- Email: [email protected]
Right Ventricular 3-Dimensional Strain in Pulmonary Hypertension
JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY
VOL. 64, NO. 1, 2014
ª 2014 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION
ISSN 0735-1097/$36.00
PUBLISHED BY ELSEVIER INC.
http://dx.doi.org/10.1016/j.jacc.2014.04.028
EDITORIAL COMMENT
Right Ventricular 3-Dimensional Strain in Pulmonary Hypertension The Quest to See the Future* Daniel G. Blanchard, MD, Anthony N. DeMaria, MD
A
ccording to legend penned by Sir Thomas
hypertension (6). Recently, Fine et al. (7) examined a
Malory (1), King Arthur’s knights searched
large population with pulmonary hypertension and
far and long for the Holy Grail. Modern cardi-
found that 2D RV strain analysis could discriminate
ologists are a far cry from the knights-errant of antiq-
between patients who had a relatively good versus a
uity, but we, too, pursue our holy grails. What quest
poor prognosis.
or goal does an echocardiographer long to see today?
In the past few years, left ventricular strain anal-
How about an accurate, foolproof echo technique to
ysis has moved forward to 3D imaging, but as
quantify mitral regurgitation? Perhaps, at last, could
described by Reichek (8), RV strain imaging has lag-
we find a reliable method to quantify myocardial
ged behind in this regard. The RV is an extremely
ischemia with contrast echocardiography? We also
asymmetric structure with a thin free wall, making
long for a more complete evaluation of right ventric-
tissue tracking more difficult and less reliable. In
ular (RV) anatomy and function. The RV has begged
addition, the proprietary software packages for 3D
for 3-dimensional (3D) assessment for years. Recent
strain analysis are all designed for the left ventricle.
studies have suggested that 3D echo imaging of the
The authors of the current paper went to great
RV is indeed feasible, and its results compare reason-
lengths to “tweak” their system and capture RV im-
ably well with magnetic resonance imaging (MRI) (2).
ages, but 21% of patient and 36% of control images were inadequate for evaluation. This problem will
SEE PAGE 41
likely not change without significant improvements in both programming and echo hardware.
In this issue of the Journal, Smith et al. (3) extend
Smith et al. (3) evaluated 3D RV free wall strain and
analysis of RV function to 3D measurement of strain.
RV ejection fraction in 97 patients with pulmonary
Although originally designed for evaluating the left
hypertension and in 60 controls. The RV was divided
ventricle, software programs for 2D strain analysis by
into 7 segments (3 basal, 3 mid, and 1 apical). Mean RV
speckle tracking have been applied effectively to the
systolic strain was measured longitudinally, circum-
RV (4). For example, 2D strain imaging of the RV has
ferentially, and radially. Strain of the entire free wall
been shown to help predict outcomes in patients
area was assessed as well. All of these values are
with left ventricular systolic failure referred for
negative except radial strain: the free wall becomes
heart transplantation (5). Also, improvement in
thicker during systole, but its circumference, long
2D RV strain with medical treatment has correlated
axis (from tricuspid annulus to apex), and total area
with better survival in patients with pulmonary
all decrease. The systolic dyssynchrony index also was calculated (essentially, the standard deviation of the mean time to peak systolic strain for the 7 RV
* Editorials published in the Journal of the American College of Cardiology
segments—the wider the dispersion, the greater the
reflect the views of the authors and do not necessarily represent the
dyssynchrony index) (9).
views of JACC or the American College of Cardiology. From UCSD Sulpizio Cardiovascular Center, La Jolla, California. Dr. DeMaria has received research funding from General Electric and Lantheus; and is a sponsored speaker for Siemens. Dr. Blanchard has re-
As one would expect, the authors found that the magnitudes of all RV strain parameters were diminished in patients versus controls. Of note, area strain
ported that he has no relationships relevant to the contents of this paper
correlated particularly well with RV ejection fraction.
to disclose.
The systolic dyssynchrony index was significantly
Blanchard and DeMaria
JACC VOL. 64, NO. 1, 2014 JULY 8, 2014:52–3
RV 3D Strain in Pulmonary Hypertension
greater in the patient population than in controls and
unacceptable and must be improved for the tech-
correlated inversely with RV ejection fraction. This
nique to be useful in day-to-day practice. Most
suggests that—similar to the left ventricle—the extent
importantly, a prospective trial to test the cutoff
of RV dyssynchrony is related to the extent of RV
points in the current study could potentially confirm
systolic dysfunction.
the prognostic utility of RV strain.
