CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 9/10, October/November 2013
AFRICA
353
Discussion
In this study, the CCAs identified were mostly benign and mostly
found in asymptomatic patients. Coronary anomalies are the
second most common cause of sudden death in young adults.
4
Determination of the incidence and presentation of high-risk
CCAs is important. Most of our knowledge on the incidence and
presentation of CCAs comes from a highly selected and biased
population of patients undergoing invasive coronary angiography.
Although conventional coronary angiography is the gold
standard for diagnosing CCA, its invasive nature, the difficulty
in selective intubation of anomalous coronary arteries, and
understanding the complex nature of the anomalous vessels during
the procedure
15-17
prevent its common usage to diagnose CCAs,
especially in asymptomatic patients. Therefore conventional
angiography may not be a true reflection of CCA incidence
and presentation. MSCT, on the other hand, is minimally
invasive, provides excellent temporal and spatial resolution, and
has therefore recently become increasingly attractive for the
diagnosis of CCAs.
MSCT studies, including our study, have reported higher
incidence rates compared with conventional invasive angiography
studies (1.3%) (Table 4). This may be related to increased
diagnosis of CCA with MSCT compared with conventional
angiography,
18,19
or it may be due to the study groups used.
For example, when compared with conventional angiography,
MSCT studies include more asymptomatic patients. A study
by Cademartiri
et al
. included 49.7% asymptomatic patients.
19
In a study by Girzades
et al
., 21.4% of patients with CCA and
MB were asymptomatic.
20
Similarly, our study included more
asymptomatic (69.92%) than symptomatic patients. Recruiting
asymptomatic patients in MSCT studies could be responsible for
the apparent increased incidence of CCA.
In previous studies, right dominance has been the most
common dominance. Similarly, the results of our study indicated
right dominance in the majority of our patients (75.5%), but
balanced dominance (14.1%) in our study was slightly higher
than reported in previous studies (4.2–7%).
19,21
Lack of consensus
on the definition of a co-dominant coronary artery system
may explain this discrepancy. We defined co-dominance as
origination of the posterior descending artery from the RCA
and the posterior left descending branch from the CFX, which is
similar to most other studies.
22
However, some authors describe
co-dominance with regard to the artery supplying the infero-
lateral portion of the posterior septum. These authors state that if
both arteries supply this portion of the septum, the system should
be referred to as co-dominant.
23
In our patient group, the detected CCAs accepted as benign,
as in previous studies,
19-21,24,25
were as follows: the conus artery
separately arising from the RCS, an absence of the left main,
superior RCA, posterior RCA and CFX, arising either from the
RCS or RCA.
26
It is important to diagnose a CFX originating
from the RCS or RCA before valve surgery so as to avoid
damage during cardiac surgery.
27
In addition, although a superior
RCA has generally been accepted as a benign anomaly, some
cardiac events caused by this anomaly have previously been
reported.
28
A coronary artery aneurysm is a localised dilatation of the
coronary artery exceeding the diameter of the adjacent normal
segment by 50%,
29
and is generally caused by atherosclerosis.
With MSCT, Adreini
et al
. found 30 aneurysms among 2 757
patients.
21
Individual aneurysms were observed in 19 of the 30
aneurysms, and the other 11 aneurysms were in the same patient.
In our study, we found one aneurysm in the right ventricular
branch of the right coronary artery, most likely caused by
atherosclerosis, which was found in all the coronary arteries. The
size of the aneurysm was small so medical therapy was chosen.
Erol
et al
. reported seven cases with fistulae (0.33%
incidence).
25
The fistulae were between the coronary and
pulmonary artery (four cases), between the sino-atrial node
artery and the left atrium (two cases) and between the right
ventricular branch artery and the left ventricle (one case).
When the Qp/Qs ratio is
≥
2.0, surgical correction should be
considered for coronary artery fistulae.
30
Our patient had severe
atherosclerosis in all the coronary vessels, which appeared to
be the cause of the fistula. In this patient, the feeder vessels
originated from both the LAD and RCA, and the ratio of total
pulmonary blood flow to total systemic blood flow (Qp/Qs) was
approximately 1. Therefore, medical therapy was chosen.
Myocardial bridging is when a segment of a coronary artery
is covered by a bridge of myocardium. The reported incidence
is between 28.7 and 58%.
31,32
In our study, the incidence of
MB was 19.1% and was mostly observed in the LAD artery
(93.7%,
n
=
134). In most patients, myocardial bridging has an
TABLE 3. MYOCARDIAL BRIDGING
Number
Incidence (%) Anomalies (%)
LAD
134
17.98
93.70
IM
2
0.26
1.39
OM1
2
0.26
1.39
OM2
1
0.13
0.69
D1
1
0.13
0.69
D2
1
0.13
0.69
RCA
1
0.13
0.69
LAD: left anterior descending artery; IM: intermediary artery; OM1: first
obtuse margin artery; OM2: second obtuse margin artery; D1: first diago-
nal artery; D2: second diagonal artery; RCA: right coronary artery sinus;
MB: myocardial bridging.
TABLE 4. STUDIES EVALUATING CORONARYANOMALIES USING 64-MSCT
No.
patients
Incidence
(%)
Absence
LMA (%)
CFX from
RCS/RCA (%) MB (%)
Fistula
(%)
Aneurysm
(%)
Conus from
aorta (%)
Right domi-
nancy (%)
Superior
RCA (%)
Cademartiri
et al
.
19
543 18.4
3.3
0.55
10.9
0.5
1.6
11.6
86.6
NA
Kosar
et al
.
24
700
3.9
0.4
0.1
37
NA NA 22
76
0.1
Girzadas
et al
.
20
446
1.8
0.7
0.4
6.9
NA 0.4
NA
NA
NA
Andreini
et al
.
21
2757 13.8
1.3
0.54
9.8
0.25
1.1
10.6
85
0.29
Erol
et al
.
25
2096
1.96
0.43
0.43
3.18 0.33
0.74
NA
NA
0.38
Karabay
et al
. (this study)
745
4.96
0.93
0.79
19.1
0.13
0.13
1.07
75.5
0.93
LM: left main artery; CFX: circumflex artery; RCA: right coronary artery; RCS: right coronary sinus; MB: myocardial bridging.
