Left atrial myxoma complicated by a coronary artery fistula due to rupture of the feeding artery: a case description

Introduction

Primary cardiac tumors are extremely rare, with an incidence of 0.05%. Of these, about 90% are benign tumors, and more than half of benign tumors are myxoma (1). Despite increasing reports of cardiac myxoma (CM) in recent years, vascularization and related complications, such as coronary artery fistulas (CAFs), remain relatively uncommon. We report a case of atrial myxoma in which the blood supply to the tumor originated from the left circumflex artery (LCA). An artery within the tumor ruptured, creating an abnormal fistula that entered the left atrial cavity. To the best of our knowledge, CAF secondary to the rupture of a vascularized myxoma represents an exceptionally rare clinical entity, with only a limited number of cases documented in the literature to date.

Case presentation

A 56-year-old male with a 5-year history of atrial fibrillation, presenting with paroxysmal palpitations, was admitted due to worsening exertional dyspnea over the past year. Upon admission, his vital signs were stable, and laboratory tests showed no significant abnormalities. Since the onset of his condition, the patient had intermittently been taking rivaroxaban, bisoprolol, and isosorbide mononitrate for treatment. On admission, a two-dimensional (2D) transthoracic echocardiogram (TTE) showed no obvious thrombus or mass lesions within the heart chambers. A three-dimensional (3D) transesophageal echocardiogram (TEE) revealed a moderately echogenic mass in the region of the oval fossa of the atrial septum, measuring approximately 12 mm × 9 mm, initially suspected to be a myxoma (Figure 1A,1B). A left atrial computed tomography angiography (CTA) showed a round, slightly low-density mass within the left atrium, consistent with a myxoma (Figure 2). Due to the patient’s atrial fibrillation, a coronary CTA was not performed. However, coronary angiography (CAG) later revealed that the blood supply to the tumor originated from the LCA. Contrast injected into the heart chamber demonstrated a left atrial-CAF, with no significant abnormalities in the other coronary vessels (Figure 3).

Figure 1 TEE identification of an atrial septal mass. (A) Mildly hyperechoic signal in the mid atrial septum (left atrial side, fossa ovalis) with well-defined margins and heterogeneous internal echogenicity (white arrow). (B) 3D-TEE volumetric visualization of the mass at the fossa ovalis. 3D, three-dimensional; TEE, transesophageal echocardiography.

Figure 2 Left atrial CTA showing a slightly hypodense, round-like mass within the left atrium, suspected to be a myxoma (white arrow). CTA, computed tomography angiography.

Figure 3 The anteroposterior view at 35°, CAG reveals the LCA as the feeding vessel of the mass (yellow arrows), with contrast agent entering the heart chamber, indicating the presence of a left atrial-CAF (white arrow). CAF, coronary artery fistula; CAG, coronary angiography; LCA, left circumflex artery.

The patient subsequently underwent tumor resection. Intraoperative TEE revealed a sessile heterogeneous mass with an anechoic area inside. Color Doppler flow imaging (CDFI) demonstrated a biphasic continuous blood flow entering the left atrium through the tumor’s lumen, with a peak velocity of 70 cm/s (Figure 4A,4B). Intraoperative exploration revealed a friable, gelatinous mass attached to the oval fossa of the atrial septum, measuring approximately 10 mm × 10 mm, with a stalk area of about 15 mm × 10 mm. Anomalous coronary artery anatomy was noted, with a coronary artery coursing through the atrial septal muscle bundle and opening at the apex of the tumor, forming a coronary artery-to-left atrium fistula. During surgery, the tumor was completely excised, and the coronary artery blood supply to the mass was ligated at the atrial septum (Figure 5). Postoperative TEE confirmed complete removal of the left atrial mass, with no residual shunt at the atrial septum.

Figure 4 Intraoperative TEE and Doppler evaluation of a cardiac mass. (A) TEE shows an irregular, sessile mass attached to the fossa ovalis, with an anechoic area inside. CDFI reveals a small blood flow jet within the tumor cavity entering the left atrium. (B) PW Doppler tracing demonstrates biphasic flow with a peak velocity of 70 cm/s. CDFI, color Doppler flow imaging; TEE, transesophageal echocardiogram; PW, pulsed wave Doppler.

