World Journal of Cardiovascular Diseases, 2011, 1, 1-12
doi:10.4236/wjcd.2011.11001 Published Online October 2011 (http://www.SciRP.org/journal/wjcd/
WJCD
).
Published Online October 2011 in SciRes. http://www.scirp.org/journal/WJCD
Diagnostic value of dobutamine stress Doppler tissue imaging
in diabetic patients with suspected coronary artery disease
Mohamed Fahmy Elnoamany, Hala Mahfouz Badran, Tarek Salah Khalil, Abdalla Mostafa Kamal,
Amany Ragab Serag, Rehab Ebraheem Yaseen
Faculty of Medicine, Menoufyia University, Menoufyia, Egypt.
Received 9 September 2011; revised 14 October 2011; accepted 20 October 2011.
ABSTRACT
Background: Coronary artery disease (CAD) is often
silent in diabetic patients, and it is typically in ad-
vanced stages of development by the time it manifests.
Various forms of stress testing have been investigated
to detect obstructive CAD in diabetes mellitus. Ob-
jectives: To assess the diagnostic value of dobutamine
stress pulsed-wave Doppler tissue imaging (DTI)
compared with standard wall motion analysis in de-
tection of myocardial ischemia in diabetic patients
with suspected CAD. Methods: The study comprised
46 diabetic patients with suspected CAD underwent
dobutamine stress echocardiography (DSE) with DTI
within 4 weeks before coronary angiography(CA).
Dobutamine infusion started at 5 µ/kg/min and in-
creased up to 40 µ/kg/min with additional atropine
during submaximal heart rate responses. In addition
to wall-motion score index (WMSI) analysis, pulsed-
wave DTI examination of basal and mid segments of
posteroseptal, lateral, anterior, inferior and antero-
septal walls was performed. Myocardial velocities
were measured at rest in the apical 4, 3 and 2-cham-
ber views. The measurements were repeated at low
dose (10 - 15 µ/kg/min) and at peak stress (40
µ/kg/min). DTI measurements included peak systolic
velocity (S), peak early diastolic velocity (E) and peak
late diastolic velocity (A) and the results were com-
pared to WMSI analysis. Patients were classified into
two groups according to CA results; group (I) dia-
betics with positive CA (n = 27) and group (II) dia-
betics with negative CA (n = 19). Results: There was
no significant difference between the two groups in
duration of diabetes, global WMSI at rest or the ∆
changes (stress-rest/rest) of WMSI (P > 0.05). Global
S and global E were significantly lower in group I
compared to group II at peak stress (11.3 ± 3.7 cm/sec
vs. 14.5 ± 2.2 cm/sec, p < 0.01) and (11.3 ± 1.6 cm/sec
vs. 13.1 ± 2.1 cm/sec, p < 0.01) respectively. The cutoff
points for global S and global E to detect obstructive
CAD in diabetics were 11.3 cm/s and 11.2 cm/s re-
spectively with 75.7%, 73.4% sensitivity and 94.7%,
89.47% specificity respectively. An increment (∆
changes) less than 0.56 in S or 0.26 in E from rest to
peak stress identified CAD with 78.8 %, 89.3% sensi-
tivity and 94.7%, 90.7% specificity respectively. The
accuracy of DTI parameters during peak stress was
higher than WMSI analysis (sensitivity 74.1% vs.
59.3% and specificity 90% vs. 79%, P < 0.01 for
each). In multivariate regression analysis, only ∆S
and ∆E were independent predictors of obstructive
CAD in diabetics (odd ratio: 36.16, 95% CI, 1.34-
532.01 and 63.77, 95% CI, 3.19-721.47) respectively.
Conclusion: Quantitative analysis, using DTI during
DSE, adds new dimension in diagnosis of myocardial
ischemia. It is more sensitive, specific, accurate and
reproducible compared with standard wall motion
analysis for recognition of significant CAD in diabetic
patients.
Keywords: Doppler Tissue Imaging; Dobutamine Stress;
Diabetes Mellitus
1. INTRODUCTION
Diabetes mellitus (DM) has recently been classified as a
major independent risk factor for development of coro-
nary artery disease (CAD). Epidemiologic data also in-
dicate that, patients with diabetes have increased car-
diovascular morbidity and mortality [1]. Diabetic pa-
tients without previous myocardial infarction have out-
comes similar to those of nondiabetic patients who had a
prior infarction. These data support aggressive risk fac-
tor modification and early noninvasive identification of
coronary artery disease in diabetic patients [2].
Exercise electrocardiography (ECG) is the standard
noninvasive technique used for diagnostic and prognos-
tic assessment of nondiabetic patients with known or

M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 2
suspected CAD [3]. In diabetic patients the accuracy of
exercise ECG may be lowered as a result of several fac-
tors such as blunted response of blood pressure and heart
rate with exercise, previous silent infarctions, high fre-
quency of conduction abnormalities, left ventricular hy-
pertrophy, and reduced exercise capacity resulting from
peripheral vascular disease [3]. Because of the reduced
diagnostic accuracy of exercise ECG, exercise or phar-
macologic stress with myocardial perfusion scintigraphy
has been recommended for diagnostic and prognostic
assessment of diabetic subjects [4].
