CONFLICT OF INTEREST: NONE
KEY WORDS: Coronary artery fistula, coronary malformation,
coronary surgery, coronary aneurysm
In the study “Long-term outcomes following surgical repair of coronary
artery fistula in adults”, Wada and associates, (1) retrospectively
evaluated 13 consecutive patients that underwent surgical repair of CAF
(coronary artery-pulmonary artery fistula, coronary artery-coronary
sinus fistula, and both) at the Kokura Memorial Hospital between
2008-2019. The surgical procedures were performed under coronary artery
bypass, and consisted of epicardial ligation of the fistula (46%),
direct closure of the fistula through a pulmonary artery incision
(38%), direct closure of the fistula through a coronary sinus incision
(8%), or the use of a patch closure of the fistula through coronary
artery incision (8%); patients who had comorbid cardiovascular disease
underwent simultaneous fistula closure and surgery for their cardiac
condition. The majority of CAFs originated from the right and left
coronary arteries and drained into the main pulmonary artery, and
preoperative findings included arrhythmias (31%), low ejection fraction
(30%), and small regional ischemia (8%). (1) No deaths, significant
ST-T changes or CAF-related events were reported in a follow-up period
of 66.2 months, and 1 patient showed poor contrast RCA#2 on
postoperative coronary CT with a myocardial scintigraphy showing no
significant change compared to the preoperative state.
Coronary artery fistulas (CAF) are rare congenital or acquired
malformations in the connection of the coronary vessels, first described
by Krause in 1865 (2). They can be classified as coronary-cameral
fistulas, which connect coronary arteries with any of the heart
chambers, or coronary artery malformations, which connect coronary
arteries with systemic or pulmonary vessels. (3) Congenital CAFs are
normally a result of abnormal embryological development, acquired CAFs
are commonly a result of cardiac traumatic injuries, and iatrogenic CAFs
are usually a result of interventional cardiac procedures. This
condition is still highly undiagnosed, as around 75% of
incidentally-found CAFs are small and clinically silent, (4) but it is
estimated that CAFs are present in about 0.9% of the general population
(5).
Although the vast majority of diagnosed CAFs are due to incidental
findings during coronary catheterization procedures, a small number of
patients develop symptoms of congestive heart failure, myocardial
infarction (MI), or pulmonary hypertension secondary to the mechanism of
“coronary steal phenomenon”. The effects of high-pressure coronary
arterial blood flow draining into a low-resistance venous circuit
through the fistula bypasses smaller myocardium arterioles and
capillaries and creates low-perfusion zones distal to the CAF, (6,7)
which, depending on the resistance (length, size and tortuosity) and
site of the fistula connection (coronary vessel or cardiac chamber), can
translate into dyspnea, angina, MI or volume overload symptoms. Chest
X-ray and echocardiography may be helpful in the initial diagnosis and
for uncovering any ensuing complications, further studies like
multidetector computed tomography (CT) and magnetic resonance imaging
(MRI) may be used to better delineate the fistula, while coronary
catheterization and coronary angiography represent the gold standard for
diagnosing CAF. (Dario)
According to American College of Cardiology and American Heart
Association guidelines (8), surgical management is a class I
recommendation for large CAFs regardless of the symptomatology and for
symptomatic small to medium-size fistulas (including MI, arrhythmia,
ventricular dysfunction of uncertain origin, and endocarditis).
Treatment options include surgical ligation (may be done by epicardial
or endocardial ligation) in large high-flow fistulas, tortuous fistulas,
fistulas with multiple communications and drainage sites, presence of
large aneurysms and if there is a need for simultaneous distal bypass
grafting; and percutaneous transcatheter closure in fistulas with a
proximal origin, single draining site, non-tortuous fistulas, fistulas
with extra-anatomic terminations, patients without comorbid
cardiovascular disease and old high-risk patients. (6)
In our experience, we have a CAF incidence of 0.05% in 10,000 cardiac
surgeries, which have demonstrated beneficial outcomes of the surgical
repair of CAFs in adults well as the beneficial effects of the
concurrent intervention of CAFs during surgery of comorbid cardiac
disease in preventing future complications related to CAFs. Authors of
this article must be congratulated for the successful development of the
study and for the contributions to the literature on this rare
condition. Further studies, with larger sample size, should be done to
evaluate the long term outcomes among the different procedures to treat
CAF.