CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 2, March/April 2010
94
AFRICA
Declaration of Helsinki, and all participants gave written consent
to participate.
Demographic parameters of the subjects were noted and
recorded. All subjects were clinically examined to evaluate
their body mass index (BMI) and cardiovascular status at rest.
Subjects were considered diabetic if they had fasting plasma
glucose (FBG) values
≥
126 mg/dl (7.0 mmol/l)
8
or if they used
hypoglycaemia medication. Fasting plasma glucose and two-
hour post-prandial plasma glucose (2HPP) values were obtained
24 hours prior to the procedures.
A resting 12-lead ECG was done to exclude patients with
baseline ST-segment abnormalities and bundle branch block.
Also excluded were patients with coexisting hypertension or
who were on antihypertensive(s), those with established chronic
renal failure or serum creatinine levels
>
1.5 mg% (132
µ
mol/l),
congestive heart failure, valvular heart disease and other diseases
known to influence LV function, such as thyroid disease and
severe obesity.
All the subjects underwent treadmill-symptom limited maxi-
mal exercise using the Bruce protocol.
9
The protocol continued
until one of several endpoints was reached. These included if
the patient achieved the age-predicted maximum heart rate;
requested that the exercise be terminated; developed severe chest
pain, fatigue, leg discomfort or dyspnea; developed frequent
premature ventricular beats; developed a systolic blood pressure
>
250 mmHg or a drop in the pre-test systolic blood pressure
>
10 mmHg; or developed any other problems necessitating termi-
nation of exercise.
The subjects also had transthoracic two-dimensional (2D) and
2D derived M-mode echocardiography performed, according to
standard procedure,
10
with simultaneous electrocardiographic
recordings while in the left lateral decubitus position, using
a standard ultrasound machine (Sonoline G60S Ultrasound
Imaging System) with 4.2-MHz transducer. Left ventricular end-
diastolic measurements were taken during at least three cycles
11
and included left ventricular internal diameter (LVIDD), poste-
rior wall thickness (PWT) and interventricular septal thickness
(IVST). Left ventricular mass was estimated from the American
Society of Echocardiography’s formula
11
:
Estimated LV mass index (g/m
2
)
=
0.80 [1.04 (LVIDD
+
PWT
+
IVST)
3
– (LVIDD)
3
]
+
0.6 g/BSA
Upper normal limits for LV mass index were 134 and 110 g/m
2
in men and women, respectively.
12
Relative wall thickness (2
×
posterior wall thickness/LV diastolic diameter) was calculated.
13
A partition value of 0.45 for relative wall thickness was used
for both men and women.
14
Patients with increased LV mass
index and increased relative wall thickness were considered to
have concentric hypertrophy, and those with increased LV mass
index and normal relative wall thickness were considered to have
eccentric hypertrophy. Those with normal LV mass index and
increased or normal relative wall thickness were considered to
have concentric remodelling or normal geometry, respectively.
Results
The diabetic subjects and controls had comparable ages and
BMIs (48.37
±
6.96 vs 48.35
±
6.13 years;
p
=
0.197 and 24.82
±
3.66 vs 24.38
±
1.94 kg/m
2
;
p
=
0.861, respectively). Diabetic
subjects had significantly higher FBG values than the controls
(8.94
±
2.13 vs 4.75
±
0.37 mmol/l;
p
≤
0.001).
As shown in Table 1, normotensive diabetic subjects had
higher exercise-induced haemodynamic parameters of peak
systolic (pSBP) and peak diastolic blood pressure (pDBP) but
lower peak heart rates (pHR). There was no statistically signifi-
cant difference in left ventricular mass index (LVMI). Nineteen
(29.7%) and 11 (17.2%) normotensive diabetic subjects had
normal left ventricular geometry and concentric left ventricular
remodelling, respectively. None of the normotensive diabetic
subjects had concentric or eccentric left ventricular hypertro-
phy. Thirty (46.8%) and four (6.3%) controls had normal left
ventricular geometry and concentric left ventricular remodelling,
respectively. None of the subjects had concentric or eccentric left
ventricular hypertrophy.
The normotensive diabetic subjects were then divided into two
groups: G1 (normal) and G2 (concentric left ventricular remod-
elling) on this basis. The groups had comparable mean ages,
BMIs, FBG and two-hour post-prandial blood glucose values,
TABLE 1. HAEMODYNAMIC RESPONSEAND ECHO-
CARDIOGRAPHIC PATTERN OF THE STUDY POPULATION
Parameters
Normotensive
diabetics
(
n
=
30)
Controls
(
n
=
34)
p
-value
(Student’s
t-test)
rHR (per min)
91.37
±
16.10 83.29
±
5.36 0.038
rDBP (mmHg)
73.03
±
5.46 71.94
±
3.13 0.713
rSBP (mmHg)
117.13
±
6.36 113.62
±
4.51 0.044
pHR (per min)
166.00
±
15.61 179.03
±
9.10
<
0.001
pDBP (mmHg)
95.67
±
9.35 89.12
±
7.12
<
0.001
pSBP (mmHg)
205.00
±
18.15 185.41
±
10.81
<
0.001
Exercise capacity (METs) 8.07
±
1.47 8.11
±
0.88 0.992
LVMI (g/m
2
)
93.97
±
17.04 90.55
±
17.09 0.512
IVST (mm)
10.24
±
1.36 9.45
±
1.44 0.084
PWT (mm)
9.70
±
1.51 9.43
±
1.50 0.771
RWT
0.45
±
0.68 0.41
±
0.07 0.038
Statistical significance at
p
<
0.05;
Values are expressed as mean
±
SD;
rHR
=
resting heart rate, pHR
=
peak heart rate.
TABLE 2. CLINICALAND DEMOGRAPHIC PATTERN
OF G1 AND G2 SUBJECTS
Parameters
Normal LV
geometry
(
n
=
19)
Concentric
LV remodel-
ling (
n
=
11)
p
-value
(Student’s
t-test)
Age
48.68
±
7.7 47.82
±
5.7 0.749
Gender
M:
n
(%)
7 (36.8%)
8 (72.7%)
0.058*
F:
n
(%)
12 (63.2%) 3 (27.3%)
BMI (kg/m
2
)
24.8
±
4.1 24.8
±
2.9 0.992
Duration of diabetes (months) 18.7
±
8.7 69.0
±
9.48 0.007
FBG (mmol/l)
9.8
±
2.03
8.1
±
1.9 0.082
2HPP (mmol/l)
12.2
±
1.9 13.8
±
3.5 0.236
rHR (bpm)
92.1
±
18.2 90.1
±
12.4 0.748
rDBP (mmHg)
72.4
±
5.8 74.2
±
4.9 0.390
rSBP (mmHg)
118.5
±
6.5 114.7
±
5.6 0.116
rPP (mmHg)
46.2
±
8.7 40.6
±
3.9 0.052
Statistical significance at
p
<
0.05;
*Chi-square. Values are expressed as mean
±
SD.
