What is the management approach for a patient with subtle but likely pathologic linear, subepicardial late gadolinium enhancement (LGE) of the inferior wall of the left ventricle (LV) suggestive of nonischemic scarring or inflammation?

Management of Subepicardial Late Gadolinium Enhancement in the Inferior Wall of the Left Ventricle

Patients with subepicardial late gadolinium enhancement (LGE) of the inferior wall of the left ventricle require comprehensive evaluation for myocarditis or cardiac sarcoidosis, followed by disease-specific management to reduce risk of arrhythmias and prevent progression to heart failure.

Diagnostic Evaluation

Initial Assessment

• Evaluate ventricular function, wall motion abnormalities, and wall thickness using echocardiography 1
• Obtain cardiac biomarkers:
  • Troponin and creatine kinase to assess myocardial damage
  • BNP/NT-proBNP to evaluate heart failure severity
  • Inflammatory markers (ESR, CRP) 1

Cardiac MRI Interpretation

• Subepicardial or mid-myocardial LGE pattern strongly suggests non-ischemic etiology 2
• Linear, subepicardial enhancement of the inferior wall specifically points toward:
  1. Myocarditis (most common cause)
  2. Cardiac sarcoidosis
  3. Other non-ischemic cardiomyopathies 2, 1

Additional Testing

• Holter monitoring (>100 ventricular ectopic beats in 24 hours suggests inflammatory process) 1
• Consider PET imaging with fluorodeoxyglucose to identify active inflammation 1
• Look for extracardiac sarcoidosis (pulmonary, lymph nodes, skin, eyes) 1
• High-resolution chest CT to evaluate for characteristic pulmonary findings of sarcoidosis 1

Management Approach

Activity Restriction

• Rest and limitation of physical activity for 3-6 months 1
• Subepicardial LGE in the left ventricular free wall is the most frequent morphologic substrate of juvenile cardiac sudden death during sports 3

Pharmacological Management

1. For suspected myocarditis:

   • Standard heart failure therapy if ventricular dysfunction is present
   • Antiarrhythmic therapy if significant arrhythmias are detected 1

2. For suspected cardiac sarcoidosis:

   • Initiate corticosteroids at high dose (prednisone 40-60 mg daily)
   • Taper slowly over months if clinical and imaging features improve
   • Consider steroid-sparing agents (methotrexate, azathioprine, mycophenolate) for maintenance 1

Arrhythmia Risk Assessment

• The presence of LGE predicts risk of malignant arrhythmia and heart failure regardless of etiology 2
• Consider electrophysiological study for risk stratification in patients with cardiac sarcoidosis 2
• ICD implantation should be considered for primary prevention in patients with LGE and reduced ejection fraction (<35%) 2, 4
• Patients with LGE have an 8-fold higher risk of adverse cardiac outcomes even after adjustment for LV volume and functional class 4

Follow-up and Monitoring

Imaging Follow-up

• Repeat cardiac MRI to assess treatment response 1
• Monitor for changes in LGE pattern and extent
• T1 and T2 mapping techniques can track changes with therapy and may be more sensitive than LGE for monitoring inflammation 2

Clinical Monitoring

• Close monitoring for relapse after discontinuation of treatment 1
• Regular assessment of ventricular function
• Monitor for symptoms of heart failure and arrhythmias
• ECG monitoring (low QRS voltages in limb leads may be present in patients with subepicardial scarring) 3

Prognosis

• The extent of LGE predicts risk of adverse outcomes 1, 4
• Persistent LGE after acute phase indicates increased risk of adverse outcomes 1
• With appropriate treatment for cardiac sarcoidosis, 5-year survival is 90-96% 1
• Poor prognostic indicators include increased LV end-diastolic diameter, higher NYHA functional class, and sustained ventricular tachycardia 1

Remember that subepicardial LGE represents myocardial fibrosis or inflammation that significantly increases risk of arrhythmias and sudden cardiac death, requiring aggressive evaluation and management even if ventricular function appears preserved.