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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018
AFRICA
363
Apical and parasternal long-axis views were used to assess both
mitral and aortic valve regurgitation.
The revised Jones criteria, which are suggested by the American
Heart Association’s Committee on Rheumatic Fever, Endocarditis
and Kawasaki Disease, were employed to differentiate pathological
valve regurgitation from a normal state on the echocardiographic
examinations. A regurgitation colour jet
≥
2 cm in length for the
mitral valve or
≥
1 cm for the aortic valve, when seen in at least two
planes with a peak velocity of
>
3 m/s and persisting throughout
systole (for mitral valve regurgitation) or diastole (for aortic valve
regurgitation), was considered pathological.
13
All the patients had
moderate to severe carditis.
Oral steroid therapy was started on all patients, regardless of
the severity of the carditis. Prednisolone (2 mg/kg/day) was given
for two weeks and then tapered off. Aspirin was started at 80–100
mg/kg/day (maximum dose 3.5 g/day) to prevent rebound.
The data of 153 gender- and age-matched healthy control
subjects were recorded from the same computerised database.
This study was approved by the local ethics committee.
A standard 12-lead ECG was recorded at a speed of 25 mm/s
and an amplitude of 1 mV/cm while the patients were lying in a
supine position at the time of diagnosis. The ECG measurements
of the PWd, QT, QTc and Tp-e intervals and the calculation of
the QT and PW dispersions and Tp-e/QT were performed by
the same blinded paediatric cardiologist. All durations were
measured manually with calipers and a magnifying glass. The
means of three measurements of the P wave, QT duration and
Tp-e interval were used for further calculations. No significant
discrepancy was present among the measurements. The intra-
observer variance for each measurement was
<
6%.
The PWd was calculated as the difference in duration between
the Pmax and Pmin.
16
The QT interval was determined as
the distance between the beginning of the QRS wave and the
end-point of the T wave with the isoelectric line. The QTc was
calculated according to Bazzet’s formula.
17
In the presence of a
U wave, the end-point of the T wave was accepted as the lowest
point between the T and U waves. Both the QT (QTd) and QTc
(QTcd) dispersions were calculated as the difference between the
maximum and minimum QT and QTc intervals.
18
The means of
three separate measurements were used to calculate the PWd,
QTd and QTcd. The Tp-e interval was measured from the peak
to the end of the T wave. Measurements of the Tp-e interval
were performed from precordial leads. The Tp-e/QT ratio was
calculated from these measurements.
19
Statistical analysis
The SPSS 18.0 package program was used (SPSS Inc, Chicago,
IL, USA) for statistical analysis. The distribution pattern of data
was evaluated by the Shapiro–Wilk test and graphic methods.
Values are expressed as either mean
±
SD, median (minimum
– maximum), or number (percentage) where appropriate. The
Student’s
t
-test was used for normally distributed data. The
Mann–Whitney
U
-test was used for abnormally distributed data.
Notably, for more than two groups, we used one-way variance
analyses and the Kruskal–Wallis test, respectively. Chi-squared
analysis was used for the comparison of categorical variables.
The correlations between parameters were assessed using
Spearman’s correlation test. The receiver operating characteristic
(ROC) curve was applied to detect significant predictor cut-off
values for the presence of myocardial involvement. A
p
-value
<
0.05 was considered statistically significant.
Results
A total of 174 patients were diagnosed with ARC between 2006
and 2016 at our centre. After the cases with insufficient data and
those that did not fulfill the revised Jones criteria were excluded,
the study included 139 patients with ARC. The median follow-
up period was 4.6 years (range: six months to 8.5 years). No
significant arrhythmic events or death were observed either at the
time of diagnosis or during the follow-up period.
The demographic and ECG characteristics of the patients and
healthy controls are listed in Table 1. Eighty-three patients were
male and 56 were female. The mean age of the patients was 10.9
±
2.4 years. The PWd, QTd and QTcd were significantly higher in
patients with ARC compared to the healthy controls (all
p
-values
<
0.001). The Tp-e interval, Tp-e/QT and Tp-e/QTc ratios were
also significantly increased in ARC patients compared to the
controls (
p
<
0.001,
p
<
0.05 and
p
<
0.05, respectively).
A QTd above 55 ms predicted the presence of myocardial
involvement, with a sensitivity of 73% and a specificity of 98%.
Analysis of the ROC curve for the QTd showed an area under
the curve (AUC) of 0.76 (
p
<
0.001) (95% CI: 70–82).
A Tp-e interval above 85 ms predicted the presence of
myocardial involvement, with a sensitivity of 56% and a
specificity of 79%. Analysis of the ROC curve for the Tp-e
showed an AUC of 0.80 (
p
<
0.001) (95% CI: 76–85).
Comparison of the ECG findings of the patients with one-
(mitral or aortic valve) and two-valve (both mitral and aortic
valve) involvement are shown in Table 2. Seventy-nine of the
patients had one-valve and the remaining patients had two-valve
involvement. There was no significant difference between the
two groups in terms of PW and QT dispersions (all
p
-values
>
0.05) and the Tp-e interval, Tp-e/QT and Tp-e/QTc ratios
Table 1. Demographic and electrocardiographic characteristics
of patients with rheumatic carditis and healthy controls
Characteristics
Patients
(
n
= 139)
Healthy controls
(
n
= 153)
p
-value
Age (years)
*
10.9
±
2.4
11.7
±
3.2
Male/female
83/56
73/80
PW dispersion (ms)
#
40 (0–100)
20 (0–80)
<
0.001
QT dispersion (ms)
#
49 (20–100)
30 (10–60)
<
0.001
QTc dispersion (ms)
#
55 (15–120)
45 (5–110)
<
0.001
Tp-e (ms)
*
95.2
±
20
85.7
±
18.7
<
0.001
Tp-e/QTc
*
0.23
±
0.04
0.22
±
0.05
<
0.05
Tp-e/QT
*
0.27
±
0.06
0.26
±
0.06
<
0.05
#
Data are expressed as median (minimum –maximum).
*
Data are expressed as mean
±
SD.
Table 2. Comparison of electrocardiographic findings of
the patients with one- or two-valve involvement
Characteristics
One valve
(
n
= 79)
Two valves
(
n
= 60)
p
-value
Tp-e (ms)
93.5
±
18.1
97.5
±
22.2
0.25
Tp-e/QTc
0.22
±
0.03
0.23
±
0.04
0.43
Tp-e/QT
0.27
±
0.05
0.28
±
0.06
0.38
PW dispersion (ms)
43.2
±
13.8
42.1
±
16.5
0.66
QT dispersion (ms)
48.5
±
15.6
45.5
±
13.9
0.20
Data are expressed as mean
±
SD