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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 1, January/February 2017
AFRICA
11
notable exceptions. Firstly, PPCM occurred at a relatively young
age in our study. Traditionally, it was generally accepted that
PPCM occurred with greater frequency in older compared to
younger women. In the United States for example, the mean
age of patients who develop PPCM is between 27 and 34 years,
with the majority of studies reporting a mean age of more than
30 years.
17
In the South African cohorts the mean ages ranged
from 29 to 31.6 years.
17
By contrast, the Zimbabwean cohort had
a mean age of 27.9 years with the majority of patients (67.4%)
being younger than 30 years.
Low socio-economic status and poverty have been consistently
linked to younger maternal age.
18
In Zimbabwe the demographic
health survey of 2010 to 2011 showed that the median age for
women at marriage was 19.7 years and the median age at first
birth was 20.2 years.
19
This may account for the younger age at
presentation of women with PPCM in this cohort.
Secondly, the proportion of patients in their first pregnancy
(34.9%) was higher than in most previously published reports. A
case in point is the original report by Demakis, which showed
that 29% of patients had a parity of either one or two.
5
In more
recent times, 24% of patients from the Haitian and 20% from
a South African cohort were primigravidas.
13,20
The reasons for
the relatively high proportion of primigravida women in this
Zimbabwean cohort is not yet established. It could be due to
the relatively large number of young primigravida women in
the Zimbabwean population in general. However, Elkayam
et
al
. also reported a higher proportion of primigravidas (37%)
in patients from the USA comprised predominately patients of
white or Hispanic ancestry (77%).
21
Lastly, a relatively large proportion (34.9%) of patients
in the current study was diagnosed with pregnancy-induced
hypertension (PIH). This figure is much higher than other
studies of black patients from Haiti and South Africa, where the
proportion of patients with PIH was reported to be 4 and 2%,
respectively.
13,14
This is most likely due to the fact that in the three
series of patients with PPCM reported by Sliwa and colleagues in
South Africa, patients with pre-eclampsia and ‘hypertension of
any degree greater than mild’ were excluded from the diagnosis of
the condition.
7,11,20
This is in contrast to the Zimbabwean cohort in
which patients with the whole spectrum of hypertensive disorders
of pregnancy were included. However the proportion of patients
diagnosed with hypertensive disorders of pregnancy was reported
to be higher in the United States.
22
Women with the whole
spectrum of hypertensive disorders of pregnancy were included
in the systematic review by Bello
et al.
22
Therefore patients who
develop PPCM in Zimbabwe are younger, of lower parity and
have a history of gestational hypertension when compared with
patients of a similar ethnic background.
Previous studies of PPCM have reported a mixed prognosis
for the condition. Data from the United States showed that
left ventricular function improved in 35 to 62.2% of patients
with PPCM, with most patients recovering within the first six
months, although some took up to two years to recover.
17
The
mortality rate in the United States ranged from 1.36 to 18%
over variable periods of time.
17
These studies enrolled mainly
Caucasian patients and it was noted that black women had
poorer outcomes. In the Haitian study, the rates of recovery
were very low with only 24% of women achieving a normal left
ventricular function after 2.2 years of follow up. The mortality
during the same period of time was 15%.
13
The result was
supported by data from South Africa, which showed that 21 to
23% of patients achieved normal left ventricular function within
six months of diagnosis, and between 10 and 27.6% of patients
died within six months.
7,11,20
In this Zimbabwean cohort, 42.9% of
patients had normalised left ventricular function by six months
of follow up, with an overall absolute mean change in ejection
fraction of 15.2
±
13.9%. The mortality rate was 11.9%. This is
more comparable to figures seen in the Western world where the
majority of patients were Caucasian.
There could be several reasons for the better outcome in
Zimbabwean patients when compared to patients of similar
ethnicity. First, the patients enrolled in the current study were
not as sick as patients in the South African and Haitian studies.
Only 46.5% of the patients from Zimbabwe had an NYHA
functional class of III/IV compared to 69 to 98% of South
African and Haitian patients at enrollment. Although not
validated, it has been suggested that NYHA functional class
could be an independent predictor of left ventricular recovery
and is a validated predictor of prognosis.
23
LVEF at baseline has also been proposed as a predictor of
left ventricular recovery and mortality.
6
However six-month
mortality rates in the Zimbabwean cohort were relatively low
compared to other South African studies, even though the
baseline LVEF of the Zimbabwean cohort (29.7
±
9.8%)
was comparable to that of the South African cohorts, which
had baseline ejection fractions of between 25 and 30%.
6,7,11,20
Mortality rates were also higher in Haitian patients, even though
left ventricular function was comparable between Haitian and
Zimbabwean PPCM patients (fractional shortening 15 vs 14.3%,
respectively).
24
LVEF also improved by a similar magnitude in all
the studies. For example, at the end of six months of follow up,
LVEF in the South African patients had increased to between
42.1 and 44.1%,
6,7,11,20
compared to 44.9% in the Zimbabwean
patients. However NYHA functional class at baseline has been
shown to more consistently predict mortality in patients with
PPCM.
6,7,25
The baseline NYHA functional class of patients in
the Zimbabwean cohort was lower than that in South African
studies.
It has been proposed that patients with hypertensive disorders
of pregnancy should be excluded from the definition of PPCM
because cardiac dysfunction may be a result of the underlying
hypertension rather than a primary cardiomyopathy resulting
from the pregnancy.
26
Hence series of supposed PPCM patients
that include women with hypertensive disorders of pregnancy
may have a better prognosis and report better outcomes than
series that do not. This is because good left ventricular recovery
by six months may be less likely to happen in patients with true
PPCM.
Although this view may hold true in some cases, it does not
make for a strong argument in all cases of PPCM. Other factors
such as higher LVEF, smaller left ventricular dimensions at
baseline and even Caucasian race may lead to faster recovery
of left ventricular function. In addition, this current group
of patients was not hypertensive on enrolment, with a mean
systolic blood pressure of 117.4 mmHg and mean diastolic blood
pressure of 73.1 mmHg. Furthermore, most patients developed
symptoms an average of five weeks after delivery, by which time
their blood pressures were back to normal.
The degree of recovery of left ventricular function, as measured
by the mean LVEF at six months, was similar in South African