Presumed right atrial myxoma causing mechanical inflow obstruction and a heart-failure-with-preserved-ejection-fraction–mimicking phenotype in a resource-limited setting: A case report

Abstract

Right atrial masses are rare and may present with features of right-sided heart failure that can be clinically mistaken for heart failure with preserved ejection fraction (HFpEF) despite preserved left ventricular systolic function. We report a 55-year-old man with a background of hypothyroidism who presented with a one-month history of progressive dyspnea and systemic congestion (NYHA class III). Transthoracic echocardiography demonstrated a large (approximately 5.0 × 3.0 cm), heterogeneous, pedunculated, and highly mobile right atrial mass located near the inferior vena cava, causing mechanical tricuspid inflow obstruction with a ball-valve effect and reduced right ventricular systolic performance (TAPSE 1.1 cm). Left ventricular systolic function and wall thickness were preserved and normal, respectively. In this resource-limited setting, advanced cross-sectional imaging, natriuretic peptide testing, and advanced cardiac histopathological confirmation were not available; the diagnosis of presumed right atrial myxoma was therefore based on echocardiographic morphology and clinical assessment. The patient improved partially with conservative management (diuretics, oxygen); surgical referral was recommended but was not feasible locally or abroad. This case highlights the importance of considering structural, right-heart mimics when a patient with apparent HFpEF has predominant right-sided congestion, and underscores the diagnostic value of echocardiography, including subcostal imaging, in low-resource environments.

Introduction

Primary cardiac tumours are rare, with an estimated incidence of 0.001–0.03% in autopsy series, the majority of which are benign myxomas typically arising in the left atrium [1]. Right atrial myxomas are considerably less common and manifest differently, often presenting with systemic venous congestion and right-sided heart failure rather than the pulmonary congestion typical of left-sided lesions [2]. In clinical practice, particularly in settings lacking advanced hemodynamic and biomarker assessment, this presentation can easily be misclassified as a primary myocardial or diastolic disease process, such as heart failure with preserved ejection fraction (HFpEF) [3]. While true HFpEF is driven by left ventricular diastolic dysfunction and elevated filling pressures, large right atrial masses produce a mechanically similar right-sided obstructive phenotype without intrinsic ventricular disease.

Echocardiography remains the cornerstone of diagnosis, particularly in resource-limited settings where advanced modalities such as cardiac magnetic resonance imaging (MRI) or computed tomography (CT) are unavailable [4]. This report aims to describe a rare case of a presumed right atrial myxoma causing mechanical venous inflow obstruction and a clinical presentation mimicking HFpEF in a resource-limited setting.

Case Presentation

A 55-year-old man with a known history of hypothyroidism presented with a one-month history of progressive exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, abdominal discomfort, and generalized body swelling, corresponding to New York Heart Association (NYHA) functional class III at presentation. He had no history of hypertension, diabetes mellitus, asthma, chronic obstructive pulmonary disease, peripheral arterial disease, or hyperlipidemia. He was a lifelong non-smoker and denied alcohol use. There was no relevant family history of cardiac disease or malignancy. He reported no fever, palpitations or documented arrhythmia, prior thromboembolic events, or known malignancy.

On examination, he was tachycardic (heart rate 110–120 bpm) with elevated jugular venous pressure and bilateral pitting lower-limb oedema. Oxygen saturation was 88% on room air. Blood pressure was hemodynamically stable, and lung auscultation was unremarkable.

A 12-lead electrocardiogram demonstrated sinus tachycardia (107 bpm), a rightward frontal-plane axis, and generalized low QRS voltages. The generalized low QRS voltage raised the possibility of a coexisting pericardial effusion, a recognized association of both hypothyroidism and congestive states; however, no significant pericardial effusion was identified on echocardiography. Nonspecific inferior T-wave changes were noted; an automated interpretation also flagged possible lateral and anteroseptal infarction of undetermined age, which was considered a nonspecific finding in the absence of any clinical history or biomarker evidence of ischemia and was not pursued further given resource constraints.

Laboratory investigations are summarized in Table 1. Findings included markedly elevated transaminases (AST 568 IU/L, ALT 333 IU/L; both upper reference limit 47 IU/L) and elevated total and direct bilirubin (2.5 mg/dL and 1.5 mg/dL respectively), consistent with congestive hepatopathy. Alkaline phosphatase was elevated (478 IU/L). Mild hyponatremia (130 mmol/L) and hypocalcemia (2.0 mmol/L) were present. Renal function, lipid profile, and urinalysis were unremarkable. Erythrocyte sedimentation rate was mildly elevated (35 mm/h). Full blood count showed a mild neutrophil predominance with lymphopenia; hemoglobin was low-normal (11.8 g/dL). Thyroid-stimulating hormone was elevated at 10.5 mIU/L (reference 0.4–5.0 mIU/L), consistent with the patient's known hypothyroidism.

Table 1.

Laboratory investigations.

