What is the appropriate management for an incidentally discovered, asymptomatic lipomatous hypertrophy of the interatrial septum in a middle‑aged to elderly adult?

Management of Lipomatous Hypertrophy of the Interatrial Septum

For an incidentally discovered, asymptomatic lipomatous hypertrophy of the interatrial septum (LHIS), conservative management with clinical observation is the appropriate approach—no surgical intervention is indicated.

Understanding the Condition

Lipomatous hypertrophy of the interatrial septum is a benign cardiac anomaly characterized by fatty tissue infiltration into the interatrial septum, typically sparing the fossa ovalis and creating a characteristic "dumbbell" or hourglass appearance 1, 2. This condition predominantly affects older, obese individuals with a higher incidence in women 2.

Diagnostic Confirmation

• Confirm the diagnosis using cardiac imaging, preferably multislice CT scanning, which provides the best visualization of fatty tissue characteristics and distribution 2
• Transthoracic or transesophageal echocardiography can identify the characteristic hourglass-shaped mass and help distinguish LHIS from other cardiac masses 1, 3
• The European Society of Cardiology notes that increased interatrial septum thickness on echocardiography can suggest infiltrative processes, including fatty deposition 4

Management Algorithm for Asymptomatic Patients

Conservative Approach (Recommended)

Reassurance and clinical observation without surgical intervention is the standard management for asymptomatic LHIS 2, 3. The rationale is straightforward:

• LHIS is histologically benign and does not undergo malignant transformation 1, 3
• Most cases remain asymptomatic throughout life and are discovered incidentally during imaging for other indications 2, 3
• Surgical excision carries unnecessary risk when the lesion is not causing symptoms 1

Monitoring Strategy

• Periodic clinical assessment to detect development of symptoms, particularly supraventricular arrhythmias or obstructive symptoms 2, 3
• ECG monitoring if palpitations or arrhythmia symptoms develop, as LHIS is associated with increased incidence of atrial arrhythmias 5, 2
• No routine interval imaging is required unless clinical status changes 1, 2

Indications for Surgical Intervention (Rare)

Surgical excision with reconstruction of the interatrial septum should be reserved only for patients who develop:

• Severe superior vena cava obstruction causing symptomatic right atrial inflow compromise 5, 2
• Intractable atrial arrhythmias refractory to medical management 2, 6
• Life-threatening cardiovascular complications directly attributable to the mass 1

Critical Pitfalls to Avoid

Do not confuse LHIS with other cardiac masses that require different management:

• LHIS is NOT hypertrophic cardiomyopathy—the guidelines on HCM management 4 do not apply to this benign fatty infiltration
• Distinguish from cardiac tumors (myxomas, sarcomas) that may require urgent surgical resection 3
• Avoid unnecessary biopsy in typical cases where imaging characteristics are diagnostic 1, 2

Do not perform prophylactic surgery even if the mass is discovered incidentally during cardiac surgery for other indications (e.g., coronary artery bypass grafting), as excision increases operative risk without benefit 1, 6.

Special Surgical Considerations

If the patient requires cardiac surgery for unrelated indications (coronary artery disease, valvular disease):

• Inform the surgical team preoperatively about the presence of LHIS, as it can cause technical difficulties with bicaval cannulation and visualization 1
• Intraoperative transesophageal echocardiography should be performed to delineate the extent of the mass 1
• Leave the mass intact unless it directly interferes with the planned procedure or causes hemodynamic compromise 1, 6
• Partial resection may be necessary only if the mass obstructs surgical access or causes significant flow obstruction 5

Patient Counseling

• Reassure the patient that LHIS is a benign condition that typically does not progress or cause complications 2, 3
• Advise weight management given the association with obesity, though this has not been proven to reduce the fatty mass 2
• Instruct the patient to report new symptoms of palpitations, syncope, or signs of superior vena cava syndrome 2, 3