Cardiovascular Journal of Africa: Vol 30 No 3 (May/June 2019)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 3, May/June 2019

AFRICA

159

score

≤

22 (15/23, 65.2%), predicting a good prognosis for

percutaneous coronary intervention (PCI).

Patients with an abnormal coronary angiogram were older

than those with normal coronary arteries (55 and 51 years,

respectively,

0.06), with no statistically significant difference.

Hypertension (

0.0001), concerning both systolic and diastolic

blood pressure, and diabetes (

0.0003) were more commonly

found in patients with an abnormal coronary angiogram,with a

statistically significant difference (Table 1).

Repolarisation disorders (

0.003) were more commonly

reported in patients with abnormal coronary exploration,

with a statistically significant difference. Transthoracic

echocardiography more frequently showed regional wall-motion

abnormalities in patients with an abnormal angiogram, but with

no statistically significant difference (

0.07).

Discussion

In our series of patients with DCM, coronary angiography

was abnormal in 34.3% of cases. Of these patients, 23 had

obstructive CAD, or 21.3% of our sample. Studies conducted

in the West on the aetiology of HF emphasise significantly

different outcomes from those conducted in sub-Saharan Africa.

In the United States, according to the ADHERE registry, CAD

accounted for 57% of the causes of HF.

The EHFS registry in

Europe reported 54% of ischaemic heart disease among 3 580

patients with HF.

In a previous systematic literature review,

the prevalence of CAD in black African patients with HF was

10%, contrasting with more than 50% in Europe and North

America and approximatively 30–40% in East Asia. These high

rates reported in developed countries are not only correlated

with the increased incidence of CAD, but also with the increased

provision of care in interventional cardiology.

The number of activities carried out by healthcare centres

in the West has risen exponentially in recent decades.

13,14

Furthermore, non-invasive imaging methods for aetiological

screening of DCM are routinely performed in wealthy countries

in HF patients.

Gaps in accessibility of imaging techniques

between developed countries and sub-Saharan Africa readily

explain contrasting findings in the aetiology of HF and DCM.

In sub-Saharan Africa, where the emergence of CAD is well

established,

16-18

there is still a low rate (7.7%) of ischaemic heart

disease, as demonstrated by the THESUS study.

Data from

this registry indicated 18.8% incidence of idiopathic DCM.

This low rate for ischaemic heart disease of 7.7% is likely to

be underestimated due to lack of diagnostic tools for detecting

coronary heart disease in sub-Saharan African countries. There

are few centres for performing coronary angiography.

In the THESUS study,

patients included from Kenya were

likely to have ischaemic heart disease, and in South Africa it

was the second leading cause of HF. Both these countries have

cardiac catheterisation laboratories.

17-18

Few other countries

across sub-Saharan Africa have interventional cardiology

facilities with routine procedures, including Sudan,

Nigeria

and Senegal.

This lack of diagnostic tools includes not only

catheterisation laboratories, but often basic diagnostic tests and

first-line therapies for HF.

To the best of our knowledge, this is the first study reporting

coronary angiographic aspects in DCM in sub-Saharan Africa.

These observations should draw our attention to the possible

ischaemic origin of DCM, which has long been associated with

an idiopathic origin. They should also lead us to assess the

coronary anatomy as soon as the diagnosis of DCM is made. In

our context, only coronary angiography can help in the detection

of CAD. Guidelines emphasise the use of invasive coronary

angiography as a diagnostic tool in patients with HF and angina

pectoris or symptomatic ventricular arrhythmias (class I, level

C), or in patients with intermediate to high pre-test probability

of CAD (class IIa, level C).

In developed countries, coronary computed tomography (CT)

scanning is gaining increasing importance for this indication,

although coronary angiography is still performed. Some expert

consensus recommends using coronary CT scan for detection of

the ischaemic aetiology of cardiomyopathies.

The benefit of

coronary CT scan is its very strong negative predictive value.

Magnetic resonance imaging also provides high-quality

functional information and, above all, myocardial tissue

characterisation. The analysis of the so-called ‘late-enhancement’

sequences after gadolinium injection may reveal sequelae of

myocardial infarction.

These examinations are not commonly

feasible in our current practice.

The median age of our study population was similar to that

observed in some African studies, where an average age of 55

years was reported.

25,26

Our patients were relatively younger

than those of European (72 years)

or North American (70

years) studies.

Rapid and uncontrolled urbanisation and

lifestyle changes

in the context of inadequate preventative

medicine expose a young population

to the manifestation

of cardiovascular diseases, especially CAD. Ischaemic heart

disease is now the third leading cause of death in developing

countries,

therefore increasing the burden of low-income

countries, which also have to deal with uncontrolled infectious

and nutritional diseases.

Patients with abnormal coronary exploration were older than

those with normal coronary arteries, but with no statistically

significant difference. The proportion of patients at

20% risk

of ischaemic heart disease within 10 years increased with older

age,

and ranged from 10.8% in those between 60 and 69 years

to 22% in those between 70 and 79 years.

Hypertension (86.5%,

0.0001) and diabetes (27.0%,

0.0003) were significantly more frequently found in patients with

coronary artery anomalies. In the case of DCM, these strong risk

factors for coronary heart disease should be an indication for

early coronary anatomy assessment. Active smoking, although

Table 4. Severity of coronary narrowing lesions

Severity of lesions

Number (

56) Percentage (%)

Type-A lesions

25.0

Type-B1 lesions

26.8

Type-B2 lesions

23.2

Type-C lesions

25.0

Table 3. Location of lesions observed in patients with obstructive CAD

Location of lesions

Number (

56) Percentage (%)

Left main

1.8

LAD

53.6

19.6

RCA

25.0

CAD: coronary artery disease, LAD: left anterior descending artery, CX: left

circumflex artery, RCA: right coronary artery.