The authors constructed receiver-operating char-
In summary, the work by Smith et al. (3) is
acteristic curves (ROC) and assessed the various
intriguing because it is the first to show that 3D RV
strain vector cutoff points for both impaired RV
strain imaging may have independent prognostic
ejection fraction and (more importantly) overall
value in patients with pulmonary hypertension. The
mortality. Figure 6 of Smith et al. (3) demonstrates
word “may” in the previous sentence cannot be
the capability of the strain parameters to discriminate
overemphasized. The authors have discovered an
between survivors and nonsurvivors with pulmonary
association between 3D strain parameters and clin-
hypertension. Interestingly, RV ejection fraction and
ical outcomes in pulmonary hypertension. This
tricuspid annular plane systolic excursion (TAPSE)
cannot be translated to say that 3D strain predicts
were less discriminating than strain. Also, RV pres-
outcome (and the authors are careful not to claim
sure did not correlate with RV strain values reliably.
this). A prospective, long-term follow-up study will
In a multivariate analysis, RV area strain emerged as
be necessary to prove or disprove this possibility. If
the only independent echocardiographic variable
such a study does demonstrate predictive value,
associated with mortality. Because this parameter
strain could both inform and potentially improve
cannot be assessed with 2D strain analysis, these re-
clinical care. If this occurs, 3D RV strain evaluation
sults suggest an incremental benefit of 3D imaging
could eventually become a standard part of the RV
in pulmonary hypertension.
echo exam, much like TAPSE and tricuspid annular
Smith et al. (3) discuss the limitations of their
velocity are today.
study, including the inability to obtain adequate im-
So, have we found the holy grail of RV 3D imaging?
ages in all subjects and the lack of validation for echo-
No, clearly not yet, but the current study is provoca-
derived RV strain with methods such as MRI or
tive. If a prospective trial confirms the predictive and
sonomicrometry. Ultimately, though, these diffi-
prognostic value of RV strain in pulmonary hyper-
culties do not negate their results.
tension, we will at least—like Galahad—be on the road
Where do we go from here? First, a study validating
to Castle Corbenic.
echo-derived 3D RV strain with MRI would be reassuring. Second, software modifications designed
REPRINT REQUESTS AND CORRESPONDENCE: Dr.
specifically for 3D RV strain are needed for more
Daniel G. Blanchard, UCSD Sulpizio Cardiovascular
complete and reliable data acquisition: inadequate
Center, 9444 Medical Center Drive, #7411, La Jolla,
RV strain imaging in w30% of patients is clinically
California 92037. E-mail: [email protected].
REFERENCES 1. Malory, Sir Thomas. Le Morte D’Arthur. Published 1485. 2. Gopal AS, Chukwu EO, Iwuchukwu CJ, et al. Normal values of right ventricular size and function by real-time 3-dimensional echocardiography: comparison with cardiac magnetic resonance imaging. J Am Soc Echocardiogr 2007;20:445–55. 3. Smith BCF, Dobson G, Dawson D, Charalampopoulos A, Grapsa J, Nihoyannopoulos P. Three-dimensional speckle tracking of the right ventricle: toward optimal quantification of right ventricular dysfunction in pulmonary hypertension. J Am Coll Cardiol 2014;64:41–51. 4. Meris A, Faletra F, Conca C, et al. Timing and magnitude of regional right ventricular function: a
speckle tracking-derived strain study of normal subjects and patients with right ventricular dysfunction. J Am Soc Echocardiogr 2010;23:823–31. 5. Cameli M, Righini FM, Lisi M, et al. Comparison of right vs. left ventricular strain analysis as a predictor of outcome in patients with systolic heart failure referred for cardiac transplantation. Am J Cardiol 2013;112:1778–84. 6. Hardegree EL, Sachdev E, Villarraga HR, et al.
pulmonary hypertension. Circ Cardiovasc Imaging 2013;6:711–21. 8. Reichek N. Right ventricular strain in pulmonary hypertension: flavor du jour or enduring prognostic index? Circ Cardiovasc Imaging 2013;6:611–3. 9. Kalogeropoulos AP, Georgiopoulou VV, Howell S, et al. Evaluation of right intraventricular dyssynchrony by two-dimensional strain echocardiography in patients with pulmonary arterial hypertension.
Role of serial quantitative assessment of right ventricular function by strain in pulmonary arterial hypertension. Am J Cardiol 2013;111:143–8.
J Am Soc Echocardiogr 2008;21:1028–34.