Test	Result	Reference range
Sodium	130 mmol/L	135–145
Potassium	5.2 mmol/L	3.6–5.5
Calcium	2.0 mmol/L	2.2–2.9
Chloride	95 mmol/L	95–108
AST (GOT)	568 IU/L	Up to 47
ALT (GPT)	333 IU/L	Up to 47
Total bilirubin	2.5 mg/dL	Up to 1
Direct bilirubin	1.5 mg/dL	0.1–0.2
Alkaline phosphatase	478 IU/L	Up to 300
Total cholesterol	106 mg/dL	< 204
Triglycerides	65 mg/dL	< 204
HDL-cholesterol	26 mg/dL	> 45
LDL-cholesterol	67 mg/dL	0–159
Creatinine	0.5 mg/dL	Up to 1.1
Urea	50 mg/dL	10–50
ESR	35 mm/h	5–20
TSH	10.5 mIU/L	0.4–5.0
Hemoglobin	11.8 g/dL	11.0–18.0
WBC	9.56 × 10⁹/L	4.00–10.00
Platelets	350 × 10⁹/L	150–450

Transthoracic echocardiography revealed preserved left ventricular systolic function (ejection fraction approximately 60%, biplane estimate) with normal left ventricular cavity dimensions and wall thickness, and a large right atrial mass (described in full under Imaging Findings).

Imaging Findings

Transthoracic echocardiography demonstrated a large, heterogeneous, pedunculated, and highly mobile intraluminal right atrial mass measuring approximately 5.0 × 3.0 cm, located near the inferior vena cava–right atrial junction and occupying a substantial portion of the right atrial cavity.

In the apical four-chamber view (Fig. 1) the mass is clearly visualized within the right atrium, distinct from surrounding cardiac structures. The lesion demonstrated marked mobility, prolapsing through the tricuspid valve during diastole, producing a dynamic ball-valve effect with partial obstruction of right ventricular inflow. Qualitative Doppler assessment across the tricuspid valve suggested a mild stenotic inflow pattern associated with the mobile mass, consistent with dynamic right ventricular inflow obstruction rather than intrinsic tricuspid valve disease.

Fig. 1.

Apical four-chamber view showing a large, heterogeneous, pedunculated mass (arrow) occupying a significant portion of the right atrium, clearly distinguished from the atrial walls and interatrial septum.

Right ventricular systolic function, assessed by tricuspid annular plane systolic excursion (TAPSE), was objectively reduced at 1.1 cm (normal > 1.6 cm) [5], consistent with impairment of right ventricular performance secondary to chronic mechanical inflow obstruction and volume/pressure overload. Left ventricular internal dimensions in diastole (4.5 cm) and systole (2.4 cm), interventricular septal thickness in diastole (1.1 cm) and systole (1.2 cm), as well as left atrial (3.5 cm) and aortic root dimensions (2.6 cm), were within normal limits, arguing against a primary left ventricular diastolic process as the driver of the patient's presentation.

Subcostal imaging (Fig. 2) demonstrated a dilated inferior vena cava measuring approximately 2.1 cm with qualitatively reduced respiratory variation, consistent with elevated right atrial pressure and systemic venous congestion.

Fig. 2.

Subcostal view focusing on the inferior vena cava (IVC) and the right atrial junction, demonstrating the venous inflow region with a dilated IVC measuring approximately 2.1 cm.

A second apical four-chamber view (Fig. 3) was used to confirm the mass’s pedunculated nature and mobility from a different imaging angle, distinguishing it from the atrial wall and excluding an imaging artefact.

Fig. 3.

Apical four-chamber view from a different imaging angle demonstrating the right atrial mass (arrow). Supplementary echocardiographic cine imaging demonstrates its high mobility and diastolic prolapse through the tricuspid valve, consistent with a dynamic ball-valve effect.

Supplementary echocardiographic video further demonstrates the dynamic mobility of the mass and its interaction with the tricuspid valve.

Differential Diagnosis

The differential diagnosis for a right atrial mass includes thrombus, infective vegetation, and primary or secondary cardiac tumors [6]. Thrombus was considered unlikely given the absence of atrial fibrillation or other arrhythmia, no prior history of venous thromboembolism, and an echocardiographic appearance (a discrete, pedunculated, highly mobile mass with a well-defined stalk) atypical for thrombus, which more commonly appears as a laminated, less mobile mass adherent to the atrial wall or appendage. Infective vegetation was considered unlikely in the absence of fever, a predisposing structural or device-related risk factor, and laboratory evidence of active infection (normal white cell differential aside from mild neutrophilia, no bacteremia sought or clinically suspected). Metastatic cardiac tumor was considered less likely given the absence of a known primary malignancy and the solitary, well-circumscribed, pedunculated morphology, which is more characteristic of a primary benign tumor such as myxoma than of metastatic disease, which more typically produces infiltrative or multifocal lesions.

On this basis, the imaging findings were judged most consistent with a presumed atrial myxoma. We acknowledge that cardiac MRI or CT would be required for further tissue characterization, but neither modality is available in our setting. Furthermore, while basic pathology services exist in Hargeisa, definitive diagnosis requires surgical excision and advanced cardiac histopathology. Because our institution operates as a cardiac center without an affiliated cardiovascular surgery center, local excision was impossible, rendering definitive confirmation unattainable.