In nondiabetic subjects, stress echocardiography has
been found to enhance diagnostic and prognostic accu-
racy compared with exercise ECG [5]. The absence of
ischemia on a stress echocardiogram identifies patients
at low risk for future cardiovascular events [6].
Doppler tissue imaging (DTI) is a relatively recent
non invasive technique that records myocardial wall
motion velocities during different phases of the cardiac
cycle. It evaluates global and regional systolic and dia-
stolic LV function [7].
The combination of pulsed-wave tissue Doppler (PWDTI)
during dobutamine stress echocardiography (DSE) may
provide quantitative component to myocardial function
assessment by measuring the contraction and relaxation
velocities of myocardial fibers from the base to the apex
[8-11].
2. AIM OF THE WORK
To assess the diagnostic value of dobutamine stress
pulsed-wave DTI compared with standard wall motion
analysis in detection of myocardial ischemia in diabetic
patients with suspected CAD.
3. PATIENTS AND METHODS
3.1. Study Population
The present study included 46 patients with known his-
tory of DM. It was performed prospectively in Menou-
fyia University Hospital in the period from June 2007 to
February 2009.
The study was approved by the appropriate Institu-
tional Review Board and Institutional Ethical Committee
for Human Research. All study subjects provided written
informed consent regarding the study procedures.
Diabetes mellitus (DM) was diagnosed according to
World Health Organization (WHO) and the American
Diabetes Association (ADA) [12-14] as fasting blood
glucose ≥ 126 mg/dL (≥7.0 mmol/L) or 2 hour post-load
plasma glucose ≥ 200 mg/dL (≥11.1 mmol/L) or random
plasma glucose ≥ 200 mg/dL.
Inclusion criteria: the study included all diabetic pa-
tients who have one or more of the following criteria:
-Known diabetic patients with 15 years duration in
Type I or 10 years duration in Type II or 5 years with
one or more risk factor for CAD [15].
-Resting ECG changes suggestive of ischemic heart
disease.
-Positive exercise stress ECG.
-Regional wall motion abnormalities in resting echo-
cardiography.
Exclusion criteria: patients with one or more of the
following were excluded from the study: 1) prior history
of acute coronary syndrome; 2)valvular heart disease; 3)
suspected or known aortic dissection; 4) acute pulmo-
nary embolism; 5) acute myocarditis, endocarditis; 6)
severe systemic hypertension (more than 180/110 mmHg);
7) pregnancy; 8) hypertrophic obstructive cardiomyopa-
thy, restrictive cardiomyopathy; 9) ventricular aneurysm;
10) serious arrhythmias.
3.2. For Each Patient the Following Was Done
1) Detailed history taking.
2) Full clinical examination.
3) Standard 12-lead resting ECG.
4) Complete two-dimensional echocardiographic ex-
amination was done using Acuson XP10 C (Acuson,
Mountain view, Calif) system equipped with DTI tech-
nology with 2.5 MHz transducer. Examination was per-
formed in the left lateral decubitus position for:
a) Measurement of wall thickness, dimensions, ejection
fraction and resting wall motion abnormality.
b) Dobutamine stress echocardiography:
Dobutamine stress echocardiography (DSE) requires
two-dimensional echocardiography with Doppler and an
infusion pump to deliver dobutamine. The area where
DSE is performed is equipped with resuscitation equip-
ment (defibrillator, endotracheal intubation, etc) [16].
Preparation for Examination: the patients abstain
from all oral intake for at least 3 hours before the proce-
dure. β-blockers were withheld 48 hours before testing.
The procedure as well as side effects and potential com-
plications were explained to the patient. If baseline echo-
cardiographic images are adequate for assessment of
regional wall motion, an intravenous cannula was placed
in an arm vein for administration of medications. An
infusion solution that consists of 100 mg of dobutamine
in 100 mL of 5% dextrose was prepared, and the appro-
priate infusion rates in milliliters per minute, based on
the patient’s body weight, to provide dosages from 5
µg/kg/min were determined. Atropine (1 mg/10 mL) was
available if needed to increase the heart rate. The short-
acting β-blocker, propranolol was available to be admin-
istrated, if necessary, to reverse the β-adrenergic effects
of dobutamine. Nitroglycerin was available for sublin-
gual administration as needed. Lidocaine hydrochloride
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M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 3
was also available for treatment of ventricular arrhyth-
mias [16].
Examination Procedure: dobutamine was adminis-
trated intravenously by an infusion pump at a starting
dosage of 5 µg/kg/min. At 3-minute intervals, the dosage
is increased to 10, 20, 30, and 40 µg/kg/min until a pre-
determined endpoint was reached. If neither target heart
rate (85% of age-predicted maximal heart rate) nor any
of the other endpoints was reached, the infusion rate was
increased up to 50 µg/kg/min, or atropine was adminis-
trated intravenously. A dose of 0.25 to 0.5 mg of atropine
was repeated at 1 minute intervals to a maximal dose of
2 mg or until an endpoint was reached and dobutamine
infusion is continued during atropine administration [17].
