CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 1, January/February 2014
AFRICA
11
Echocardiography
Two-dimensional, M-mode, pulsed and colour-flow Doppler
echocardiographic examinations were performed on all patients
by one cardiologist with a Vivid 7 Pro echocardiography system
(GE, Horten, Norway, 2–4 MHz phased-array transducer).
During echocardiography, a single-lead electrocardiogram was
recorded simultaneously. Data were recorded from the average
of three cardiac cycles. M-mode and Doppler measurements
were performed, adhering to the American Society of
Echocardiography guidelines.
24
A 10-MHz linear transducer was
used for the brachial artery examination.
Endothelial function of all subjects was assessed by a
single ultrasonographer blinded to the coronary flow groups.
Measurements were performed in a temperature-controlled
room (22°C) in the morning and after eight to 12 hours of a
fasting period. Ingestion of substances that might have affected
measurements, such as caffeine, high-fat foods and vitamin C
was not allowed for 12 hours before the study. Any vasoactive
medication was discontinued at least five serum half-lives before
the brachial studies.
The right brachial artery was imaged above the antecubital
fossa in the longitudinal plane. Upon acquiring an appropriate
image, the surface of the skin was marked. The arm and
the ultrasound probe were kept at the same position by the
ultrasonographer during the entire study. The diameter of
the brachial artery was measured from longitudinal images
in which the lumen–intima interface was visualised on the
anterior and posterior walls at end-diastole (onset of the R wave
on the electrocardiogram), and the mean of the three highest
measurements from five consecutive cardiac cycles was taken.
After the basal lumen diameter and blood flow were noted at
rest, a sphygmomanometer cuff was placed on the forearm and
the cuff was inflated to 250 mmHg for arterial occlusion. After
five minutes, the cuff was deflated and the lumen diameter was
recorded one minute later, to assess endothelium-dependent
flow-mediated dilatation (FMD) This was defined as both the
maximum absolute change and maximum percentage change in
vessel diameter during reactive hyperaemia:
FMD
=
(diameter of reactive hyperaemia – diameter of baseline)
_____________________________________
diameter of baseline
×
100
Statistical analysis
All continuous variables were expressed as mean
±
standard
deviation and median (interquartile range). All measurements
were evaluated with the Kolmogorov–Smirnov test, and the
Shapiro–Wilk test was used to determine normal distribution.
Comparisons of parametric and non-parametric values between
the two groups were performed by means of Mann–Whitney
U-
or student
t
-tests. Categorical variables (risk factors and
polymorphisms) were analysed using the chi-square test.
Spearman’s correlation test was used for correlation between
TIMI frame count and endothelial function.
All statistical studies were carried out with the program SPPS
(version 15.0, SPSS, Chicago, Illinois, USA);
p
-values < 0.05
were accepted as statistically significant. Risk estimations for
the association of SCF with the polymorphisms were calculated
using odds ratios (OR) and 95% confidence intervals (CI) by
comparing the genotypic combinations.
Results
Clinical and laboratory findings of the subjects are shown in
Table 1. Mean age and systolic blood pressure were similar
between the two groups and all subjects were in sinus rhythm
(55.8
±
10.3 vs 53.9
±
11.8 years,
p
=
0.456 and 126.4
±
127.4
vs 127.4
±
127.4 mmHg,
p
=
0.712, respectively). The TIMI
frame counts for each epicardial artery were higher in patients
with CSF than control subjects. Mean TIMI frame count was
also significantly higher in CSF patients (24.2
±
4.0 vs. 13.1
±
2.5 fpm,
p
=
0.001).
Echocardiographic and FMD measurements of the subjects
are summarised in Table 2. Left ventricular ejection fraction
(LVEF) was significantly lower in patients with CSF [59 (27–76)
vs 64% (28–76), I
=
0.019). FMD was significantly lower in
CSF patients than controls (4.9
±
6.6 vs 7.9
±
5.6%,
p
=
0.029).
TIMI frame count and FMD were negatively correlated in the
correlation analysis (
r
=
–0.269,
p
=
0.015).
Genotype properties and allele frequencies were similar in
the two groups. The
PAI-1
5G allele was found to be marginally
associated with the possibility of CSF, however it was not
statistically significant (
p
=
0.06, OR: 2.82, 95% CI: 0.94–8.45)
(Table 3).
Discussion
This study showed that
ACE
,
PAI
and
eNOS
gene polymorphisms
were not related to CSF in our population. Brachial artery FMD
was impaired in patients with CSF, and the TIMI frame count
was negatively correlated with FMD.
ACE plays an important role in vascular wall haemostasis
and endothelial function. The
ACE
D/D allele genotype was
Table 1. Clinical characteristics and laboratory parameters
of csf patients and healthy controls
Charactheristics
CSF
(
n
=
33)
Controls
(
n
=
48)
p
-value
Age (years, mean
±
SD)
55.8
±
10.3
53.9
±
11.8 0.456
Heart rate (bpm)
69
±
11
69
±
8
0.989
Fasting glucose (mg/dl)
99 (79–281)
91 (72–188)
0.048
LDL cholesterol (mg/dl)
113
±
35
120
±
29
0.350
HDL cholesterol (mg/dl)
44
±
13
46
±
10
0.447
BSA (m
2
)
1.87 (1.61–2.19) 1.79 (1.47–2.28) 0.231
Male,
n
(%)
20 (58.8)
14 (29.8)
0.009
Hypertension,
n
(%)
17 (50)
25 (53.2)
0.777
Diabetes mellitus,
n
(%)
9 (26.5)
7 (14.9)
0.197
Cigarette smoking,
n
(%)
9 (26.5)
12 (25.5)
0.924
Medications,
n
(%)
ACE inhibitor
12 (35.3)
12 (25.5)
0.656
Beta-blocker
6 (17.6)
8 (17)
0.941
Statins
11 (32.4)
4 (8.5)
0.006
Acetyl salicylic acid
21 (61.8)
12 (25.5)
0.001
TIMI frame count
RCA
28 (16–38)
14 (4–22)
0.001
LCx
22 (11–40)
13 (8–21)
0.001
LAD
39.5 (22-56)
18 (10-34)
0.001
Mean TIMI frame count
24.2
±
4
13.1
±
2.5
0.001
CSF, coronary slow flow; LDL, low-density lipoprotein; HDL, high-density
lipoprotein; BSA, body surface area; TIMI, thrombolysis in myocardial infarc-
tion; RCA, right coronary artery; LCx, left circumflex artery; LAD, left ante-
rior descending artery; bpm, beats per minute.
