Voluminous Fistula Between the Right Coronary Artery and a Branch of the Pulmonary Artery Causing Myocardial Ischemia

ABSTRACT: A 76-year-old female patient was referred to our institution because of typical chest pain. A continuous murmur was audible at the lower sternal border. A transthoracic echocardiogram showed non-dilated right and left ventricles with mild left ventricular inferior wall hypokinesia and an exercise stress test was positive for myocardial ischemia. A coronary angiogram showed no signs of atherosclerotic coronary artery disease, but it revealed a voluminous fistula between the proximal segment of the right coronary artery and a branch of the pulmonary artery, which was percutaneously closed using 3 embolization coils. Such late presentation of a voluminous coronary fistula is extremely rare and, to the best of our knowledge, very few case reports like this have been published.

J INVASIVE CARDIOL 2012;24(7):E139-E141

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Case Report. A 76-year-old woman with a history of arterial hypertension was referred to our institution because of a 5-month progressively aggravating condition consisting of moderate fatigue and constrictive precordial pain triggered and repetitively reproduced by moderate effort. Basal electrocardiogram and physical exam were unremarkable, with the exception of a continuous murmur audible at the lower sternal border. The transthoracic echocardiogram showed a moderately dilated left atrium, non-dilated right and left ventricles with mild left ventricular inferior wall hypokinesia. An exercise stress test was positive for significant myocardial ischemia.

A coronary angiogram showed no signs of atherosclerotic coronary artery disease. However, it revealed a voluminous fistula between the proximal segment of the right coronary artery and a branch of the pulmonary artery. Without other plausible causes for her condition, the patient was subsequently called for percutaneous closure of the coronary fistula, which was successfully performed using 3 AZUR embolization coils (platinum coils coated with hydrocolloid gel). Figures 1-3 show the coronary fistula before, during, and after the procedure. One month later, she is asymptomatic.

Discussion. Coronary arteriovenous fistulas (CAVF) are rare congenital anomalies consisting of abnormal communication between a coronary artery and one of the cardiac chambers or vessels adjacent to the heart. CAVF are visualized in nearly 0.25% of patients submitted for catheterization and are present in 0.002% of the general population.^1,2 Most of these fistulas arise from the right coronary (55% of cases) or left anterior descending (35% of cases) arteries; the circumflex coronary artery is rarely involved.³ Most coronary artery fistulas are small, asymptomatic, and are clinically undetectable until echocardiography or coronarography is performed for an unrelated cause. Nevertheless, symptoms and complications may develop with age and mortality and morbidity are higher when corrective surgery of percutaneous procedures are performed later in life.⁴

Although the diagnosis of a CAVF may be challenging, it should be considered in patients presenting with cardiac murmurs, irrespective of the absence of symptoms. Differential diagnosis includes patent ductus arteriosus, pulmonary and systemic arteriovenous fistulas, ruptured sinus of Valsalva aneurysm, aortopulmonary window, prolapse of the right aortic cusp with a supracristal ventricular septal defect, and internal mammary artery to pulmonary artery fistula.⁵ Some of these diagnosis are rare in adulthood. In the present case, the patient had no history of vasculitis, coronary artery disease, or trauma, indicating most likely a coronary fistula of congenital etiology with delayed presentation. The presentation of such voluminous fistula at this age is extremely rare. Most cases present during infancy/childhood and, although smaller fistulas are usually asymptomatic, moderate-large fistulas only rarely present at such late stage. Some case reports of late-presenting CAVF have been published,6,7 and yet, this is the oldest reported patient with first presentation of large coronary artery fistula to the best of our knowledge.

