Discussion:
In the current study, systolic and diastolic dysfunctions determined by
echocardiographic parameters were found similar with the healthy
subjects. However, TD evaluation showed significant myocardial
dysfunction. Although various studies declared that global cardiac
functions were reserved and evaluated as normal by conventional
echocardiographic findings in thalassemia major, regional wall
abnormalities were shown by TD measurements.8,9,11-13
When we measured Em, Am and Sm velocities from three different regions
of the myocardium, only Sm velocity were found significantly impaired in
left ventricular and septal walls compared to the controls. However,
these velocity measurements were not different from the controls in the
right ventricular wall (p>0.05). This result showed that
systolic functions in the left ventricle and septum were impaired in our
patients. In addition to that, in the septal region Am velocity was
different from controls. Agha et al.14, Yüksel et
al.15, Balcı et al.16 and Ragap et
al.17 were found only diastolic dysfunction according
to velocities. But the another studies were found both diastolic and
systolic dysfunctions.8,18-20 Interestingly Marci et
al.21 were found Sm abnormalities, and ıt was
correlated onset of adverse cardiac event. Mean age was 32 in this
study. Although we found normal functions of the right ventricle,
according to velocities, abnormalities were detected in the other
studies.13,14,16,19 These studies were not same and
there were many differences between them. For example; age groups
studied, measured areas and TD parameters evaluated were different. In
addition, some studies were correlated the results with BNP, ferritin or
T2* MRI. Since the studies are not homogeneous, it is difficult to
compare with each other.
In our study, we evaluated not only Em, Am and Sm velocities, but also
time intervals such as ET, IVRT and indexes such as MPI and IVA. Limited
data was found evaluated time intervals and
indexes.17,20,22 Arı et al.20 found
IVCT abnormality in left ventricle and septum, but ET, MPI and IVRT were
normal. Uçar et al.22 found MPI and ET abnormality
three different area, but IVRT was normal in the septum. Ragap et
al.17 found MPI, ET and IVRT abnormality in the septum
and lateral wall. These studies’ mean ages were under our study. We
found MPI abnormality in the all three area, ET was only abnormal in the
left ventricle. IVRT abnormality was found in left and right ventricle.
We found a negative correlation between MPI-septal and T2*MRI scores
(r:-0.343, p=0.05, Figure 2). In the Uçar et al.22study, MPI was found correlate BNP, but not was used MRI, and they
reported that MPI was important for seeking early impairment. Also Arı
et al.20 found correlation with MPI and T2* MRI result
in the iron overload group. We found another positive correlation in the
iron overloaded group was ET-septal and MRI results.
In the current data, we calculated IVA index. This parameter was very
important in determining myocardial acceleration during isovolumetric
contraction (early systolic phase) which was resistant to physiologic
load changes.10 Our study was the second study
evaluating IVA in thalassemia patients. Cheung at
al.23 found similar IVA compared with controls in the
resting, but during exercises, changes in the IVA was found low from
controls. It was showed impaired contractile reserve in this patients.
All of them had no cardiac co-morbidities, no Arrhythmias or bundle
branch block. Like MPI, we found IVA abnormalities in all region, and in
non iron-loaded patients compared with controls.
In thalassemia patients, the mean T2*MRI scores did not change according
to serum ferritin levels (p>0.05). Neither TD nor T2*MRI
measurements were correlated with serum ferritin level
(p>0.05). Various studies also supported this finding that
serum ferritin levels in thalassemia patients were not a reliable marker
in estimating myocardial iron overload.3,18,22
We compared with according to T2*MRI result, only MPI-septal measurement
was different between iron load or non-load group. There are a limited
number of studies to evaluate comparisons. Arı et
al.20, found Sm, Em and Am abnormalities in the left
ventricular wall and detected Sm, MPI and IVCT abnormalities in the
septal wall between iron load and non-load group. Agha et
al.14 evaluated only velocities from three region and
found tricuspid annular A and E/A abnormalities between iron load and
non-load group. Vogel et al.8 was found 87% wall
motion abnormalities in patient with T2*MRI<20 ms, versus
found 35% wall motion abnormalities in patient with T2*MRI≥20 ms.
In our study, the septal measurements of Sm, Am and Em velocities, MPI,
ET, IVRT were found similar with the controls in thalassemia patients
with non-load group (T2*MRI≥20 ms.). Interestingly, when they were
measured from left and right ventricular walls, they were found
significantly impaired compared to the controls (Table III). When we
searched the literature, only Agha et al.14 evaluated
velocities from three region and found tricuspid annular A´ and E´/A´
abnormalities between non-iron load and control group. But there was no
data comparing TD time intervals or indexes between healthy subjects and
non-iron overloaded thalassemia patients. This patients who are T2*MRI
result is ≥20 ms are usually considered as patients with no cardiac
complications. T2* MRI shows myocardial iron load measured from septal
region.4 Iron accumulation and its toxic effect are
not evenly distributed in myocardium, regional differences can
occur.24-26 Our data determined that only T2*MRI
evaluating was insufficient to cardiac status in this group. Therefore,
we strongly suggested to obtain TD measurements from right and left
ventricular walls in thalassemia patients with T2*MRI≥20ms especially
elder patients.