Figure 5 The surgically excised mass measures approximately 10 mm × 10 mm.

The postoperative pathological examination confirmed that the mass was a myxoma, with features of calcification and hemosiderin deposition, along with multinucleated giant cell reactions and infiltration of chronic inflammatory cells (Figure 6). Follow-up evaluations at 3 and 9 months postoperatively showed no signs of tumor recurrence.

Figure 6 Pathology confirms the mass as a myxoma, with calcification, hemosiderin deposition, multinucleated giant cell reaction, and infiltration of chronic inflammatory cells. HE staining, 200× magnification. HE, hematoxylin-eosin.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s), and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Although primary cardiac tumors are relatively rare, CMs are the most common benign primary cardiac tumors, accounting for 50–85% of all clinical cases (2). Approximately 75% of myxomas originate in the left atrium, with the most common location being the fossa ovalis of the atrial septum. Studies have shown that multipotent mesenchymal stem cells are present in the region of the fossa ovalis, and these stem cells secrete vascular endothelial growth factor, which induces angiogenesis and promotes the early growth of myxomas (2-4). Thus, when the tumor was detected in the fossa ovalis region through TEE and left atrial CTA in our patient, the initial diagnosis was myxoma. The typical structure of a myxoma is loose and often attaches via a stalk, allowing for significant mobility, which increases the risk of myxoma-related intracranial complications, including intracranial aneurysm, embolic stroke, and arteriovenous malformation (4). Therefore, timely surgical resection remains the preferred treatment for atrial myxomas.

Lee et al. have suggested that preoperative CAG or coronary CTA should be routinely performed in myxoma patients to exclude concomitant coronary artery disease and identify the feeding artery of the CM (5). It was previously believed that CMs were composed of poorly vascularized tissue, resulting in limited blood supply to the tumor (6). However, current angiographic data show that 33.3–55.6% of myxoma patients exhibit significant blood flow to the tumor, with most myxomas being supplied by the right coronary artery or the LCA (7). In the case of our patient, CAG revealed that the myxoma was supplied by the LCA, with the vessel passing through the tumor and forming a left atrial fistula.

CAF is a rare congenital or acquired anomaly of coronary artery connections, with an estimated prevalence of approximately 0.002% in the general population. Among these cases, 50% of the fistulas originate from the right coronary artery, 42% from the LCA, and the most common drainage sites are the right ventricle and right atrium; only 5% of fistulas drain into the left atrium (8,9). The fistula in this case originated from the tumor-feeding branch, exhibiting anatomical features inconsistent with the common patterns of congenital coronary CAF. Furthermore, the patient had no prior history of cardiac murmurs or congenital heart disease, and the onset of exertional dyspnea temporally correlated with tumor growth and fistula formation. Based on these findings, we hypothesize that this case represents a rare acquired coronary artery-to-left atrium fistula, secondary to the arterial supply of a myxoma. Although no direct intraoperative or histopathological evidence of arterial rupture—including vessel wall disruption, active bleeding, or ruptured vasculature—was observed, intraoperative TEE demonstrated hypoechoic regions within the tumor mass accompanied by biphasic continuous blood flow emanating from the lesion. Surgical exploration further revealed an anomalous opening of the feeding artery at the superior margin of the atrial septal incision. Postoperative histopathological analysis provided compelling evidence of chronic intratumoral hemorrhage. Based on these cumulative findings, we propose that the coronary artery-left atrial fistula developed secondary to chronic rupture of the tumor’s feeding artery. This hypothesis is mechanistically grounded in the integration of intraoperative imaging, surgical observations, and pathological evidence. The underlying mechanisms for the fistula formation can be hypothesized as follows: First, the nutrient vessels supplying the myxoma from the atrial septal side may be mobile, leading to degeneration and rupture of elastic fibers, which subsequently causes vessel rupture and intratumoral hemorrhage. Furthermore, the patient’s intermittent use of the anticoagulant rivaroxaban may have increased the risk of intratumoral hemorrhage. Over time, the tumor tissue became increasingly fragile and sparse, and its surface eventually ruptured, resulting in the formation of a coronary artery-to-left atrium fistula through a fistulous tract (10). Second, the relatively small size of the tumor in this case may have contributed to increased intratumoral pressure due to enhanced coronary blood flow. This, combined with the external hemodynamic forces exerted by blood flow within the atrial cavity, likely facilitated the development of the CAF through the combined effect of internal and external pressures.

