Recommended Citation
Jacobsen S, Paolella G, Bentsen C, et al. Mystery Stalk: Thrombus or Myxoma. Presented at Scientific Day; May 20, 2026; Milwaukee, WI.
Abstract
Introduction/Background:
Left atrial (LA) masses in patients with new onset atrial fibrillation (AF) are uncommon but clinically consequential findings. Differentiating between LA thrombus and myxoma is critical in determining proper management, which may include anticoagulation, cardioversion, and/or surgery. While cardiac magnetic resonance imaging (cMRI) is considered the gold standard for tissue characterization, overlap in imaging features may limit diagnostic certainty in select cases. This case highlights management options when the gold standard fails to provide a definitive diagnosis.
Description:
A 74-year-old woman with HFpEF presented with chest pain and dyspnea and was admitted with new onset atrial fibrillation with RVR. TTE and TEE demonstrated mild mitral stenosis, severe left atrial enlargement, and a large, mobile, pedunculated LA mass arising from the LAA, raising concern for myxoma vs organized thrombus. Cardioversion was subsequently deferred, and the patient was managed with rate control and apixaban for anticoagulation. cMRI was performed for definitive clarification; however, despite contrast-enhanced imaging, the findings were unable to distinguish myxoma from organized thrombus. Several days later, she developed acute limb ischemia requiring thrombectomy, a small ischemic stroke, and renal infarcts. Anticoagulation was maintained with a heparin drip perioperatively and later transitioned to apixaban. Shortly after thrombectomy, a repeat TTE showed near resolution of the mass with only a thin stalk, and follow-up TEE revealed a small residual thrombus with dense spontaneous echo contrast.
Discussion:
This case highlights the diagnostic limitations of cMRI in differentiating LA myxoma from thrombus, even when classic tumor features such as pedunculated stalk are present. Although cMRI is regarded as the gold standard for intracardiac mass evaluation, clinical behavior and serial imaging proved more informative than morphology alone. Massive left atrial enlargement and mild mitral stenosis likely predisposed the patient to thrombus formation despite short AF duration, ultimately resulting in sequalae of shower emboli. When imaging findings are discordant or indeterminate, proper management may include minimizing embolic risk with anticoagulation and monitoring response to therapy with surveillance imaging.
Presentation Notes
Presented at Scientific Day; May 20, 2026; Milwaukee, WI.
Full Text of Presentation
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Document Type
Poster
Open Access
Available to all.
Mystery Stalk: Thrombus or Myxoma
Introduction/Background:
Left atrial (LA) masses in patients with new onset atrial fibrillation (AF) are uncommon but clinically consequential findings. Differentiating between LA thrombus and myxoma is critical in determining proper management, which may include anticoagulation, cardioversion, and/or surgery. While cardiac magnetic resonance imaging (cMRI) is considered the gold standard for tissue characterization, overlap in imaging features may limit diagnostic certainty in select cases. This case highlights management options when the gold standard fails to provide a definitive diagnosis.
Description:
A 74-year-old woman with HFpEF presented with chest pain and dyspnea and was admitted with new onset atrial fibrillation with RVR. TTE and TEE demonstrated mild mitral stenosis, severe left atrial enlargement, and a large, mobile, pedunculated LA mass arising from the LAA, raising concern for myxoma vs organized thrombus. Cardioversion was subsequently deferred, and the patient was managed with rate control and apixaban for anticoagulation. cMRI was performed for definitive clarification; however, despite contrast-enhanced imaging, the findings were unable to distinguish myxoma from organized thrombus. Several days later, she developed acute limb ischemia requiring thrombectomy, a small ischemic stroke, and renal infarcts. Anticoagulation was maintained with a heparin drip perioperatively and later transitioned to apixaban. Shortly after thrombectomy, a repeat TTE showed near resolution of the mass with only a thin stalk, and follow-up TEE revealed a small residual thrombus with dense spontaneous echo contrast.
Discussion:
This case highlights the diagnostic limitations of cMRI in differentiating LA myxoma from thrombus, even when classic tumor features such as pedunculated stalk are present. Although cMRI is regarded as the gold standard for intracardiac mass evaluation, clinical behavior and serial imaging proved more informative than morphology alone. Massive left atrial enlargement and mild mitral stenosis likely predisposed the patient to thrombus formation despite short AF duration, ultimately resulting in sequalae of shower emboli. When imaging findings are discordant or indeterminate, proper management may include minimizing embolic risk with anticoagulation and monitoring response to therapy with surveillance imaging.
Affiliations
Advocate Lutheran General Hospital