Cardiovascular Journal of Africa: Vol 28 No 6 (November/December 2017)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 6, November/December 2017 AFRICA 375
Al-Naamani et al.20 showed that ECG abnormalities in V1 were
superior to abnormalities in V5 and V6, possibly due to lower LV
influence in the left precordial leads.
Ahearn et al.23 found that an ECG was not sufficient for
diagnosing PH, although, from all the parameters, QRS ≥ 100°
was the best discriminator and was highly suggestive of RV
enlargement. This was, however, a study on PAH in particular,
therefore not to be extrapolated without caution to PH of
other causes. This emphasises the need to analyse the predictive
values of ECG according to the aetiology of PH. In our cohort,
left heart disease was the aetiology of PH in 46% of the cases.
This could also have influenced the ECG results by possibly
concealing mild right ventricular involvement.
Limitations
Our study has some limitations. First, we acknowledge that the
gold standard for diagnosing PH is right heart catheterisation.
However it is not always accessible or affordable in our setting
and it also has a non-negligible procedure-related mortality
rate and serious-events risk, even in an expert’s hands.24
Doppler echocardiography is a good alternative as it is safe and
non-invasive. Furthermore, the study by Janda et al.25 showed a
good correlation between right ventricular systolic pressure on
echocardiography and pulmonary artery systolic pressure on
RHC at baseline.
Second, other useful ECG parameters for our calculations
were not recorded. These are R in V1 ≥ 7 mm, R in V5 ≤ 5 mm,
R in lead I ≤ 1 mm, S in V1 ≤ 2 mm, R/S in V5 ≤ 1 mm and R in
V1 + S in V5 ≥ 10 mm. These have previously been shown to have
a good positive predictive value,20 and including them in a future
study may add to the value of an ECG for screening. Other studies
on PH from China and America26,27 found that prolonged QRS
and QTc durations were associated with impaired right ventricular
function and the prediction of adverse outcomes in PAH.
Third, the small number of participants with PH most likely
affected our capacity to detect significant findings. Lastly, the
cardiac disease-free sub-group in this study was an external
cohort in whom the echocardiographic assessment ruled out
only cardiac disease and PH. This, in turn, could have resulted in
differences in case-mix and affected the diagnostic performance
of ECG abnormalities for PH.
The strengths of this study include the rigorous approach to
ECG interpretation and data analysis, and that the data were
derived from the first multicentre study of PH across Africa,
where the burden of the condition is increasing.
Conclusion
ECG abnormalities are common in African patients with PH,
but those relating to RV strain specifically are less frequent.
When present, ECG features suggestive of PH strongly indicate
the disease, but a normal ECG does not rule out disease. The
presence of QRS right-axis deviation of ≥ 100° and/or R/S ratio
in V1 > 1 or R wave in V1 > 7 mm had good specificity and
therefore warrants further investigation with echocardiography.
Innovative measures in electrocardiography are required to
improve the diagnosis of PH in SSA. This could include
studies combining ECG with echocardiography, clinical criteria
and cardiac biomarkers to better define the criteria for early
diagnosis of PH without exposing patients to unnecessary and
costly right heart catheterisation in resource-limited settings.
Our sincere appreciation goes to the entire PAPUCO study investigators for
their efforts in creating and keeping the PH registry. We are grateful to the
patients who participated.
The study and the publication were partly funded by the Pulmonary
Vascular Research Institute, Bayer Healthcare, and the Maurice Hatter
Foundation and the Non-Communicable Disease Research and Leadership
programme of the National Institute of Health, University of the
Witwatersrand, Johannesburg, South Africa.
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