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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 3, May/June 2015
122
AFRICA
Tumour dimensions were measured in three different planes.
The maximum diameter in any of the planes was taken as
a reference of the size of the tumour in that plane (Fig. 1).
By calculating the average radius of the tumour in three
different planes, the approximate echocardiographic volume of
the tumour was calculated using the formula 4/3
π
r
3
.
21
Statistical analysis
Statistical analysis was performed using a statistical software
program (SPSS for Windows, version 15.0; SPSS Inc, Chicago,
Illinois, USA). Continuous variables were expressed as
medians (min–max), controlled for normal distribution by the
Kolmogorov–Smirnov test and compared using non-parametric
tests (Mann–Whitney
U
-test) because of abnormal distribution.
Categorical data between two or more groups were compared
with the Pearson
χ
2
test. Pre- and postoperative ECG data were
compared with the Wilcoxon test. A logistic regression analysis
was used to determine significant predictors of postoperative AF
in patients with LA myxoma. A
p
-value
<
0.05 was considered
statistically significant.
Results
The study included 36 consecutive patients with LA myxoma
(10 men, mean age: 49.3
±
15.7 years). The most commonly
reported symptom was dyspnoea, which was observed in 13
patients. Eight patients presented with palpitations, three with
angina, five complained of syncope and seven had a transient
ischaemic attack or cerebrovascular event. Seven patients were
asymptomatic.
The LA myxoma was excised through a left atriotomy in 19
patients, whereas the trans-septal and biatrial approach were
used in the remaining nine and eight patients, respectively. After
removing the mass, the resulting atrial septal defect was repaired
by direct suture in 34 patients and by insertion of a Dacron patch
in two. The tumour volume of the patients ranged from 4.2 to
63.7 cm
3
(mean: 20.3
±
12.7 cm
3
). The tumour volume of those
with cerebral symptoms was significantly higher than in the
other patients (median: 23.1 vs 14.3 cm³,
p
=
0.015).
Ten patients had developed AF after surgery. The
characteristics of the patients are shown in Table 1, while Tables
2 and 3 show their pre-operative electrocardiographic and
echocardiographic parameters. The patients who developed AF
postoperatively were significantly older than those who did not
develop AF (median: 61.5 vs 46 years,
p
=
0.009). Among the
electrocardiographic parameters, only Pd differed significantly
between AF and non-AF patients (median: 57.6 vs 39.8 ms,
p
=
0.004). The LV ejection fraction (median: 62.5 vs 65%,
p
=
0.019)
and mean E/A (median: 0.8 vs 1.3,
p
=
0.05) were lower in the AF
group than in non-AF patients. The tumour volume was similar
in AF and non-AF patients.
The pre-operative and postoperative ECG findings are
listed in Table 4. P-wave amplitude, duration and Pd differed
significantly after the surgical procedure (
p
<
0.001,
p
=
0.001 and
p
<
0.001, respectively).
We modelled a logistic regression analysis to determine
the independent predictors of postoperative AF. Age, LA
dimension, tumour volume, aortic cross-clamping time and Pd
were included in the model. Logistic regression analysis revealed
Pd (OR: 1.11, 95% CI: 1.003–1.224,
p
=
0.043) and age (OR:
1.13, 95% CI: 1.001–1.278,
p
=
0.048) as independent predictors
of postoperative AF in our cohort of patients.
Discussion
This study indicated that postoperative AF may also occur
after the excision of the tumour in patients with LA myxoma.
LA myxomas may cause severe mitral valve stenosis.
22
Atrial
arrhythmias such as AF or flutter may also be identified in
Table 1.The clinical characteristics of the patients
Postoperative
AF group (
n
=
10)
Non-AF group
(
n
=
26)
p
-value
Median Min–max Median Min–max
Age (years)
61.5 42–79
46
20–72 0.009
Body mass index (kg/m
2
)
28.5 20.7–35.1 25.9 17.9–41.1 0.168
Hypertension,
n
(%)
6 (60)
6 (23.1)
0.053
Diabetes,
n
(%)
1 (10)
3 (11.5)
1.00
Hyperlipidaemia,
n
(%)
1 (10)
1 (3.8)
0.484
AF: atrial fibrillation; Max: maximum; Min: minimum.
Table 2.The pre-operative electrocardiographic
parameters of the patients
Postoperative
AF group (
n
=
10)
Non-AF group
(
n
=
26)
p-value
Median Min–max Median Min–max
Heart rate (beats/min)
76.5 64–127 85.5 53–109 0.349
P-wave amplitude (mV)
1.5 0.93–2.72 2.05 0.81–3.64 0.129
P-wave duration (ms)
124 99.6–129.2 112.4 57.6–134 0.069
P-wave dispersion (ms)
57.6 41.2–71.6 39.8 17.2–70 0.004
QTc dispersion (ms)
50
40–100
40 40–130 0.124
Increased P-wave
dispersion (
n
)
10
9
< 0.001
AF: atrial fibrillation; Max: maximum; Min: minimum; QTc: corrected QT
interval.
Table 3.The pre-operative echocardiographic parameters of the patients
Postoperative
AF group (
n
=
10)
Non-AF group
(
n
=
26)
Median Min–max Median Min–max
p
-value
LA diameter (mm)
42
31–51
37
29–60 0.147
LV end-diastolic diameter (mm) 48.5 45–64
48
38–64 0.241
LV end-systolic diameter (mm)
31
23–55
29
23–40 0.107
LV ejection fraction (%)
62.5 30–65
65
50–80 0.019
E/A
0.8 0.67–1.50 1.3 0.6–1.71 0.05
Tumour size (mm
3
)
21.2 9.4–63.7 17.2 4.2–51.3 0.331
AF: atrial fibrillation; E/A: early/late diastolic peak flow velocity; LA: left
atrium; LV: left ventricle; Max: maximum; Min: minimum.
Table 4.The electrocardiographic parameters of the patients
one day before and one week after surgery
Pre-operative
Postoperative
Median Min–max Median Min–max p-value
Heart rate (beats/min)
82
53–127 86.5 64–144 0.606
P-wave amplitude (mV)
1.98 0.81–3.64 1.28 0.64–2.17
<
0.001
P-wave duration (ms)
117.2 57.6–134 98.4 70.8–126 0.001
P-wave dispersion (ms)
50.5 17.2–71.6 30
10–60
<
0.001
P–R interval (ms)
160 110–240 150 90–230 0.063
QRS interval (ms)
90
80–98
90
70–130 0.837
QTc dispersion (ms)
50
10–130
40
10–90 0.437
Max: maximum; Min: minimum; QTc: corrected QT interval.