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CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 2, March 2013
AFRICA
35
resting 12-lead electrocardiographs (ECGs), exercise ECGs,
cardiac biomarkers (troponins, CKMB) and cardiac imaging
such as echocardiography, coronary angiography, computed
tomography (CT) angiography, intravascular ultrasound scans
(IVUS) and radionuclide myocardial perfusion studies.
Resting 12-lead ECGs, although generally more widely
available and relatively inexpensive, have limited sensitivity
and specificity for the diagnosis of acute coronary syndromes.
Furthermore, there are high rates of non-specific ST-segment
and T-wave changes suggestive of myocardial ischaemia in up to
10% of asymptomatic African men and 20% of women over the
age of 40 years.
1
Physiologically or pharmacologically induced stress tests are
helpful to differentiate cardiac from non-cardiac aetiology of
chest pain in patients with inducible ischaemia due to obstructive
coronary artery disease. The safe performance of provocative
stress testing and IVUS requires appropriate professional
competence, careful selection of patients and availability of
resuscitation equipment in cases of adverse events during testing.
Low autopsy rates often coupled with uncertified deaths outside
health facilities exacerbate the situation.
This lack of evidence on IHD in SSA is erroneously reinforced
by beliefs that IHD affects only the wealthy and elderly, that it
arises from freely acquired risks and that its management is
expensive, ineffective and of a lower priority than infectious
diseases such as HIV/AIDS, tuberculosis, malaria, and a number
of neglected tropical diseases. Moreover, there are strong
opinions that IHD in SSA affects mainly small Westernised
populations and that it is a less serious cause of morbidity
and mortality.
2
Some of these authorities are of the opinion
that cardiovascular risk factors in groups of older Africans,
including obesity, diabetes and metabolic disorders are virtually
non-existent and that IHD is bound to be a less serious threat, as
there are very few black populations in the older age category.
2
Others have expressed disbelief of the potential epidemic of
IHD in SSA in the next few decades and contend that resources
should be appropriated to the current threats, particularly
rheumatic heart disease and cardiomyopathies.
3
Additional
setbacks accrue from lack of appropriate resources and skills
to guide and direct epidemiological studies of ischaemic heart
disease; crisis management often focused on acute conditions
and infectious diseases; and perpetual uncoordinated approaches
to health issues that are often reactionary, leading to neglect of
NCDs.
The majority of the 57 countries in the world with critical
shortages of health workers are in SSA. The total health
workforce density in SSA is the lowest in the world with just
2.3 per 1 000 population, compared to 18.9 and 24.8 per 1 000
population in Europe and the Americas, respectively. In fact,
SSA has only 4% of the global number of health workers but
25% of the global burden of disease.
4
Sadly, some of the myths regarding IHD in SSA are fuelled
by the notion that the various cardiovascular disease (CVD)
risk factors, although prevalent in urban black Africans, appear
to exert their influence in a far less noxious manner than is the
case in most Western populations. Also that lipid profiles are
generally less atherogenic, leading to suggestions of the ‘genetic
resistance’ of black Africans to IHD.
The view that IHD is rare in SSA is rooted in old beliefs
arising from earlier authors such as Cook
5
and Donnison,
6
and
needs to be effectively demystified. Firstly, atherothrombotic
cardiovascular disease is a global problem that afflicts every
community regardless of region, ethnicity or gender. The burden
of cardiovascular disease is increasing rapidly in Africa and it
is now a public health problem throughout the African region,
particularly hypertension, stroke, cardiomyopathies, and not
least, ischaemic heart disease. Rheumatic heart disease is still a
major concern.
Scarcity of data on IHD and the non-existence of
epidemiological surveillance systems for cardiovascular diseases
in most of SSA should not be construed to mean rarity of the
disorder. INTERHEART, a global case–control study of acute
myocardial infarction (AMI) of 28 000 subjects in 52 countries
showed that nine risk factors accounted for 90% of population-
attributable risk (PAR) in all regions.
7
These risk factors included
hypertension, diabetes, central obesity, dyslipidaemia, physical
inactivity, psychological stress, tobacco use, inadequate intake of
fruits and vegetables, and inadequate or no alcohol intake.
Although the results of the INTERHEART study have been
challenged on account of it being a case–control study rather
than a prospective study, the major contributing individual risk
factors for acute myocardial infarction are generally consistent
across the globe and reminiscent of the conclusions of the
original Framingham Heart study several decades ago, as well
as its 30-year follow-up study.
8,9
Some have questioned the
reliability of information on some of the cardiovascular risk
factors used in the INTERHEART study, for example history
of hypertension and diabetes mellitus, and have raised concerns
about recall bias regarding diet and psychosocial factors in
the setting of devastating effects of index acute myocardial
infarction on a person’s mental state. In some parts of SSA,
haemoglobinopathies such as haemoglobin S or haemoglobin
C might contribute to ischaemic heart disease due to vaso-
occlussive crises.
Secondly, despite variations in genetic susceptibilities to
IHD in different ethnic groups, the common environmental and
traditional coronary heart disease risk factors pathogenetically
play their roles through a common final pathway in the
development of clinical atherosclerotic heart disease in all ethnic
groups. Marked regional differences in the impact of CVDs
merely reflect a myriad of factors, among them the level of care,
quality of health statistics, and differences in stages of socio-
economic, nutritional and epidemiological transition between
countries, communities and even between individuals.
Thirdly, as societies undergo ‘urbanisation’, risk-factor levels
for CVDs including IHD increase. For instance, only about 5%
of Africans were urbanised by 1900. At the start of independence
in the 1950s, 14.7% of inhabitants of Africa were urban. In 2000,
the urbanisation rate had risen to 37.2%, and by 2015 the rate is
expected to hit 45.3% with continually high rates of rural–urban
migrations across Africa.
10
The burden of cardiovascular risk factors
in SSA
Hypertension
Systemic arterial hypertension poses a special challenge in
SSA, with immense socio-economic implications because of
its high prevalence, especially in urban dwellers. Hypertension
is arguably the most powerful cardiovascular risk factor in the