Clinical presentation mainly depends on the severity of left-to-right shunt,⁸ most patients presenting with dyspnea and right ventricular dilatation/failure related to progressive fistula enlargement and increase in left to right shunting.⁹ Late stage chest pain or myocardial ischemia are uncommon forms of presentation^10,11 and thought to be caused by a phenomenon known as coronary steal, whereby blood flow is shifted away from the distal coronary vascular bed. Subacute bacterial endocarditis, rupture, thrombosis of the CAVF, and associating arterial aneurysms are rare but severe complications, which increase with age.¹²

Clinical symptoms of ischemia, such as exertional angina or dyspnea, are the primary indication for closure of a fistula. In fact, controversy exists regarding the management of fistulas in the absence of associated clinical symptoms. Some authors recommend closure of CAVF even in asymptomatic patients to prevent the age-related progressively increasing risk of fistula-related complications (such as heart failure, endocarditis, and myocardial ischemia).^9,12

A variety of approaches can be used to manage coronary artery fistulas. Procedural options can be optimized by careful identification of the number of fistulous connections, nature of feeding vessel(s), drainage sites, quantification of myocardium at risk for injury or loss, and the hemodynamic shunt related to the fistula. The aim of treatment is obliteration of fistulae while preserving normal coronary blood flow.

Surgical closure of CAVF by epicardial and endocardial ligations has been the gold standard for the treatment of CAVF, remaining a safe and effective option.^12,13 Simpler and easily accessible CAVFs may be surgically occluded on beating heart without cardiopulmonary bypass,¹⁴ although the exploration of the pulmonary artery with the use of cardiopulmonary bypass is recommended in patients having CAVF in combination with other vascular malformations.

The first successful percutaneous closure of a coronary fistula was reported in 1983.¹⁵ Catheter-based closure methods have since become the preferred treatment option, if technically feasible. Anatomy of the fistula should be favorable (nontortuous vessel, single fistula, distal portion accessible, and distal narrowing to avoid embolism to the drainage site)¹⁶ and there should be no coexisting cardiac pathology requiring surgical intervention (in this case, patients should be referred to surgical closure).

Although successful fistula occlusion has been reported with inflatable and detachable balloons,^17-19 percutaneous embolization technique with micro-particles of polyvinyl alcohol foam,^20,21 and with umbrellas,²² the use of implantable coils is currently considered the preferential method due to improved control and delivery techniques, higher success rate, and lower risk of complications.²³ Stainless steel coils^,24 controlled-release coils (such as the Terumo detachable AZUR Peripheral HydroCoil Embolization System used in our case), controlled-release PDA coils, and the Amplatzer PDA occluder²⁵ are potential options. The most frequent complication associated with catheter-based closure is embolization of the occlusion device (occurring in 7 out of 40 patients described by Qureshi et al²³).

There are no reports of long-term results following transcatheter closure of coronary fistulas in adults, although some authors have followed adult patients for short-intermediate periods of time.²⁶ Cardiac catheterization and selective coronary angiography may be performed 12 to 24 months after coil occlusion to evaluate coronary artery dimensions and fistula persistence. In case of fistula leakage after primary coil occlusion, given the risk of bacterial endocarditis and the presence of a foreign body (the coil), some authors recommend repeat catheterization and coil occlusion after 3 to 6 months²⁷ as placement of additional coils appears to be efficacious in abolishing persistent fistula leaks.²⁸

Conclusions

Coronary artery fistulas, even relatively large ones, may present up to the 8th decade of life. Although surgical closure has been the gold standard of treatment for coronary fistulas for many years, transcatheter coil occlusion is currently the preferred option in selected cases with suitable fistula anatomy, as results have been comparable to surgery without associated morbidities of cardiopulmonary bypass and/or sternotomy. The long-term patient outcome after fistula occlusion remains unknown. Therefore, patients who have undergone coil occlusion of coronary fistulae require close follow-up.

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From the Cardiology Department, Coimbra Hospital and University Centre, Centro Hospitalar de Coimbra, Coimbra, Portugal.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Manuscript submitted November 22, 2011, provisional acceptance given February 22, 2012, final version accepted February 27, 2012.
Address for correspondence: R. António F. Fiandor 112 – 4 Dto, 4430-017 V. N. Gaia, Portugal. Email: sergioncbarra@gmail.com