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Assessment of Left Ventricular Mass in HypertrophicCardiomyopathy by Real-Time Three-Dimensional

Echocardiography Using Single-Beat Capture Image

Sung-A Chang, MD, Hyung-Kwan Kim, MD,* Sang-Chol Lee, MD,* Eun-Young Kim, RDCS,

Seung-Hee Hahm, RDCS, Oh Min Kwon, RDCS, Seung Woo Park, MD, Yeon Hyeon Choe, MD,

and Jae K. Oh, MD, Seoul, South Korea; Rochester, Minnesota

Background: Left ventricular (LV) mass is an important prognostic indicator in hypertrophic cardiomyopathy.Although LV mass can be easily calculated using conventional echocardiography, it is based on geometricassumptions and has inherent limitations in asymmetric left ventricles. Real-time three-dimensional echocar-diographic(RT3DE) imaging with single-beat capture provides an opportunity for the accurate estimation of LVmass. The aim of this study was to validate this new technique for LV mass measurement in patients withhypertrophic cardiomyopathy.

Methods: Sixty-nine patients with adequate two-dimensional (2D) and three-dimensional echocardiographicimage quality underwent cardiac magnetic resonance (CMR) imaging and echocardiography on the same day.Real-time three-dimensional echocardiographic images were acquired using an Acuson SC2000 system, andCMR-determined LV mass was considered the reference standard. Left ventricular mass was derived usingthe formula of the American Society of Echocardiography (M-mode mass), the 2D-based truncated ellipsoidmethod (2D mass), and the RT3DE technique (RT3DE mass).

Results: Themean time for RT3DE analysis was5.856 1.81 min.Intraclass correlation analysis showeda closerelationship between RT3DE and CMR LV mass (r= 0.86,P < .0001). However, LV mass by the M-mode or 2Dtechnique showed a smaller intraclass correlation coefficient compared with CMR-determined mass (r= 0.48,P = .01, and r= 0.71, P < .001, respectively). Bland-Altman analysis showed reasonable limits of agreementbetween LV mass by RT3DE imaging and by CMR, with a smaller positive bias (19.5 g [9.1%]) comparedwith that by the M-mode and 2D methods (35.1 g [20.2%] and 30.6 g [17.6%], respectively).

Conclusions: RT3DE measurement of LV mass using the single-beat capture technique is practical and moreaccurate than 2D or M-mode LV mass in patients with hypertrophic cardiomyopathy. (J Am Soc Echocardiogr2013;26:436-42.)

Keywords: Left ventricular mass, Three-dimensional echocardiography, Hypertrophic cardiomyopathy

Left ventricular (LV) mass is an important prognostic indicator of heart

failure and sudden cardiac death in patients with hypertrophic cardio-

myopathy (HCM).1,2 Although cardiac magnetic resonance (CMR)

imaging is the most accurate noninvasive method for assessing

myocardial mass in vivo,3 it is relatively expensive and time consum-

ing and is limited in patients with claustrophobia or implantedpacemakers, limiting its routine use in the daily clinical practice.

Transthoracic echocardiography is a widely used modality for assess-

ing LV morphology and function in patients with HCM and can be

easily performed for longitudinal assessment. Furthermore, it provides

more accurate information on hemodynamic changes.4,5 LV mass

determination using M-mode or two-dimensional (2D) echocardiog-

raphy has been well validatedin normal or hypertensive patients with

symmetrically shaped left ventricles,6-8 but LV mass calculations using

M-mode and 2D techniques are based on the assumption of

symmetric LV geometry. Accordingly, it can be presumed that these

conventional methods have inherent limitations that might produce

erroneous results in patients with HCM.

Three-dimensional (3D) assessments, which are free of geometric

assumptions, might provide more accurate measures of LV mass in

From the Division of Cardiology, Department of Medicine (S.-A.C., S.-C.L., S.W.P.,

J.K.O.), and the Department of Radiology (Y.H.C.), Cardiovascular Imaging Center

(S.-A.C., S.-C.L., E.-Y.K., S.-H.H., S.W.P., Y.H.C., J.K.O.), Samsung MedicalCenter, Sungkyunkwan University School of Medicine, Seoul, Korea; the

Department of Internal Medicine, Cardiovascular Center, Seoul National University

Hospital, Seoul, Korea (H.-K.K., O.M.K.); and the Division of Cardiovascular

Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota (J.K.O.).

This study was supported by the Korea Healthcare Technology R&D Project,

Ministry for Health, Welfare & Family Affairs, Republic of Korea (A070001).

