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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 3, May/June 2020
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AFRICA
practices within SHD pregnancies at Groote Schuur Hospital.
Predominant use of a BB type within a subgroup prohibited
analysis of BB subtype effects within each SHD subgroup.
Adverse foetal outcomes that were compared between the
BB-exposed and non-exposed groups included Apgar score,
preterm delivery (
<
37 weeks), LBW (
<
2 500 g) and SGA. SGA
was defined as birth weight under 10% of expected weight for
that gestational age. Variables such as the presence of IUGR
and maternal parameters such as weight gain during pregnancy
were not available for all pregnancies. They were therefore not
incorporated in deciding whether to classify a delivery as SGA,
as this may have affected interpretation of the results, especially
when comparing them with other studies.
No significant differences were noted for all adverse foetal
outcomes when comparing all SHD pregnancies exposed to BB
and those not exposed to BB. Repeating the comparison between
the different subgroups, we found a significant increase in SGA
(
p
=
0.01) and LBW (
p
=
0.003) pregnancies in the BB-exposed
group in the valvular subgroup only. As mentioned before, this
most likely results from the predominant atenolol use within this
subgroup, as well as the principle of confounding by indication.
No bradycardia in foetuses or newborns was documented in the
hospital records of women who had received BB therapy.
Previous studies have shown a significant inverse correlation
between the duration of BB treatment (days) versus the relative
deviation from expected FBW. We had detailed information
regarding days of treatment with BB for 24 patients within our
cohort. For these 24 pregnancies, we found a non-significant
direct correlation (
r
=
0.20), showing that increased duration of
treatment in pregnancy did not significantly correlate with an
increase or decrease in deviation from expected FBW.
It has been previously described that HIV
37
or severity of
cardiac condition
38
in pregnant women may influence foetal
outcome. Despite some interesting tendencies towards an impact
of HIV on LBW or abnormal Apgar scores, non-significant
differences were observed in our cohort. It would appear that
NYHA was not associated with poor foetal outcome.
Limitations and strengths
Limitations for this study include sample size, particularly in the
BB group. Secondly, the principle of confounding by indication
complicates interpretation of results, as pregnancies with more
severe disease are more likely to receive BBs and thereby increase
the probability of an adverse foetal outcome. Multivariate
analysis was not performed and hence we could not delineate
the contribution of several maternal variables to the outcome of
FBW and adverse foetal outcomes. Comparison between studies
is also limited due to the variation in inclusion criteria for the
different SHD subgroups in different studies. Results concerning
BB subtype are mainly applicable in low- to middle-income
countries were atenolol is regularly used.
Despite these limitations, this study addresses a clinically
relevant topic and the information could be very helpful to
obstetricians and cardiology care providers. Indeed, the topic
of BB use in pregnancy in these women deserves attention, and
prospective data are required in this field. Furthermore, most
data about pregnancy in structural heart disease come from
high-income countries, while this is a relatively large cohort from
an (upper) middle-income country.
Conclusion
Use of BBs in a South African cohort of pregnancies complicated
with SHD was found to have no significant effect on the
outcomes of mean FBW and adverse foetal outcomes. The use
of carvedilol, an
α
- and
β
-receptor blocker resulted in a notable
although not significant increase in mean FBW, compared
to SHD pregnancies using atenolol. The results of this study
reiterate the importance of making clinical decisions on an
individual patient basis with careful consideration of both type
of BB and subgroup of SHD being treated.
The authors acknowledge the support of Mrs Sylvia Dennis, Hatter Institute
for Cardiovascular Research in Africa, in final proof-reading and submission
of the manuscript. We also thank the physicians and nurses at the Department
of Cardiology and Obstetrics for their support
.
This research could not have been conducted without the funding support
towards running costs of the Hatter Institute for Cardiovascular Research
in Africa from the University of Cape Town, the Medical Research Council,
South Africa (Grant ID 488000), the National Research Foundation, South
Africa (Grant ID 105867) and the Maurice Hatter Foundation. In addition,
the Hatter Institute received unconditional research grant support from
SERVIER.
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