0.98), p = 0.02 for LAV/BSA, EF and Vo(2), respectively). Receiver operator characteristic (ROC) curve analysis identified the best cut-off values for prediction of the end point. LAV/BSA >63 ml, EF <30% and Vo(2) <16 ml/kg/min were considered to be risk factors. Patients with three risk factors had an HR of 38 (95% CI 11 to 129) compared with patients with no risk factors.

CONCLUSION

LAV provides powerful prognostic information incrementally and independently of Vo(2). LAV, EF and Vo(2 )can be used to build a risk prediction model, which can be used clinically.

Prognostic significance of left atrial size in patients with hypertrophic cardiomyopathy (from the Italian Registry for Hypertrophic Cardiomyopathy)

This study assessed left atrial (LA) dimension as a potential predictor of outcome in hypertrophic cardiomyopathy (HC). From the Italian Registry for Hypertrophic Cardiomyopathy, 1,491 patients (mean age 47 +/- 17 years; 61% men; 19% obstructive), followed for 9.4 +/- 7.4 years after the initial echocardiographic evaluation, constituted the study group. The mean LA transverse dimension was 43 +/- 9 mm and was larger in patients with severe symptoms (48 +/- 9 mm for New York Heart Association classes III and IV vs 42 +/- 9 mm for classes I and II, p <0.001), atrial fibrillation (47 +/- 9 vs 42 +/- 8 mm in sinus rhythm, p <0.001), and left ventricular outflow obstruction (46 +/- 9 mm for >or=30 mm Hg at rest vs 42 +/- 9 mm for <30 mm Hg at rest, p <0.001). On univariate analysis, each 5-mm increase in LA size was associated with a hazard ratio (HR) of 1.2 for all-cause mortality (p <0.0001). On multivariate analysis, a LA dimension >48 mm (the 75th percentile) had a HR of 1.9 for all-cause mortality (p = 0.008), 2.0 for cardiovascular death (p = 0.014), and 3.1 for death related to heart failure (p = 0.008) but was unassociated with sudden death (p = 0.81). Similar results were obtained after the exclusion of patients with atrial fibrillation (HR 1.7, p = 0.008) or outflow obstruction (HR 1.8, p = 0.003). The predictive power of LA dimension >48 mm was also validated in an independent HC cohort from the United States, with similar HRs (1.8 for all-cause mortality, p = 0.019). In conclusion, in a large cohort of patients with HC from a nationwide registry, a marked increase in LA dimension were predictive of long-term outcome, independent of co-existent atrial fibrillation or outflow obstruction. LA dimension is a novel and independent marker of prognosis in HC, particularly relevant to the identification of patients at risk for death related to heart failure.

P-wave morphology correlation with left atrial volumes assessed by 2-dimensional echocardiography

To correlate prespecified P-wave morphologies with echocardiographically derived left atrial volumes (LAVs), we studied a convenience sample of 71 patients with predominantly normal left ventricular systolic function (mean ejection fraction = 58.2% +/- 6.6%) who underwent concurrent 2-dimensional echocardiogram and 12-lead electrocardiogram. Left atrial volume was calculated from apical end-systolic images by the biplane method of disks and was indexed for body surface area (BSA). Electrocardiograms were assessed manually with calipers, measuring leading edge to leading edge. Patients included 34 men and 37 women with a mean age of 53 +/- 14 years. P-wave duration/PR-segment duration in lead II and depth and duration of terminal P wave in lead V1 (P terminal force) correlate poorly with LAV and provided only modest predictive power (area under receiver operating characteristic curve = 0.466-0.619 and r = 0.30-0.42, P = .014-.021). Total P-wave duration in lead II correlated moderately (r = 0.47, P < .001) and predicted LAV (LAV/BSA = 8.0 + 0.2 [P-wave duration in lead II]), as did P-wave area in lead II (r = 0.49, P < .001) (LAV/BSA = 18.6 + 1.7 [P-wave duration in lead II]). The 4 P-wave morphologies were found to be poorly sensitive but highly specific for left atrial enlargement.

