Keywords anomalous single coronary artery - coronary angiography - dual left anterior descending
artery - non-ST elevation acute coronary syndrome - coronary anomalies
Introduction
In a single coronary artery (SCA), the entire coronary tree arises as a single trunk
from the ascending aorta and no evidence of a second coronary artery is found.[1 ]
Dual left anterior descending (LAD) artery was first described by Spindola-Franco
et al,[2 ] in 1983. Based on conventional coronary angiography and computerized tomographic
(CT) angiography data, the prevalence of dual LAD is estimated to be 1 and 4%, respectively.[3 ]
Case Presentation
A 38-year-old female patient with no cardiovascular morbidities presented to the emergency
department with chief complaint of acute central chest pain that started 3 hours earlier
and worsened in the last hour before coming to hospital. Patient had normal vital
signs and unremarkable physical examination. Her 12-lead electrocardiogram (ECG) showed
0.5 mm ST segment depression in the left-sided limb and lateral precordial leads (I,
aVL, V5, and V6). High-sensitive cardiac troponin I (hs-cTnI) was slightly positive
at 0.12 ng/mL (normal range <0.04 ng/mL). She received a loading dose of dual antiplatelet
(DAPT) agents and was planned for elective coronary angiography (CAG) during the same
hospital admission. She was categorized as a case of non-ST elevation acute coronary
syndrome. A bedside transthoracic echocardiography showed no regional wall motion
abnormalities and an ejection fraction of 60% with no valvular abnormalities.
CAG through the right femoral artery unexpectedly demonstrated a SCA branching from
the right coronary sinus (RCS). There was no left coronary system arising from the
corresponding left coronary sinus. The right coronary artery (RCA) was normal in course
and anatomy with large caliber, dividing into posterior descending artery and right
posterolateral branches. The left system originated separately from the RCS, giving
rise to a small left circumflex artery and two left anterior descending arteries with
no obstructive disease along their course ([Fig. 1 ]; [Video 1 ] [available in the online version])
Fig. 1 Coronary angiographic image showing single coronary artery (SCA) arising from the
right sinus of Valsalva as a short common trunk which divides into (A ) right coronary artery (RCA) that courses normally and bifurcates distally into posterior
descending artery and posterolateral ventricular artery. (B ) Both long distal left anterior descending (LAD) artery and left circumflex (LCX)
artery originate separately from a common origin of SCA from the right sinus of Valsalva.
Video 1
Coronary angiography of a single coronary artery arising from the right sinus of Valsalva
subsequently divided to normal right coronary artery and both long distal left anterior
descending artery and left circumflex artery originating separately from a common
origin of SCA from right sinus of Valsalva.
Coronary computed tomography angiography (CCTA) was done to further characterize the
course of the anomalous SCA, as well as to delineate the type of surgery indicated.
This confirmed our diagnosis and demonstrated a benign course of the first proximal
LAD artery, but a malignant course was to be distal long LAD that was running between
the aorta and the right ventricular outflow tract ([Figs. 2 ] and [3 ]; [Video 2 ] [available in the online version]).
Fig. 2 Computed tomography coronary angiography showing (A ) axial view depicting a common coronary origin from the right sinus of Valsalava
branching into right coronary artery (RCA) and long distal left anterior descending
(LAD). Short axis of the short proximal LAD, long distal LAD and left anterior descending
(LCX) arteries can be seen as well. (B ) Maximum intensity projection images in the sagittal view depicting the interarterial
course of the short proximal LAD between the aortic root and right ventricular outflow
tract (RVOT).
Fig. 3 Computed tomography (CT) coronary angiography colored three-dimensional volume rendered
CT angiography images showing (A ) single coronary artery (SCA) arising as a common trunk from the right sinus of Valsalva
and bifurcating into the right coronary artery (RCA) branching distally into posterior
descending artery (PDA) and posterolateral ventricular (PLV) artery. A long distal
left anterior descending (LAD) artery giving a small septal branch then coursing toward
the left ventricular apex. A short proximal LAD artery giving a small diagonal branch
and left circumflex (LCX) artery altogether with the long distal LAD originating separately
from the SCA. (B ) Left anterior oblique cranial view with the pulmonary trunk removed demonstrating
the dual LAD anomaly with the short proximal LAD branching from the SCA from right
sinus of Valsalva and passing between the right ventricular outflow tract (RVOT) and
the aortic root taking a malignant interarterial course. Asc Ao, ascending aorta;
PL, posterolateral; RCS, right coronary sinus.
