VOLUME 11 NUMBER 3 • SEPTEMBER 2014
129
SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
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 nephropathywas 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
Table 2.
ECG changes in 420 men and women with type 2 diabetes
Men
Women
Total
Variables
n
(%)
n
(%)
p
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)
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
ischaemia was inflated in our study for at least two reasons: (1) in
the absence of a correlation between ECG aberrations and clinical
features, some of the observed ST-segment and T-wave changes
could have been variants of normal ECGs, as previously described
in blacks;
14
(2) some of the repolarisation changes could have been
secondary to hypertension, which is very common in diabetes
patients in this region.
5
In a cohort of black and white subjects with no known
Table 3.
Odds ratio and 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
