CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 10, November 2012
534
AFRICA
The use of this modality however varies substantially, guided
essentially by the availability of ECG machines and the cost
of such investigations. As a result, the regional office of the
International Diabetes Federation (IDF) for Africa recommends
ECG monitoring in diabetes only at the secondary or tertiary
level of the healthcare system where facilities for performing an
ECG are more readily available.
4
Therefore in sub-Saharan Africa, the majority of patients with
diabetes who receive care in primary healthcare facilities do not
have routine ECG screening. Failure to perform regular ECGs
means that opportunities to improve cardiovascular health in
this population are being missed. Furthermore, our knowledge
of the major ECG abnormalities and their determinants in this
environment remains very limited.
In this study we assessed the distribution of ECG aberrations
and investigated their potential determinants in a group of
individuals with type 2 diabetes who were receiving chronic care
in two referral hospitals in the two largest cities of Cameroon,
Central Africa.
Methods
The out-patient sections of the Yaoundé Central Hospital’s
diabetes and endocrine service, and the Douala General Hospital’s
(
DGH) internal medicine service and sub-specialties served
as settings for recruitment of participants for this study. The
Yaoundé Central Hospital (YCH) has been described in detail
elsewhere.
5,6
The DGH internal medicine and sub-specialities
service has an individualised, dedicated endocrine section, which
is the main referral centre for endocrine diseases and diabetes in
Douala, the second major city of Cameroon (approximately 2.5
million people). Patients with diabetes and its complications,
residing in Douala and surrounding regions were the most likely
to receive care in our clinic during the study period.
Overall, the healthcare system in Cameroon is organised into
primary, secondary and tertiary levels. Care at the primary level
is provided by nurses and general practitioners and is essentially
geared towards acute conditions. Secondary-level facilities
provide access to some form of specialist care. Tertiary-level
facilities (including YCH and DGH) serve as a referral hospital
for primary- and secondary-level health facilities, and for routine
consultations and follow up, as in our study.
From January 2010, the Yaoundé health service has had three
endocrinologists and the Douala health service two. Patients
with diabetes who received chronic care in the two study clinics
were required to have an annual evaluation as part of their
routine care. In addition to a clinical consultation, this evaluation
included: (1) an assessment of diabetes control (fasting glucose
and haemoglobin A
1
c
levels); (2) an assessment of chronic
complications (eyes: fundoscopy, kidney function: albuminuria,
serum urea and creatinine levels); (3) a cardiovascular work up
including an assessment of lipid profiles (total cholesterol, high-
density lipoprotein cholesterol and triglycerides) and a resting
ECG.
Participants in this study were recruited from patients
presenting for these annual evaluations. The study was approved
by the administrative authorities of the two health facilities, and
ethical clearance was obtained from the Cameroon National
Ethics Committee.
Four hundred and twenty individuals with type 2 diabetes
receiving chronic care in the two study facilities were
consecutively enrolled over a two-year period from January
2008
to January 2010. Only the patients’ first consultation during
this period was considered, and no other exclusion criteria were
applied. The type of diabetes was based on the diagnosis of the
attending physician. In addition, patients had to be at least 30
years of age at the time of their first diagnosis of diabetes.
Blood pressure (mmHg) was measured on the right arm with
the participant in a seated position, after 10 minutes’ rest, with
an Omron
®
MX2 basic electronic device (Omron Healthcare Co,
Ltd, Kyoto, Japan) with the appropriate cuff size. The average of
two measurements recorded five minutes apart was used in this
study. Body weight (kg) was measured in light clothing, using
a SECA
®
scale, and height (m) was measured with a standard
stadiometer.
The body mass index (BMI) for each patient was calculated
as weight/height
2
(
kg/m
2
).
The waist circumference (cm) was
measured with a tape measure on the horizontal plane midway
between the lowest rib margin and upper edge of the iliac crest.
A 12-lead resting ECG was done on all subjects using
the Cardi Max Fx-7302
®
.
All ECG tracings were centrally
interpreted by the same investigator who is a cardiologist (AD)
and did not know the subjects’ backgrounds. Significant ECG
findings such as ST-segment elevation or depression, T-wave
aberrations (inversion or tall T wave), bundle branch block, left
ventricular hypertrophy (LVH), right and left atrial enlargement,
arrhythmias and other changes were noted.
LVH was defined according to three different criteria:
•
Cornell voltage-duration product [(RaVL
+
SV3)
×
QRS
complex duration]
>
2.623
mm
×
ms in men and
>
1.558.7
mm
×
ms in women,
7
•
Cornell voltage (SV3
+
RaVL
>
24
mm in women and 28
mm in men)
•
Sokolov-Lyon index (SV1
+
RV5/6
>
35
mm).
Compared with echocardiography, the cut-off values for the
Cornell voltage duration product gave the best sensitivity with a
specificity of 95%.
7
ECG measurements were done with a ruler on the resting
ECG tracings, and were expressed as the average of three
determinations on consecutive QRS complexes. R-wave
amplitude in aVL and S-wave depth in V3 were measured as the
distance (mm) from the isoelectric line of their zenith and nadir,
respectively. QRS duration was measured from the beginning to
the end of the QRS complex. QTc prolongation was defined as a
QTc
>
460
ms in both men and women.
A diagnosis of ischaemic heart disease was made based on
the American Heart Association criteria. These criteria include
ECG features of significant ST-segment depression, defined
as an ST-segment depression
>
1
mm in more than one lead,
and T-wave inversion. Myocardial infarction was defined as an
ST-segment elevation (convex upwards)
>
0.08
s, associated with
T-wave inversion in multiple leads, and reciprocal ST-segment
depression in opposite leads.
Statistical analysis
Data were analysed using SPSS
®
version 17 for Windows
(
SPSS, Chicago, IL). Differences in means and proportions
for participants’ characteristics were assessed using analysis of
variance and
χ
2
tests as applicable, and the influence of likely