The pathophysiology of CAF is dependent on the origin and drainage site of the fistulous tract, with the resistance influenced by factors such as the size, tortuosity, and length of the fistula (11). In this case, the fistula was relatively small and did not result in significant clinical symptoms. In contrast, larger fistulae can lead to coronary steal syndrome, as reported in previous cases. Myxomas, in particular, have been linked to coronary artery steal, potentially causing paroxysmal chest pain and exertional dyspnea (12,13). Chronic coronary steal can lead to vascular remodeling, increasing the risk of aneurysm formation, and may ultimately result in myocardial ischemia, which could progress to myocardial infarction. Therefore, during myxoma resection, meticulous suturing and ligation of the coronary branches supplying the atrial septum are critical to prevent the occurrence of atrial coronary steal. In this case, despite the small caliber of the feeding artery allowing intraoperative ligation of the fistula as a minor bleed, preoperative multimodal imaging was critical for surgical planning. It precisely mapped the fistula’s origin and vascular anatomy, facilitating targeted coronary ostium ligation to minimize intraoperative oversight and recurrence risk. Low-flow, persistent fistula patency may lead to coronary steal syndrome via chronic blood diversion. Thus, a clear preoperative diagnosis remains vital for surgical planning. Both CM and CAF are most commonly and effectively evaluated using 2D-TTE, which remains the preferred and most widely used imaging technique. TTE provides accurate assessment of the mass’s location, size, shape, attachment points, and mobility, as well as its hemodynamic consequences. In the present case, the initial TTE failed to detect the myxoma, likely due to the small size of the mass and its distal position relative to the ultrasound beam, leading to a missed diagnosis. Cardiac CTA is capable of detecting smaller myxomas and visualizing adjacent cardiovascular and soft tissue structures; however, its ability to visualize small vessels within the myxoma is limited. CAG is the gold standard for assessing CAF, and a study has shown a detection rate of up to 91% for vessels supplying the myxoma. However, CAG is unable to provide detailed information regarding the size, shape, location, or mobility of the myxoma (5). TEE offers superior temporal and spatial resolution compared to TTE, proving more effective in detecting myxoma (100% vs. 95%) and identifying attachment points (95.2% vs. 64.5%) (2). When combined with CDFI, TEE provides significant advantages in visualizing blood flow within the mass. Guidelines recommend the use of very low mechanical index perfusion imaging and intermittent high mechanical index techniques during contrast echocardiography to better characterize the vascular features of cardiac masses, helping to differentiate between thrombus and benign or malignant tumors. In terms of clinical feasibility, these techniques have advantages over delayed contrast-enhanced magnetic resonance imaging (14). Furthermore, contrast echocardiography can aid in more clearly delineating the fistulous structure. Evidence has demonstrated that 3D-TEE offers significant advantages in visualizing anatomical structures, providing more precise technical support for the closure of CAF (9).

