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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 1, January/February 2016
42
AFRICA
values were significantly improved during the later period
compared to the early period.
TAPSE is easily obtainable and is a measure of RV
longitudinal function.
13
The preferred method to evaluate RV
systolic function is often TAPSE, which is known to correlate
with RVEF.
24
TAPSE
>
15 mm is reported to substantially
decrease mortality rates.
14,25
As Hayrapetyan
et al
. have shown,
TAPSE
<
14 during the 24 hours following RV-STEMI is
associated with a poor prognosis.
26
In our study, mean TAPSE
values were improved at the one-month follow up in both groups.
Mean TAPSE was similar between the groups in the early period
and at the one-month follow up.
RV-S
′
is a very reliable and easily measured parameter
in young adults. However, it may fail to fully reflect systolic
function in the elderly. It can be measured from the tricuspid
lateral annulus by means of tissue Doppler. RV-S
′
<
10 cm is
associated with RV systolic dysfunction.
13,23,27
In our study there
were no significant differences between the groups in the early
period and at the one-month follow up according to mean RV-S
′
.
It was significantly improved in the intra-group changes during
these periods.
Assessment of RV function using conventional echo-
cardiography is challenging due to the complex geometry of
the RV and the predominantly longitudinal orientation of its
myofibrils.
28,29
Therefore, we used a novel technique, 2D-STE,
which is a sensitive, quantitative measure of contractility,
emerging as a potent measure of RV function that can determine
RV systolic dysfunction.
30,31
Strain can be decreased even in
the setting of normal contractility if regional or global stress
such as afterload is elevated. This is even more pronounced
in the setting of RV circulation, which is especially sensitive
to afterload elevation and may be useful for evaluating subtle
changes compared with other conventional echocardiographic
techniques.
13
Peak RV longitudinal strain, which quantifies the maximal
shortening in the RV free wall from apex to base, is likely to
be a good estimator of RV function because 80% of the stroke
volume is generated by longitudinal shortening of the RV free
wall.
32
In our study RV-free-S and RV-free-SR means were
similar in the early period. Mean regional and mean RV free-
wall strain/strain rates observed at the one-month follow up were
significantly increased compared to the pre-PCI period within
each individual group.
According to conventional methods, sensitive changes in
RV circulation can be detected earlier with 2D-STE.
33
Since
evaluation of the RV with conventional echocardiography after
acute MI is not always possible, 2D-STE may be useful in this
regard.
RV dysfunction is an independent predictor of adverse
prognosis after acute MI. The involvement of the RV during
inferior acute MI has been defined as a strong predictor of
morbidity and in-hospital mortality.
7,8
Previous studies described
proximal RCA occlusion compromising flow to the major RV
branches as the most common anatomical substrate for RV
dysfunction.
34-36
However our study confirmed that the location
of the proximal RCA lesion was similar between the study
groups.
In the study by Mehta
et al
., post-PCI, TIMI 0–2 flow rate
was reported as 14.7%.
37
Brosh
et al.
reported TIMI 0–1 flow
rates as 6.7%.
38
In the study by Henriques
et al
., however, no
reflow was 11%.
39
Although initial TIMI 0, TIMI 1–2 and
TIMI 0–2 flow rates were 1.9, 6.2 and 8.1%, respectively in our
study, similar results to these studies are available. There was no
statistical difference between the groups in terms of TIMI flow
rates.
In a recent study, ventricular tachycardia (VT) and fibrillation
rates were higher in the TT group. Patients were monitored
by event recorder monitors in the intensive care unit and
service follow ups. Therefore, reperfusion arrhythmias such as
accelerated idioventricular rhythm were excluded in the VT
evaluation. The rates given in the tables were documented from
the time of admission to hospital until discharge. However
re-MI, re-hospitalisation and mortality rates were similar in both
groups in hospital and at the one-month follow up.
Patients should be revascularised as early as possible in order
to minimise potential complications following RV-STEMI. RV
function may recover within days or weeks, especially after
successful reperfusion.
40-43
The findings of our study demonstrated
similar improvement in RV dimensions and volumes among
patients treated with PPCI, or PCI within three to 12 hours
after TT. This results from the rapid improvement in RV systolic
function once revascularisation is achieved. Both the PPCI and
TT groups exhibited near-normal values for the parameters at
the one-month follow up compared to at admission.
Limitations of the study
The main limitation of this study is its relatively small sample
size. Our study included the in-hospital and one month after
RV-STEMI periods only, and may therefore have failed to capture
differences in relevant parameters. For this study, a group had
been planned to include patients undergoing PCI within 12 to 24
hours of TT; however, the number of patients revascularised at
our centre during this time period was insufficient for statistical
analysis.
Because the patients in the TT group had been referred
from external centres, echocardiographic evaluation prior to
thrombolytics was not possible. Therefore theRV systolic function
determined in the TT group may have been overestimated.
RV strain was assessed by 2D speckle-tracking
echocardiography software, which has been developed mainly
for LV strain. However, investigators demonstrated that the
reproducibility of RV strain was acceptable using a speckle-
tracking programme for LV strain.
Moreover, RV septal and RV free wall were not separately
evaluated during the RV strain analysis. However, previous
studies suggested that RV septal strain showed no association
with RV functional parameters. A possible explanation is that
current speckle-tracking software cannot accurately separate LV
septal from RV septal components, because the latter includes
both RV and LV functional components.
In our study, we could not evaluate 2D-derived estimation
of RVEF because of the heterogeneity of methods and the
numerous anatomical assumptions. We did not have 3D software
during the study period.
Conclusions
Our study included inferior STEMI with RV involvement alone.
RV function, which evaluated conventional and RV strain/strain