7. Fine NM, Chen L, Bastiansen PM, et al. Outcome prediction by qualitative right ventricular function assessment in 575 subjects evaluated for
KEY WORDS 3-dimensional imaging, echocardiography, pulmonary hypertension, right ventricle, speckle tracking
53
VOL. 64, NO. 1, 2014
ª 2014 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION
ISSN 0735-1097/$36.00
PUBLISHED BY ELSEVIER INC.
http://dx.doi.org/10.1016/j.jacc.2014.04.028
EDITORIAL COMMENT
Right Ventricular 3-Dimensional Strain in Pulmonary Hypertension The Quest to See the Future* Daniel G. Blanchard, MD, Anthony N. DeMaria, MD
A
ccording to legend penned by Sir Thomas
hypertension (6). Recently, Fine et al. (7) examined a
Malory (1), King Arthur’s knights searched
large population with pulmonary hypertension and
far and long for the Holy Grail. Modern cardi-
found that 2D RV strain analysis could discriminate
ologists are a far cry from the knights-errant of antiq-
between patients who had a relatively good versus a
uity, but we, too, pursue our holy grails. What quest
poor prognosis.
or goal does an echocardiographer long to see today?
In the past few years, left ventricular strain anal-
How about an accurate, foolproof echo technique to
ysis has moved forward to 3D imaging, but as
quantify mitral regurgitation? Perhaps, at last, could
described by Reichek (8), RV strain imaging has lag-
we find a reliable method to quantify myocardial
ged behind in this regard. The RV is an extremely
ischemia with contrast echocardiography? We also
asymmetric structure with a thin free wall, making
long for a more complete evaluation of right ventric-
tissue tracking more difficult and less reliable. In
ular (RV) anatomy and function. The RV has begged
addition, the proprietary software packages for 3D
for 3-dimensional (3D) assessment for years. Recent
strain analysis are all designed for the left ventricle.
studies have suggested that 3D echo imaging of the
The authors of the current paper went to great
RV is indeed feasible, and its results compare reason-
lengths to “tweak” their system and capture RV im-
ably well with magnetic resonance imaging (MRI) (2).
ages, but 21% of patient and 36% of control images were inadequate for evaluation. This problem will
SEE PAGE 41
likely not change without significant improvements in both programming and echo hardware.
In this issue of the Journal, Smith et al. (3) extend
Smith et al. (3) evaluated 3D RV free wall strain and
analysis of RV function to 3D measurement of strain.
RV ejection fraction in 97 patients with pulmonary
Although originally designed for evaluating the left
hypertension and in 60 controls. The RV was divided
ventricle, software programs for 2D strain analysis by
into 7 segments (3 basal, 3 mid, and 1 apical). Mean RV
speckle tracking have been applied effectively to the
systolic strain was measured longitudinally, circum-
RV (4). For example, 2D strain imaging of the RV has
ferentially, and radially. Strain of the entire free wall
been shown to help predict outcomes in patients
area was assessed as well. All of these values are
with left ventricular systolic failure referred for
negative except radial strain: the free wall becomes
heart transplantation (5). Also, improvement in
thicker during systole, but its circumference, long
2D RV strain with medical treatment has correlated
axis (from tricuspid annulus to apex), and total area
with better survival in patients with pulmonary
all decrease. The systolic dyssynchrony index also was calculated (essentially, the standard deviation of the mean time to peak systolic strain for the 7 RV
* Editorials published in the Journal of the American College of Cardiology
segments—the wider the dispersion, the greater the
reflect the views of the authors and do not necessarily represent the
dyssynchrony index) (9).
views of JACC or the American College of Cardiology. From UCSD Sulpizio Cardiovascular Center, La Jolla, California. Dr. DeMaria has received research funding from General Electric and Lantheus; and is a sponsored speaker for Siemens. Dr. Blanchard has re-
As one would expect, the authors found that the magnitudes of all RV strain parameters were diminished in patients versus controls. Of note, area strain
ported that he has no relationships relevant to the contents of this paper
correlated particularly well with RV ejection fraction.
to disclose.
The systolic dyssynchrony index was significantly
Blanchard and DeMaria
JACC VOL. 64, NO. 1, 2014 JULY 8, 2014:52–3
RV 3D Strain in Pulmonary Hypertension
greater in the patient population than in controls and
unacceptable and must be improved for the tech-
correlated inversely with RV ejection fraction. This
nique to be useful in day-to-day practice. Most
suggests that—similar to the left ventricle—the extent
importantly, a prospective trial to test the cutoff
of RV dyssynchrony is related to the extent of RV
points in the current study could potentially confirm
systolic dysfunction.
the prognostic utility of RV strain.