Assessment of atrial regional and global electromechanical function by tissue velocity echocardiography: a feasibility study on healthy individuals

Background

The appropriate evaluation of atrial electrical function is only possible by means of invasive electrophysiology techniques, which are expensive and therefore not suitable for widespread use. Mechanical atrial function is mainly determined from atrial volumes and volume-derived indices that are load-dependent, time-consuming and difficult to reproduce because they are observer-dependent.

Aims

To assess the feasibility of tissue velocity echocardiography (TVE) to evaluate atrial electromechanical function in young, healthy volunteers.

Subjects and methods

We studied 37 healthy individuals: 28 men and nine women with a mean age of 29 years (range 20–47). Standard two-dimensional (2-D) and Doppler echocardiograms with superimposed TVE images were performed. Standard echocardiographic images were digitized during three consecutive cardiac cycles in cine-loop format for off-line analysis. Several indices of regional atrial electrical and mechanical function were derived from both 2-D and TVE modalities.

Results

Some TVE-derived variables indirectly reflected the atrial electrical activation that follows the known activation process as revealed by invasive electrophysiology. Regionally, the atrium shows an upward movement of its walls at the region near the atrio-ventricular ring with a reduction of this movement towards the upper levels of the atrial walls. The atrial mechanical function as assessed by several TVE-derived indices was quite similar in all left atrium (LA) walls. However, all such indices were higher in the right (RA) than the LA. There were no correlations between the 2-D- and TVE-derived variables expressing atrial mechanical function. Values of measurement error and repeatability were good for atrial mechanical function, but only acceptable for atrial electrical function.

Conclusion

TVE may provide a simple, easy to obtain, reproducible, repeatable and potentially clinically useful tool for quantifying atrial electromechanical function.

Value of echocardiography for diagnosis and prognosis of chronic Chagas disease cardiomyopathy without heart failure

OBJECTIVES

To establish the usefulness of echocardiography for the clinical classification of patients with Chagas disease and to determine the predictors of mortality and clinical events.

METHODS

849 patients with chronic Chagas disease with a mean follow up of 9.9 years were studied. On admission, ECG, chest radiograph, and two dimensional echocardiogram were obtained from all patients. Clinical events were defined as new ECG abnormalities, change in clinical status resulting in transfer to another group, and death. Morphologically characterised segmental lesions were also seen in 12 patients on a second harmonic echocardiogram with intravenous contrast agent. Univariate and multivariate analysis for clinical events and mortality were performed.

SETTING

Community of San Martín, Buenos Aires, Argentina.

RESULTS

Change in clinical group (68 of 833 survivors v 15 of 16 who died, p < 0.001), left ventricular systolic dimension (mean (SD) 3.06 (0.72) cm v 4.71 (0.90) cm, p < 0.0001), and ejection fraction (mean (SD) 0.67 (0.11)% v 0.42 (0.17)%, p < 0.0001) were found to be the only predictors of mortality. ECG abnormalities related to the disease (in 220 of 699 patients with no clinical event v 98 of 150 patients with a clinical event, p < 0.0001), left ventricular diastolic dimension (mean (SD) 4.88 (0.54) cm v 5.44 (0.83) cm, p < 0.0001), left ventricular systolic dimension (mean (SD) 2.98 (0.62) cm v 3.64 (1.03) cm, p < 0.0001), and ejection fraction (mean (SD) 0.68 (0.10)% v 0.60 (0.16)%, p < 0.0001) were predictors of clinical events. Segmental lesions were observed in 211 of 849 patients (25%). Segmental lesions were seen in 66 (13%) and systolic dysfunction was seen in four of 505 (0.8%) patients with normal ECG. Significant differences were found between the groups of patients (group 0: reactive serology and normal ECG and chest radiography without cardiac enlargement and no signs of heart failure; group 1: reactive serology and abnormal ECG and chest radiography without cardiac enlargement; group 2: reactive serology and abnormal ECG and chest radiography with cardiac enlargement and no signs of heart failure).