Throughout the dobutamine infusion the ECG was con-
tinuously monitored and recorded at 1 min intervals and
BP is recorded every third minute. End-points for inter-
ruption of the test were [11]: 1) achievement of target
heart rate; 2) maximal dose of both dobutamine and at-
ropine; 3) extensive new wall motion abnormalities; 4)
horizontal or downsloping ST-segment depression (0.2
mV 80 ms after the J-point compared with the baseline);
5) severe angina; 6) symptomatic reduction in systolic
blood pressure > 40 mmHg from baseline; 7) hyperten-
sion (blood pressure > 240/120 mmHg); 8) significant
arrhythmias or 9) any serious side effect regarded as
being due to dobutamine infusion.
Doppler Tissue imaging (DTI): pulsed-wave DTI
examination was performed after activation of the DTI
mode of the same machine. The gain was set to an opti-
mal level to minimize noise. A 5 mm sample volume
was used and Doppler signals were recorded at sweep
speed 100 mm/s
The left ventricle was divided into 16 segments ac-
cording to the recommendation of American society of
Echocardiography [18]. As previous studies have already
indicated that, the apex is fairly stationary and velocities
obtained in that region are negligible; so myocardial
velocity was not measured in that region [19,20]. The
resulting 12 LV segments were combined to reflect the
territories of the coronary arteries: midseptum, antero-
septal, and anterior segments were assigned to the left
anterior descending artery (LAD), basal septum and in-
ferior segments to the right coronary artery (RCA), and
lateral and posterior segments to the left circumflex
(LCX) [18].
In each patient, echocardiographic velocities were ob-
tained from the apical 4, 3, 2 chambers views. These
views provided visualization of septal and lateral walls
(apical 4), anterior and inferior walls (apical 2) an-
teroseptal wall (apical 3). The basal and mid segments of
each wall were examined.
During systole, a major positive velocity wave (S) was
recorded when the annulus moves toward the cardiac
apex. During diastole, when the annulus moves toward
the base away from the apex, 2 major negative velocity
waves were recorded: one during the early phase of di-
astole (E) and another during the late phase of diastole
(A) [21].
The regional myocardial velocity waveforms meas-
ured were systolic velocity (S) (Figure 4), peak early
diastolic filling velocity (E) (Figure 5) and peak late
diastolic filling velocity (A) (Figure 6) [22]. The iso-
volumic contraction time (IVCT) was calculated from
the beginning of QRS in ECG till beginning of S wave
while the isovolumic relaxation time (IVRT) was calcu-
lated from the end of S wave (Figure 1) till beginning of
E wave (Figure 3). Time to peak S wave was measured
from beginning of QRS in ECG till peak of S wave
(Figure 2). Time to peak E was measured from begin-
ning of QRS in ECG till peak of E wave. All measure-
ments were obtained at baseline, low-dose, and peak
stress and were taken in a good-signal cycle with aver-
aging its value in 3 different cycles. Cardiac cycles with
extrasystolic, post extrasystolic beats, or rhythm distur-
bance were excluded [19].
Wall motion score index (WMSI) also was determined
at rest and peak stress. Using a 4-point scale as follows:
normal (1), hypokinetic (2), akinetic (3), dyskinetic (4).
The WMSI was calculated by dividing the wall motion
score by the number of segments. Normal contraction
results in a WMSI of 1; a higher score index is indicative
of wall motion abnormalities [18].
Dobutamine stress test was considered to be positive
in cases of new or worsening wall thickening (or motion)
Figure 1. Measurement of isovolumic contraction time at
the basal posterior septal wall in apical four chambers view
at rest (56 ms) in one patient of group II.
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M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 4
Figure 2. Measurement of duration of S wave (contraction
time) at the basal posterior septal wall in apical four cham-
ber view at rest (264 ms) in one patient of group II.
Figure 3. Measurement of isovolumic relaxation time at the
basal posterior septal wall in apical four chambers view at
rest (88 ms) in one patient of group II.
abnormalities at any dobutamine (or atropine) stage in
more than one segment of the same region (Figure 7),
the condition of akinesia becoming dyskinesia was not
considered [11, 23].
5) Coronary Angiography
Selective coronary angiography was performed with
the standard Judkins approach within 1 month from DSE.
The equipment used was the digital Siemens Hicor 1000
system. All coronary angiograms were interpreted by
two experienced cardiologists who were unaware of re-
sults of DSE. No cardiac events occurred for any of the
Figure 4. Measurement of peak velocity of S wave at the
basal posterior septal wall in apical four chamber view at
rest (9 cm/s) in one patient of group II.
Figure 5. Measurement of peak velocity of E wave at the
basal posterior septal wall at rest (measured 17 cm/s) in one
patient of group II.
studied patients in the interval between the time of DSE
study and coronary angiography. Significant CAD was
defined as the presence of ≥50% luminal diameter nar-
rowing of one or more major epicardial arteries or its
major branches localized in the first or middle segments
of the coronary arterial tree, observed in two orthogonal
angiograms [11,24]. For CAD location, left main steno-
sis was regarded as disease of the LAD and the LCX. A
“diffuse disease” was defined by the presence of signifi-
cant stenosis in ≥ 2 coronary vessels with stenosis in ≥ 2
segments of each vessel. The results of coronary an-
giography were compared to those of dobutamine stress
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M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 5
Figure 6. Measurement of peak velocity of A wave at the
basal posterior septal wall at rest (measured 9 cm/s) in one
patient of group II.
with standard wall motion analysis and DSE with DTI.
