Keywords coronary artery fistula - coronary angiography - coronary aneurysm - transcatheter
interventions - coils
Coronary artery fistula (CAF) is a rare anomaly through which coronary blood flow
is usually shunted into either a cardiac chamber, great vessel, or other structures,
bypassing the myocardial capillary network. Usually, it is detected as an incident
finding during coronary angiography, other noninvasive thoracic imaging or occasionally,
incidental finding of a continuous murmur, characteristically heard over the left
sternal border and at the apex might be present. The detection has recently increased
because of the widespread use of diagnostic modalities including coronary angiography,
multidetector computed tomography, and magnetic resonance imaging for other diseases.[1 ]
It is reported to be present in approximately 0.2% of routine coronary angiograms.[2 ] However, symptomatic cases with complications such as high-output heart failure,
pulmonary hypertension, myocardial ischemia, and infective endocarditis have been
reported. Treating physicians are usually on crossroads in cases with asymptomatic
detection because of lack of consensus on the management strategy. Data on presumed
low sudden death rate in asymptomatic patients are limited because of lack of large
studies with long follow-ups. With increasing detection of asymptomatic cases, it
is prudent to revise our traditional approach. In this article, we cross-examine the
conventional approach with different views and suggest an alternative strategy by
eliciting our case.
Case Report
A 78-year-old hypertensive woman with episodic chest pressure was referred to our
cardiac catheterization laboratory for angiographic evaluation. Patient recently immigrated
to United States in her usual health status 3 months ago. She started developing present
symptoms 2 months before her clinic visit and initially attributed these symptoms
to her underlying chronic acid reflux. Progression of symptoms infrequency and severity
led to follow-up visit and was referred to emergency room for further evaluation.
Patient had a prior coronary angiographic evaluation for similar symptoms 5 years
ago in her native country, and she was told to have normal findings. However, results
were unobtainable.
Physical examination revealed a blood pressure of 158/78 mm Hg, and a regular pulse
of 86 beats per minute. Electrocardiography showed nonspecific ST-T wave changes.
The cardiologist decided to proceed with coronary angiography that revealed mild luminal
irregularities and preserved left ventricular systolic function. In addition, angiography
also showed a left anterior descending coronary artery to main pulmonary trunk fistula
with an in-between saccular aneurysm. The aneurysm was 2.0 × 2.5 cm in maximum dimension
([Fig. 1 ]). The CAF feeding this aneurysm was less than 2 mm in diameter. A right heart catheterization
was performed to further evaluate any systemic-to-pulmonary shunt. There was no significant
left-to-right heart shunt. Right heart hemodynamic study revealed normal pulmonary
pressures with pulmonary artery pressure of 36/19 mm Hg and pulmonary capillary wedge
pressure of 12 mm Hg.
Fig. 1 Coronary angiogram showing the aneurysmal sac at the end of coronary injection (arrow).
Arrowhead showing the termination of fistula connection near the pulmonary artery.
Patient refused any further work-up with velocity encoded cine magnetic resonance
imaging, which was recommended for better quantification of the shunt size as proximal
location of CAF in the main pulmonary trunk might have influenced angiographic shunt
calculation due to streaming of oxygenated blood. Patient was deemed to be at high
risk for future complications secondary-to-spontaneous aneurismal rupture on the basis
of the large aneurysm diameter to feeder artery diameter ratio and a decision was
made for percutaneous intervention. Two Cook coils (Cook Medical Inc., Bloomington,
IN) were deployed. Subsequent angiographic images showed little residual blood flow
through the aneurysm with a small clot formation and undetectable coronary artery
to pulmonary artery blood flow ([Fig. 2 ]). Patient remained asymptomatic after 3 months of follow-up. Her symptom of episodic
chest burning was cured by oral proton-pump inhibitor therapy.
Fig. 2 Arrow showing the coil applied proximal to the aneurysmal sac. There is less blood
in the aneurysm (less dense dye) and a possible thrombus inside the sac. Also, there
is no blood flow after the aneurysm to the pulmonary artery.
Discussion
Most CAFs are congenital but rarely could these be acquired.[3 ]
[4 ] Although most remain asymptomatic during childhood and adolescence, many develop
symptoms because of complications in adulthood. Aneurysm formation has been reported
in around one in five cases.[5 ] Rupture of these aneurysms is rare and usually occurs in large ones. Ruptured aneurysm
may clinically be presented as chest pain, pericardial effusion, cardiac tamponade,
or even sudden cardiac death and could mimic the presentation of acute aortic dissection.[6 ]
Available treatment options for CAF include surgical ligation either with or without
coronary artery bypass surgery, and percutaneous transcatheter closure. It is widely
accepted that fistula closure should be considered in symptomatic patients with heart
failure, myocardial ischemia, or high shunt ratios to prevent further complications.[7 ] However, there is no consensus on the management of asymptomatic aneurysms.[8 ] The treatment of large asymptomatic CAF remains controversial and the recommendations
are based solely on anecdotal cases, individual experiences, or small retrospective
series.[9 ] Many believe that giant aneurysms larger than 5-cm warrant intervention.[10 ]
[11 ]
We derive, indirectly, from the data accumulated from studies done on renal artery
aneurysm that aneurysm diameter greater than 2 cm may be associated with complications.[12 ] However, because there is no national or international registry of patients with
CAF, it would be hard to know the real complication rate. Asymptomatic CAF with small
aneurysm should be closely observed and early intervention in those with progressive
dilatation during follow-up might be considered. When managed conservatively, prophylactic
precautions of subacute bacterial endocarditis are recommended, as bacterial endocarditis
is a recognized complication in CAF patients with aneurysm.[13 ] Antiplatelet therapy is recommended, especially in patients with distal CAFs and
dilated coronary arteries.
We suggest that while discussing management options with asymptomatic patients with
large aneurysm, percutaneous transcatheter intervention should be brought up in the
discussion because the risk of sudden death in these patients is largely unknown.
However, this statement should not be deduced as a justification for an invasive procedure.
There is a need to design a national/international registry for further insights into
optimal management of CAF especially asymptomatic ones.
Author Contributions
Both A.J. and C.H.P. participated in the management of this patient. A.J. wrote the
first draft of this manuscript. C.H.P. helped in editing the manuscript.