* Drs. Kim and Lee contributed equally.

Reprint requests: Hyung-Kwan Kim, MD, PhD, Division of Cardiology, Department

of Internal Medicine, Cardiovascular Center, Seoul National University College

of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea (E-mail:

hkkim73@snu.ac.kr).

0894-7317/$36.00

Copyright 2013 by the American Society of Echocardiography.

http://dx.doi.org/10.1016/j.echo.2012.12.015

436

mailto:hkkim73@snu.ac.krhttp://dx.doi.org/10.1016/j.echo.2012.12.015http://dx.doi.org/10.1016/j.echo.2012.12.015mailto:hkkim73@snu.ac.kr

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asymmetric left ventricles than

conventional 2D methods, but

the effort required to acquire

and analyze 3D echocardio-

graphic data limits clinical utility.

However, the recent develop-

ment of real-time 3D echocar-diographic (RT3DE) imaging

with single-beat capture has

been shown to provide a straight-

forward, highly accurate means

of determining LV volume and

function.9 Additionally, this ap-

proach provides a means for cal-

culating LV mass that is free of

geometric assumptions.

We hypothesized that the ac-

curacy of LV mass calculation in

patients with HCM could be im-

proved using RT3DE imaging

with single-beat capture compared with conventional methods such

as M-mode or 2D imaging. We also examined the feasibility and accu-

racy of this novel RT3DE technique for the determination of LV mass

in patients with HCM, with CMR as the reference standard.

METHODS

Study Population

Consecutive patients with HCM in normal sinus rhythm at two ter-

tiary referral hospitals (Samsung Medical Center and Seoul

National University Hospital) with established diagnoses of HCM

and scheduled for CMR and echocardiography on the same day

were considered for this study. Patients with poor 2D echocardio-graphic windows, defined as those in whom an experienced sonogra-

pher could not sufficiently discriminate the endocardial and/or

epicardial borders on 2D echocardiographic images, and patients

with contraindications to CMR were excluded a priori. Ultimately,

71 patients were enrolled, and these patients constituted the study co-

hort. The study protocol was approved by the institutional review

boards of the two participating hospitals.

CMR Imaging

All patients underwent CMR studies using a 1.5-Tscanner (Magnetom

Avanto, syngo MR; Siemens Healthcare, Erlangen, Germany) during

repeated breath holds. After localization, cine images for LV and right

ventricular functional parameters were acquired using a steady-statefree precession sequence (repetition time, 810 msec; echo time,

35 msec; flip angle, 20; in-plane resolution, 1.4 to 1.6 mm 2.2to 2.5 mm; temporal resolution, 46 6 8 msec) with eight to 10 con-

tiguous short-axis slices to cover the entire left and right ventricles,

with s lice thickness of 6 mm and 4-mm gaps.10

Image analysis was performed to determine LV mass from CMR

images using commercial software (Argus version 4.02; Siemens

Healthcare) by a single experienced observer blinded to all echocar-

diographic results. In each case, the end-diastolic frame with the larg-

est LV cavity size was selected for LV mass measurement by

retrospective image review. Endocardial and epicardial borders

were manually traced in the selected image frame for the LV cavity

volume and total LV volume (defined as the sum of LV cavity volume

and LV myocardial volume) calculations. Papillary muscles and LV tra-

beculae were excluded from endocardium and included in LV cavity

volume. At the base of the heart, slices were considered to be within

the LV if the blood volume was surrounded by$50% of ventricular

myocardium. Left ventricular myocardial volume was calculated by

subtracting LV cavity volume from total LV volume. Finally,

LV mass was calculated by multiplying LV myocardial volume by

myocardial density (1.05 g/mL).

Echocardiographic Image Acquisition

After CM R acquisition, transthoracic echocardiography was per-

formed using commercially available equipment (Acuson SC2000;

Siemens Medical Solutions USA, Inc., Mountain View, CA) by a single

experienced sonographer at each center, with subjects in the left

lateral decubitus position. After each routine echocardiographic

examination, 2D targeted M-mode echocardiographic images were

acquired at the level of the mitral valve leaflet tips, in accordance

with the American Society of Echocardiography (ASE) guidelines

for chamber quantification.7 To calculate LV mass using 2D echocar-

diograms, short-axis view images at the mid ventricle and apical four-

chamber view images were acquired. Great care was taken to avoidforeshortened acquisition of apical images.

