18 / 68
CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 3, May/June 2015
116
AFRICA
under the same basal conditions. Reproducibility of atrial
electromechanical intervals obtained by TDI was assessed by
coefficient of variation (CV) between measurements. Intra- and
inter-observer coefficients of variation for echocardiographic
measurements were found to be
<
5% and non-significant.
Statistical analysis
All analyses were conducted using SPSS 15.0 (SPSS for Windows
15.0, Chicago, IL, USA). Continuous variables were expressed as
mean
±
standard deviation; categorical variables were defined as
percentages. Categorical data were compared with the chi-square
test. All numerical variables of the study groups presented a
normal distribution. Mean values of continuous variables were
therefore compared using analysis of variance (ANOVA), and
the
post hoc
Tukey test was used for comparison of groups.
Pearson’s correlation coefficients were used to assess the strength
of the relationship between continuous variables. A
p-
value
<
0.05 was considered significant. We performed the power
analysis using G*Power software version 3.1.5. The power of our
study was calculated to be 0.96.
Results
Basic clinical and laboratory values, and M-Mode and
two-dimensional echocardiographic measurements of the three
groups are listed in Table 1. Age, body mass index (BMI),
body surface area (BSA), systolic and diastolic blood pressure,
heart rate, LV end-diastolic diameter, interventricular septal
thickness, posterior wall thickness, LVEF, LA dimension, mitral
E velocity, mitral A velocity, E/A ratio, systolic pulmonary
artery pressure, and glucose, total cholesterol, triglyceride,
high-density lipoprotein (HDL) cholesterol and low-density
lipoprotein (LDL) cholesterol levels were similar between the
three groups (
p
>
0.05).
Left atrial mechanical function
The three groups were similar with regard to V
max
, V
min
and V
p
,
LAPEV, LATEV and LATEF (
p
=
0.322,
p
=
0.052,
p
=
0.087,
p
=
0.161,
p
=
0.976,
p
=
0.170, respectively). However, LAPEF was
significantly decreased and LAAEV was significantly increased
in the MP groups but not in the control group (
p
=
0.012 and
p
=
0.024, respectively), and LAAEF was significantly increased in
the cigarette smoking group and not in the control group (
p
=
0.003) (Table 2). The amount of MP used and cigarette smoking
(pack years) were weakly but significantly correlated with
LAAEV and LAAEF (
r
=
0.26,
p
=
0.009,
r
=
0.25,
p
=
0.013,
respectively) (Figs 1, 2).
Atrial electromechanical intervals
The atrial electromechanical coupling intervals measured from
different sites by TDI are shown in Table 3. PA lateral was
significantly higher in the MP users than in the controls. Also,
PA septum was statistically higher in cigarette smokers than
in the controls (
p
=
0.05 and
p
=
0.04, respectively). Intra- and
inter-atrial dyssynchrony was prolonged in both MP users and
cigarette smokers, but did not reach statistical significance. The
measurements of atrial electromechanical coupling intervals
were similar between MP users and cigarette smokers.