CONCLUSION

Echocardiography was useful both to characterise and to determine the prognosis of patients with chronic Chagas disease without heart failure.

Increase in atrial size in long-term survivors of heart transplant

Atrial size in recipients of orthotopic heart transplant (OHTX) who have long-term survival is not well described in the literature. We reviewed 2-dimensional echocardiograms of 14 recipients of OHTX who survived at least 5 years. Apical 4-chamber images were used for measurements starting at 1-year post-OHTX. The recipients of OHTX were 8 (57%) men and 6 (43%) women with a mean age of 43.6 +/- 12.1 (20-60) years and mean survival of 9.5 +/- 2.6 (5.8-14.4) years. All chambers increased with time post-OHTX (r > 0.83, P <.002). The changes in left atrium (LA) and right atrium (RA), remnants of donor LA and RA, and remnants of recipients' LA areas correlated inversely with patient survival post-OHTX (r > 0.83, P <.002). The change in RA recipient remnant area did not correlate with survival (r = 0.58, P =.06). In recipients of OHTX with long-term survival, there is a significant correlation between the echocardiographic size of LA and RA, and donor and recipient remnants with time and survival.

How should left atrial size be reported? Comparative assessment with use of multiple echocardiographic methods

BACKGROUND

Determination of left atrial (LA) size is important in clinical decision-making. The LA anteroposterior dimension (APD) has been routinely reported as LA size assessment. Early studies indicated that the APD may have limited accuracy in quantification. Conventional 3-dimensional reconstruction (C3DR) of the LA has been validated. However, its process is time-consuming and not applicable for daily practice. To explore an accurate and practical approach, we compared different echocardiographic measurements with C3DR in 141 patients with different LA sizes.

METHODS AND RESULTS

LA size was measured with (1) the cubic equation with APD (Cub); (2) the ellipsoidal formula (Ellp); (3) biplane modified Simpson rule (biplane); and (4) simplified 3-dimensional reconstruction from 3 standard apical views with B spline interpolation (S3VR). All four methods were compared with C3DR. S3VR and biplane methods provided a close agreement to C3DR (y = 0.94x + 3.6, r = 0.95, SEE = 7.6 mL, mean difference = -1.3% for S3VR; y = 0.87x + 2.9, r = 0.91, SEE = 9.0 mL, mean difference = -9.4% for biplane). The Cub and Ellp calculations were less accurate, with significant volume underestimation (P <.001).

CONCLUSIONS

LA single dimension is not accurate for LA size measurement. Among four different methods of LA size measurement, biplane and S3VR provide the closest agreement to C3DR. The biplane, which is readily applicable with current echocardiographic equipment, should be routinely applied in clinical practice.

Prognostic value of serial cardiac assessment and familial screening in patients with dilated cardiomyopathy

OBJECTIVES

This prospective study was performed to analyse whether routine clinical follow-up investigations at 12+/-6 months add to risk stratification and improve survival rates in patients with a first diagnosis of dilated cardiomyopathy (DCM).

METHODS

Four hundred and eighty consecutive patients (mean age 53.4+/-12.3 years, 369 males, mean NYHA class 2.4+/-0.8) with invasively confirmed DCM were included and followed for 3.9+/-3.5 years. Patients were requested to adhere to a follow up investigation within 6-18 months either at the referring physicians or at our out patient department. Two hundred and eighty-one of the 480 patients presented for follow up which consisted of a detailed evaluation of symptoms, standardized physical examination, 12-lead-electrocardiogram recording and echocardiography. Seventeen patients were lost for follow up, 182 did not seek specialized medical follow up. Patients outcome was assessed by structured telephone interviews.

