Determinant of left atrial dilation in patients with hypertrophic cardiomyopathy: A real-time 3-dimensional echocardiographic study

Left atrial remodeling in hypertrophic cardiomyopathy and Fabry disease: A CMR-based head-to-head comparison and outcome analysis

BACKGROUND

Hypertrophic cardiomyopathy (HCM) and Fabry disease cardiomyopathy (FD) are phenocopies, as they show left ventricular hypertrophy (LVH). The left atrium (LA) is emerging as a potential marker of disease severity in both cardiomyopathies. The present study compares HCM and FD cardiomyopathy with similar degree of LVH, exploring LA morpho-functional parameters and the correlates of clinical outcome.

METHODS

We performed a comprehensive CMR-based comparison between 30 HCM and 30 FD patients matched on age, sex, BSA, LV mass and major cardiovascular risk factors affecting LA remodeling (arterial hypertension and diabetes). 30 healthy controls were also included. CMR feature tracking (CMR-FT) analysis, T1 mapping and conventional parameters were evaluated. Patients also underwent transthoracic echocardiography for LV diastolic function assessment. Clinical events at follow-up were collected (atrial and ventricular events, bradyarrhythmia, heart failure (HF) hospitalization and death).

RESULTS

HCM patients showed greater LA remodeling compared to FD patients, namely higher LA end-systolic volume index (LAVi max), lower LA-ejection fraction (LA-EF) and worse reservoir (εs) and booster function (εa) (all p < 0.05). Accordingly, these parameters have demonstrated good potential for distinguishing between FD and HCM (AUC 0.68-0.73, all p < 0.05), with LAVi max being an independent predictor for HCM diagnosis (OR 1.07, 95%CI 1.011-1.132, p 0.02). Moreover, in HCM patients a significant association between εs and HF occurrence was observed at 2-year follow-up (OR 0.85, 95%CI 0.72-0.99, p 0.04).

CONCLUSIONS

In HCM, LA remodeling is greater than in FD cardiomyopathy with similar LVH, and reservoir strain is associated with HF at follow-up.

Cardiac Remodeling in Elite Aquatic Sport Athletes

OBJECTIVE

To characterize and compare the sport-specific cardiac structure of elite swimmers (SW), water polo players (WP), and artistic swimmers (AS).

DESIGN

A cross-sectional assessment of elite aquatic athletes' hearts.

SETTING

The athletes' village at the 2019 FINA World Championships.

PARTICIPANTS

Ninety athletes from swimming (SW) (20 M/17 F), water polo (WP) (21 M/9 F), and artistic swimming (AS) (23 F).

ASSESSMENT AND MAIN OUTCOME MEASURES

An echocardiographic assessment of cardiac structure was performed on noncompetition days.

RESULTS

Male SW displayed primarily eccentric volume-driven remodeling, whereas male WP had a greater incidence of pressure-driven concentric geometry (SW = 5%, WP = 25%) with elevated relative wall-thickness (RWT) (SW = 0.35 ± 0.04, WP = 0.44 ± 0.08, P < 0.001). Female SW and WP hearts were similar with primarily eccentric-remodeling, but SW and WP had greater concentricity index than artistic swimmers (SW = 6.74 ± 1.45 g/(mL)2/3, WP = 6.80 ± 1.24 g/(mL)2/3, AS = 5.52 ± 1.08 g/(mL)2/3, P = 0.007). AS had normal geometry, but with increased posterior-wall specific RWT (SW = 0.32 ± 0.05, AS = 0.42 ± 0.11, P = 0.004) and greater left atrial area than SW (SW = 9.7 ± 0.9 cm2/m2, AS = 11.0 ± 1.1 cm2/m2, P = 0.003). All females had greater incidence of left ventricular (LV) posterior/septal wall-thickness ≥11 mm than typically reported (SW = 24%, WP = 11%, AS = 17%).