For LV mass quantification by RT3DE imaging, a special 3D image

acquisition transducer (4Z1c) was used. This transducer has a matrix

array with a maximum volume angle of 90 90. Volume anglesand frame rates were optimized for each patient to allow visualization

of both endocardial and epicardial borders.

Echocardiographic Analysis of LV Mass Measurement

Echocardiographic images were transferred to a central laboratory

and analyzed by two experienced observers (E.-Y.K. and S.-H.H),

who independently analyzed M-mode, 2D, and 3D echocardio-

graphic data without knowledge of CMR data. Analyses were per-

formed using 2D and 3D software analysis packages supplied withthe echocardiographic system.

For LV mass measurement using the M-mode technique, we used

the formula suggested by the ASE8:

LV mass g 0:80h

1:04PWT LVIDd SWT3

LVID3i

0:6 g;

where PWT is LV end-diastolic posterior wall thickness (millimeters),

LVIDd is LVend-diastolic dimension (millimeters), and SWT is LVend-

diastolic septal wall thickness (millimeters).

For LV mass calculations by 2D echocardiography, we used the

area-length method, as described in an ASE document on LV quanti-

tation11; LV mass was calculated by subtracting endocardial volume

from epicardial volume:

LV mass g 1:05

5=6Aepi Lepi Aendo Lendo:

For LV mass quantification by RT3DE imaging, analysis was per-

formed online using an embedded program (Volume Cardiac

Analysis Package Volume Left Ventricular Analysis version 1.6) on

the SC2000 system. In each case, a suitable end-diastolic frame de-

picting the maximally dilated LV cavity was chosen (Figure 1). After

applying the automatic contouring algorithm, several manual correc-

tions were made by visual assessment to adjust the endocardial bor-

der. After completing the endocardial tracing, the epicardial border

was manually traced. On the basis of these tracings, the 3D analysis

program in the platform calculated LV myocardial volume and pro-

vided a value for LV mass (grams). Time required for the analysis

Abbreviations

ASE = American Society ofEchocardiography

CMR = Cardiac magneticresonance

HCM = Hypertrophiccardiomyopathy

ICC = Intraclass correlationcoefficient

LV= Left ventricular

RT3DE = Real-time three-dimensionalechocardiographic

3D = Three-dimensional

2D = Two-dimensional

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was recorded for each case. Real-time three-dimensional echocardio-

graphic image quality was graded as good (the endocardium and epi-

cardium were entirely visualized) or suboptimal but interpretable

(one segment of the endocardium or epicardium was not visualized,

but tracing was possible by interpolation).

For interobserver variability of LV mass assessment, echocardio-

graphic images in 12 randomly selected patients were analyzed by

two independent reviewers blinded to each others measurement.

These measurements were also repeated by one reviewer blinded to

the first measurement, at least 1 month apart from each measurement.

Statistical Analysis

Left ventricular mass data obtained using the different echocardio-

graphic techniques and CMR are presented as mean 6 SD.

Agreement is expressed using Bland-Altman plots with mean differ-

ences and95% limits of agreements. Intraclass correlation coefficients

(ICC) were used for comparisons among different measurement

techniques. Intraobserver and interobserver variability was defined

as the absolute difference between the corresponding repeated mea-

surements expressed as a percentage of their mean. Variability values

obtained for each parameter in each patient for each observer were

averaged over the whole group of patients and are expressed as

mean 6 SD. Statistical significance was accepted for P values < .05.

RESULTS

Study Population

Seventy-one consecutive patients were enrolled, but two patients

were excluded from final analyses because of poor RT3DE image

quality. Characteristics of the study subjects are briefly summarized

in Table 1. Apical hypertrophy was the most common HCM subtype,

and most of the study subjects were men. Mean LV mass determined

using the M-mode formula was greater than that measured by other

modalities (CMR, 2D echocardiography, and RT3DE imaging;

Table 1).

Figure 1 Three-dimensional echocardiography and the analysis of LV mass. (A) An end-diastolic frame, containing a maximallydilated LV cavity, was selected by retrospective review. RT3DE images were reviewed in four planes (short-axis view and apicaltwo-chamber, three-chamber, and four-chamber views), and brightness and contrast were optimized. (B) After the automatic con-touring algorithm for endocardial border tracking was applied, several manual corrections were applied with visual assessment toadjust correct tracing for endocardial border. (C)After completion of endocardial tracing, the epicardial border was manually traced.