RESULTS

Independent predictors of death or transplantation at initial diagnosis were LV-ejection fraction <30% (P=0.0001, risk ratio 2.25), LV-end diastolic pressure >or=15 mmHg (P=0.002, risk ratio 2.0), age >or=54 years, (P=0.04, risk ratio 1.55), and presence of left bundle branch block (P=0.046, risk ratio 1.53). On follow up investigations only deterioration of clinical status by at least one NYHA-class (P=0.001, risk ratio 2.6) and new onset or worsening of mitral regurgitation (P=0.02, risk ratio 1.8), remained independent prognostic factors for cardiac death. Patients who presented for routine follow up revealed significant better 5-year survival rates (n=281, 70%) than those who did not (n=153, 55%, P=0.005).

CONCLUSIONS

Routine clinical follow up investigations within 6-18 months after first diagnosis of DCM adds to risk stratification and improves survival rates.

Left atrial volume determination by three-dimensional echocardiography reconstruction: validation and application of a simplified technique

Left atrial (LA) size assessment by anteroposterior dimension is limited in accuracy. Conventional 3-dimensional (3D) reconstruction has been validated, but the process is time-consuming and the 3D system is not widely available. We developed an algorithm to simplify 3D reconstruction of LA on the basis of 3 standard apical views, tested it in 44 hemodynamic stages of 8 open-chest dogs, and compared it with LA volumes assessed by conventional 3D reconstruction. Simplified 3D reconstruction provided an accurate LA volume measurement (y = 0.93x + 0.7, r = 0.95, standard error of the estimate [SEE] = 3.6) with more than 60% of time saved. Cubic equation of anteroposterior dimension and biplane modified Simpson's method were less accurate (for biplane modified Simpson's method, y = 0.8x + 2.6, r = 0.88, SEE = 5.0; for cubic equation of anteroposterior dimension, y = 0.65x + 2.6, r = 0.76, SEE = 8.2). Without the need for a 3D-imaging acquisition tool, simplified 3D reconstruction can be applied in the clinical setting for LA size quantitation with significant time saved.

Prognostic implications derived from ultrasonic tissue characterization with myocardial integrated backscatter in patients with dilated cardiomyopathy

BACKGROUND

Various clinical parameters have been reported to predict survival in patients with dilated cardiomyopathy (DCM). Myocardial ultrasonic integrated backscatter (IB) imaging has a potential to perform in vivo tissue characterization. The present study was performed to examine whether myocardial IB analysis can predict the prognosis of DCM patients.

METHODS AND RESULTS

We prospectively carried out echocardiographic examinations with IB analysis in 43 patients with DCM (31 males, 12 females) under the standard treatment. IB analysis was performed in the left ventricular wall and the calibrated (subtracting pericardial data) myocardial IB intensity (IBI) was obtained from the interventricular septum and the left ventricular posterior wall. After the follow-up (8-39 months), 31 followed a good clinical course, but eight had cardiac death, one had partial left ventriculectomy for uncontrolled heart failure and three were hospitalized for worsening heart failure. Beta-blocker responded in 27 (87%) of the 31 with good clinical course, but it did not respond in 11 among the 12 with poor course. In these 12 DCM, left ventricular fractional shortening (LVFS) was lower (good: 18+/-5%, poor: 14+/-4, P<0.03) and calibrated IBI was higher in both the septum (good: -16.4+/-5.6 dB, poor: -11.1+/-4.2 dB, P<0.006) and the posterior wall (good: -19.5+/-3.6 dB, poor: -13.8+/-5.6 dB, P<0.004). On the Cox proportional hazard model analysis, only calibrated IBI in the septum >-17 dB, the cut-off score of calibrated IBI discriminating non-responders to beta-blocker therapy in our previous report, was related to the poor outcome (chi(2)=4.43, P=0.035). The stepwise multivariate analysis revealed that both calibrated IBI in the septum>-17 dB (chi(2)=4.43, P=0.035) and LVFS<15% (chi(2)=3.89, P=0.049) were useful to predict the poor clinical outcome. The event free rate assessed by the Kaplan-Meier method was also significantly reduced in patients with calibrated IBI in the septum >-17 dB (chi(2)=6.594, P=0.01) and calibrated IBI in the posterior wall>-17 dB (chi(2)=4.215, P=0.04). However, LVFS<15% (chi(2)=3.576, not significant) did not contribute to discriminating the event free rate in the clinical course.

