CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 8, September 2012
AFRICA
435
Increased relative wall thickness is a marker of
subclinical cardiac target-organ damage in African
diabetic patients
PILLY CHILLO, JOHNSON LWAKATARE, JANET LUTALE, EVA GERDTS
Abstract
Objective:
To assess the prevalence and covariates of abnor-
mal left ventricular (LV) geometry in diabetic outpatients
attending Muhimbili National Hospital in Dar es Salaam,
Tanzania.
Methods:
Echocardiography was performed in 61 type 1
and 123 type 2 diabetes patients. LV hypertrophy was taken
as LV mass/height
2.7
>
49.2
g/m
2.7
in men and
>
46.7
g/m
2.7
in
women. Relative wall thickness (RWT) was calculated as the
ratio of LV posterior wall thickness to end-diastolic radius
and considered increased if
≥
0.43.
LV geometry was defined
from LV mass index and RWT in combination.
Results:
The most common abnormal LV geometries were
concentric remodelling in type 1 (30%) and concentric
hypertrophy in type 2 (36.7%) diabetes patients. Overall,
increased RWT was present in 58% of the patients. In multi-
variate analyses, higher RWT was independently associated
with hypertension, longer isovolumic relaxation time, lower
stress-corrected midwall shortening and circumferential end-
systolic stress, both in type 1 (multiple
R
2
=
0.73)
and type 2
diabetes patients (multiple
R
2
=
0.66),
both
p
<
0.001.
These
associations were independent of gender, LV hypertrophy or
renal dysfunction.
Conclusion:
Increased RWT is common among diabetic sub-
Saharan Africans and is associated with hypertension and
LV dysfunction.
Keywords:
left ventricular geometry, African diabetes, relative
wall thickness
Submitted 10/3/11, accepted 6/4/12
Published online 20/3/12
Cardiovasc J Afr
2012;
23
: 435–441
DOI: 10.5830/CVJA-2012-023
The co-existence of diabetes with other cardiovascular risk
factors, such as hypertension and obesity, may contribute to
the association of diabetes with subclinical cardiac target-
organ damage such as left ventricular (LV) hypertrophy and
dysfunction. In addition, several reports have suggested that
diabetes has direct adverse effects on the heart, independent of
obstructive coronary artery disease.
1,2
In the Strong Heart study,
non-insulin dependent diabetes was associated with a 12 to 14%
higher LV mass/height
2.7
as well as reduced LV systolic function
and increased arterial stiffness.
3
Among hypertensive diabetic
African Americans, increased relative wall thickness (RWT)
and LV hypertrophy have been found to be more prevalent,
4,5
and earlier development of cardiac end-organ damage than in
Caucasians has been suggested.
6
In sub-Saharan Africa, diabetes and other cardiovascular
diseases were considered rare.
7
As a result, research focus has
been on infectious diseases. However, recent publications in the
region have shown an increase in the prevalence of diabetes,
hypertension and other cardiovascular risk factors,
8
and a high
prevalence of LV hypertrophy, in particular in hypertensive
patients, has been reported.
9
However, there are limited data on
subclinical cardiac target-organ damage in diabetic patients.
The aim of the present study was therefore to determine the
prevalence and covariates of abnormal LV geometry among type
1
and type 2 diabetes outpatients of African origin attending
Muhimbili National Hospital in Dar es Salaam, Tanzania.
Methods
This study was a prospectively planned follow-up examination
of 244 diabetic patients of African origin who participated in a
diabetes study programme that included clinical and biochemical
examination at Muhimbili National Hospital in Dar es Salaam,
Tanzania in 2003–2004.
10,11
Of the total 244 patients who
participated in the first survey, 184 patients (75%) were still
receiving care at the diabetes outpatient clinic in Muhimbili
National Hospital in 2008. Patients were informed about the
follow-up study when attending their regular visits at the diabetes
outpatient clinic and subsequently invited to participate. All 184
patients agreed to participate and signed informed consent.
A structured questionnaire was used for interviewing the
patients on socio-demographic characteristics, history of other
cardiovascular risk factors and duration of diabetes. Height and
weight were measured and used to calculate body mass index.
Waist circumference was measured at the level of the umbilicus
and used as a measure of central obesity. Blood pressure was
measured using a mercury sphygmomanometer and appropriate
cuff size. After five minutes’ rest in the sitting position, a set
of three readings was taken five minutes apart. The average
of the last two readings was taken as the patient’s clinic blood
pressure.
12
Hypertension was defined as blood pressure
≥
140/90
mmHg or use of antihypertensive medication.
Fasting capillary blood glucose and glycated haemoglobin
Institute of Medicine, University of Bergen, Norway
PILLY CHILLO, MD,
EVA GERDTS, MD, PhD
Department of Heart Disease, Haukeland University
Hospital, Bergen, Norway
PILLY CHILLO, MD
EVA GERDTS, MD, PhD
Muhimbili National Hospital and Muhimbili University of
Health and Allied Sciences, Dar es Salaam, Tanzania
PILLY CHILLO, MD
JOHNSON LWAKATARE MBCHB, MRCP
JANET LUTALE, MD, PhD