CONCLUSIONS

Male athletes presented classic sport-specific differentiation, with SW demonstrating primarily volume-driven eccentric remodelling, and WP with greater concentric geometry indicative of pressure-driven remodeling. Female SW and WP did not display this divergence, likely because of sex-differences in adaptation. AS had unique LV-specific adaptations suggesting elevated pressure under low-volume conditions. The overall incidence of elevated wall-thickness in female athletes may point to an aquatic specific pressure-stress.

Left atrioventricular coupling index in hypertrophic cardiomyopathy and risk of new-onset atrial fibrillation

BACKGROUNDS

This study aimed to investigate the association between left atrioventricular coupling index (LACI) and the occurrence of atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM).

METHODS

A total of 373 patients with HCM and no history of AF were evaluated by transthoracic echocardiography. LACI was defined by the ratio of left atrial (LA) end-diastolic volume divided by left ventricular (LV) end-diastolic volume. The cut-off value for LACI (≥40%) to identify LA-LV uncoupling was chosen based on the risk excess of new-onset AF described with a spline curve analysis.

RESULTS

The median LACI was 37.5% (IQR: 24.4-56.7) and LA-LV uncoupling (LACI ≥40%) was observed in 171 (45.8%) patients. During a median follow-up of 11 (IQR 7-15) years, 118 (31.6%) subjects developed new-onset AF. The cumulative event-free survival at 10 years was 53% for patients with LA-LV uncoupling versus 94% for patients without LA-LV uncoupling (p < 0.001). Multivariable Cox regression analyses performed separately for each LA parameter showed an independent association between new-onset AF and LACI (hazard ratio [HR], 1.021; 95% CI, 1.017-1.026), LA maximum volume indexed (HR, 1.028; 95% CI, 1.017-1.039), LA minimum volume indexed (HR, 1.047; 95% CI, 1.037-1.060) and LA emptying fraction (HR, 0.967; 95% CI, 0.959-0.977, all p < 0.001). The inclusion of LACI in the multivariate model provided a larger improvement in the risk stratification for new-onset AF, as compared to conventional LA parameters.

CONCLUSION

In patients with HCM, LACI was more predictive of the occurrence of new-onset AF than conventional LA parameters.

Detection of Congestive Heart Failure and Myocardial Dysfunction in Cats With Cardiomyopathy by Using Two-Dimensional Speckle-Tracking Echocardiography

Congestive heart failure (CHF) is a life-threatening condition in cats with cardiomyopathy. We hypothesized that myocardial dysfunction may induce progression to CHF pathophysiology in cats with cardiomyopathy. However, no previous studies have evaluated the involvement of myocardial dysfunction in cats with CHF. In this study, we aimed to evaluate the relationship between CHF and myocardial function assessed using two-dimensional speckle-tracking echocardiography (2D-STE). Sixteen client-owned healthy cats and 32 cats with cardiomyopathy were enrolled in this study. Cats were classified into three groups: healthy cats, cardiomyopathy without CHF (CM group), and cardiomyopathy with CHF (CHF group). Left ventricular (LV) longitudinal and circumferential strains (SL and SC, respectively), and right ventricular (RV) SL were measured using 2D-STE. Logistic regression analysis was performed to assess the relationship between CHF and echocardiographic variables, including 2D-STE. Results comparing the healthy cats and CM vs. CHF groups showed that increased left atrial to aortic diameter ratio and decreased LV apical SC were significantly associated with the existence of CHF (odds ratio [95% confidence interval]: 1.40 [1.16-1.78] and 1.59 [1.06-2.36], respectively). Results comparing the CM vs. CHF group showed that increased end-diastolic RV internal dimension and decreased RV SL were significantly associated with the existence of CHF (odds ratio: 1.07 [1.00-1.13] and 1.34 [1.07-1.68], respectively). Left atrial enlargement and depressed LV apical myocardial function may be useful tools for predicting the progression to CHF in cats. Furthermore, RV enlargement and dysfunction may lead to the onset of CHF in asymptomatic cats with cardiomyopathy.

