Late Thrombosis With Ischemia After Left Main Coronary Artery Fistula Closure

Abstract

Background

Coronary artery fistulae are rare congenital or acquired anomalies, comprising <0.2% of congenital cardiac malformations. Surgical closure is the gold standard for complex or high-flow fistulae, typically via direct chamber closure or tract ligation.

Case Summary

We report a left main coronary-to-right atrial fistula in a patient with Factor VII deficiency. Given the deep intramediastinal course and heightened bleeding risk, we performed right atrial egress patch closure with mid-fistula ligation rather than extensive resection. Although this strategy minimized operative complexity, the patient later developed a left main coronary aneurysm with late thrombosis, raising concern that a more aggressive initial repair may have reduced long-term risk.

Discussion

This rare presentation highlights the surgical dilemma between procedural safety and definitive repair.

Take-Home Messages

Operative planning must balance bleeding risk against durable reconstruction. The management of residual coronary aneurysms after fistula closure remains uncertain.

Visual Summary

Case Presentation

A 60-year-old presented with chest pain on exertion. She had a history notable for Factor VII deficiency. Subsequent cardiac computed tomography (CT) performed demonstrated a large, long tortuous coronary fistula extending from the left main, with egress to the right atrium (Figure 1). Distally, the fistula has a maximal diameter of up to 2.2 cm.

Take-Home Messages

• •Operative planning must balance bleeding risk against durable reconstruction.
• •The management of residual coronary aneurysms after fistula closure remains uncertain.

Figure 1.

Large, Long Tortuous Coronary Fistula (Black Arrow) Extending From the Left Main, With Egress to the Right Atrium

The patient was diagnosed with the fistula in 1990 following the onset of traumatic gum bleeding. She was referred to an interventional cardiologist for attempts at coiling of the fistula in April and May of 2023; however, due to the substantial tortuosity of the fistula, wire access could not be obtained for coiling, and the procedure was abandoned, and she was referred for surgery in June of 2023. A subsequent redo operation was performed in July of 2024.

Initial Treatment

Surgery was performed with standard median sternotomy and cardiopulmonary bypass and a beating heart. The egress of the fistula was easily identified in the right atrium with torrential flow associated with it. This area was closed with the use of a pericardial patch.

Due to the size and tortuosity and location of the path of the fistula behind the aorta and pulmonary artery, the decision was made to ligate the fistula in its more readily-accessible midportion, visualized between the aorta and superior vena cava. This was deemed preferable but a more complex approach involving division of the aorta and pulmonary artery with complex reconstruction of the left main coronary artery which may have conferred more risk. In addition, there was concern that a complex repair may result in a heightened risk of bleeding complications in view of her Factor VII deficiency. The fistula here was ligated with ties, and Doppler assessment confirmed no flow throughout the path of the fistula.

Her postoperative course was unremarkable. She was prescribed 3 months of anticoagulation with apixaban due to concerns that the remnant and aneurysmal left main coronary may pose a nidus for thrombus. At 3-month follow-up, her chest pain had resolved, CT demonstrated progressive thrombosis and obliteration of the fistula and a patent left main coronary (Figure 2). In view of her Factor VII deficiency, a decision was jointly made between the cardiac surgery, cardiology, and hematology services to cease anticoagulation with apixaban and remain on aspirin only.

Figure 2.

Progressive Thrombosis (Yellow Arrow) and Obliteration the Fistula and a Patent Left Main Coronary

Progress

One year after her initial surgery, the patient experienced cardiac arrest at home and received cardiopulmonary resuscitation, initially by family members and then subsequently by emergency medical staff. Resuscitation was successful, and she arrived at our center and underwent coronary angiography, which demonstrated thrombotic occlusion of her circumflex artery and thrombus in her aneurysmal left main coronary (Figure 3). She had moderate left ventricular dysfunction and was maintained on cangrelor infusion and intra-aortic balloon pump support.

Figure 3.

Thrombotic Occlusion of Circumflex Artery (Yellow Arrow) and Thrombus in Aneurysmal Left Main Coronary (Blue Arrow)

Given the presence of coronary aneurysm thrombosis, the decision was made to perform emergency surgery. In this instance, the surgical plan was made to exclude the left main aneurysm and perform coronary artery bypass grafting (CABG), as this represented the most simple and reproducible approach given her acute status. We had considered the alternative of left main coronary aneurysm excision and artery reconstruction using vein grafts but felt this would be too complex and involve greater risk.

