Cardiovascular Journal of Africa: Vol 29 No 6 (November/December 2018)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018 364 AFRICA
(all p-values > 0.05). When patients were evaluated in terms of
correlation between acute-phase reactants and repolarisation
indices, including white blood cell count, ESR, PWd, QTd and
QTcd, Tp-e interval, and Tp-e/QT and Tp-e/QTc ratios, we found
no correlation between these parameters (Table 3).
Discussion
This study demonstrated that the P-wave, QTandQTc dispersions,
Tp-e interval, and Tp-e/QT and Tp-e/QTc ratios were increased
in patients with ARC. To the best of our knowledge, this study is
the first to evaluate the parameters of transmural dispersion of
repolarisation of the Tp-e interval, and Tp-e/QT and Tp-e/QTc
ratios in a large number of patients with ARC.
Both the P-wave dispersion and themaximumP-wave durations
are important non-invasive ECG indicators for assessing the
homogenous distribution of sinus node impulses through the
atrial myocardium. These parameters reflect the tendency of the
atrial myocardium to have rhythm disturbances, such as atrial
flutter and fibrillation.10,16,20 Age-related changes in the size of the
heart, electrolyte imbalances, inflammation and distension of the
atria may affect the atrial conduction systems.10,18
In a prospective, long-term, follow-up study, Alp et al.10
demonstrated that PWd was higher in children with acute
RC. They also found a positive correlation between increased
PWd and the severity of valvular involvement. These authors
speculated that PWd can be used as a minor criterion in the
diagnosis of RF using the Jones criteria. Similarly, in our study,
PWd was found to be higher in the RC group. From the present
results, it can be suggested that patients with ARC may be more
susceptible to atrial arrhythmias.
Both QT and QTc dispersions represent the heterogeneity
of ventricular repolarisation.21,22 Several previous studies have
demonstrated that patients with increased QTd were more prone
to ventricular arrhythmias and sudden cardiac death (SCD).18,21
Similar to our results, Polat et al.9 and Alp et al.10 showed that
QTd and QTcd were higher in patients with RC. Additionally,
they reported some cut-off values for predicting RC (> 55 ms
and > 52 ms, respectively).9,10 Although Polat et al.9 observed a
decrease in the PR interval, QTd and QTcd during follow up,
Alp et al.10 did not observe any decrease in the QTd and QTcd
after an acute period of carditis. These results indicate that
the heterogeneity of ventricular repolarisation may increase in
children with RC. The effect of RF on the myocardium may
be permanent, and these patients might be more susceptible to
ventricular arrhythmias, not only during the acute phase but also
during the follow-up period.10
Electrical heterogeneity of the myocardium is well recognised.
The myocardium consists of three distinct myocardial cell
types in terms of trans-myocardial repolarisation: epicardial,
endocardial and mid-myocardial M cells, which have
different electrophysiological properties. 12 The differences in
the repolarisation phases lead to the heterogeneity of trans-
myocardial repolarisation, which causes arrhythmias.23,24 The
action potential of mid-myocardial M cells is longer than
that of epicardial cells. Therefore the earliest completion of
repolarisation occurs in the epicardial cells and represents the
peak of the T wave (Tp), while the completion of mid-myocardial
cell repolarisation represents the end of the T wave (Te).
Recently, the Tp-e interval and Tp-e/QT ratio emerged as
novel non-invasive electrocardiographic markers of dispersion of
ventricular repolarisation.12,19,23 Previously reported studies have
shown a prolonged Tp-e interval and increased Tp-e/QT ratio
in patients with Brugada, long-QT syndrome and myocardial
infarction.23,25,26 Panikkath et al.27 suggested that a prolonged Tp-e
interval and high Tp-e/QT ratio were associated with SCD.
In another study, Lubinski et al.28 showed that patients with
coronary artery disease who have a prolonged Tp-e interval and a
high Tp-e/QT ratio were more prone to ventricular arrhythmias.
Moreover, the Tp-e/QT ratio was found to be a more accurate
indicator of ventricular arrhythmogenesis than the Tp-e interval
and QTd because of its independence from a patient’s heart
rate.12,29 Some researchers have found that both QTd and QTcd
were higher in patients with ARC, and they have also stated that
QTd was associated with the severity of valvular regurgitation. 9
In previously reported studies, increased transmural
dispersion of repolarisation was found to be correlated with
increased inflammatory activity. It was reported that TDR is
increased in patients with ankylosing spondylitis and familial
Mediterranean fever,30,31 however, valvular regurgitation is
the leading determinant of prognosis in patients with ARC.
Myocardial involvement is a well-known manifestation of RC.
Therefore, myocardial involvement may cause the heterogeneity
of repolarisation in children with ARC.
In our study, in addition to the QTd and QTcd, we evaluated
the novel markers of TDR in the Tp-e interval, and Tp-e/QT and
Tp-e/QTc ratios in ARC patients; these parameters were all found
to be higher in the ARC group. To our surprise, we found no
correlation between TDR and the number of valves involved. We
also found no correlation between the acute-phase reactants and
QTd, QTcd, Tp-e interval, Tp-e/QT and Tp-e/QTc. It may be that
the increase in TDR and myocardial involvement occurred as an
all-or-none phenomenon in our patients. Our results indicate that
the heterogeneity of TDR occurs independently from the severity
of acute inflammation and the number of valves involved.
Study limitations
Our study had certain limitations, with the retrospective design
being the primary one. We did not evaluate the correlation
between the degree of valvular involvement and the TDR
parameters. In addition, we could not follow up with the study
population prospectively for ventricular arrhythmic episodes.
Therefore, we could not assess the TDR parameters regarding
future arrhythmic events. Accordingly, although our study is
the first to show increased Tp-e interval and Tp-e/QT ratios in
patients with RC, long-term, prospective follow-up studies are
needed to determine the prognostic value of these parameters in
patients with RC. It is also notable that the ECGs were evaluated
Table 3. Correlation of electrocardiographic findings
and acute-phase reactants
PWd QTcd QTd Tp-e Tp-e/QTc Tp-e/QT
ESR (mm/h)
r –0.04 0.03 0.00 0.07 0.09 0.02
p 0.63 0.70 0.95 0.40 0.28 0.81
WBC (cells/mm3)
r –0.08 0.06 0.04 0.12 0.08 0.12
p 0.33 0.41 0.58 0.14 0.34 0.15
ESR, erythrocyte sedimentation rate; WBC, white blood cell count.