The Indices of Cardiovascular Magnetic Resonance Derived Atrial Dynamics May Improve the Contemporary Risk Stratification Algorithms in Children with Hypertrophic Cardiomyopathy

Introduction: The most efficient risk stratification algorithms are expected to deliver robust and indefectible identification of high-risk children with hypertrophic cardiomyopathy (HCM). Here we compare algorithms for risk stratification in primary prevention in HCM children and investigate whether novel indices of biatrial performance improve these algorithms. Methods and Results: The endpoints were defined as sudden cardiac death, resuscitated cardiac arrest, or appropriate implantable cardioverter-defibrillator discharge. We examined the prognostic utility of classic American College of Cardiology/American Heart Association (ACC/AHA) risk factors, the novel HCM Risk-Kids score and the combination of these with indices of biatrial dynamics. The study consisted of 55 HCM children (mean age 12.5 ± 4.6 years, 69.1% males); seven had endpoints (four deaths, three appropriate ICD discharges). A strong trend (DeLong p = 0.08) was observed towards better endpoint identification performance of the HCM Risk-Kids Model compared to the ACC/AHA strategy. Adding the atrial conduit function component significantly improved the prediction capabilities of the AHA/ACC Model (DeLong p = 0.01) and HCM Risk-Kids algorithm (DeLong p = 0.04). Conclusions: The new HCM Risk-Kids individualised algorithm and score was capable of identifying high-risk children with very good accuracy. The inclusion of one of the atrial dynamic indices improved both risk stratification strategies.

Detection of congestive heart failure by Doppler echocardiography in cats with hypertrophic cardiomyopathy

Background

Left‐sided congestive heart failure (CHF) is characterized by increased filling pressures and related Doppler echocardiographic (DE) filling patterns.

Hypothesis

Doppler echocardiographic variables of left ventricular filling derived from transmitral flow, pulmonary vein flow, and tissue Doppler can be used to detect CHF in cats with hypertrophic cardiomyopathy (HCM).

Animals

Forty‐seven client‐owned cats.

Methods

Prospective clinical cohort study. Cats underwent physical examination, thoracic radiography, analysis of N‐terminal pro‐brain natriuretic peptide (NT‐proBNP), and transthoracic echocardiography and were divided into 3 age‐matched groups: Group 1 (apparently healthy control), Group 2 (preclinical HCM), and Group 3 (HCM and CHF). Measured and calculated variables included respiratory rate, DE estimates, serum NT‐proBNP concentration, and radiographic CHF score. Groups were compared using ANOVA, and receiver operating characteristic (ROC) curve and multivariate analyses were used to identify diagnostic cutoffs for the detection of CHF.

Results

Fifteen cats were in Group 1, 17 in Group 2, and 15 in Group 3. The ROC analysis indicated that the ratio of peak velocity of early diastolic transmitral flow to peak velocity of late diastolic transmitral flow (area under the curve [AUC], 1.0; diagnostic cutoff, 1.77; P = .001), ratio of left atrial size to aortic annular dimension (AUC, 0.91; diagnostic cutoff, 1.96; P = .003), left atrial diameter (AUC, 0.89; cutoff, 18.5 mm; P = .004), diastolic functional class (AUC, 0.89; cutoff, class 2; P = .005), respiratory (AUC, 0.79; cutoff, 36 breaths per minute [brpm]; P = .02), and the ratio of the peak velocity of fused early and late transmitral flow velocities to the peak velocity of the fused early and late diastolic tissue Doppler waveforms (AUC, 0.74; cutoff, 15.1; P = .05) performed best for detecting CHF.

Conclusions and Clinical Importance

Various DE variables can be used to detect CHF in cats with HCM. Determination of the clinical benefit of such variables in initiating treatments and assessing treatment success needs further study.