Table 1 Characteristics of the study population (n = 69)

Variable Value

Age (y) 58.2 6 10.9Men 58 (83%)

Type of HCMSeptal 17 (24.6%)

Apical 32 (46.4%)Septal plus apical 10 (14.5%)

Diffuse 3 (4.3%)Others 7 (10.1%)

LV mass (g)ASE formula 212.8 6 61.5

2D ellipsoid method 148.3 6 49.1RT3DE imaging 159.4 6 45.8

CMR 178.9 6 64.4LV ESV (mL) by CMR 41.2 6 16.4

LV EDV (mL) by CMR 138.8 6 29.9LV EF (mL) by CMR 70.3 6 8.7

EDV, End-diastolic volume; EF, ejection fraction; ESV, end-systolicvolume.Data are expressed as mean 6 SD or as number (percentage).

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Feasibility of and Times Required for LV Mass Analysis by

RT3DE Imaging

When 2D echocardiographic image quality was satisfactory (n = 71),

LV mass analysis by RT3DE imaging was possible in 97% of patients

(n = 69). Image quality was suboptimal in 37 of these 69 patients

(53.6%), and in most of these, border interpolation involved epicardial

border tracing of apical segments in cases of apical HCM. The mean

time required forRT3DELV mass analysis was5.8561.81 min (range,

312.5 min), and the mean frame rate required for optimal image

acquisition was 16.76 4.8 frames/sec.

LV Mass as Determined by M-Mode Echocardiography,

2D Echocardiography, and RT3DE Imaging Comparedwith CMR

A summary regarding comparisons of LV mass data acquired using the

different echocardiographic methods and CMR is provided in

Figure 2. Intraclass correlation analysis showed a close association be-

tween RT3DE andCMR LV mass (r=0.86, P< .0001), witha relatively

narrow distribution along the reference line, highlighting a high con-

cordance with LV mass by CMR (Figure 2C). Left ventricular masses

determined by the M-mode and 2D techniques were less well corre-

lated with CMR data (Figures 2A and 2B). Left ventricular mass by

M-mode analysis displayed only a moderate correlation with LV

mass by CMR analysis (r = 0.48, P < .001), with a relatively wide

distribution and a large negative bias in the Bland-Altman plot

(Figure 2A). In addition, although LV mass determined using the 2D

ellipsoid method showed better agreement with CMR-determined

values in comparison with those by the M-mode method, the ICC

for the 2D method (r = 0.82, P < .001) was lower than for the

RT3DE method (r= 0.90, P< .001) (Table 2). Furthermore, in several

cases, LV mass was considerably different from the CMR-determined

value (Figure 2B). On the other hand, LV mass determined by RT3DE

imaging displayed a substantially better correlation with CMR-

determined values (r = 0.86, P < .001), had a narrower distribution

along the reference line, and showed little bias (Figure 2C).

We also analyzed the ICC of each modality for LV mass measure-

ment in relation to HCM type (nonapical vs apical; Table 3). Of note,

RT3DE imaging was more beneficial in the nonapical type, compared

with the apical type, in terms of LV mass measurement. Left ventric-

ular mass assessed by the M-mode or 2D techniques showed lower

ICCs for the nonapical type than for the apical type.

Intraobserver and Interobserver Variability

Intraobserver variability was 4.9 6 2.9%, 5.37 6 5.0%, and 5.0 6

5.2% for LV measurements by M-mode, 2D, and RT3DE imaging.

Interobserver variability was 10.2 6 7.3%, 13.1 6 8.6%, and 6.3 6

4.5%, respectively.

DISCUSSION

This is the first study to evaluate the accuracy and feasibility of

LV mass measurements in patients with HCM using online

analysis of RT3DE images with single-beat full-volume capture

technology. Our comparison with conventional M-mode or 2D

Figure 2 LV mass measured by M-mode and 2D echocardiography, RT3DE imaging, and CMR. (A) LV mass determined using theASE formula was found to be moderately correlated with CMR-determined LV mass, though a large negative bias toward the refer-ence method (CMR) was observed in the Bland-Altman plot. (B) LV mass determined using the 2D ellipsoid method showed betteragreement with the CMR value than that obtained using the ASE formula, but a large positive bias and several results extreme outlierswere observed. (C) LV mass determined using RT3DE imaging with single-beat capture showed good agreement with the CMR valueand better limits of agreement (LOA) with less bias in the Bland-Altman plot than the other two methods.

