Percutaneous closure of a giant coronary fistula mimicking a cardiac mass in a young woman. (QF_TH_003)

Description of Clinical Presentation: A 45-year-old woman with a history of atrial tachycardia (2022), treated with bisoprolol 1.25 mg qd. The patient was referred to our Institute for treatment of dilated cardiomyopathy due to findings on transthoracic echocardiogram (07/26/2023), consisting of LVEF 66%, left ventricle with eccentric hypertrophy, biatrial dilatation, with LAVI of 47 ml/m2 and mild tricuspid regurgitation.

At the first medical attention, the patient reported being asymptomatic and the cardiovascular physical examination revealed a regurgitant murmur in the tricuspid focus, pansystolic, harsh, intensity II/VI, without irradiation. The rest of the physical examination was unremarkable. A cardiac magnetic resonance study was requested, with a surprising result of a giant coronary fistula from the LMCA to the right atrium. She was referred for left heart catheterization, which confirmed the diagnosis and the fistula was closed with a coil, improving the angiographic coronary blood flow. The patient evolved favorably, without complications, and was discharged.

Diagnostic Techniques and Their Most Important Findings: Cardiac magnetic resonance (09/19/2023):
1. Fistula of the left coronary trunk to the right atrium, with aneurysm of its distal portion:
The left coronary trunk in its proximal segment is dilated measuring 15x14mm. The fistula, which measures 9mm in transverse diameter, took a retro-aortic path, crosses the interatrial septum and drains into the right atrium. In its distal segment, in the right atrium, an aneurysm of 26x39x36mm is observed, in its inferosuperior, transverse and anteroposterior diameters, respectively; there are at least two drainage sites towards the 3mm aneurysm. The aneurysm drains into the right atrium through two rupture sites of 3.5 and 4 mm.
2. Dilated ventricles, with normal systolic function. LVEF 62%. RVEF 60%.
3. Biatrial and pulmonary trunk dilatation.
4. Mild tricuspid and mitral regurgitation.
5. Non-ischemic, intramyocardial, anteroseptal basal LGE.
6. Mild inferior pericardial effusion.

Left heart catheterization (01/11/2024): Coronary fistula from the left coronary trunk to the right atrium with dilatation of the LMCA. Coronary fistula closure was performed with a 16 mm AVP II occluder device.

Learning Points from this Case: There are two lessons in this case. First, analyzing the cardiac magnetic resonance images, especially in the apical 4-chamber window, a mass in the roof of the right atrium is clearly visualized in the cine sequence, which then appears intermittently in the resting perfusion sequence, T1 and T2 mapping, and in the LGE sequence. Due to its dynamic behavior, additional sections of the cine sequence were made that showed that it was a coronary fistula from the LMCA to the right atrium with aneurysmal drainage, which atypically can mimic a cardiac mass, for which the cardiologist must be analytical during the acquisition of the magnetic resonance images in order to focus and seek a diagnosis that integrates the observed findings with more specific sequences, for example phase contrast sequences to assess 2D flow of this coronary anomaly, that allow us a better anatomical characterization, as was the case with this cardiac pseudomass, visualized as the aneurysmal outlet of a coronary fistula. Second, it should be noted that echocardiographic follow-up confirmed recovery of ventricular diameters due to hemodynamic improvement secondary to the lower coronary flow produced by the coronary fistula.

Cardiac magnetic resonance. A,B. Cine images, apical 4-chamber view, in ventricular diastole and systole, a mass is observed in the roof of the right atrium. C. Cine image, coronal view, a dilated left coronary trunk is seen. D. T1 wi, the mass is not observed in the right atrium. E,F. First-pass perfusion images, the mass is initially observed, but it disappears when perfusion is completed. G. T1 mapping, the mass is not observed. H. T2 mapping, the mass is observed again. I,J. Late gadolinium enhancement sequences, in the right atrium the cardiac mass is partially visualized.

Cardiac magnetic resonance, specifics phase contrast sequences to the fistula from the left coronary trunk to the right atrium, confirming the fistulous tract through 2D flows. A,B. Coronal view. CD. Axial view.

Therapeutic left heart catheterization. A. The left coronary trunk with a fistula and aneurysmal dilatation at its connection to the right atrium can be seen. B. A coil support is positioned in the coronary fistula through the right atrium. C. The coil is successfully released, with improvement in left coronary flow.