Introduction

For the past 60 years, reports from all parts of Africa have shown a remarkable unanimity in the pattern of heart diseases among black Africans. While ischaemic heart disease is the dominant cardiovascular disease in the Western world, it is rare in black Africans. This was followed by diseases that primarily affected the myocardium then rheumatic heart disease, followed by endomyocardial fibrosis. Recent data among the same ethnic group show that the prevalence of hypertension has doubled, there is no difference in the prevalence of dilated cardiomyopathy, the prevalence of ischaemic heart disease remains low, while that of rheumatic heart disease has decreased considerably.

Prior to the description of the tropical forms of EMF, there were also reports of a similar disease that was characterised by the presence of hypereosinophilia. It was first described by Löffler in 1936,and was known as Löffler’s endocarditis parietalis fibroplastica. This disease was initially believed to be confined to only the temperate zones of the world and was considered to be a separate illness from the tropical forms of EMF. However several reports have now confirmed its presence in Africa and other countries of the world where the tropical forms of EMF is prevalent. Some have even suggested that it is the early form of tropical EMF.

 

Classification of the cardiomyopathies in Africa

Hypertrophic cardiomyopathy

In the pre-echocardiography era, hypertrophic cardiomyopathy (HCM) was hardly diagnosed in Africa. All abnormal electrocardiographs (ECGs) suggestive of left ventricular hypertrophy (LVH) were attributed by clinicians to hypertensive heart disease since hypertension was the dominant cardiovascular disease among Africans and was extremely common in African populations. The widespread use of echocardiographic examination all over Africa changed all this as it showed that HCM indeed occurs among Africans.

Arrythmogenic right ventricular cardiomyopathy (ARVC)

Reports from Africa about this disease have come from only South Africa. There are familial cases of ARVC as well as non-familial ones. Although the disease has been associated with enteroviral and adenoviral myocarditis, it is not considered to be primarily caused by myocarditis. Lately it has been shown that the disease is not confined to the right ventricle as the name suggests, because the left ventricle may be affected in up to 75% of the patients.

Hypertension

For a long time, several workers in Africa had suspected that many patients who were labelled as having DCM were really hypertensives. And there had been several debates at world conferences where this assertion was actively advanced by many workers. Mokhobo, from South Africa advised caution in making a diagnosis of cardiomyopathy since ‘cardiomyopathy and hypertension are both common in black patients and confusion may arise between them’. Lowenthal, also from South Africa wrote as follows: ‘these cases are regarded as evidence in favour of the hypothesis that many cases of cryptogenic heart disease are in fact hypertensives presenting with normotensive cardiac failure.

Myocarditis

Studies in the seventies also showed that myocarditis was the cause of a significant number of patients diagnosed at the time as heart muscle disease of unknown cause, especially among young people below the age of 30 years. At that time, it was only possible to investigate the role of Coxsackie B virus and Toxoplasma gondii in the patients studied, but higher antibody levels were found in the patients compared with control subjects. About 45% of the patients eventually turned out to be hypertensive, implying that myocarditis was playing some part in the genesis of their myocardial damage.

Peripartum cardiomyopathy (PCM)

PCM commonly occurs during the last trimester of pregnancy and the first six months after delivery.

Reports from Haiti have shown that partial improvement of systolic function occurred in the first year of follow up.50 In fact a third of their women with PCM recovered fully within five years. Mortality rates were 15% in the first six months and 42% during 25 years of follow up. The Hausas in the northern part of Nigeria have the highest known incidence of PCM in the world – about 13% of all female admissions at the Ahmadu Bello University Teaching Hospital, Zaria

 

Summary

From all these studies, concludes as follows:

Hypertension contributes to some of the cases diagnosed clinically as DCM in Africa. Such patients should be identified and reclassified as having hypertensive heart failure with varying degrees of myocardial dysfunction.

Chronic alcohol consumption and myocarditis have also been identified as the causes of myocardial damage in some of the patients clinically diagnosed as cardiomyopathy in Africa and even worldwide.

Familial cases of DCM have been described in Africa but limited research has been done on the continent.

Lack of facilities and technical know-how have also made the routine diagnosis of myocarditis in Africa impossible. Many are therefore missed.

Estimation of markers of inflammation such as C-reactive protein, inflammatory markers such as the tumour necrosis factor α, and the plasma marker of apoptosis (Fas/Apo-1) may perhaps help in making a preliminary diagnosis of myocarditis. This needs to be further explored.

Source

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3721909/