According to the results of the coronary angiography,
the patients were divided into two groups: group (I); DM
with CAD comprised 27 patients with significant (>50%)
coronary stenosis and group (II); DM without CAD
comprised 19 patients with normal findings or non-sig-
nificant lesions in coronary arteries.
4. STATISTICAL ANALYSIS
Data were analyzed by SPSS statistical package version
16.0 (SPSS INC, Chicago, IL, USA). Quantitative data
expressed as mean and standard deviation (SD). Student-
t test used for comparison of the means of two groups of
quantitative variables. Qualitative data expressed as
number and percentage and analyzed by Chi-square (X2)
or Fisher exact test when appropriate.
Diagnostic performance of DSE tested by measuring
sensitivity, specificity, positive predicative value (PPV),
negative predicative value (NPV) and accuracy.
The diagnostic performance of global S, Delta (∆) S,
global E, Delta (∆) E or the ability to discriminate dis-
eased cases from normal cases is evaluated using Re-
ceiver Operating Characteristic (ROC) curve analysis to
determine the appropriate cut-off points.
Multivariate logistic regression was used to assess in-
dependent predicators of positive coronary angiography
(ischemia) among patients using clinical, laboratory and
echocardiographic variables. Level of significance was
set as p value < 0.05 [25].
5. RESULTS
From 56 diabetic patients recruited for the study, 46 pa-
(a)
(b)
(c)
Figure 7. Example of biphasic response of S wave velocity
indicating ischemia in one patient of group (I). The peak
velocity of S wave measured at mid posterior septal wall at
rest, panel (a) (7 cm/s), low dose, panel (b) (15 cm/s) and
peak stress, panel (c) (12 cm/s).
tients were included for the study analysis (10 patients
did not undergo coronary angiography). According to
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M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 6
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coronary angiographic results diabetic patients were
classified into 2 groups; group I diabetic patients with
positive coronary angiography included 27 patients (16
males & 11 females with mean age 64.52  6.6 years)
and group II diabetic patients with negative coronary
angiography included 19 patients (11 males & 8 females
with mean age 59.11  6.5 years).
By comparing both groups, no significant difference
was found between group I and group II as regard the
age, gender difference, diabetes duration, prevalence of
hypertension, systolic or diastolic blood pressure levels,
resting heart rate, total cholesterol or triglycerides levels
(P > 0.05). The percentage of smokers was significantly
higher in group I than group II (P < 0.05) (Table 1).
Concerning conventional echocardiographic parame-
ters, no significant difference was found between the
group I and group II except in WMSI with stress which
was significantly higher in group I in comparison to
group II (P < 0.05) (Table 1).
There was a significant difference between group I
and group II as regard response of systolic (S) velocity
and early diastolic (E) velocity measured during dobu-
tamine DTI from rest to peak stress (P < 0.001 for each).
On the contrary there was no significant difference be-
tween the 2 groups regarding the response of late dia-
stolic (A) velocity (P > 0.05) (Table 2).
Comparative analysis of dobutamine stress DTI pa-
rameters at different LV walls demonstrated that, iso-
volumic contraction time (IVCT), contraction time (CT),
time to peak S and time to peak E were significantly
prolonged in all walls at peak stress in group I compared
to group II, while S and E velocities were significantly
lower in group I when compared to the values of the
corresponding walls in group II. The isovolumic relaxa-
tion time measured at peak stress was found to be more
prolonged in all LV walls in group I compared to group
II, however the difference did not reach the statistically
significant level. As regard the late diastolic velocity (A),
no significant difference was detected between the two
groups at peak stress (Table 3).
Changes in global myocardial systolic and early dia-
stolic velocities measured from rest to peak stress and (∆)
change in these velocities (measured as the difference
between the peak stress-rest values) were all signifi-
cantly lower in group (I) when compared group (II) (Ta-
ble 4).
Using ROC curve, the cutoff points with best validity
criteria (sensitivity and specificity) were determined for
each DTI parameter for prediction of obstructive CAD in
diabetic patients. The cutoff points for global S and
Table 1. Baseline demographic, clinical, laboratory & echocardiographic data of the studied groups.