The authors constructed receiver-operating char-
In summary, the work by Smith et al. (3) is
acteristic curves (ROC) and assessed the various
intriguing because it is the first to show that 3D RV
strain vector cutoff points for both impaired RV
strain imaging may have independent prognostic
ejection fraction and (more importantly) overall
value in patients with pulmonary hypertension. The
mortality. Figure 6 of Smith et al. (3) demonstrates
word “may” in the previous sentence cannot be
the capability of the strain parameters to discriminate
overemphasized. The authors have discovered an
between survivors and nonsurvivors with pulmonary
association between 3D strain parameters and clin-
hypertension. Interestingly, RV ejection fraction and
ical outcomes in pulmonary hypertension. This
tricuspid annular plane systolic excursion (TAPSE)
cannot be translated to say that 3D strain predicts
were less discriminating than strain. Also, RV pres-
outcome (and the authors are careful not to claim
sure did not correlate with RV strain values reliably.
this). A prospective, long-term follow-up study will
In a multivariate analysis, RV area strain emerged as
be necessary to prove or disprove this possibility. If
the only independent echocardiographic variable
such a study does demonstrate predictive value,
associated with mortality. Because this parameter
strain could both inform and potentially improve
cannot be assessed with 2D strain analysis, these re-
clinical care. If this occurs, 3D RV strain evaluation
sults suggest an incremental benefit of 3D imaging
could eventually become a standard part of the RV
in pulmonary hypertension.
echo exam, much like TAPSE and tricuspid annular
Smith et al. (3) discuss the limitations of their
velocity are today.
study, including the inability to obtain adequate im-
So, have we found the holy grail of RV 3D imaging?
ages in all subjects and the lack of validation for echo-
No, clearly not yet, but the current study is provoca-
derived RV strain with methods such as MRI or
tive. If a prospective trial confirms the predictive and
sonomicrometry. Ultimately, though, these diffi-
prognostic value of RV strain in pulmonary hyper-
culties do not negate their results.
tension, we will at least—like Galahad—be on the road
Where do we go from here? First, a study validating
to Castle Corbenic.
echo-derived 3D RV strain with MRI would be reassuring. Second, software modifications designed
REPRINT REQUESTS AND CORRESPONDENCE: Dr.
specifically for 3D RV strain are needed for more
Daniel G. Blanchard, UCSD Sulpizio Cardiovascular
complete and reliable data acquisition: inadequate
Center, 9444 Medical Center Drive, #7411, La Jolla,
RV strain imaging in w30% of patients is clinically
California 92037. E-mail: [email protected].
REFERENCES 1. Malory, Sir Thomas. Le Morte D’Arthur. Published 1485. 2. Gopal AS, Chukwu EO, Iwuchukwu CJ, et al. Normal values of right ventricular size and function by real-time 3-dimensional echocardiography: comparison with cardiac magnetic resonance imaging. J Am Soc Echocardiogr 2007;20:445–55. 3. Smith BCF, Dobson G, Dawson D, Charalampopoulos A, Grapsa J, Nihoyannopoulos P. Three-dimensional speckle tracking of the right ventricle: toward optimal quantification of right ventricular dysfunction in pulmonary hypertension. J Am Coll Cardiol 2014;64:41–51. 4. Meris A, Faletra F, Conca C, et al. Timing and magnitude of regional right ventricular function: a
speckle tracking-derived strain study of normal subjects and patients with right ventricular dysfunction. J Am Soc Echocardiogr 2010;23:823–31. 5. Cameli M, Righini FM, Lisi M, et al. Comparison of right vs. left ventricular strain analysis as a predictor of outcome in patients with systolic heart failure referred for cardiac transplantation. Am J Cardiol 2013;112:1778–84. 6. Hardegree EL, Sachdev E, Villarraga HR, et al.
pulmonary hypertension. Circ Cardiovasc Imaging 2013;6:711–21. 8. Reichek N. Right ventricular strain in pulmonary hypertension: flavor du jour or enduring prognostic index? Circ Cardiovasc Imaging 2013;6:611–3. 9. Kalogeropoulos AP, Georgiopoulou VV, Howell S, et al. Evaluation of right intraventricular dyssynchrony by two-dimensional strain echocardiography in patients with pulmonary arterial hypertension.
Role of serial quantitative assessment of right ventricular function by strain in pulmonary arterial hypertension. Am J Cardiol 2013;111:143–8.
J Am Soc Echocardiogr 2008;21:1028–34.
7. Fine NM, Chen L, Bastiansen PM, et al. Outcome prediction by qualitative right ventricular function assessment in 575 subjects evaluated for
KEY WORDS 3-dimensional imaging, echocardiography, pulmonary hypertension, right ventricle, speckle tracking
53