CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 4, July/August 2014
AFRICA
151
Sudden cardiac death in Africa
Ashley Chin
Africa is facing a huge health burden of both communicable and
non-communicable diseases. Cardiovascular disease is becoming
an important cause of mortality in Africa.
1
Unfortunately,
statistics on the incidence of cardiovascular disease in Africa are
not readily available and in many sub-Saharan African countries
there is no information or only poor-quality data.
Sudden cardiac death (SCD) is an unexpected natural death
due to cardiovascular disease that occurs within one hour of
the onset of symptoms.
2
The epidemiology of SCD in Africa is
unknown. In the United States, SCD results in approximately
300 000 deaths per year.
2
Ischaemic heart disease is responsible
for 80% of cases, followed by non-ischaemic myopathic diseases,
such as hypertrophic and dilated cardiomyopathy, which account
for 10 to 15% of cases. Approximately 5% of cases of SCD can
be attributed to primary electrical disorders such as congenital
long QT syndrome and Brugada syndrome.
In this article of the Journal, Bonny
et al
. and the Pan-African
Society of Cardiology task force on Sudden Cardiac Death
present the rationale and design of the Pan-African SCD
study (page 176). This will be a multicentre, community-based,
prospective cohort registry that will report on cases of SCD
from all African regions. The well-designed, epidemiological
study will be the first and largest of its kind from Africa. This
registry will be community-based and led by senior physicians,
working together with a multidisciplinary team. Genetic testing
and autopsy data will be obtained to confirm clinical diagnoses
as far as possible.
This study is important for several reasons. The Pan-African
SCD study may highlight important differences in the incidence
and relative causes of SCD in Africa.
In contrast to the developed world, cardiovascular disease
in Africa is still predominantly non-ischaemic.
1,3
The THESUS-
HF registry has confirmed that the major causes of acute heart
failure in Africa are non-ischaemic. Hypertensive heart disease,
cardiomyopathy (peripartum cardiomyopathy, idiopathic dilated
cardiomyopathy and endomyocardial fibrosis), pericardial disease
and rheumatic valvular heart disease account for the majority
of cases. Left ventricular hypertrophy, whether confirmed by
ECG or echocardiogram, is a strong independent predictor of
cardiovascular death and SCD.
2
An autopsy study from Nigeria
found that hypertensive heart disease was the most common
cause of SCD in that region.
4
Therefore the Pan-African SCD
study may provide insight into the burden of SCD due to
neglected diseases that are endemic to Africa, such as rheumatic
valvular heart disease and tuberculous myo/pericardial disease.
Tuberculosis is a major cause of mortality in Africa and
reports suggest that tuberculous myocarditis may cause SCD.
1,5
While SCD due to degenerative aortic stenosis and mitral
regurgitation is well appreciated, less is known about SCD
in patients with underlying rheumatic aortic and mitral valve
disease. These pre-transitional diseases are now uncommon in
the developed world and have been neglected in major society
guidelines of implantable cardioverter defibrillators (ICDs) in
the prevention and treatment of SCD.
6
This study has important
implications for other developing countries, such as India and
China, where these diseases are still prevalent.
This study will also highlight the magnitude of well-recognised
causes of SCD in Africa. Countries in Africa find themselves
at different stages of the epidemiological transition. Many
countries, such as South Africa, have reported a rising incidence
of ischaemic heart disease.
7
According to the Global Burden
of Disease in 2010, ischaemic heart disease was responsible for
more deaths in Africa than either rheumatic heart disease or
hypertensive heart disease.
1
With the introduction of antiretroviral therapy (ART),
patients with HIV/AIDS are living longer, and with the increasing
atherogenic complications of ART, sub-Saharan Africa is facing
an impending epidemic of cardiovascular and metabolic disease.
8
The Pan-African SCD study will provide contemporary data on
the burden of SCD secondary to ventricular arrhythmias related
to ischaemic heart disease.
There is little doubt that the primary inherited arrhythmia
syndromes [congenital long QT syndrome, arrhythmogenic
right ventricular dysplasia (ARVD), Brugada syndrome, early
repolarisation (ER) syndrome] exist in Africa. These diseases
are frequently under-recognised and are missed diagnoses.
Nevertheless, there have been several large cohorts reported from
Africa, which report a similar presentation to other populations
around the world.
In a large series of 50 ARVD patients from South Africa,
the study found a similar clinical presentation and an annual
mortality rate comparable to other large registries in North
America and Europe.
9
Brugada syndrome has also been described
in 23 patients from Tunisia, who share a similar clinical profile to
their Asiatic and Western counterparts.
10
In another series of 44
congenital long QT 1 syndrome patients in South Africa, a strong
founder effect was found, with a single mutation responsible for
52% of cases.
11
An important study finding will be whether the
ER pattern is associated with SCD in young black Africans.
While a report from Cameroon reported that the ER
pattern may occur in up to 20% of patients who present with
cardiovascular symptoms, a recent study found that the ER
pattern in the precordial leads was not associated with increased
mortality in black African-Americans.
12,13
If an association of
the ER pattern and SCD indeed exists, it will have major clinical
implications because of the high prevalence rate of this ECG
pattern in black Africans.
The study will face significant challenges in terms of diagnosis
and management. First, one can expect that a significant
proportion of patients who survive SCD will be managed
by general physicians or cardiologists, who may have limited
experience in the diagnosis and management of these complex
patients.
Second, special investigations such as echocardiography,
cardiac catheterisation, magnetic resonance imaging,
electrophysiological testing and Holter monitoring may be
unavailable in many African centres. Certain diseases, such
as ARVD, which require multiple investigations to make a
diagnosis, may prove difficult to diagnose in the absence of
clinical expertise and special investigations.