Management and Outcome

The patient was managed conservatively with loop diuretics and supplemental oxygen, with close monitoring of renal function and electrolytes given the diuretic therapy. Surgical excision was recommended as the definitive treatment; however, this was not feasible locally owing to the absence of a cardiovascular surgery center. While medical cardiac services are available, referral abroad for cardiothoracic surgery could not be arranged because of the patient's financial constraints. With conservative management, the patient's dyspnea, oxygen saturation, and peripheral oedema showed partial improvement over the course of inpatient management, and he was discharged on oral diuretic therapy with outpatient follow-up arranged. At the time of writing, longer-term follow-up data (including recurrence, interval change in mass size, or eventual access to surgical referral) were not yet available; this is discussed further under limitations.

Discussion

This case illustrates a rare presentation in which a right atrial mass produced a clinical phenotype of right-sided congestion with preserved left ventricular systolic function, superficially resembling heart failure with preserved ejection fraction (HFpEF). True HFpEF is defined by diastolic dysfunction of the left ventricle, typically supported by echocardiographic markers of impaired relaxation and elevated filling pressures (eg, E/e', left atrial enlargement, left ventricular hypertrophy) and elevated natriuretic peptides [7]. In this case, left ventricular wall thickness and left atrial size were normal, and the dominant abnormality was mechanical: a mobile right atrial mass intermittently obstructing tricuspid inflow with a ball-valve effect, together with objectively reduced right ventricular systolic performance (TAPSE 1.1 cm). This represents a structural mimic of the right-heart-failure phenotype rather than true HFpEF.

Right atrial myxomas are considerably less common than their left atrial counterparts and account for a minority of cardiac myxomas reported in surgical and autopsy series [1,2]. When right-sided myxomas do become symptomatic, they more typically present with signs of systemic venous congestion, right heart failure, or, less commonly, syncope or embolic phenomena, rather than the pulmonary congestion typical of left atrial myxoma [6]. Prior case reports have described right atrial masses causing tricuspid inflow obstruction and a right-heart-failure phenotype, but reports explicitly framing this as a mimic of a defined heart-failure syndrome with complementary echocardiographic assessment of right-heart function and mechanical inflow obstruction remain limited, particularly from resource-limited settings. The present case adds to this literature by documenting this mechanism with complementary echocardiographic views and objective evidence of right ventricular impairment.

Transthoracic echocardiography was the primary and, in this setting, only available diagnostic modality [4]. It successfully demonstrated the intracardiac mass, its dynamic interaction with the tricuspid valve, and reduced right ventricular systolic performance, illustrating that a focused, systematic echocardiographic examination (including subcostal views for IVC assessment) can characterize clinically important structural heart disease even where advanced cross-sectional imaging is unavailable.

This case also highlights a broader diagnostic and management challenge in resource-limited settings: even when a treatable structural lesion is correctly identified, definitive management may remain inaccessible because of the absence of cardiovascular surgical centers and the high cost of overseas referral, as reflected in this patient's own account (see Patient Perspective). This underscores the importance of investment in regional cardiac surgical capacity and structured international referral pathways for patients in similar circumstances. The key clinical lesson is that any patient presenting with an apparent HFpEF phenotype dominated by right-sided congestion should undergo systematic echocardiographic assessment of the tricuspid valve and inferior vena cava—including subcostal views—to avoid the diagnostic pitfall illustrated here.

Limitations

This report has several limitations. Definitive histopathological confirmation of the mass was not obtained, as surgical excision was not accessible; the diagnosis of myxoma therefore remains presumptive, based on echocardiographic morphology and clinical context. Furthermore, while general pathology is available locally, advanced cardiac histopathology is not. Cardiac CT and MRI, which could have provided additional tissue characterization and more precise anatomical delineation, were also unavailable. Natriuretic peptide testing and a full formal assessment of left ventricular diastolic function (mitral inflow E/A ratio, tissue Doppler e', E/e') were not performed, limiting our ability to formally exclude coexisting diastolic dysfunction. Right atrial and right ventricular chamber volumes and a formal IVC collapsibility index percentage were not recorded. Follow-up at the time of writing was limited to the immediate post-discharge period, and longer-term outcome data are not yet available.

Conclusion

A presumed right atrial myxoma, or other right atrial tumor, should be considered in patients presenting with apparent HFpEF and predominant right-sided congestion, particularly when echocardiography identifies intracardiac obstruction. Echocardiography, including subcostal views, remains an essential and often the only accessible diagnostic tool for characterizing such lesions in resource-limited settings.

Patient perspective

“I was relieved to understand the cause of my illness, but I am worried because I cannot access the surgery and definitive treatment I need.”

Author contributions

All authors contributed to the conception, drafting, revision, and final approval of the manuscript.

Ethical approval

Ethical approval was obtained from the Hargeisa Group Hospital Research and Ethical Review Committee.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Appendix. Supplementary materials

Supplementary Video 1 – Apical four-chamber echocardiographic cine loop demonstrating the highly mobile right atrial mass prolapsing through the tricuspid valve during diastole, consistent with a dynamic ball-valve effect.