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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 5, September/October 2017
AFRICA
291
a significantly higher RHD prevalence rate in a more socio-
economically disadvantaged community in South Africa.
17
The prevalence of RHD in the small group of older school
children/adolescents was higher than in the younger school children.
With valvular damage becoming more evident with elapsed time,
the cumulative prevalence of RHD would be expected to increase
with progressing age among children and adolescents. Of note is
the fact that in the report by Engle and colleagues, the population
appeared somewhat older than in our present population. This may
have influenced the higher prevalence reported by these workers.
Increasing age would also offer more opportunities for
recurrences of RF, since it appears that none of these children
had been previously diagnosed and therefore were not receiving
prophylactic antibiotics.
In those 17 subjects found to have either ‘definite’ (
n
=
4) or
‘borderline’ (
n
=
13) valvular RHD, the mitral valve was most
often affected (Table 2). Again, none of those subjects who
met WHF criteria for RHD had been previously diagnosed.
Therefore, none of the 17 subjects had been receiving secondary
RF prophylaxis prior to this project. In fact, we were unable to
elicit a history of RF from any of the 2 501 echocardiographically
examined subjects as it has been found in other somewhat similar
studies.
7
This observation requires additional investigation.
An important challenge facing the application of the WHF
2012 criteria pertains to its specificity in our presumed higher-risk
Rwandan population. Evidence from a recent study in a low-risk
population suggests high specificity of the morphological mitral
and aortic valve features of RHD, but low specificity for the
isolated pathological mitral regurgitation criteria.
17
Of note,
almost 95% of our borderline RHD cases were based on the
mitral regurgitation criteria. Therefore the issue of specificity of
the morphological and Doppler-assessed valvular regurgitation
criteria is an important one, and appropriate follow up of such
identified patients is mandatory.
The WHF 2012 criteria used during this evaluation
10
differed
significantly from earlier criteria used in several other published
studies conducted in the sub-Saharan region. Those studies
employed earlier clinical and/or echocardiographic criteria for
diagnosing valvular RHD.
13-15
The present report is the second
that used only the 2012 WHF echocardiographic criteria in a
sub-Saharan school-age population.
7
We believe that our assessment of these 2 501 subjects
accurately adhered to the published WHF criteria. However,
we recognise that the final conclusion will depend on long-term
(prospective) follow up, which should include not only subsequent
serial echocardiograms, but also documentation of adherence to
secondary antibiotic prophylaxis for those subjects who initially
met the criteria for valvular RHD.
18
Secondary prophylaxis would
help to reduce/eliminate the possibility of recurrent attacks of
RF, which would confuse long-term follow-up studies.
The 2015 revised Jones Criteria for the Diagnosis of ARF
from the American Heart Association have been endorsed by the
World Heart Federation.
12
Both guidelines underscore the key
advantages of using Doppler echocardiography in the diagnosis
of ‘subclinical carditis’ – an important diagnostic criterion.
Limitations
Questions may arise about whether the selected subject
sample was representative of all similar-age school children in
Rwanda. Students in the Gasabo district were deemed by local
authorities and the investigators to be representative of the
socio-demographics of school children in Rwanda. Selecting a
district closer to the capital was a practical consideration, but
could possibly have introduced bias.
Second, the smaller percentage (9%) of relatively older
children in the examined sample may have (unintentionally)
affected the calculated overall prevalence of RHD, as has been
previously mentioned.
Third, technical aspects of the echocardiographic studies
require consideration. Although care was taken to standardise
both equipment settings and transducer selection in an effort
to minimise technical error, we used equipment from different
manufacturers. The same paediatric transducers were not
universally used for all subjects. Our care to include only
experienced, registered sonographers as well as subsequent
independent reporting by four experienced US-certified
cardiologists/echocardiographers reflects the intent to minimise
such potential sources of error.
The absence of echocardiographic findings compatible with
congenital bicuspid aortic valves (BAV) in the present study
was an unexpected finding. Congenital BAV is a frequent
differential when considering rheumatic aortic valvular disease.
On average, approximately 1% of children have been reported
to have congenital BAV. The reason(s) for the unexpectedly low
prevalence of BAV among these Rwandan school children is
unclear and requires confirmation.
Conclusions
These data from a single geographic district of Rwanda confirm
the significant prevalence of RHD, as has been reported
from other sub-Saharan African countries.
13-15
The feasibility
of echocardiographic screening of relatively large numbers
of subjects using the 2012 WHF criteria for detecting
mild/‘borderline’ RHD in these populations appears to be
confirmed. However, intensive and prospective long-term (years)
follow up is required to support the conclusions from this
sample. The present data will prove useful to health authorities
in determining resource planning and allocation for control
programmes for this preventable cardiovascular disease.
RF and RHD remain important medical and public health
issues in sub-Saharan Africa. Cost-effective public health
control programmes are urgently needed.
16,17
Educational efforts
targeting healthcare professionals, lay populations (including
school children) and public health authorities must be included.
The data presented here, while informative, need to be further
supported by additional comprehensive studies, including
sustainable, cost-effective approaches involving less-expensive
and highly portable echocardiographic instruments as well as
larger study samples.
These studies were designed and implemented by collaborative efforts between
Team Heart, Inc, Boston, Massachusetts, and the Rwanda Heart Foundation,
Kigali, Rwanda. A sincere debt of gratitude is owed to the following sonogra-
phers whose significant personal commitments and enthusiasm actually made
this effort possible: David Adams, Lisa Bruno, Marc Couturier, Kim Fanning,
Marlee Griffith, Jennifer Kane, Peggy Lospennato, Carlene McClanahan,
Lauren Motola, Jennifer Neary (lead sonographer), Eva Osypiuk, MD,
Stephen Preiss, Lauren Skillins and Nicole Zafiris. Additionally, Mr David