Left atrial remodeling postseptal myectomy for severe obstructive hypertrophic cardiomyopathy: Analysis by two-dimensional speckle-tracking echocardiography

BACKGROUND

Septal myectomy relieves left ventricular outflow obstruction (LVOTO) and is associated with excellent long-term outcomes. LVOTO is associated with diastolic dysfunction and increased left atrial (LA) size. We sought to investigate the changes in LA volumes and function postmyectomy and the association between these changes with clinical outcomes postmyectomy.

METHODS

Sixty-six hypertrophic cardiomyopathy patients undergoing myectomy were retrospectively studied. Preprocedural and 6- to 18-month postmyectomy follow-up transthoracic echocardiographic images were obtained. LA volumes and strain were assessed by two-dimensional speckle-tracking echocardiography.

RESULTS

Left atrial volumes, that is, indexed maximal, minimal, and pre-A volumes reduced postmyectomy, yet remained increased compared to controls (105.6 ± 34.5 mL vs 84.9 ± 26.7 mL, 45.2 ± 25.7 mL vs 35.4 ± 22.6 mL, 70.1 ± 31.4 mL vs 35.4 ± 22.6 mL, respectively, P < 0.05). The total emptying index did not improve postmyectomy and remained lower than controls (58.6 ± 12.4 vs 59.9 ± 12.8, P = NS) whereas atrial contraction improved, yet did not normalize (active emptying index 36.1 ± 14.9 vs 41.1 ± 16.2, P < 0.05). The conduit volume remained reduced postmyectomy (18.6 ± 13.3 mL vs 16.6 ± 15.1 mL, P = NS). LA strain also did not improve postmyectomy (26.8 ± 7.3 vs 28.5 ± 8.8, P = NS). A multivariable logistic regression identified preprocedural E/e' ratio and indexed maximal LA volume, as independent predictors for LA volume reduction ≥20% postmyectomy. During a mean follow-up of 4.9 ± 2.3 years postmyectomy, 24.2% of the patients developed atrial fibrillation and <5% of patients were severely symptomatic. We found no associations between LA volumes/function and atrial fibrillation or symptoms postmyectomy.

CONCLUSION

Postmyectomy LA volumes decreased, and the contractile function improved. There was no association between LA volumes/function and clinical outcomes postmyectomy. Notably, the LA remained enlarged (though to a lesser degree) with reduced strain and emptying fraction, suggesting possible atrial myopathy.

Left Atrial Size and Function in Hypertrophic Cardiomyopathy Patients and Risk of New-Onset Atrial Fibrillation

BACKGROUND

The value of left atrial (LA) diameter, volume, and strain to risk stratify hypertrophic cardiomyopathy patients for new-onset atrial fibrillation (AF) was explored.

METHODS AND RESULTS

A total of 242 hypertrophic cardiomyopathy patients without AF history were evaluated by (speckle-tracking) echocardiography. During mean follow-up of 4.8±3.7 years, 41 patients (17%) developed new-onset AF. Multivariable analysis showed LA volume (≥37 mL/m²; hazard ratio, 2.68; 95% confidence interval, 1.30-5.54; P=0.008) and LA strain (≤23.4%; hazard ratio, 3.22; 95% confidence interval, 1.50-6.88; P=0.003), but not LA diameter (≥45 mm; hazard ratio, 1.67; 95% confidence interval, 0.84-3.32; P=0.145), as independent AF correlates. Importantly, 59% (n=24) of AF events occurred despite a baseline LA diameter <45 mm, observed in 185 patients. In this patient subset, LA strain (area under the curve 0.73) and LA volume (area under the curve 0.83) showed good predictive value for new-onset AF. Furthermore, patients with LA volume <37 versus ≥37 mL/m² and LA strain >23.4% versus ≤23.4% had superior 5-year AF-free survival of 93% versus 80% (P=0.003) and 98% versus 74% (P=0.002), respectively. Importantly, LA volume <37 mL/m² and strain >23.4% yielded high negative predictive value (93% and 98%, respectively) for new-onset AF. Likelihood ratio test indicated incremental value of LA volume assessment (P=0.011) on top of LA diameter to predict new-onset AF in hypertrophic cardiomyopathy patients with LA diameter <45 mm, which tended to increase further by addition of LA strain (P=0.126).

