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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 1, January/February 2019
62
AFRICA
Aetiologies of PH differ between high- and low-income nations,
but left heart disease (LHD) has progressively been credited to be
the most common cause of PH in contemporary clinical settings.
4,5
Despite these improvements in understanding PH aetiologies,
the condition is still diagnosed at an advanced stage in a
significant proportion of patients, due to poor medical awareness
and the paucity of symptoms in the early stages of the disease.
6
This has negative impacts on subsequent quality of life and
survival.
7
The American College of Cardiology/American Heart
Association
8
and the European Society of Cardiology/European
Respiratory Society
7
guidelines have each provided a regularly
updated diagnostic algorithm, based on prevalent aetiologies
of PH as well as availability of several diagnostic tests, and
especially, RHC in high-income countries.
This algorithmmay not apply or may be difficult to implement
in low-income countries where human and financial resources
more than just science often influence the diagnostic approach.
In sub-Saharan Africa (SSA), given the additional high and
increasing prevalence of chronic and endemic risk factors of PH,
which are almost specific to the region, such as chronic infectious
diseases (HIV, tuberculosis and schistosomiasis), hypertensive
heart disease, peripartum cardiomyopathies and rheumatic
heart disease,
9
a clear diagnostic approach to PH due to LHD
(PHLHD) is of particular importance. Furthermore, the high
cost, low availability and scarcity of expertise for RHC limit its
utility in this part of the world and justify the interest in a more
pragmatic algorithm.
Based on the experience and evidence from the Pan-African
Pulmonary Hypertension Cohort (PAPUCO) study, we
previously developed an algorithm,
10
and herein suggest a four-
step diagnostic approach for PHLHD in low-resources settings.
These steps include (1) clinical evaluation to detect predisposing
conditions for PHLHD, (2) assessment with chest X-ray (CXR)
and electrocardiogram (ECG) to uncover the presence of
PHLHD, (3) confirmation of the presence of PHLHD using
Doppler echocardiography (echo), and (4) exploration of
differential aetiologies of PHLHD and classification of the type
of PH.
Step 1: clinical evaluation and detection of a
predisposing condition
Data from the PAPUCO study
11
showed that PH should be
suspected in any African patient with otherwise unexplained
shortness of breath, fatigue, palpitations, cough, dizziness and/
or signs of right ventricular dysfunction and right heart failure.
Two-thirds of patients are likely to present in World Health
Organisation functional class (WHO FC) III or IV and one-third
may not walk further than 300 metres on a six-minute walk test.
Clinical examination may reveal a systolic murmur (57%) or a
loud P2 (41%). These clinical observations are largely similar for
men and women.
In the presence of these symptoms, clinicians should actively
inquire about predisposing conditions, which in the SSA context,
include hypertension (42%), previous or concurrent tuberculosis
(22 and 5%, respectively), indoor cooking/heating without
a chimney (32%) and HIV infection (22% overall). In the
PAPUCO study, there were no significant differences in the
risk-factor profiles of men and women besides exposure to
indoor cooking/heating without a chimney (more women),
history of smoking (more men) and alcohol abuse (more men).
Also, although being a traditional risk factor for PH, the
endemicity of schistosomiasis was only related to one case. In
some predisposing groups, such as sickle cell disease, PH signs
and symptoms may often be subtle and may not be apparent for
months as they are generally non-specific.
When the clinical evaluation is not suggestive of PH, the
clinician should search for other causes of symptoms (e.g.
tuberculosis, chronic pulmonary disease, LHD, malignancy). On
the other hand, as shown in Fig. 1, when step 1 is suggestive of
PH, the patient should systematically undergo step 2, non-invasive
investigations, which should include a CXR and ECG.
Step 2: the role of chest X-ray and electrocardiogram
Chest X-ray
In SSA where pulmonary tuberculosis and HIV-associated
chronic lung diseases are common (e.g. recurrent pneumonia,
pneumocystis pneumonia), CXR allows moderate to severe
lung diseases to be reasonably excluded but also, abnormalities
on CXR are frequent in PHLHD and after completion of TB
treatment. In the PAPUCO registry, 59% of patients presented
with cardiomegaly and 22% had prominent pulmonary arteries
(Fig. 2A).
Other findings supportive of underlying cardiac disease
include left atrial enlargement, mild to moderate pleural effusion
and cephalisation. In other circumstances, the presence of
central pulmonary arterial dilatation, which contrasts with
‘pruning’ (loss) of the peripheral blood vessels, is very suggestive
of PH. Right atrial and right ventricular (RV) enlargement may
be seen in more advanced cases.
Electrocardiogram
The diagnostic utility of ECG in patients with PH was
investigated in a sub-study of the PAPUCO registry.
11
Our
findings demonstrated that a normal ECG is very rare among
patients with PH. Sinus tachycardia and left ventricular strain
pattern were observed in around one-fifth of cases (Fig. 2B),
but PH-specific abnormalities such as p-pulmonale (14%)
and evidence of right ventricular hypertrophy (19%) were
documented in less than one-quarter of cases.
The sensitivity of ECG criteria for right heart strain ranged
between 6.2 and 47.7%, while specificity ranged between 79.3
and 100%. Negative predictive value ranged between 81.5 and
88.9%, and positive predictive value between 25 and 100%.
Positive predictive value was lowest (25%) for right bundle
branch block and QRS right-axis deviation (
≥
100°) and highest
(100%) for QRS axis
≥ +
100°, combined with R/S ratio
≥
1 or R
in V1
>
7 mm.
In short, signs involving PH on ECG were highly indicative of
disease, but a normal ECG would not exclude disease. Because
ECG patterns focusing on the R and S amplitude in V1 and
right-axis deviation had good specificity and negative predictive
value, their presence should trigger further investigation with
Doppler echo (Fig. 1).
Step 3: the key role of Doppler echocardiography
A transthoracic Doppler echo examination is the next and most
appropriate course of study. Doppler echo provides several