Group I Positive CA (n = 27)Group II Negative CA (n = 19)T test P value
Age (Mean  SD) 64.52  6.6 59.11  6.5 1.29 >0.05
Gender
Male
Female
16 (59.3%)
11 (40.7%)
11 (57.9%)
8 (42.11%)
X2 = 2.24 >0.05
BMI (Kg/m2) 30.24  5.5 31.5  5.8 0.71 >0.05
Hypertension (%) 19 (70.4%) 15 (78.9) X2 = 0.42 >0.05
DM duration (years) 10.82  5.82 9.28  5.14 2.11 >0.05
Smoking (%) 11 (40.7%) 4 (21.1%) X2 = 1.96 <0.05
SBP (mmHg) 135.19  14.24 135.26  15.76 0.01 >0.05
DBP (mmHg) 87.04  9.12 84.74  7.72 0.89 >0.05
HR (b/min) 75.70  7.28 79.84  7.41 1.88 >0.05
Total cholesterol(mg/dL) 232.41  40.36 224.32  46.20 1.48 >0.05
Triglycerides (mg/dL) 160.93  37.30 155.53  33.19 0.50 >.0.05
IVS (mm) 10.41 ± 1.9 11.21 ± 2.3 1.28 >0.05
LVEDD(mm) 48.26 ± 4.9 48.21 ± 3.9 0.03 >0.05
LVESD(mm) 10.74 ± 3.8 11.89 ± 5.2 0.86 >0.05
LVPW(mm) 29.78 ± 6.0 28.21 ± 5.6 0.89 >0.05
FS% 35.59 ± 4.3 37.05 ± 5.8 0.98 >0.05
EF% 65.93 ± 5.5 67.68 ± 5.8 1.04 >0.05
WMA (%) 2 (7.4%) 1 (5.3%) Fisher exact >0.05
WMSI At rest
With stress
1.05 ± 0.18
1.52 ± 0.49
1.05 ± 0.23
1.18 ± 0.38
0.01
2.59
>0.05
<0.05
BMI, body mass index; DM, diabetes mellitus; SBP, systolic blood pressure; DBP, diastolic blood pressure; HR, heart rate; IVS, Interventricular septum;
LVEDD, left ventricular end diastolic diameter; LVESD, left ventricular end systolic diameter; LVPW, left ventricular posterior wall; FS, fractional shortening;
EF%, ejection fraction; WMA, wall motion abnormality; WMSI, wall motion score index.

M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 7
Table 2. Myocardial velocities response to dobutamine stress in studied groups.
Group I Positive CA (n = 27) Group II Negative CA (n = 19)
Peak systolic velocity (S) No % No % X2 P
Decreased 10 37.04 0 0.0
Biphasic 10 37.04 3 15.8
Increased 7 25.9 16 84.2
9.05 <0.001
Early diastolic velocity (E)
Decreased 18 66.67 4 21.1
Biphasic 2 7.41 0 0.0
Increased 7 25.9 15 78.9
10.98 <0.001
Atrial diastolic velocity (A)
Decreased 3 11.1 2 10.5
No change 1 3.7 0 0.0
Increased 23 85.2 17 89.5
0.73 >0.05
Table 3. Comparison of myocardial velocities and time intervals between diabetic groups at peak stress.
Items IVCT (ms)S (cm/s) CT (ms) Time to peak E
(ms)
Time to peak S
(ms) E (cm/s) A (cm/s) IVRT (ms)
Group I 57.48 ± 20.99 10.94 ± 4.247 206.00 ± 47.86440.93 ± 75.3499.00 ± 31.3110.37 ± 2.02 14.09 ± 2.41 107.56 ± 35.9
Group II 47.37 ± 9.54 13.31 ± 3.587 180.21 ± 34.21385.74 ± 40.7981.89 ± 19.1513.68 ± 3.01 14.684 ± 2.21 91.58 ± 34.04
Posterior
Septal wall
Dobutamine
DTI at peak
stress P <0.05 <0.05 <0.05 <0.01 <0.05 <0.05 >0.05 >0.05
Group I 62.96 ± 23.28 10.75 ± 4.41 210.33 ± 48.65430.63 ± 79.37118.93 ± 45.1311.85 ± 2.20 13.89 ± 2.57 90.59 ± 27.39
Group II 44.63 ± 7.45 14.97 ± 2.42 172.53 ± 28.28371.95 ± 41.0690.32 ± 21.7114.05 ± 2.70 15.34 ± 2.08 80.53 ± 21.34
Lateral wall
Dobutamine
DTI at peak
stress P <0.001 <0.001 <0.01 <0.01 <0.01 <0.01 >0.05 >0.05
Group I 66.67 ± 23.53 10.85 ± 4.276 209.85 ± 46.36440.96 ± 79.99114.37 ± 38.8410.24 ± 2.39 13.91 ± 2.54 91.85 ± 25.79
Group II 43.58 ± 9.03 14.05 ± 3.55 178.82 ± 32.30376.89 ± 55.3486.74 ± 21.3713.29 ± 2.53 15.684 ± 2.78 84.00 ± 26.73
Anterior wall
Dobutamine
DTI at peak
stress P <0.001 <0.05 <0.05 <0.01 <0.01 <0.01 >0.05 >0.05
Group I 59.70 ± 20.93 12.05 ± 3.91 206.59 ± 43.87428.07 ± 73.45105.00 ± 30.6411.481 ± 2.37 15.333 ± 2.56 95.41 ± 37.18
Group II 40.63 ± 7.45 15.73 ± 2.06 167.37 ± 29.46369.21 ± 48.0783.37 ± 26.6713.9 ± 2.16 15.684 ± 1.96 82.53 ± 29.00
Inferior wall
Dobutamine
DTI at peak
stress P <0.001 <0.01 <0.001 <0.01 <0.05 <0.05 >0.05 >0.05
Group I 58.94 ± 21.08 11.90 ± 4.48 206.44 ± 54.46429.56 ± 78.71107.56 ± 32.9711.44 ± 2.44 16.074 ±
10.05 98.52 ± 33.41
Group II 39.16 ± 7.00 15.36 ± 2.54 169.47 ± 24.52367.42 ± 42.7182.95 ± 25.1813.98 ± 2.07 15.789 ± 2.11 81.89 ± 28.29
Anterior septal
wall
Dobutamine
DTI at peak
stress P <0.001 <0.01 <0.01 <0.001 <0.05 <0.05 >0.05 >0.05
IVCT, isovolumic contraction time; S, systolic velocity; CT, contraction time; E, early diastolic velocity; A, late diastolic velocity; IVRT, isovolumic relaxation
time; DTI, Doppler tissue imaging.
global E were 11.3 cm/s and 11.2 cm/s with 75.7%, 73.4% sensitivity and 94.7%, 89.47% specificity respect-
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M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 8
Table 4. Changes of global Myocardial systolic velocity (S),
early diastolic velocity (E) and ∆ change from rest to stress
in studied patients.