Discussion
The main finding of this study was that atrial electromechanical
coupling intervals were prolonged and left atrial mechanical
function was impaired in MP users and cigarette smokers
Table 1. Clinical characteristics, laboratory and
echocardiographic findings of the groups
Group I
controls
(
n
=
50)
Group II
smokers
(
n
=
50)
Group III
MP users
(
n
=
50)
p-
value
Age (years)
30.1
±
5.8
32.1
±
6
32.5
±
5.4 0.086
BMI (kg/m
2
)
26.3
±
3.7
25.9
±
3.5
26.9
±
3.9 0.462
BSA (m
2
)
1.96
±
0.14 1.95
±
0.15
1.92
±
0.16 0.388
Systolic BP (mmHg)
125.3
±
7.4 121.2
±
6.4
120.7
±
8.3 0.354
Diastolic BP (mmHg)
79.5
±
6.3
78.5
±
5.4
77.9
±
5.8 0.789
Heart rate (beats/min)
72.2
±
10.4 74.6
±
9.6
74.5
±
10.1 0.407
LVEDD (mm)
48.7
±
3.1
47.7
±
2.5
48.6
±
3.4 0.224
IVS
9.5
±
0.8
9.9
±
0.8
9.8
±
0.8 0.060
PW
8.7
±
0.7
8.9
±
0.6
9.1
±
0.7 0.087
LVEF (%)
69.8
±
2.6
68.4
±
3.2
68
±
3.4 0.314
LA dimension (mm)
33.2
±
3.1
32.9
±
2.7
34.3
±
3.1 0.071
Mitral E velocity (cm/s)
78.9
±
14.5 78.5
±
14.8 81.0
±
16.7 0.429
Mitral A velocity (cm/s)
57.3
±
12.9 56.7
±
10.9 56.4
±
10.3 0.922
E/A
1.44
±
0.38 1.41
±
0.28 1.46
±
0.32 0.398
sPAP (mmHg)
19.5
±
3.8
19.4
±
3.9 21.1
±
3.5 0.057
Glucose (mg/dl)
92.7
±
15.7 92.8
±
16.6 93.7
±
19.8 0.951
(mmol/l)
5.14
±
0.87 5.15
±
0.92 5.20
±
1.10
Total cholesterol (mg/dl) 184.5
±
41.4 180.5
±
46.8
174.0
±
35 0.444
(mmol/l)
4.78
±
1.07 4.67
±
1.21 4.51
±
0.91
Triglycerides (mg/dl)
151
±
88.2 173.7
±
112.4 186.6
±
130 0.275
(mmol/l)
1.71
±
1.00 1.96
±
1.27 2.11
±
1.47
HDL cholesterol (mg/dl)
42.8
±
8.7
39.2
±
9.1
39.8
±
8.8 0.105
(mmol/l)
1.11
±
0.23 1.02
±
0.24 1.03
±
0.23
LDL cholesterol (mg/dl) 110.2
±
34.6 106.9
±
36.5
100
±
27.7 0.297
(mmol/l)
2.85
±
0.90 2.77
±
0.95 2.59
±
0.72
Duration (pack years)
–
13.6
±
6.2 10.9
±
6.6 0.014*
BMI: body mass index, BSA: body surface area, BP: blood pressure, LV: left
ventricular, LVEDD: LV end-diastolic dimension, EF: ejection fraction, HDL:
high-density lipoprotein, LDL: low-density lipoprotein. All
p
-values
>
0.05
(ANOVA test).
*
p
-value for group II vs III.
Table 2. Left atrial volume measurements in smokers,
Maras powder users and control groups
Group I
controls
(
n
=
50)
Group II
smokers
(
n
=
50)
Group III
MP users
(
n
=
50)
p-
value
LA maximal volume (cm
3
/m
2
)
22.9
±
5.3 21.7
±
6.2 23.3
±
5.5 0.322
LA minimal volume (cm
3
/m
2
)
8.9
±
3.4 7.8
±
2.8 9.2
±
3.2 0.052
Volume at the onset of atrial
systole (cm
3
/m
2
)
14.7
±
4.7 14.5
±
4.8 16.4
±
4.3
0.087
LA passive emptying volume
(cm
3
/m
2
)
8.2
±
3.2 7.1
±
3.4 6.9
±
4.3 0.161
LA passive emptying fraction
(%)
0.36
±
0.11 0.32
±
0.12 0.28
±
0.14* 0.012
LA active emptying volume
(cm
3
/m
2
)
5.8
±
2.2 6.8
±
3.0 7.2
±
2.5
#
0.024
LA active emptying fraction (%) 0.39
±
0.10 0.46
±
0.10
§
0.43
±
0.11 0.003
LA total emptying
volume (cm
3
/m
2
)
14.0
±
3.3 13.9
±
4.6 14.1
±
4.2 0.976
LA total emptying fraction (%) 0.61
±
0.9 0.63
±
0.9 0.6
±
1.0 0.170
LA
=
left atrial. *
p
=
0.012 versus group I,
#
p
=
0.024 versus group I,
§
p
=
0.003
versus group I.