What is the significance of lipomatous atrial septal hypertrophy on transthoracic echocardiogram (TTE)?

From the Guidelines

Lipomatous atrial septal hypertrophy (LASH) on transthoracic echocardiogram (TTE) is a benign cardiac condition that does not require specific treatment, as it is generally asymptomatic and considered a normal variant. The condition is characterized by excessive fat deposition in the interatrial septum, typically appearing as a dumbbell-shaped thickening of the septum 1.

Key Points

• No specific treatment is required for LASH, and regular cardiac follow-up with periodic echocardiographic monitoring is recommended to ensure stability of the finding.
• If the thickening exceeds 2 cm or causes hemodynamic compromise, further evaluation with transesophageal echocardiography or cardiac MRI may be warranted to distinguish it from other pathologies like lipomas or atrial myxomas.
• LASH is more common in older, obese individuals and women, and addressing any underlying cardiovascular risk factors is always prudent 1.
• Patients should be reassured about the benign nature of this finding to alleviate unnecessary anxiety.

Recommendations

• Regular cardiac follow-up with periodic echocardiographic monitoring is recommended to ensure stability of the finding.
• Further evaluation with transesophageal echocardiography or cardiac MRI may be warranted if the thickening exceeds 2 cm or causes hemodynamic compromise.
• Addressing any underlying cardiovascular risk factors is always prudent. The 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline for the management of hypertrophic cardiomyopathy recommends the use of TTE in the initial evaluation of patients with suspected HCM, as well as during follow-up, particularly when there is a change in cardiovascular symptoms or an event 1. However, this guideline does not specifically address LASH, and the management of this condition should be based on its benign nature and the absence of symptoms.

From the Research

Significance of Lipomatous Atrial Septal Hypertrophy on TTE

• Lipomatous hypertrophy of the atrial septum (LHAS) is a rare, but increasingly recognized, anomalous developmental or neoplastic lesion of the heart 2.
• It is characterized by an infiltration of adipocytes into myocytes of the interatrial septum, sparing the fossa ovalis, which gives a characteristic hourglass-shaped image on echocardiogram 3.
• LHAS can be associated with supraventricular arrhythmias and sudden death, although it is often asymptomatic 2.
• The diagnosis of LHAS can be made using transthoracic echocardiography (TTE), but multimodality imaging, including transesophageal echocardiography (TEE), computed tomography (CT), and cardiac magnetic resonance (CMR), may be necessary to confirm the diagnosis and rule out other conditions 4, 5.

Diagnostic Features on TTE

• LHAS typically appears as a homogenous echo-dense mass within the interatrial septum on TTE 5.
• The mass may have a characteristic "dumbbell" or hourglass shape, but atypical appearances can occur 5.
• TTE may not always provide a clear diagnosis, and additional imaging modalities may be necessary to confirm the presence of LHAS 4, 5.

Clinical Implications

• LHAS is generally considered a benign condition, and surgical treatment is usually not necessary unless the patient is experiencing life-threatening cardiovascular complications 3.
• Multimodality imaging is important for establishing a diagnosis and guiding management decisions 4, 5.
• The presence of LHAS may have implications for cardiac surgery, and awareness of the condition is necessary to avoid technical problems during surgery 3.