Group I (n = 27) Group II (n = 19) T testP value
Global S (cm/s) 11.30 ± 3.66 14.48 ± 2.16 3.69 <0.01
Global E (cm/s) 11.27 ± 1.63 13.12 ± 2.10 3.16 <0.01
∆S 0.50 ± 0.51 0.93 ± 0.30 3.56 <0.01
∆E 0.21 ± 0.16 0.42 ± 0.16 4.40 <0.001
S, systolic velocity; E, early diastolic velocity; ∆, Delta.
tively. For ∆S and ∆E the cutoff points were 0.56, 0.26
with 78.8 %, 89.3% sensitivity and 94.7%, 90.7% speci-
ficity respectively (Table 5).
Comparing the validity criteria of WMSI and DTI
dobutamine stress in detection of CAD in diabetic pa-
tients, the latter was found to be more sensitive (74.1%
vs. 59.3%) and more specific (90% vs. 79%).
Moreover, dobutamine stress DTI had higher positive
predictive value (91% vs.80 %), higher negative predic-
tive value (71% vs. 57.7%) and better accuracy (80.4 %
vs. 67.4 %) in detection of CAD in the studied patients
(Table 6).
In multivariate logistic regression analysis of all clini-
cal, laboratory and echocardiographic variables for pre-
diction of obstructive CAD in patients with DM, only
∆E ≤ 0.26 was the most significant powerful independ-
ent predictor followed by ∆S ≤ 0.56, (P < 0.01, < 0.05
respectively) (Table 7).
In analyses testing the reproducibility, the interob
Table 5. Cutoff points of Doppler tissue parameters in di-
agnosis of CAD in diabetic patients.
Sens. (95% C.I.) Spec. (95% C.I.)
Global S ≤ 11.3 (cm/s) 75.7(55.4 - 94.3) 94.7 (73.9 - 99.1)
Global E ≤ 11.2 (cm/s) 73.4 (54.6 - 93.1) 89.47 (66.8 - 98.4)
∆S ≤ 0.56 78.8 (54.3 - 95.7) 94.7 (73.9 - 99.1)
∆E ≤ 0.26 89.3 (68.7 - 105.9) 90.7 (71.4 - 101.4)
S, systolic velocity; E, early diastolic velocity; ∆, Delta; CI, confidence
interval.
server and intraobserver variability were compared in 40
consecutive measurements and were 2.1% and 3.3%,
respectively, for the measurement of ∆S and for meas-
urement of ∆E were 3.9% and 3.7%, respectively. Ac-
cordingly, each parameter has good limits of interob-
server and intraobserver variability accounting for good
reproducibility. Validation had been confirmed in previ-
ous studies [11,26].
6. DISCUSSION
Coronary artery disease (CAD) is the leading cause of
death in patients with DM. Patients often present with
advanced and asymptomatic disease [27]. Although mor-
tality from cardiovascular disease has declined in the
general population, the decline is much less in diabetic
men and in diabetic women there is actually an increase
in cardiovascular mortality [28]. These data emphasize
the importance of accurate risk stratification of diabetic
patients to identify diabetic patients with subclinical
disease at high risk of future cardiac events.
In the present study, diabetic patients were investi-
gated for CAD using dobutamine stress DTI. To the best
of our knowledge this is the first study to assess the di-
agnostic accuracy of dobutamine stress DTI in diabetic
patients with suspected CAD.
In our study, the validity of DTI parameters during
peak stress was higher than WMSI analysis (sensitivity
74.1% vs. 59.3% and specificity 90% vs. 79%, P < 0.01
for each). Moreover, dobutamine stress DTI had higher
positive predictive value (91% vs. 80%), higher negative
predictive value (71% vs. 57.7%) and better accuracy
(80.4% vs. 67.4%) in detection of CAD in diabetic pa-
tients.
Doppler Tissue Imaging (DTI) provides a quantitative
analysis of regional myocardial function through its ex-
cellent ability to quantify regional myocardial contrac-
tion and relaxation velocities and has good temporal
resolution allowing accurate estimation of the very short
time intervals during the cardiac cycle [29]. In our study,
addition of DTI to DSE has the advantage of quantitative
analysis that enables to detect the appropriate cut off
values during peak stress that differentiate between pa-
tients with obstructive (group I) and normal or non ob-
structive(group II) CAD (Global S ≤ 11.3 cm/s, Global E
≤ 11.2cm/s, ∆S ≤ 0.56 and ∆E ≤ 0.26). Furthermore, in
multivariate logistic regression analysis of predictors of
obstructive CAD in patients with DM, only ∆E ≤ 0.26
was the most significant powerful independent predictor
followed by ∆S ≤ 0.56. (P < 0.01, < 0.05 respectively).