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echocardiographic analyses using CMR as a reference modality

showed that RT3DE imaging more accurately determines LV mass

in patients with HCM. The clinical feasibility and the higher accuracy

of RT3DE LV mass measurements are of substantial clinical relevance,

because LV mass is considered an important prognostic indicator in

HCM. In addition, freedom of the assumption of symmetry is another

important advantage of the RT3DE technique for LV mass measure-

ment. This is of particular importance in patients with HCM, because

its various phenotypic expressions make geometric assumptions

implausible and thus make estimations based on these assumptions

inherently inaccurate.

Limitations of Conventional Echocardiographic Methods

for LV Mass Evaluation in Patients with HCM

Left ventricular hypertrophy is an important risk factor of many car-

diovascular diseases, and therefore, researchers have made continued

efforts to devise a noninvasive, accurate means of assessing LV mass.

However, previously described methods involve calculations based

on geometric assumptions. For example, the formula advocated by

the ASE assumes that the left ventricle is spherical, which clearly dif-

fers from its true shape. Nevertheless, a previous comparative study

that used necropsy findings as a reference showed an excellent corre-

lation (r = 0.90, P < .001)8 when it was applied to symmetrically

shaped left ventricles. Another approach, the area-length method,supposes that the left ventricle is conically shaped,6which seems a bet-

ter assumption than the spherical shape, and not surprisingly, the data

obtained using the area-length method were found to be better cor-

related with CMR-based LV mass data in comparison with those ob-

tained using the M-mode method. However, the area-length method

considers only the midwall plane of the left ventricle and thus does

not take into account the presence of regional hypertrophy localized

to basal and/or apical walls, frequently observed findings in patients

with HCM.

Left ventricular mass determination by CMR is also limited by par-

tial volume artifacts and difficulties associated with the discrimination

of right ventricular trabeculation and the septal wall. Nevertheless, it is

a simple volumetric method that applies multiple stack analysis to im-ages with high signal-to-noise ratios and acceptable spatial resolution,

which better delineate the blood-endocardium border because of

high signal difference between blood and myocardium. Currently,

CMR is considered the most accurate in vivo technique for LV

mass assessment and has been reported to be more accurate than

echocardiographic methods in this respect.3,12 One small-scale com-

parative evaluation of LV mass as determined by echocardiography

and CMR in patients with HCMshowed a wide discrepancy between

echocardiography and CMR but showed only small differences in

normal subjects.13 Furthermore, the findings of this previous study

suggest that the asymmetric shape of the left ventricle contributes

to the inaccuracies of echocardiographic estimations of LV mass.

Left ventricular mass estimation using 3D echocardiography

adopts volumetric algorithms, which are more powerful for deter-

mining LV mass because they do not involve geometric assump-

tions. Furthermore, the CMR method for LV mass assessment is

based on the summation of 2D image stacks, but there are gaps

between imaging planes, and thus 3D echocardiography may be

more accurate in vivo than CMR for determining LV myocardial

mass.

Feasibility, Image Quality, and Technical Pitfalls of RT3DE

Imaging

Multiple-beat RT3DE imaging has already been shown to significantly

improve accuracy in LV mass quantification in comparison with 2D

approaches, with CMR as a reference, irrespective of geometric as-

sumptions or using manual adjustment for accurate delineation of en-

docardial and epicardial borders.14-19 These studies included about

20 patients and acquired RT3DE images with four wedged

subvolumes and analyzed them offline. None of these studies

included patients with HCM. Our study has some strengths,

compared with the previous works. First, we tested a novel RT3DE

technology in our real-world clinical practice. Our images were

analyzed online using a program that has been already installed in

echocardiographic equipment. We also provide data on analysis

time, suggesting that RT3DE imaging with single-beat capture is

a strong candidate for incorporation into daily clinical echocardio-

graphic practice. Second, we showed the clinical utility of RT3DE im-

aging in a highly specified, unique HCM population. Because HCM is

characterized by asymmetric hypertrophy of the left ventricle, geo-

metric assumptions underlying LV mass quantification by 2D or

M-mode methods do not seem to be appropriately applied, which

is in clear contrast in patients with symmetric hypertrophy of the

left ventricle, as in hypertensive LV hypertrophy. Previously published

works involved small numbers of study patients and included a variety

of clinical conditions. Hence, direct application of those results to the

real-world clinical arena appears to be premature. Bicudo et al.20

reported LV mass quantification using RT3DE imaging in patients

with HCM, but they used a multiple-beat capture 3D technique

with offline analysis in a small number of patients, a significant

drawback for clinical application.

