CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 6, July 2013
222
AFRICA
The literature from developed countries on the presence of
viral genomes in cardiomyopathy has pointed to enterovirus,
adenovirus, cytomegalovirus and HIV-1 as the dominant
opportunistic viral infections in the heart tissue of patients
with HIV-associated cardiomyopathy.
17–19
By contrast, our study
revealed Epstein-Barr and herpes simplex viruses to be the most
prevalent cardiotropic viruses in patients with HIV-associated
cardiomyopathy.
Epstein-Barr virus and herpes simplex virus are common
herpes viruses that have a latency stage; they are reactivated
in immunocompromised individuals, causing tissue damage.
Similarly, enteroviruses, which were common in our cases
with HIV-associated cardiomyopathy and idiopathic dilated
cardiomyopathy, are also known have a latency stage, which
could have important consequences for the clinical course of
the disease. Parvovirus B19 had the lowest prevalence in all
groups of patients, whereas it is one of the commonest causes of
viral myocarditis in North America and Europe.
20,21
We found no
obvious pattern of association with any of these viral genomes
with myocarditis, in line with previous observations.
22
While the phenomenon of multiple viral infections is known
to occur in patients with end-stage dilated cardiomyopathy, the
prevalence of cardiotropic viral infection is much higher in
African patients (100%) compared to elsewhere in the world
(
~
65%).
22
It is of interest that the number of viruses per case
ranged from one to four, with a mean viral burden of 2.3
types of viruses in HIV-associated cardiomyopathy, zero to
four in heart transplant recipients with a mean viral burden
of 2.2 types per case, and one to two in those with idiopathic
dilated cardiomyopathy with a mean viral burden of 1.1 per
case. These findings, which suggest an increased susceptibility
to viral infection in immunosuppressed groups, point to the
possibility that the damage to the myocardium in patients with
cardiomyopathy is not only through post-viral autoimmune
mechanisms but may also be as a result of repeated infections by
different cardiotropic viruses.
The finding of myocarditis in a significant proportion of
patients with idiopathic dilated cardiomyopathy may have
prognostic implications. Kindermann and colleagues showed that
the risk of death or need for cardiac transplantation in patients
with myocarditis was worse in those with inflammation than in
those without, as assessed by immunohistology.
23
Significant
inflammation was present in 25% of the participants who
underwent endomyocardial biopsy testing as part of investigation
of unexplained dilated cardiomyopathy.
It is essential to determine whether the cellular and
imunohistological changes have prognostic effects in African
patients with dilated cardiomyopathy. Furthermore, interferon-
beta treatment may eliminate enterovirus and adenovirus
and improve left ventricular function in immuno-competent
patients with myocardial persistence of viral genomes and
left ventricular dysfunction.
20
There is a need to assess the
effectiveness of interferon-beta treatment in African patients
with cardiomyopathy, in the light of the discovery of the
overwhelming presence of viral genomes in our patients.
The major weakness of the study was the small sample size.
The number of analysed patients may have beeen insufficient to
reliably determine the proportion of patients with HIV-associated
cardiomyopathywith acutemyocarditis, or to delineate differences
between the HIV-infected and HIV-negative patients with dilated
cardiomyopathy. However, while the small sample size limits the
generalisability of the findings, it provides a strong basis for the
exploration of the findings in larger studies.
Furthermore, the use of a prospective consecutive design
with two different types of controls has, however, ensured that
the study has internal validity with regard to the diagnosis of
myocarditis and patterns of viral infection in immunosuppressed
hosts. The heart transplant recipients, as expected, had evidence
of acute myocarditis due to varying degrees of rejection. It was
also interesting to note that the burden of viral infection was
higher in the immunosuppressed patients (by HIV and heart
transplantation), with cytomegalovirus infection being observed,
as expected, only in immunosuppressed individuals.
24
We included
all eligible patients with HIV-associated cardiomyopathy during
the period of the study (five years), and the sample size was not
different from that of similar studies.
25
The prevalence of myocarditis in HIV-associated
cardiomyopathy in our study is similar to the rates found in
North America in the pre-HIV era, and the frequency of chronic
myocarditis in idiopathic dilated cardiomyopathy is consistent
with findings elsewhere in the world.
8,26
The external validity of
this study is confirmed by the finding of a high prevalence of
enteroviruses in HIV-positive heart tissue, which corresponds
with data that were reported by Herskowitz in patients with
AIDS nearly two decades ago.
8
Conclusion
Myocarditis and cardiotropic viral infection appear to be
common and may play a significant role in the pathogenesis
of HIV-associated and idiopathic dilated cardiomyopathy in
Africans. The results of this small pilot study need to be
confirmed in larger studies to endorse these observations and
determine the prognostic and therapeutic implications of our
findings. If the pathogenetic role of cardiotropic viral infection
in cardiomyopathy is confirmed in other studies, this might
lead to the development of appropriate immunisation to aid
the prevention of the disease and reduce the prevalence of
cardiomyopathies, which are endemic in Africa.
27
We thank Sisters Naomi Hare, Joanne Hartnick and Maitele Tshifularo for
assistance with this research. We also greatly appreciate the Claude Leon
Foundation for providing us with the sponsorship of Dr Gasnat Shaboodien.
Funding was provided by the Medical Research Council and the National
Research Foundation.
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