6.1. Conventional DSE and WMSI in Diagnosis
of CAD among Diabetics
T
he prognostic value of DSE in diabetic patients with
C opyright © 2011 SciRes. WJCD

M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 9
WJCD
Table 6. Criteria of the validity of DSE with Doppler tissue imaging versus standard wall motion analysis in diagnosis of CAD
in Diabetes mellitus.
Coronary angiography
Doppler tissue imaging
Group I (n = 27) Group II (n = 19)
Sensitivity% Specificity% PPV% NPV% Accuracy%
Positive 20 2
Negative 7 17
74.1 90 91 71 80.4
WMSI
Positive 16 4
Negative 11 15
59.3 79 80 57.7 67.4
PPV, positive predictive value; NPV, negative predictive value; WMSI, wall motion score index.
Table 7. Multivariate logistic regression analysis of predic-
tors of obstructive CAD in diabetes mellitus.
95.0% C.I. for OR
Variables B S.E. Wald X2P OR Lower Upper
Age
Male sex
Hypertension
Smoking
DM (year)
TC > 200 mg/dl
WMSI > 1
∆S ≤ 0.56
∆E ≤ 0.26
Constant
0.22
1.29
0.29
–0.52
0.13
1.608
–0.39
3.58
4.15
–16.56
0.12
1.75
1.33
1.85
0.11
1.23
1.32
1.68
1.52
8.56
3.11
0.54
0.04
0.07
1.53
1.69
0.08
4.55
7.39
3.84
>0.05
>0.05
>0.05
>0.05
>0.05
>0.05
>0.05
<0.05
<0.01
<0.05
1.25
3.65
1.34
0.59
1.14
4.99
0.67
36.16
63.77
0.97
0.11
0.09
0.01
0.92
0.44
0.05
1.34
3.19
1.61
113.36
18.46
22.43
1.42
56.20
9.00
532.01
721.47
DM, diabetes mellitus; TC, total cholesterol; WMSI, wall motion score
index; S, systolic velocity; E, early diastolic velocity; ∆, delta; CI, confi-
dence interval; OR, odds ratio; SE, standard error.
known or suspected CAD has been previously demon-
strated [30,31]. However, given their high-risk status for
the development of cardiovascular diseases, diabetic
patients present with a substantially increased pretest
likelihood of adverse outcome. Thus, to verify whether
the test conveys similar prognostic information in dia-
betic and nondiabetic patients is of primary clinical rele-
vance [32].
In our study, despite WMSI measured during peak
dose DSE was higher in diabetic patients with obstruc-
tive CAD, it has lower sensitivity, specificity and predic-
tive power compared to dobutamine stress DTI.
In agreement with our findings, Masoor et al. [28]
postulated that, diabetic patients with negative DSE were
twice as likely to have cardiac events and 4 times more
likely to have nonfatal infarctions compared with non-
diabetic subjects. They suggested that, the absence of
ischemia is a less reliable predictor of event-free survival
in diabetic patients. The cause of the reduced predictive
value of a negative DSE in diabetic patients is unknown.
One possibility is that, diabetic patients are more likely
to have diffuse distal vessel disease. In this setting, re-
gional wall motion abnormalities may be more difficult
to detect with stress because of global rather than re-
gional reduction of perfusion reserve [28].
Furthermore, Anne et al. [33] reported that, diabetic
patients with normal DSE appear to have a greater risk
for subsequent cardiovascular events than nondiabetic
patients, particularly beyond 2 years. Similarly, Kama-
lesh et al. [34] found increased incidence of cardiac
events despite negative DSE in DM cohort (6% vs. 2.9%
yearly).
6.2. Additional role of DTI to DSE in Diagnosis
of CAD among Diabetics
In our study, application of DTI during DSE makes the
procedure easy, quantitative, with higher sensitivity,
specificity, accuracy and reproducibility than standard
WMSI analysis. This superiority helps to diagnose ob-
structive CAD in diabetics more accurately without ad-
ditional risk or cost.
In agreement with our findings, Pellikka [26] demon-
strated that, DTI is promising technique to reduce in-
traobserver and interobserver variability for interpreta-
tion of stress echocardiograms. Moreover, this technique
offers the potential to quantify the extent of ischemia. In
addition to assessment of indices of contractile function,
distinct patterns of diastolic function can be depicted

M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 10
during ischemia with an accuracy which probably cannot
be appreciated by the naked eye [26].
Fraser et al. [35] in the MYDISE (Myocardial Dop-
pler in Stress Echocardiography) study, used myocardial
Doppler velocities during DSE for diagnosis of CAD
comparing its results with coronary angiography. They
demonstrated that, CAD can be diagnosed accurately
and objectively, from off-line measurements of myocar-
dial velocities recorded non-invasively by DTI during
DSE. Furthermore the accuracy of DTI in diagnosis of
CAD is much more than conventional analysis of wall
motion abnormalities. [35]
Wall motion analysis of the inferobasal segment of the
left ventricle is a common problem during DSE and may
be a cause for unnecessary coronary angiography. Even
resting imaging of the inferobasal segment often demon-
strates abnormal motion as a result of close proximity of
the mitral valve and atrioventricular groove. During DSE,
this impairment may become more prominent and can be
interpreted incorrectly as ischemia [36]. Leitman et al.