Video 2
Computed tomography coronary angiography of a single coronary artery arising as a
common trunk from the right sinus of Valsalva.
After a heart team assessment, the patient was counselled to perform coronary artery
bypass graft (CABG) surgery with reimplantation of the anomalous coronaries. However,
she declined any surgical intervention, and she was treated conservatively with DAPT,
B-blocker and statins followed by aspirin for life.
On frequent follow-up visits for the following 18 months, the patient was well, with
no angina or effort intolerance.
Discussion
Coronary anomalies are one of the most common cardiovascular causes of sudden death
in young patients.[4 ]
CCTA can precisely delineate the course of the anomalous artery and provide three-dimensional
(3D) information about the relation of the anomalous artery to other cardiovascular
structures, namely, cardiac chambers and major arteries.[5 ]
Dual LAD anomalies have been classified into six different types based on the origin
and course of the long LAD ([Table 1 ]).[6 ] In types I, II, and III, both the long and the short LADs originate from the proximal
LAD. In types IV, V, and VI, the long LAD originates from the proximal RCA or from
the RCS. In types IV and V, the long LAD takes either an epicardial course or an intramyocardial
course within the septal crest, while in type VI, which has recently been described
by Maroney and Klein,[6 ] the long LAD courses between the right ventricular outflow tract (RVOT) and the
aortic root. Type-VI dual LAD anomaly may have greater clinical significance than
other types because compression of the coronary artery between the RVOT and the aortic
root in situations of increased pulmonary blood flow could cause coronary blood flow
restriction and sudden cardiac death.[7 ]
Table 1
Classification of dual left anterior descending coronary artery
Type
Short LAD
Long LAD
Origin of major diagonal vessels
Origin
Course
Origin
Course
I
Proximal LAD
Proximal
AIVG
Proximal LAD
Epicardial course on the left ventricular side of the proximal AIVG, reentering the
distal AIVG
Proximal LAD and/or long LAD
II
Proximal LAD
Proximal
AIVG
Proximal LAD
Epicardial course on the right ventricular side of the proximal AIVG, reentering the
distal AIVG
Proximal LAD
III
Proximal LAD
Proximal
AIVG
Proximal LAD
Intramyocardial course in the proximal septum, then either (i) emerging epicardially
in the distal AIVG, or (ii) terminating intramyocardially as septal perforator arteries
Proximal LAD or short LAD
IV
LMCA
Proximal
AIVG
RCA
(i) Epicardial free wall course anterior to the infundibulum of the RV traversing
to the distal AIVG, or (ii) intramyocardial course within the septal crest emerging
epicardially in the distal AIVG
Short LAD
V
LCS
Proximal
AIVG
RCS
Intramyocardial course within the septal crest emerging epicardially in the distal
AIVG
Short LAD
VI
LMCA
Proximal
AIVG
RCA
Underneath the RVOT in the area of the interventricular septum
Short LAD
AIVG, anterior interventricular groove; LAD, left anterior descending artery; LCS,
left coronary sinus; LMCA, left main coronary artery; Proximal LAD, the portion of
the LAD just after bifurcation of the left main coronary artery into the LAD and left
circumflex; RCA, right coronary artery; RCS, right coronary sinus; RV, right ventricle;
RVOT, right ventricular outflow tract.
Recognition of anatomic variants of dual LAD anatomy is crucial for correct identification
of these vessels during surgery and angiographic coronary interventions for coronary
artery disease.[2 ]
[3 ]
In an autopsy study among 126 military recruits, an anomalous coronary artery was
responsible for one-third (21 of 64) of the cardiac deaths. In each case, the left
coronary artery arose from the right sinus of Valsalva, coursing between the aorta
and the pulmonary artery, leading to sudden cardiac death.[4 ]
Surgical interventions include reimplantation of the anomalous artery to the aorta,
osteoplasty, CABG of the anomalous artery, and pulmonary artery translocation.[8 ]
In our patient, one of the two LAD arteries ran a malignant interarterial course,
resulting in a presentation of ACS, however, with no clear coronary stenosis. Unfortunately,
our patient was not willing to undergo surgery.
It is difficult to determine the course of an anomalous SCA using angiography alone.
The 3D-CT images are extremely useful in demonstrating the dual LAD anatomy, as depicted
in our case.