Our data showed, to some extent, inferior results compared with

previous studies in LV mass quantification, which can be best ex-

plained by differences in study populations compared with those in

the Western world. In Western countries, apical HCM is extremely

rare, but it is common in Asian countries, which may also be true in

the present study. Of interest, Table 3 highlights that LV mass quanti-

fication by RT3DE imaging is more beneficial in nonapical HCM than

in apical HCM. The more asymmetric shape of the nonapical type

may be a possible explanation. Another possible explanation maybe poor delineation of the LV apex in apical HCM. Moreover, the epi-

cardium of the hypertrophied LV apex usually bulges outward and

presents some technical difficulties in accurate measurement.

Furthermore, the current version of single-beat RT3DE imaging

used in our study did not allow us to obtain images >90 in

width, and thus the epicardial border of the hypertrophied apex

can sometimes drop out or be vaguely addressed.

In the present study, we showed better feasibility than that re-

ported in a previous study by our group using RT3DE imaging with

single-beat capture technology.9 In the previous study, we included

many patients with dilated left ventricles or dilated apexes, which

are not issues for most subjects with HCM, rendering the feasibility

of this study much better than that of the previous work. Despite

the high feasibility of RT3DE imaging in this study, the ICC for LV

Table 2 Summary of intermodality correlation and bias

M-mode vs CMR 2D vs CMR RT3DE imaging vs CMR

ICCr 0.66 0.82 0.90

P

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mass measurement between RT3DE and CMR imaging was 50% of the study

population). Echocardiographic images in apical HCM were more

or less limited in completely demonstrating apical morphology com-

pared with those of septal HCM, because the epicardial contour

shows bulging in some cases; hence, epicardial tracing of the apex

is not uncommonly challenging, and this hurdle might be a potentialcause of underestimation of LV mass in this HCM subtype. Actually,

about half of our study subjects required interpolation of the epi-

cardial border during the tracing procedure.

Although the mean time required for LV mass measurement by

RT3DE imaging was about 5 min, it varied from 3 to 12 min, and

the amount of time taken was determined primarily by how effec-

tively the automatic contouring algorithm delineated the endocardial

border and thus how much the time for manual correction of border

delineation could be minimized. Another practical limitation is that

the contemporary analysis program does not support the automatic

contouring algorithm for epicardial border tracing but provides only

a crude outline of the epicardial border. Future advances in automatic

contouring techniques for epicardial border tracing are expected toshorten the time required for analysis, which facilitates rapid incorpo-

ration of this novel technique for LV measurement into daily echocar-

diographic practice.

Limitations

The subjects enrolled in our study were all Korean. Thus, a rela-

tively high proportion of apical HCM was included in the present

study. This cohort makeup may have affected study results and

may limit extrapolation of the present results to patients with the

HCM type frequently observed in Western countries, because

asymmetric septal hypertrophy is more prevalent in the West.

However, as we demonstrated, RT3DE imaging was more benefi-cial for LV mass measurement in nonapical hypertrophy than apical

hypertrophy.

Real-time three-dimensional echocardiographic imaging with

single-beat capture has potential advantages in terms of avoiding

stitch artifacts, especially in patients with arrhythmias such as atrial

fibrillation. However, in the present study, we included only patients

in sinus rhythm, and thus our results may not be extended to patients

with HCM with atrial fibrillation. Nevertheless, the single-beat capture

approach likely holds promise, given its freedom from stitch artifacts,

an inherent limitation of multiple-beat RT3DE imaging. This should

be further investigated. Head-to-head comparison between the two

approaches (i.e., single-beat capture vs multiple-beat capture) would

be interesting in terms of LV mass measurements in patients with

HCM with atrial fibrillation.

CONCLUSIONS

Although conventional echocardiography provides a useful, noninva-

sive means for evaluating hemodynamics and ventricular function in

patients with HCM, its accuracy in determining LV mass is limited.

The present study shows that RT3DE imaging with single-beat cap-

ture is both more feasible and more accurate than 2D or M-mode

echocardiography in terms of LV mass assessment, especially in non-

apical HCM. Real-time three-dimensional echocardiographic mea-

surements were more reproducible than 2D or M-modeechocardiography. Thus, we expect this technique to be incorporated

into daily clinical practice in the near future.

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Table 3 LV mass measurement according to HCM type: nonapical versus apical

Nonapical (n = 37) Apical ( n = 32)

M-mode 2D RT3DE imaging M-mode 2D RT3DE imaging

ICC (reference modality: CMR)

r 0.49 0.73 0.91 0.81 0.87 0.85P .03

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