CONCLUSIONS

LA diameter, volume, and strain all relate to new-onset AF in hypertrophic cardiomyopathy patients. In patients with normal LA size, however, both LA volume and strain further refine risk stratification for new-onset AF.

Echocardiographic evaluation of left ventricular diastolic function in cats: Hemodynamic determinants and pattern recognition

Left ventricular (LV) diastolic dysfunction is highly prevalent in cats and is a functional hallmark of feline cardiomyopathy. The majority of cats with hypertrophic, restrictive, and dilated cardiomyopathy have echocardiographic evidence of abnormal LV filling, even during the occult (preclinical) phase. Moderate and severe diastolic dysfunction is an indicator of advanced myocardial disease, is associated with clinical signs including exercise intolerance and congestive heart failure, affects outcome, and influences therapeutic decisions. Therefore, identification and quantification of LV diastolic dysfunction are clinically important. Surrogate measures of diastolic function determined by transthoracic two-dimensional, M-mode, and Doppler echocardiographic (DE) methods have been used widely for such purpose. Major functional characteristics of LV diastole, including global function, relaxation and untwist, chamber compliance, filling volume, and the resultant filling pressures can be semi-quantified by echocardiographic methods, and variables retrieved from transmitral flow, pulmonary vein flow, and tissue Doppler recordings are most frequently used. Although there is still a critical lack of well-designed studies in the field, knowledge has steadily accumulated over the past 20 years, reference ranges of diastolic echocardiographic variables have been determined, epidemiological studies have been conducted, and new treatments of diastolic dysfunction in cats have been evaluated. This report will give the reader a summary of the current status in the field of feline diastology with focus on the noninvasive diagnostic methods and interpretation of echocardiographic surrogate measures of LV diastolic function. Lastly, a grading system using a composite of left atrial size and various DE variables potentially useful in the functional classification of LV diastole in cats is introduced.

Predictors of Atrial Fibrillation Risk in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic cardiovascular disease that predisposes individuals to the development of arrhythmias. The most common sustained arrhythmia is atrial fibrillation (AF). Compared with the general population, patients with HCM are more prone to the development of AF. To avoid embolic complications and the clinical deterioration caused by the development of AF in HCM, identifying patients with a tendency toward AF might affect the management of HCM. In this review, we evaluated the predictors of AF development in patients with HCM.

Effects of septal myectomy on left ventricular diastolic function and left atrial volume in patients with hypertrophic cardiomyopathy

Ventricular septal myectomy in patients with obstructive hypertrophic cardiomyopathy (HC) has been shown to reduce left ventricular (LV) outflow tract (LVOT) gradient and improve symptoms, although little data exist regarding changes in left atrial (LA) volume and LV diastolic function after myectomy. We investigated changes in LA size and LV diastolic function in patients with HC after septal myectomy from 2004 to 2011. We studied 25 patients (age 49.2 ± 13.1 years, 48% women) followed for a mean of 527 days after surgery who had serial echocardiography at baseline and at most recent follow-up, at least 6 months after myectomy. In addition to myectomy, 3 patients (12%) underwent Maze surgery and 13 (52%) underwent mitral valve surgery, of whom 5 had a mitral valve replacement or mitral annuloplasty. Patients with mitral valve replacement or mitral annuloplasty were excluded from LV diastolic function analysis. LA volume index decreased (from 47.2 ± 17.6 to 35.9 ± 17.0 ml/m(2), p = 0.001) and LV diastolic function improved with an increase in lateral e' velocity (from 7.3 ± 2.9 to 9.8 ± 3.1 cm/sec, p = 0.01) and a decrease in E/e' (from 14.8 ± 6.3 to 11.7 ± 5.5, p = 0.051). Ventricular septal thickness and LVOT gradient decreased, and symptoms of dyspnea and heart failure improved, with reduction in the New York Heart Association functional class III/IV symptoms from 21 (84%) to 1 (4%). In conclusion, relief of LVOT obstruction in HC by septal myectomy results in improved LV diastolic function and reduction in LA volume with improved symptoms.