[36] investigated changes of the inferobasal segment
during DSE with DTI in 50 patients with more than 70%
stenosis of RCA and compared the results with coronary
angiography. They reported that, conventional stress
echocardiography was falsely positive in 10.3% and
falsely negative in 27.3%. When DTI was combined
with conventional stress echocardiography, it enhances
the diagnosis of inferior ischemia during DSE and it
improves sensitivity and specificity up to 81.8% and
97.4% respectively and accordingly can be added to
conventional imaging protocol in those patients [36].
6.3. Changes in Myocardial Velocities and Time
Intervals during Dobutamine Stress-DTI
In our study, comparing measurements of dobutamine
stress DTI parameters at different walls in the two stud-
ied groups with results of coronary angiography revealed
that, peak systolic velocity (S) and early diastolic veloc-
ity (E) become significantly lower in all walls at peak
stress in group I compared to group II. Regarding late
diastolic velocity (A), there was no significant difference
between the two groups.
These results are in agreement with data reported by
Von Bibra et al. [37] using pulsed Doppler myocardial
mapping of 12 left ventricular segments during DSE,
and reported, a stress-induced reduction of peak length-
ening of early diastolic velocity which was accurate and
superior to peak systolic tissue Doppler recordings for
detecting coronary artery stenosis [37].
Several investigators had shown Doppler myocardial
velocity imaging to be a sensitive alternative to the con-
ventional echocardiographic and scintigraphic imaging
techniques to evaluate stress tests. The peak velocity
response for both systole and diastole has been shown to
be significantly lower during dobutamine stress in mal-
perfused myocardial regions compared to normal [37,
38].
Jelena et al. [39] examined 60 patients without previ-
ous myocardial infarction who underwent DSE. Peak
systolic, early and late diastolic velocities were meas-
ured at rest and during stress and they found that, there
was no significant difference between ischemic and
non-ischemic groups in systolic and both diastolic ve-
locities at rest. However, pronounced differences devel-
oped during stress in all segments, peak systolic velocity
in the ischemic group during stress was lower than in the
non-ischemic group (P < 0.05). Furthermore clear dif-
ference between the two groups was found in the mag-
nitud e of early diastolic filling wave (E') during stress (P
< 0.04) [39].
Concordant to our findings, Ofelia et al. [40] studied
63 patients for CAD by measuring regional diastolic
velocities using DTI during DSE and comparing it to
results of coronary angiography and they concluded that,
E velocity in patients with CAD showed a lower value at
peak stress compared with control (P < 0.001). On the
other hand, the A velocity in both groups did not show
any significant difference at baseline and peak stress
[40]. Similraly, Yamada et al. [38] reported blunting of
the E velocity from baseline to peak stress in ischemic
compared with nonischemic segments.
In our study, the isovolumic contraction time, contrac-
tion time, time to peak S and time to peak E showed
significant prolongation during peak stress in group I
compared with group II. These parameters represent
more deterioration of myocardial function (both systolic
and diastolic) during peak stress. Although the iso-
volumic relaxation time measured at peak stress was
found to be more prolonged in group I compared to
group II, the difference did not reach the statistically
significant level.
Similar to our data, Jun et al. [41] reported prolonga-
tion of isometric contraction time and ejection time in
ischemic patients using pulsed-wave DTI with DSE.
Kugacka et al. [42] reported that, the value of iso-
volumic relaxtion time corrected for heart rate (IVRTc) =
80 ms at peak dobutamine infusion is able to discrimi-
nate patients with residual ischemia from those without
with a sensitivity of 80% and a specificity of 70%.
However, these time intervals are not so reliable due
to different variability of its measurement especially at a
higher heart rate when both systolic and diastolic time
intervals are getting shorter.
Study limitations: the limited number of patients
could limit the strength of the findings obtained from the
study; future large scale studies are recommended for
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M. F. Elnoamany et al. / World Journal of Cardiovascular Diseases 1 (2011) 1-12 11
more validation of the results. The difficulty of quanti-
fying the apical segments using myocardial Doppler
velocities because of the relatively immobile nature of
the apex, and therefore an inherent limitation of the as-
sessment of base-apex axis function. However, despite
the inability of the test to identify apical wall motion
abnormalities, this did not emerge as a major impedi-
ment to overall sensitivity in this study. When using the
pulsed wave-DTI technique, the procedure is relatively
time consuming because of the large number of meas-
urements needed to be recorded from the standard myo-
cardial segments. Doppler tissue imaging measurements
are affected by cardiac translational movements, tether-
ing effect and angulations however these could be mini-
mized by using more relatively recent DTI techniques
and choosing myocardial regions of interest within 15 -
20 degrees of the axis of Doppler interrogation.
7. CONCLUSIONS
Doppler tissue imaging is promising technique allowing
accurate quantification of ischemia induced regional
diastolic and systolic dysfunction and when used during
dobutamine stress echocardiography, it adds new dimen-
sion in diagnosis of myocardial ischemia in diabetic pa-
tients. It is more sensitive, specific, accurate and repro-
ducible than standard wall motion analysis for recogni-
tion of significant CAD in such category of patients.
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