CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 9/10, October/November 2013
AFRICA
361
Coronary flow of both groups was documented by the
thrombolysis in myocardial infarction (TIMI) frame count
(TFC). The TIMI frame count method is a simple, reproducible
and quantitative index of coronary flow.
14
To obtain corrected
TFC for the left anterior descending (LAD) coronary artery,
the TIMI frame count was divided by 1.7. The mean TFC for
both groups was calculated by adding the TFC for the LAD, left
circumflex artery (LCx) and right coronary artery (RCA), and
then dividing the obtained value by three.
The TFC in the LAD and the LCx were assessed in a right
anterior oblique projection with caudal angulation (right anterior
oblique caudal view) and TFC in the RCA was assessed in a left
anterior oblique projection with cranial angulation (left anterior
oblique cranial view). All angiograms were filmed at 30 frames/
sec.
The TFC, a quantitative method of assessing coronary artery
flow, was evaluated on the three main coronary branches (LAD,
LCX and RCA), using the protocol described by Gibson
et
al
.
14
Patients with a corrected TFC greater than two standard
deviations from the normal published range (36.2
±
2.6 frames
for LAD, 22.2
±
1.4 for LCx and 20.4
±
3 for RCA) for the
particular vessel were considered as having slow coronary
flow, while those whose corrected TFC fell within two standard
deviations (cut-off value for the LAD
>
38 frames, for the LCx
>
28 frames, for the RCA
>
26 frames) of the published normal
range were labelled as having normal coronary flow.
14
Patients with a history of coronary artery disease, recent
myocardial infarction or an acute coronary syndrome (within
the last two months), coronary vasospasm, coronary ectasia,
left ventricular dysfunction, echocardiographically proven
left ventricular hypertrophy, uncontrolled hypertension, renal
dysfunction and connective tissue disease were excluded from
the study. Additionally, patients in both groups who had taken
any vitamin supplements within the previous eight weeks were
also excluded from the study. All subjects were informed about
the study and written consent was obtained from each.
Venous blood samples were collected into tubes containing
ethylenediamine tetraacetic acid (EDTA) after an eight-hour
fast and immediately stored on ice at 4°C. The plasma was then
separated from the cells by centrifugation at 3 000 rpm for 10
min and stored in several aliquots at –80°C until assayed.
Chemicals 2-thiobarbituric acid (TBA),
α
-tocoferol, and
2.4.6-tris (2-pyridyl)-s-triazine (TPTZ) were supplied by
Sigma-Aldrich (Steinheim, Germany). All other chemicals used
were obtained from Merck Darmstadt (Germany) and were of
analytical grade.
Plasma AOA was measured using a method defined as AOA
by Koracevic.
15
In this method, the hydroxyl radical, the most
potent biological radical, is produced in a standardised solution
of Fe-EDTA complex reacted with hydrogen peroxide by a
Fenton-type reaction. These reactive oxygen species degrade
benzoate, resulting in the release of thiobarbituric acid reactive
substances (TBARS).
16,17
Antioxidants from the added sample of
human fluid cause suppression of the production of TBARS. The
inhibition of colour development is defined as AOA.
Plasma vitamin E levels were measured using a
spectrophotometric method developed by Martinek.
18
The assay
results are expressed in μmol/l.
Statistical analysis
Parametric data were expressed as mean
±
standard deviation,
and categorical data as percentages. SPSS 16.0 (SPSS, Inc,
Chicago, Illinois) was used to perform statistical procedures.
Continuous variables were tested for normal distribution with
the Kolmogorov-Smirnov test. Parametric data were evaluated by
independent samples
t
-test, non-parametric data were evaluated
by Mann-Whitney
U
-test, and categorical data via chi-square
test. A
p
-value
≤
0.05 was accepted as significant.
Results
Clinical and laboratory characteristics of the subjects are
summarised in Table 1. Since mean TFC was higher in the study
group as it was an enrolment criterion, it is not discussed in detail
in the text. There were no significant differences in age, gender,
hypertension, lipid profile, CRP levels and diabetes, except
for smoking, between patients with SCF and controls. There
were no significant differences in AOA levels between the two
groups. However, plasma vitamin E levels in the SCF group were
significantly lower than in the NCF group (Table 2).
Among the non-smokers in both groups, vitamin E levels
were lower in those with SCF compared to the control group
(Table 3). However, among smokers in both groups, there was
no significant difference in vitamin E levels. There was no
significant difference in antioxidant activity between the groups
and within each group in smokers and non-smokers with normal
coronary flow and slow coronary flow (Table 4).
Discussion
Slow coronary flow phenomenon is an important clinical entity
because it may be the cause of angina at rest or during exercise,
TABLE 1. CLINICALAND LABORATORY CHARACTERISTICS
OF THE GROUPS
Variables
SCF group
(
n
=
40)
NCF group
(
n
=
40)
p
-value
Age (year)
51
±
12
48
±
10
NS*
Gender: female/male,
n
(%) 13 (32.5)/27 (67.5) 21 (52.5)/19 (47.5) NS**
Hypertension,
n
(%)
37 (92.5)
25 (62.5)
NS**
Diabetes mellitus,
n
(%)
3 (7.5)
2 (5)
NS**
Smoking,
n
(%)
27 (67.5)
12 (30)
0.001**
Triglycerides (mg/dl)
175
±
112
169
±
103
NS*
Total cholesterol (mg/dl)
187
±
28
179
±
29
NS*
HDL cholesterol (mg/dl)
38
±
9
42
±
15
NS*
LDL cholesterol (mg/dl)
107
±
24
104
±
25
NS*
CRP (mg/l)
6
±
3.1
5.9
±
2.6
NS*
Data expressed as mean
±
standard deviation.
*Independent samples t-test, **Chi-square test.
CRP, C-reactive protein; HDL, high-density lipoprotein; LDL, low-density lipo-
protein; NCF, normal coronary flow; NS, not significant; SCF, slow coronary
flow.
TABLE 2.ANTIOXIDANTACTIVITYANDVITAMIN E
LEVELS IN THE STUDY GROUPS
Variables
NCF group
(
n
=
40)
SCF group
(
n
=
40)
p
-value*
Vitamin E (
μ
mol/l)
109.5
±
31.6
85.6
±
28.5
0.001
Antioxidant activity (
μ
mol/l)
2.5
±
0.6
2.7
±
0.5
0.139
*Independent samples
t
-test.
NCF, normal coronary flow; SCF, slow coronary flow.