Functional assessment of the left atrium by real-time three-dimensional echocardiography using a novel dedicated analysis tool: initial validation studies in comparison with computed tomography

AIMS

A novel real-time three-dimensional echocardiography (RT3DE) analysis tool specifically designed for evaluation of the left atrium enables comprehensive evaluation of left atrial (LA) size, global, and regional function using a dynamic 16-segment model. The aim of this study was the initial validation of this method using computed tomography (CT) as the method of reference.

METHODS AND RESULTS

The study population consisted of 34 prospectively enrolled patients with clinical indication for pulmonary vein isolation. A dynamic polyhedron model of the left atrium was generated using RT3DE. LA maximum and minimum volumes (LA(max)/LA(min)) and emptying fraction (LAEF) were determined and compared with the results obtained by CT. High correlations between RT3DE and CT were found for LA(max) (r = 0.92, P < 0.001), LA(min) (r = 0.95, P < 0.001), and LAEF (r = 0.82, P < 0.001). LA(max) and LA(min) were lower by RT3DE than by CT (95.0 ± 44.7 vs. 119.8 ± 50.5 mL, P < 0.001 and 58.1 ± 41.3 vs. 83.3 ± 52.6 mL, P < 0.001, respectively), whereas LAEF was measured higher by RT3DE (42.8 ± 15.2 vs. 34.2 ± 15.4%, P < 0.001, respectively). RT3DE measurements closely correlated in terms of intra-observer (intra-class correlation r = 0.99, r = 0.99, r = 0.96, respectively) and inter-observer variability (r = 0.97, r = 0.98, r = 0.88, respectively).

CONCLUSIONS

LA volumes and EF as assessed by RT3DE correlate highly with CT measurements, albeit there is some bias between the imaging modalities. Most importantly, RT3DE measurements using the novel dedicated LA analysis tool are robust in terms of observer variability and thus suitable for follow-up analyses.

[The role of real-time three-dimensional echocardiography in the evaluation of hypertrophic cardiomyopathy]

Hypertrophic cardiomyopathy is a relatively common hereditary disorder, which is associated with cardiac morphologic and functional alterations. Echocardiography is a non-invasive, simple and easy-to-learn method to evaluate patients with cardiomyopathy. The aim of this review paper is to demonstrate the possible diagnostic role of one of the newest echocardiographic development, the real-time 3-dimensional echocardiography in the evaluation of hypertrophic cardiomyopathy.

Two-dimensional strain analysis in patients with hypertrophic cardiomyopathy and normal systolic function: a 12-month follow-up study

BACKGROUND

Although left ventricular (LV) and left atrial (LA) echo indices may reliably reflect loading conditions in patients with hypertrophic cardiomyopathy (HCM), little is known about 2-dimensional strain imaging. We evaluated LV and LA 2-dimensional strain imaging in relation to long-term outcome in patients with HCM.

METHODS

Fifty consecutive patients (58% men, aged 51 +/- 18 years) with familial HCM and normal LV ejection fraction underwent 2-dimensional LV and LA strain imaging; total LA strain was defined as the sum of maximum positive and maximum negative atrial strain. Patients were followed up for 12 months for cardiovascular events, defined as death or hospitalization for cardiovascular causes.