Surgical Treatment

The patient was brought to the operating room. Intraoperative transesophageal echocardiography was able to discern the left main coronary aneurysm and mobile thrombus within it (Figure 4).

Figure 4.

Intraoperative Transesophageal Echocardiography Demonstrating the Left Main Coronary Aneurysm and Mobile Thrombus Within It

The patient underwent re-sternotomy and institution of cardiopulmonary bypass uneventfully. Saphenous vein was harvested endoscopically. Once cardioplegic arrest was established, the aorta was opened, and the left main coronary ostium was identified and oversewn so as to control the aneurysm proximally.

The heart was retracted, and the left main aneurysm was identified epicardially. It was oversewn with multiple sutures placed epicardially at its bifurcation. CABG to the left anterior descending artery (LAD) and the obtuse marginal branch of the circumflex was performed using vein grafts, the proximal aspects of which were attached to the ascending aorta.

The patient was weaned off cardiopulmonary bypass with some improvement of left ventricular function.

The patient's intra-aortic balloon pump was removed on postoperative day 2, and she made an uneventful recovery and was discharged on postoperative day 6, remaining on aspirin and ticagrelor as this is associated with enhanced vein graft patency. To summarize the antithrombotic regimen across the entire course for this patient, no anticoagulation was involved before the index surgery, apixaban after the index surgery, and aspirin and ticagrelor after the redo surgery.

Postoperative repeat cardiac CT at 3 months demonstrated patent bypass grafts and progressive thrombosis and obliteration of the left main coronary aneurysm (Figure 5).

Figure 5.

Progressive Thrombosis and Obliteration of the Left Main Coronary Aneurysm (Yellow Arrow)

In terms of surveillance imaging, we planned an annual computed tomography angiography chest to assess graft patency and continued exclusion of the aneurysm; earlier if ischemic symptoms appeared.

Discussion

Coronary artery fistulae (CAF) are rare congenital or acquired anomalies, accounting for <0.2% of all congenital cardiac malformations. They most commonly arise from the right coronary artery and terminate in the right-sided chambers, with left main CAF being particularly uncommon. The hemodynamic significance of such fistulae depends on their size, tortuosity, and chamber of drainage. In our patient, the presence of a large, tortuous left main to right atrial fistula resulted in exertional angina and ultimately mandated intervention.

While transcatheter closure with coils or plugs has become the preferred approach for many CAFs due to its less-invasive nature and favorable success rates, tortuosity, size, and proximity to major coronary branches can preclude percutaneous therapy, as was the case here. Surgical closure therefore remains the gold standard for anatomically complex or high-flow fistulae. Standard operative strategies include direct closure at the site of chamber entry or ligation along the tract. In the initial surgery, we pursued a simplified approach: closure of the right atrial egress with a patch and mid-fistula ligation given the deep intramediastinal course of the fistula and the patient's Factor VII deficiency, which heightened bleeding risk.

In retrospect, a more comprehensive strategy—division of the aorta and pulmonary artery with formal fistula exclusion, aneurysm resection, and coronary reconstruction of the left main, LAD, and circumflex using vein grafts—might have provided a more definitive solution.¹ However, such an approach would have entailed a longer, more technically demanding procedure, with greater potential for bleeding and morbidity in this patient. The decision reflected an attempt to balance the competing risks of complexity vs safety, but the subsequent evolution of a left main coronary aneurysm and late thrombosis raises the important question of whether a more aggressive first operation might have mitigated long-term risk.

Management of coronary aneurysms remains an area of ongoing uncertainty, both in terms of indications for intervention and optimal antithrombotic therapy. In this case, the patient was left with a residual left main aneurysm following the initial surgery, but she experienced symptomatic improvement and no ischemia with a reassuring postoperative cardiac CT scan, thus favoring conservative management with temporary anticoagulation. A further confounding factor was our expectation that her congenital Factor VII deficiency might confer a degree of “auto-anticoagulation,” reducing thrombotic risk. However, her later presentation with cardiac arrest and coronary thrombosis underscores the limitations of this assumption, as well as the inherent unpredictability of aneurysmal disease.

