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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 1, January/February 2017
AFRICA
5
VividiVingmed Ultrasound; Horten, Norway). Comprehensive
two-dimensional (2D) and Doppler echocardiographic
evaluation were performed with the patient in the left lateral
decubitus position before coronary angiography.
Transthoracic echocardiography was performed within
the first 24 hours of initial diagnosis. While performing
transthoracic echocardiography all patients were monitored by
ECG, and echocardiographic parameters were measured with
synchronisation by ECG.
In the apical four-chamber view, mitral inflow velocities
were measured with the Doppler sample placed at the tip of the
valve leaflets, at the left ventricular outflow tract, and below the
aortic valve plane. All measurements were averaged over three
consecutive cardiac cycles.
Isovolumic relaxation time (IVRT) was measured from
closure of the aortic valve to opening of the mitral valve.
Isovolumic contraction time (IVCT) was measured from closure
of the mitral valve to opening of the aortic valve. Ejection time
(ET) was measured from the opening to the closure of the aortic
valve on the left ventricular outflow velocity profile. MPI was
calculated as the sum of the IVRT and IVCT divided by the ET.
Peak velocities of early (E) and late (A) filling were determined
according to the mitral inflow velocity curve.
Angiographic examination
All patients underwent selective coronary angiography via the
Judkins technique (IntegrisAllura 9; Philips Medical Systems,
Eindhoven, the Netherlands). All angiograms were evaluated
by two experienced interventional cardiologists blinded to
the clinical baseline characteristics of the patients. In cases of
discrepancy, the opinion of a third interventional cardiologist
was obtained, and the final decision was made by consensus.
The severity of coronary artery lesions was scored using a
modified Gensini scoring system.
1
In brief, coronary circulation
was divided into eight proximal segments; the percentage by
which each lesion in the proximal coronary circulation narrowed
the artery was assessed according to the maximal narrowing of
the diameter of the artery in all projections.
The extent and severity of proximal coronary disease was
assessed by assigning points to each lesion as follows: less
than 50% stenosis of the luminal diameter, one point; 50 to
74% stenosis, two points; 75 to 99% stenosis, three points; and
total obstruction, four points. The points for each lesion in the
proximal coronary circulation were added, and a score for the
severity of coronary atherosclerosis was obtained.
According to the modified Gensini scoring system, the degree
of coronary stenosis was classified as follows: mild lesions, one
to six points; moderate lesions, seven to 13 points; and severe
lesions,
>
13 points. Patients were divided into tertiles according
to the GS: low GS
<
19; mid GS
>
19 and
≤
96; and high GS
>
96 points.
Statistical analysis
Statistical analysis was performed using SPSS (Statistical
Package for Social Sciences) for Windows version 12 (Chicago,
Illinois). Continuous variables are expressed as mean
±
SD, and
categorical variables are expressed as numbers and percentages.
Continuous variables were compared between groups using
one-way analysis of variance for normally distributed data, and
the chi-squared test was used for nominal variables. Correlations
between variables were calculated using the Pearson correlation
coefficient. Multiple linear regression analysis was performed to
identify the factors related to the GS. A
p
-value of
<
0.05 was
considered significant.
Results
Of the 90 patients included in this study, 24 were assigned to the
low-GS group (26.7%), 38 to the mid-GS group (42.2%) and 28
to the high-GS group (31.1%). The demographic and clinical
characteristics of the 90 patients with NSTEMI according to the
GS are presented in Table 1.
The mean patient age was significantly higher in the high-
GS group than in the low- and mid-GS groups (
p
=
0.035).
Table 1. Baseline characteristics and laboratory findings
Variables
Group 1
(
n
=
24)
Group 2
(
n
=
38)
Group 3
(
n
=
28)
p-
value
Age (years)
49.4
±
11.1 54.7
±
10.3 56.7
±
9.3 0.035
Male,
n
(%)
18 (75)
29 (76.3)
26 (92.9)
0.15
Diabetes
mellitus,
n
(%)
6 (25)
13 (34.2)
7 (25)
0.63
Hypertension,
n
(%)
12 (50)
16 (42.1)
8 (8.6)
0.27
Hyperlipidaemia,
n
(%) 4 (16.7)
9 (23.7)
2 (7.1)
0.20
Current smokers,
n
(%) 17 (70.8)
26 (68.4)
21 (75)
0.84
Glucose (mg/dl)
(mmol/l)
128.6
±
66.2
(7.14
±
3.67)
136.0
±
59.7
(7.55
±
3.31)
132.0
±
54.0
(7.33
±
3.00)
0.91
LDL (mg/dl)
(mmol/l)
111.1
±
35.4
(2.88
±
0.92)
131.4
±
38.8
(3.40
±
1.00)
132.5
±
35.9
(3.43
±
0.93)
0.07
HDL (mg/dl)
(mmol/l)
41.1
±
16.7
(1.06
±
0.43)
36.7
±
9.0
(0.95
±
0.23)
39.4
±
8.5
(1.02
±
0.22)
0.34
eGFR (ml/min/1.73 m
2
) 96.8
±
25.5 96.5
±
19.5 92.1
±
21.1 0.66
Haemoglobin (g/dl)
14.2
±
1.0 13.6
±
1.7 13.9
±
1.5 0.31
Leukocytes (× 10
3
/ml) 8513
±
2506 8826
±
3527 8813
±
2288 0.91
Platelet count (× 10
3
/
ml)
248
±
68
253
±
81
233
±
62 0.55
LDL, low-density lipoprotein cholesterol; HDL, high-density lipoprotein
cholesterol; eGFR, estimated glomerular filtration rate.
Table 2. Echocardiographic findings in the three groups
Variables
Group 1
(
n
=
24)
Group 2
(
n
=
38)
Group 3
(
n
=
28)
p-
value
IVRT (ms)
88.9
±
18.9 101.7
±
29.1 113.1
±
29.9 0.008
IVCT (ms)
67.3
±
25.1 61.4
±
31.6 74.0
±
20.4 0.18
ET (ms)
283.0
±
24.1 273.9
±
31.5 241.0
±
21.4
<
0.001
MPI
0.50
±
0.11 0.60
±
0.21 0.72
±
0.12
<
0.001
E/A
1.0
±
0.29 0.97
±
0.46 0.91
±
0.39 0.31
E/e
′
5.8
±
1.5 6.1
±
2.1 6.1
±
1.9
0.87
EF (%)
58.2
±
3.9 56.4
±
5.3 53.8
±
6.2 0.01
Left atrium (cm)
3.30
±
0.4 3.39
±
0.4 3.50
±
0.4 0.25
LVEDD (cm)
4.76
±
0.3 4.74
±
0.4 4.84
±
0.3 0.61
RV (cm)
2.11
±
0.1 2.21
±
0.2 2.2
±
0.1
0.24
IVRT, isovolumic relaxation time; IVCT, isovolumic contraction time;
ET, ejection time; MPI, myocardial performance index; E/A, ratio of
peak velocities of early (E) and late (A) transmitral filling; E/e
′
, ratio
between early mitral inflow velocity and mitral annular early diastolic
velocity; EF, ejection fraction; LVEDD, left ventricular end-diastolic
diameter; RV, right ventricle.