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Assessment of Coronary Artery Stenoses by Myocardial Contrast Stress Echocardiography
Assessment of Regional Wall Motion in
Figure 1: Non-invasive Modalities for the Diagnosis of
Contrast Stress Echocardiography
Myocardial Ischaemia
The evaluation of myocardial function by regional/segmental wall
motion scoring of contractility and wall thickening is highly dependent
90
on image quality and optimal visualisation of the endocardial border.
80
The introduction of ultrasound contrast for left ventricular 70
opacification during stress echocardiography to improve endocardial 60
border delineation was tested in the Randomized Cross-Over Study for
50
Evaluation of the Effect of Image Optimization With Contrast on the
40
Diagnostic Accuracy of Dobutamine Echocardiography in Coronary
30
Artery Disease (OPTIMIZE) trial,
10
which demonstrated that
20
improvement of endocardial border visualisation by contrast resulted
10
in higher confidence of interpretation and greater accuracy in
0
evaluating CAD at rest, and even more so during stress. Contrast also
Ex-ECG SPECT DSE CMR MCE
increased the number of left ventricular wall segments interpretable at
Sensitivity (%) Specificity (%)
rest and especially during stress, and it markedly reduced the number
of patients who could not be properly evaluated by stress echo-
Overview of sensitivity and specificity of exercise echocardiography (Ex-ECG), single-photon emission computer
tomography (SPECT), dobutamine stress ECG (DSE), cardiac magnetic resonance (CMR) and myocardial contrast
cardiography due to suboptimal image quality. Contrast in stress
stress echocardiography (MCE) for the detection of ischaemia.
echocardiography has also been shown to reduce inter-observer
Sources: Detrano R, Prog Cardiov Dis, 1989;32:173–206; Klocke FJ, JACC, 2003;42:1318; Pelikka PA, JASE,
2007;20(9):1021–41; Rieber J, Eur Heart J, 2006;27(12):1465–71; Dijkmans PA, JACC, 2006;5:2168–77.
variability. Furthermore, improved visualisation of the left ventricular
segments by the introduction of contrast in echocardiography was also study from our laboratory examining patients scheduled for
demonstrated in a multicentre study evaluating contrast for left percutaneous coronary intervention due to significant coronary artery
ventricular opacification and perfusion against 2D echocardiography, stenoses diagnosed by quantitative coronary angiography.
14
In this
demonstrating higher accuracy in the detection of regional myocardial study, 95% of patients did not reach the target heart rate during
abnormalities when contrast was used.
11
stress, a common problem in patients on beta-blockade where
withdrawal before testing is not desirable. However, perfusion analysis
Administration of ultrasound contrast agent is routinely used in many was significantly more sensitive in detecting coronary artery stenoses
advanced echocardiography laboratories for the assessment of than wall motion analysis, especially in detecting prognostically
myocardial wall motion abnormalities during stress echocardiography. important CAD as multivessel disease or proximal LAD stenoses even
Use of ultrasound contrast in left ventricular opacification to improve at the intermediate stress level.
14
endocardial border delineation is implemented in the current
indications for contrast echocardiography.
5
In stress echocardiography, Thus, regional myocardial perfusion is more sensitive for detecting CAD
ultrasound contrast is well established to improve assessment of than wall motion analysis, especially at lower stress levels. This may be
myocardial wall motion abnormalities,
12
and according to the American explained by several factors, including the fact that in the ischaemic
Society of Echocardiography (ASE) guidelines for performance, cascade abnormal perfusion precedes contractile abnormality when
interpretation and application of stress echocardiography, contrast is ischaemia is induced,
15
and in chronic ischaemia capillary de-recruitment
indicated during stress echocardiography when two or more segments occurred distally to coronary stenosis to maintain perfusion pressure. This
are not well visualised.
5
capillary de-recruitment explains a common finding in contrast stress
echocardiography: hypoperfusion without wall motion abnormality is
Assessment of Myocardial Perfusion in often referred to as mechanically silent ischaemia.
16,17
Contrast Stress Echocardiography
Contrast stress echocardiography in the assessment of regional Compared with coronary angiography, perfusion imaging is less
myocardial perfusion, which focuses on contrast enhancement in specific than wall motion scoring in detecting CAD. Possible
the myocardium, has so far not been included in the stress explanations could be the development of collateral circulation due to
echocardiography guidelines.
5
However, several studies suggest that chronic ischaemia, small-vessel disease only affecting myocardial
adding perfusion analysis to wall motion analysis during contrast stress microcirculation that cannot be detected by coronary angiography,
echocardiography increases the sensitivity to diagnose CAD.
2,13
In a which is recognised as a gold standard in the diagnosis of CAD, and
meta-analysis by Dijkmans, the accuracy of myocardial perfusion individual variation in coronary artery anatomy significantly influences
assessment by myocardial contrast stress echocardiography was the relation between perfusion defects and anatomical stenoses in
compared with wall motion analysis in the detection of chronic epicardial coronary arteries.
angiographic coronary artery stenoses.
2
The meta-analysis included 12
studies and 674 patients, and demonstrated a statistically significant Quantification of Regional Myocardial Perfusion in
increase in sensitivity in detecting angiographic CAD by perfusion Contrast Stress Echocardiography
analysis. The increase in sensitivity was demonstrated for all coronary The additional value of using quantification of regional myocardial
territories, showing the highest sensitivity in the left anterior perfusion in the evaluation of CAD compared with simple perfusion
descending (LAD) territory, followed by the circumflex and right scoring has yet to be demonstrated in larger studies. As previously
coronary arteries. The difference in sensitivity was particularly high at published, regional myocardial perfusion can be calculated using
intermediate stress levels. This is in accordance with results in a recent parametric imaging.
7
Myocardial perfusion may be assessed by a
EUROPEAN CARDIOLOGY 65
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