CONCLUSIONS

The present study demonstrated that myocardial IB intensity was higher in DCM patients who followed a poor clinical course rather than in those with a good outcome. Therefore, it is clarified that myocardial ultrasonic tissue characterization in DCM patients is useful for assessing their clinical outcome after receiving not only the standard treatment but also beta-blocker therapy.

Long-term prognosis of patients with mildly dilated cardiomyopathy

The long-term prognosis of patients with mildly dilated cardiomyopathy (MDCM) was investigated in 21 patients. MDCM was defined as left ventricular ejection fraction < or = 40% and left ventricular end-diastolic volume < or = 120 ml/m2 by left ventriculography. During a follow-up period of 6.8+/-3.7 years, there were 9 cardiac events (5 heart failure deaths, 2 sudden deaths, and 2 re-hospitalizations for heart failure). Only in the patients without cardiac events was there a significant decrease in left ventricular size (end-diastolic dimension decreased from 58+/-6 mm to 50+/-8 mm, p<0.001) and an improvement in systolic function (fractional shortening increased from 17+/-5% to 26+/-11%, p=0.007). However, left atrial dilation was observed in the patients with an event (from 39+/-5 mm to 43+/-5 mm, p=0.02). Based on proportional hazard analysis, left ventricular end-diastolic pressure and mean pulmonary artery pressure at diagnosis and left atrial dimension at the time of follow-up were significant predictors of poor outcome. A subset of patients with MDCM has impaired hemodynamics at diagnosis, left atrial dilation at follow-up and a poor prognosis, and must be followed carefully even if the left ventricular dilatation is mild.

Comparison of left atrial dimensions by transesophageal and transthoracic echocardiography

Left atrial (LA) size, as determined by transthoracic echocardiography (TTE), predicts the risk of atrial fibrillation and stroke and the success of cardioversion. Transesophageal echocardiography (TEE) is increasingly used in these clinical situations. However, unlike TTE, measurement of LA size by TEE has not been standardized. To validate TEE measurement, we determined LA dimensions in 4 standard views by TTE at the same time in 121 patients undergoing TEE. The mid-esophageal basal short-axis view at the level of the aortic valve (TEE 30-60) was the only view in which complete visualization of a LA axis of measurement could be obtained with an acceptably high yield (97.2%). The measurement from this view provided a value that had the highest correlation between TTE and TEE (r = 0.758, P <.0001, 95% confidence interval 0.68-0.86; bias 0.37 +/- 1 cm). Overall, TEE underestimated the LA dimension by 9% compared with TTE. These results suggest that the short-axis view at the level of the aortic valve is the preferred site for measuring the LA dimension by TEE.

Modulation of left atrial function by ventricular filling impairment

Left atrial function is an important determinant of ventricular filling. Assessment of the complex role that the atrial cavity exerts in the ventricular filling process can be made noninvasively. Computing the net instantaneous difference between mitral and pulmonary venous flow is an approach which permits the construction of the left atrial volume curve throughout the cardiac cycle (as well as the left ventricular volume curve during diastole), and to quantify the 3 different functions that the cavity performs. In particular, increasing degrees of ventricular filling impairment are met by mechanical left atrial adaptations which basically rely on the Starling mechanism, with the reservoir/pump complex activated to the limit of the preload reserve of the cavity. At end-stage left ventricular dysfunction, however, the atrial reservoir and the booster pump function decline and conduit takes precedence, suggesting afterload mismatch, impaired atrial compliance and, perhaps, depressed atrial contractility. Increased wall stiffening and reduced elastic recoil induced by chronic atrial distension might explain the additional power of atrial size in stratifying prognostically patients with left ventricular dysfunction.