RESULTS

Twenty patients (40%) experienced an event after a median time of 98 days: 2 (4%) died and 18 (36%) were hospitalized. In multivariate analysis, total LA strain was the strongest predictor of 12-month outcome (odds ratio 0.858, 95% CI 0.771-0.954, P = .005); a cutoff of 21% predicted events with 90% sensitivity and 86% specificity. Total LA strain was also an independent predictor of atrial fibrillation requiring hospitalization (odds ratio 0.853, 95% CI 0.748-0.972, P = .017).

CONCLUSIONS

In patients with HCM and normal systolic function, total LA strain predicts 12-month outcome in terms of death and/or hospitalization.

Left atrial function assessed by real-time 3-dimensional echocardiography is related to right ventricular systolic pressure in chronic mitral regurgitation

BACKGROUND

Left atrial (LA) volume is a prognostic index in chronic mitral regurgitation (MR). However, little is known about LA function in this setting. We hypothesized that LA dysfunction is related to pulmonary hypertension in chronic MR.

METHODS

Seventy-one patients with organic chronic MR who underwent real-time 3-dimensional transthoracic echocardiography (RT3DE) were studied. Left atrial volumes and peak passive and active LA emptying rates were obtained. Total LA emptying fraction was calculated as follows: [(maximum - minimum LA volume)/maximum LA volume] x 100. Similarly, active and passive LA emptying fractions were calculated. From transmitral flow, the peak early (E) and late (A) diastolic filling velocities and E/A ratio were obtained. The early (E') and late (A') diastolic myocardial velocities were obtained by tissue Doppler interrogation of mitral annulus.

RESULTS

Effective regurgitant orifice area (EROA) was 0.57 +/- 0.29 cm(2). Right ventricular systolic pressure (RVSP) was measured in 57 patients and averaged 37 +/- 13 mm Hg. Patients with MR and high RVSP displayed higher minimum LA volume, E/A ratio, E/E' ratio, EROA, and MR volume, and lower A' velocity, peak active LA emptying rate, active LA emptying fraction, and total LA emptying fraction than patients with MR and normal RVSP. Multiple regression analysis revealed that EROA (r = 0.51, P = .01) active LA emptying fraction (r = -0.53, P = .02), E/E' ratio (r = 0.50; P = .04), and the lateral A' velocity (r = -0.46; P = .003) were independently correlated with RVSP.

CONCLUSIONS

Left atrial function determined by RT3DE had significant correlation with RVSP in chronic MR, irrespective of MR severity. Thus, pulmonary hypertension in chronic MR may depend not only on MR severity but also on LA function.

Impact of the number of image planes of real-time three-dimensional echocardiography on the accuracy of left atrial and ventricular volume measurements

Real-time three-dimensional (3D) echocardiography (RT-3DE) has emerged as a new technique in measuring left atrial and ventricular volume. However, the impact of cutting planes of RT-3DE on the accuracy of volume measurement in patients with a normal or enlarged heart is still unknown. We enrolled 30 normal subjects (control group) and 30 patients with heart failure (patient group). RT-3DE was performed to measure maximal volume of the left atrium (LAVmax) and left ventricular end-diastole volume (LVEDV) with 2-, 4-, 8- and 16-cutting planes, compared with cardiac magnetic resonance imaging (CMRI). In both groups, LAVmax by RT-3DE using 2- and 4-cutting planes was significantly underestimated (mean difference: -10.4 +/- 16.6 mL, p = 0.001 and -8.8 +/- 14.2 mL, p = 0.002 in the control group and -13.4 +/- 19.6 mL, p = 0.001 and -11.2 +/- 17.5 mL, p = 0.001 in the patient group, respectively). These differences became nonsignificant when 8- and 16-cutting planes were adopted (mean difference: -2.1 +/- 7.6 mL and -1.9 +/- 7.4 mL in the control group and -2.7 +/- 8.4 mL and -2.2 +/- 8.3 mL in the patient group, respectively). The agreement for LVEDV was acceptable when 4- or more cutting planes were used in the control group and when 8- or 16-cutting planes were used in the patient group. The time expense for data analysis of LAVmax with 8-image planes was only 7 +/- 4 min in the control group and 6 +/- 5 min in the patient group, almost halving that of the 16-image planes. Similarly, 4- and 8-cutting planes were required for an accurate measurement of LVEDV in the control and patient groups, respectively. In conclusion, RT-3DE with 8-cutting planes is both accurate and timesaving for measurement of LAVmax and LVEDV in patients with normal or enlarged left atria and ventricles.