Conclusions

We have reported a case of a vascularized left atrial myxoma complicated by rupture of its feeding artery, resulting in a coronary artery-to-left atrial fistula. The tumor was subsequently resected, and the feeding artery was ligated during surgery. This case highlights the distinct advantages and limitations of various imaging modalities. In particular, TEE demonstrated unique value in detecting neovascularization within the myxoma and identifying the potential coronary artery-left atrial fistula. These findings underscore the importance of multimodal imaging techniques in achieving accurate diagnosis of cardiac masses in clinical practice.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-185/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s), and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was provided by the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Chen Y, Huang Q, Bai C, Zhang H, Zhang B. Preoperative management and anticoagulant efficacy in atrial myxoma-associated acute ischemic stroke: a case report and literature review. Front Cardiovasc Med 2024;11:1435047. [Crossref] [PubMed]
2. Islam AKMM. Cardiac myxomas: A narrative review. World J Cardiol 2022;14:206-19. [Crossref] [PubMed]
3. Saad EA, Mukherjee T, Gandour G, Fatayerji N, Rammal A, Samuel P, Abdallah N, Ashok T. Cardiac myxomas: causes, presentations, diagnosis, and management. Ir J Med Sci 2024;193:677-88. [Crossref] [PubMed]
4. Xia M, Wang Y, An X, Huang Y, Wei K, Zhou J, Li K, Yao G, Huang H. A male patient with atrial myxoma and multiple metastatic intracranial aneurysms: A case report and literature review. J Int Med Res 2025;53:3000605251333690. [Crossref] [PubMed]
5. Lee SY, Lee SH, Jung SM, Choi JH, Chon MK, Hwang KW, Kim JS, Park YH, Kim JH, Chun KJ, Je HG, Park JS. Value of Coronary Angiography in the Cardiac Myxoma. Clin Anat 2020;33:833-8. [Crossref] [PubMed]
6. Umeda Y, Matsuno Y, Imaizumi M, Mori Y, Iwata H, Takiya H. Right atrial myxoma with tumor vascularity originated from the left and right coronary arteries. Int J Cardiol 2009;131:e137-9. [Crossref] [PubMed]
7. Peng X, Xiao Y, Guo Y, Zhu Z, Liao L, Liao X, Hu X, Fang Z, Li X, Zhou S. Clinical Significance of Angiographically Detectable Neovascularity in Patients with Cardiac Myxoma. Cardiovasc Innov Appl 2021;6:99-108.
8. Shah L, Kundapur D, Nosib S. Stolen from the coronaries: Left-to-Left shunts presenting as chest pain syndrome! BMJ Case Rep 2021;14:e242425. [Crossref] [PubMed]
9. Sharifkazemi M, Mohseni-Badalabadi R, Hosseinsabet A, Hajizeinali A. Case report: Multimodal imaging diagnosis of a giant coronary artery fistula: A report of two cases. Front Cardiovasc Med 2022;9:986078. [Crossref] [PubMed]
10. Sakaguchi T, Kojima T, Miyamoto T, Urashita S, Uekihara K, Matsukawa M, Hirayama R, Suzuki R. Left Atrial Myxoma with Coronary Artery-left Atrial Fistula:Report of a Case. Kyobu Geka. 2021;74:962-5.
11. Shah BN, Abbas A. Genesis of a coronary-cameral fistula. Echocardiography 2021;38:1422-4. [Crossref] [PubMed]
12. Su Y, Song H. Hemorrhage and associated fistula formation in a left atrial myxoma causing coronary artery steal syndrome. Echocardiography 2019;36:1191-3. [Crossref] [PubMed]
13. Tran P, Le HD, Tran TM, Doan DK, Nguyen H, Le HTT, Phan VX, Tran H, Trinh BN, Nguyen HV. A Rare Case of left Atrial Myxoma With Coronary Fistula In A Patient With Dyspnea On Exertion. J Am Coll Cardiol 2021;77:3012.
14. Porter TR, Mulvagh SL, Abdelmoneim SS, Becher H, Belcik JT, Bierig M, Choy J, Gaibazzi N, Gillam LD, Janardhanan R, Kutty S, Leong-Poi H, Lindner JR, Main ML, Mathias W Jr, Park MM, Senior R, Villanueva F. Clinical Applications of Ultrasonic Enhancing Agents in Echocardiography: 2018 American Society of Echocardiography Guidelines Update. J Am Soc Echocardiogr 2018;31:241-74. [Crossref] [PubMed]