CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 10, November 2012
536
AFRICA
The distribution of ECGabnormalities was:T-wave aberrations
(20.9%),
left ventricular hypertrophy according to the Cornell
product criteria (16.4%), arrhythmia (16.2%), ischaemic heart
disease (13.6%), conduction defects (11.9%), QTc prolongation
(10.2%)
and ectopic beats (4.8%). Unlike T-wave aberrations and
left ventricular hypertrophy, the prevalence of major aberrations
was similar in men and women (Table 2). The distribution
of subtypes of arrhythmia, conduction defects and T-wave
aberrations is shown in Fig. 1.
The distribution of subtypes of conduction defects was
significantly different in men and women (
p
=
0.03).
Significant
predictors of ECG abnormalities are shown in Table 3. Age
variables (age at diabetes diagnosis and duration of diagnosed
diabetes), and blood pressure variables were the common
significant predictors of ECG abnormalities.
The presence of diabetic nephropathy was significantly
associated with T-wave aberrations [OR: 0.45 (95% CI: 0.24–
0.83)]
and ischaemic heart disease [OR: 0.47 (0.23–0.95)];
otherwise, diabetes medications and markers of disease control
were not associated with the outcomes. Waist circumference
was associated with a 3% (95% CI: 1–6%) higher risk of
QTc prolongation, otherwise no other marker of adiposity
was associated with the outcomes. Similarly, none of the lipid
variables was significantly associated with ECG abnormalities.
Discussion
This study revealed the high prevalence of ECG aberrations in
this population of individuals with a short duration of clinically
overt type 2 diabetes. While some of these aberrations were
benign, others were potential indicators of the presence of
serious conditions such as ischaemic heart disease, or were
associated with increased future risk of fatal and non-fatal
cardiovascular events. The minimal use of preventive treatment
for cardiovascular disease in this population highlights the
scope for improving cardiovascular health in people with type 2
diabetes in this region.
Some aspects of ECG abnormalities in people with diabetes,
such as those relating to LVH,
8
ischaemic heart disease
9
or
QTc prolongation
10
have been investigated in a few studies on
diabetics in Africa. To the best of our knowledge, however,
there is no recent study that has investigated the full spectrum
of resting ECG aberrations and potential determinants in people
with diabetes in this part of the world.
In accordance with a previous study in Tanzania,
8
we found
a 16% prevalence of LVH in our study. Interestingly, blood
pressure variables were also the main determinants of LVH, with
approximately similar range of effects.
8
That more than one in 10 participants in the current study
had ECG aberrations suggestive of ischaemic heart disease has
relevance in sub-Saharan Africa where cardiovascular diseases
are not considered a major priority health issue in people with
diabetes.
11
In a previous study in the same region, using both
resting and exercise ECGs, a prevalence of 7.5% for cardiac
ischaemia was found; although this was based on a small sample
size.
12
Even after accounting for the uncertainties around the
estimates from this and other studies in sub-Saharan Africa,
9
our findings support a growing prevalence of ECG-diagnosed
ischaemic heart disease in diabetes patients in our region
over time. This prevalence was similar to that found in stroke
survivors in Africa,
13
and therefore provides more evidence in
support of the high cardiovascular risk of diabetes patients in this
part of the world.