Relationship Between Left Atrial and Left Ventricular Function in Hypertrophic Cardiomyopathy: A Real-time 3-Dimensional Echocardiographic Study

BACKGROUND

Left atrium (LA) in patients with hypertrophic cardiomyopathy (HC) has been known to have an increased size and decreased contractile function. The purpose of this study was to investigate LA and left ventricular (LV) volume change and function with real-time 3-dimensional (3D) echocardiography and to investigate association between LA and LV function in HC.

METHODS

We performed real-time 3D echocardiography on 26 patients with HC and on 15 control subjects. LA and LV time-volume curves were obtained from real-time 3D echocardiography and the maximal slope of the time-volume curve was expressed as dV/dt. LA active emptying fraction was calculated as: [(precontraction LA volume - minimal LA volume)/precontraction LA volume] x 100.

RESULTS

The maximal LA volume index was larger, and LA active emptying fraction was lower, in those with HC than control subjects (50.1 +/- 15.9 vs 30.1 +/- 6.8 mL/m(2) and 33.3 +/- 13.7 vs 40.4 +/- 8.6%, both P< .05). LA active emptying fraction showed a negative correlation with precontraction LA volume (r = -0.64, P < .01) in HC. Patients with HC showed decreased LV early diastolic dV/dt compared with control subjects (0.10 +/- 0.05 vs 0.14 +/- 0.04 mL/ms, P < .05). LA passive and active emptying dV/dt were correlated with LV early and late diastolic dV/dt, respectively (r = 0.47 and r = 0.48, both P < .05).

CONCLUSION

Our 3D echocardiographic study showed that increased LA volume was related to decreased LA contraction in HC. LA passive emptying was related to LV relaxation whereas LA active contraction was related to LV stiffness.

Left Atrial Index Is a Predictor of Exercise Capacity in Patients with Hypertrophic Cardiomyopathy

BACKGROUND

Left atrial (LA) enlargement is related to diastolic dysfunction and mitral regurgitation (MR), both of which are common in patients with hypertrophic cardiomyopathy (HCM). This study investigates the association between LA size and exercise capacity in patients with HCM.

METHODS

All HCM patients who underwent a treadmill test with direct measurement of oxygen consumption (VO2) and a standard transthoracic echocardiography within 30 days in the years 2001-2003 were identified. Patients with significant comorbidities were excluded. Exercise capacity was defined as percentage of predicted peak VO2. Clinical and echocardiographic parameters were compared with those of a group of normal subjects.

RESULTS

Compared with normal subjects, HCM patients had increased left atrial (LA) volume index (36 vs 21 mL/m2; P < .0001) and mitral E/e' ratio (14 vs 9; P < .0001); 27% of the patients had at least moderate MR. LA volume index demonstrated borderline correlation with exercise capacity (r = -.20; P = .06) but was an independent predictor of exercise capacity in a multivariate linear analysis, together with body mass index, heart rate at rest, and left ventricular end-systolic diameter. Including the parameters E/e' ratio or moderate or severe MR did not add incremental value to the model.

CONCLUSION

LA volume index, reflecting the combined influences of MR and diastolic dysfunction, was independently associated with objective measures of exercise capacity in patients with isolated HCM.