CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 10, November 2012
AFRICA
537
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
cardiovascular disease who were participants of the Health,
Aging, and Body Composition study (Health ABC study),
the presence of major or minor ECG aberrations at baseline
was associated with coronary heart disease risk during follow
up, independent of classical cardiovascular risk factors.
15
The
findings of the Health ABC study suggest that the presence
of ECG aberrations, including those used to diagnose cardiac
ischaemia in our study, should be given consideration as they
may indicate an adverse underlying cardiovascular risk profile.
Approximately 13% of participants in this study were on a
statin, preventive treatment widely recommended for routine use
in people with diabetes. No correlation was found between statin
use and ECG-diagnosed ischaemic heart disease. This suggests
that the use of statins in this population could be almost doubled
by using ECG criteria to diagnose for ischaemic heart disease.
It was shown in a recent study that the use of recommended
preventive therapies for cardiovascular disease risk reduction,
based on global risk evaluation, was limited in Africa in people
with diabetes and those without.
16
Our study had some limitations. In the absence of follow
up, we were unable to establish any causal relationship between
identified predictors of cardiovascular risk and ECG aberrations.
This was a hospital-based study and therefore included
participants who may not have been typical of those in the
community where the majority of type 2 diabetes persons remain
undiagnosed.
17
While this could have affected the prevalence
of ECG changes found in our study, it was less likely to have
affected the direction of associations described, and therefore
would not have invalidated the major findings from this study.
That ECGs were interpreted by an investigator who was
unaware of the clinical background of the patients, which
could have affected the prevalence of some of the outcomes.
Indeed, using such an approach resulted at best in a description
of significant changes, with no assumption about possible
correlations between coincident aberrations in the same patient.
Our study had some major advantages, including the
considerable sample size, which gave us reasonable statistical
power to reliably investigate the parameters. We were also able to
investigate the full spectrum of resting ECG aberrations, which
no previous study has achieved in Africa. The extensive data
collection of both clinical and biological profiles enabled a wide
range of predictors to be investigated for their possible link with
prevalent ECG aberrations.
Conclusion
ECG aberrations are frequent in people with diabetes in
sub-Saharan Africa. While some may be benign, others are
indicators of serious underlying conditions or high future risk
for cardiovascular disease. These aberrations have the potential
to improve cardiovascular disease risk stratification and the
implementation of preventative strategies in people with diabetes
in sub-Saharan Africa.
The growing prevalence of serious ECG aberrations over time
suggests the need for strategies to monitor such changes and
their determinants, so as to refine the cardiovascular preventative
strategies in sub-Saharan Africa. Elsewhere, dedicated diabetes
registries have successfully served these functions.
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