The recurrence with ischemia and aneurysm thrombosis necessitated urgent surgical intervention. In this setting, our strategy was guided by the need for a rapid, reproducible, and definitive solution. We elected to exclude the left main aneurysm proximally and distally and to perform CABG. While excision of the aneurysm with complex reconstruction of the left main and its branches could be considered in an elective setting, such an approach was impractical in the emergent, hemodynamically unstable context.

Another key surgical decision was the choice of conduits. We opted for saphenous vein grafts rather than multiarterial grafts. This choice was influenced by concerns regarding the flow reserve of arterial grafts in the context of intentional occlusion of the left main coronary artery. Arterial grafts, while superior in long-term patency, have limited capacity to immediately accommodate large-volume coronary flow demands. In contrast, vein grafts provide higher flow reserve in the acute setting, which was particularly important given that both the LAD and circumflex territories would be dependent on the bypass conduits after exclusion of the left main. In the context of acute ischemia and thrombotic burden, maximizing flow reserve and safety was prioritized over long-term graft durability.

We did not consider just a double bypass without ligation of the left main orifice or ligating the aneurysm to maintain some form of dual blood supply in case the vein grafts thrombose or become stenotic. This is primarily because keeping the aneurysm patent would allow growth and later mass effect. In addition, keeping the aneurysm patent could subject the patient to thromboembolism down the LAD and circumflex arteries, as well as potentially retrograde embolism into the aorta, hence the decision to close at multiple points.

This case therefore highlights the multifaceted challenges in managing complex CAFs and associated coronary aneurysms, where anatomy, comorbidity, operative risk, and uncertain natural history all must be weighed.

Clinical Relevance

This case underscores the importance of tailoring operative strategy for CAF and associated aneurysms to both anatomy and patient-specific comorbidities. Although initial symptom resolution can be achieved with simplified closure techniques, residual aneurysms may predispose to late thrombotic complications. Careful long-term imaging surveillance, individualized antithrombotic planning, and readiness to reintervene surgically remain critical. In emergent settings, prioritizing strategies that maximize coronary flow reserve, even at the expense of long-term conduit durability, may optimize survival and recovery.

Summary of Case Relevance

• •Rare presentation of a left main coronary–to–right atrial fistula in the setting of Factor VII deficiency.
• •Provides rationale for surgical decision-making between simplified ligation and formal aneurysm resection and reconstruction.
• •Highlights uncertainty in the management of residual coronary aneurysms after fistula closure.
• •Documents a rare late complication: left main coronary aneurysm thrombosis leading to cardiac arrest.
• •Explains conduit choice in emergent CABG, emphasizing the importance of flow reserve in vein vs arterial grafts after intentional left main occlusion.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Visual Summary.

Sequence of Developments

Timeline	Events
1990	A 60-y-old patient with a past medical history of Factor VII deficiency was initially diagnosed with a large, long tortuous coronary fistula extending from the left main, with egress to the right atrium following the onset of traumatic gum bleeding.
April-May 2023	The patient presented with chest pain on exertion. She was referred to an interventional cardiologist for attempts at coiling of the fistula. Due to the substantial tortuosity of the fistula, wire access could not be obtained for coiling, and the procedure was abandoned.
June 2023	The patient was referred for surgery where the fistula was ligated.
September 2023	At 3-mo follow-up, the patient's chest pain had resolved. Computed tomography (CT) demonstrated progressive thrombosis and obliteration the fistula and a patent left main coronary.
July 2024	The patient experienced cardiac arrest at home and received cardiopulmonary resuscitation. Resuscitation was successful, and she arrived at our center and underwent coronary angiography, which demonstrated thrombotic occlusion of her circumflex artery and thrombus in her aneurysmal left main coronary. The decision was made to perform emergency surgery. The surgical plan was made to exclude the left main aneurysm and perform coronary artery bypass grafting.
October 2024	Postoperative repeat cardiac CT at 3 mo demonstrated patent bypass grafts and progressive thrombosis and obliteration of the left main coronary aneurysm.