It is possible that the prevalence of ECG-diagnosed cardiac
TABLE 3. ODDS RATIOAND 95% CONFIDENCE INTERVALS FOR PREDICTORS OF ECG CHANGES
Variables
Arrhythmia
Conduction
T-wave
changes
Long QTc
IHD
LVH
Ectopic beat
Age at diabetes diagnosis (years)
1.02 (0.99–1.04) 1.06 (1.02–1.09)* 1.02 (0.99–1.04) 1.02 (0.99–1.06) 1.00 (0.97–1.03) 1.05 (1.02–1.08)* 1.06 (1.01–1.12)*
Duration of diagnosed diabetes (years)
1.02 (0.97–1.06) 1.01 (0.96–1.07) 1.04 (1.00–1.08)* 1.08 (1.03–1.13)* 1.02 (0.98–1.07) 1.05 (1.00–1.10)* 1.04 (0.97–1.12)
Gender (men vs women)
1.16 (0.69–1.96) 0.66 (0.36–1.22) 0.55 (0.34–0.89)* 1.40 (0.73–2.68) 0.62 (0.35–1.09) 4.86 (2.54–9.25)* 0.84 (0.34–2.12)
Recruitment centre (Yaoundé vs Douala) 0.89 (0.52–1.53) 0.89 (0.48–1.66) 1.78 (1.10–2.87) 1.05 (0.55–2.02) 1.28 (0.73–2.26) 3.79 (2.13–6.75)* 2.36 (0.93–5.95)
Presence/history of nephropathy
0.69 (0.34–1.38) 0.76 (0.33–1.73) 0.45 (0.24–0.83)* 0.53 (0.25–1.15) 0.47 (0.23–0.95)* 0.66 (0.31–1.40) 0.52 (0.17–1.66)
Metformin use
1.06 (0.61–1.84) 0.87 (0.46–1.67) 1.04 (0.63–1.73) 1.86 (0.97–3.55) 0.85 (0.46–1.56) 0.89 (0.48–1.64) 0.47 (0.15–1.46)
Suphonylurea use
0.87 (0.51–1.47) 0.90 (0.49–1.65) 0.71 (0.44–1.15) 1.47 (0.76–2.86) 0.58 (0.33–1.02) 1.23 (0.69–1.20) 0.62 (0.25–1.57)
Insulin use
0.60 (0.31–1.18) 3.26 (0.96–11.09) 1.06 (0.54–2.09) 0.51 (0.26–1.11) 1.11 (0.50–2.47) 0.93 (0.40–2.17) 1.44 (0.31–6.75)
Waist circumference (cm)
0.98 (0.96–1.00) 1.01 (0.98–1.03) 0.98 (0.96–1.00) 1.03 (1.01–1.06)* 1.00 (0.97–1.02) 1.02 (1.00–1.04) 1.01 (0.97–1.04)
Systolic blood pressure (mmHg)
1.00 (0.99–1.01) 1.01 (1.00–1.03)* 1.01 (1.00–1.02)* 1.02 (1.01–1.03)* 1.01 (0.99–1.02) 1.02 (1.01–1.03) 1.01 (0.99–1.02)
Diastolic blood pressure (mmHg)
1.00 (0.98–1.02) 1.01 (0.99–1.04) 1.01 (0.99–1.03) 1.05 (1.02–1.07)* 1.01 (0.99–1.03) 1.01 (0.99–1.04) 1.01 (0.98–1.05)
Pulse pressure (mmHg)
1.01 (0.99–1.02 1.02 (1.00–1.04)* 1.02 (1.00–1.03) 1.02 (1.00–1.03) 1.01 (0.99–1.03) 1.03 (1.01–1.05)* 1.00 (0.98–1.03)
Heart rate (beats/min)
1.01 (0.99–1.03) 0.98 (0.96–1.01) 0.98 (0.96–1.00)* 1.05 (1.03–1.08)* 0.99 (0.97–1.01) 0.99 (0.97–1.01) 1.03 (0.97–1.04)
Total cholesterol (mg/dl)
0.60 (0.35–1.04) 1.15 (0.63–2.10) 1.55 (0.96–2.52) 1.22 (0.64–2.36) 1.27 (0.72–2.24) 1.24 (0.71–2.16) 1.19 (0.48–2.97)
HDL cholesterol (mg/dl)
0.66 (0.15–2.82) 1.39 (0.29–6.51) 2.23 (0.63–7.98) 1.03 (0.17–6.01) 3.82 (0.92–15.96) 1.13 (0.24–2.39) 1.97 (0.19–19.98)
*
p
<
0.05;
IHD, ischaemic heart disease; LVH, left ventricular hypertrophy;
all models are adjusted for gender, age and diabetes diagnosis, known duration of diabetes and study centre
TABLE 2. ECG CHANGES IN 420 MENANDWOMENWITHTYPE 2 DIABETES
Variables
Men
n
(%)
Women
n
(%)
p
Total
n
(%)
Number (%)
207 (49) 213 (51)
420
Arrhythmia
31 (15) 37 (17.4)
0.51 68 (16.2)
Conduction changes
28 (13.5) 22 (10.3)
0.37 50 (11.9)
Ectopic beats
10 (4.8) 10 (4.7)
0.99 20 (4.8)
T-waves changes
53 (25.6) 35 (16.4)
0.02 88 (20.9)
QTc prolongation
18 (8.7) 25 (11.7)
0.34 43 (10.2)
Ischaemic heart disease
34 (16.4) 23 (10.8)
0.12 57 (13.6)
Left ventricular hypertrophy by diagnostic criteria
Cornell product
14 (6.7) 55 (25,8)
<
0.001 69 (16.4)
Sokolov index
17 (8.2) 7 (3.3)
0.03 24 (5.7)
Cornell index
12 (5.8) 5 (2.3)
0.09 17 (4.1)