Best method in clinical practice and in research studies to determine left atrial size

Although the anteroposterior dimension of the left atrium is universally used in clinical practice and research, we hypothesized that it may be an inaccurate surrogate for volume because its use is based on the unlikely assumption that there is a constant relation among atrial dimensions. The following measurements of the left atrium were made at end ventricular systole: (1) M-mode-derived anteroposterior linear dimension from the parasternal long-axis view; (2) digitized planimetry of the left atrial (LA) cavity from the apical 4-chamber view; and (3) digitized planimetry of the LA cavity from the apical 2-chamber view. The following volume calculations were obtained from these digital measurements: (1) volume derived from the M-mode dimension assuming a spherical shape; (2) volume derived from the single plane area-length of apical 4-chamber view, which assumes that LA geometry can be generalized from a single 2-dimensional plane; and (3) volume derived from the biplane method of discs. The correlation coefficient between the M-mode and biplane methods of determining LA volume was r = 0.76. The mean difference (+/-2 SDs) between these methods is -25 +/- 33 ml. The correlation coefficient between the single plane apical 4-chamber and biplane methods of determining LA volume is r = 0.97. The mean difference (+/-2 SDs) between these methods was -5.0 +/- 12 ml, indicating good agreement. The M-mode measure of the left atrium is an inaccurate representation of its size. Two-dimensional-derived LA volumes provide a more accurate measure of the true size of the left atrium and are more sensitive to changes in LA size. When an echocardiographic measure of LA size is made either in an individual patient or as a variable in a research study, the M-mode measure should be avoided.

Prognostic value of nocturnal Cheyne-Stokes respiration in chronic heart failure

BACKGROUND

Nocturnal Cheyne-Stokes respiration (CSR) occurs frequently in patients with chronic heart failure (CHF), and it may be associated with sympathetic activation. The aim of the present study was to evaluate whether CSR could affect prognosis in patients with CHF.

METHODS AND RESULTS

Sixty-two CHF patients with left ventricular ejection fraction </=35%, in NYHA class II to III, underwent clinical evaluation, Doppler echocardiography, ergospirometry, phenylephrine test, Holter recording, and a sleep study to evaluate the occurrence of CSR, expressed as percentage of periodic breathing, and apnea/hypopnea index (AHI) (ie, the number of apneas and hypopneas per hour of recording). During a mean follow-up of 28+/-13 months, 15 patients died of cardiac causes. Nonsurvivors were in a higher NYHA functional class than survivors (P<0.001) and had a more depressed left ventricular ejection fraction (P<0.03), a shorter deceleration time of early filling (P<0. 05), larger left and right atria (P<0.05 and P<0.02, respectively) and a lower peak V(O2) (P<0.05). Nonsurvivors also spent a greater percentage of the night in periodic breathing (P<0.01) with a greater AHI (P<0.03) and showed lower values of diurnal baroreflex sensitivity (P<0.05) and of heart rate variability (sdNN: P<0.01). Multivariate analysis revealed the AHI (chi2, 10.4; P<0.01), followed by left atrial area (chi2, 5.7; P<0.01), as the only independent and additional predictors of subsequent cardiac death. Patients at very high risk for fatal outcome could be identified by an AHI >/=30/h and left atria >/=25 cm2.

CONCLUSIONS

The AHI is a powerful independent predictor of poor prognosis in clinically stable patients with CHF. The presence of an AHI >/=30/h adds prognostic information compared with other clinical, echocardiographic, and autonomic data and identifies patients at very high risk for subsequent cardiac death.