What is the workup for non-ischemic scarring or inflammation on a Cardiac MRI (Magnetic Resonance Imaging) with Gadolinium scan showing late gadolinium enhancement?

Workup for Subepicardial Late Gadolinium Enhancement on Cardiac MRI

The workup for subepicardial late gadolinium enhancement (LGE) on cardiac MRI suggesting non-ischemic scarring or inflammation should include comprehensive cardiac evaluation with laboratory markers of inflammation, additional cardiac imaging, and consideration of specific disease-targeted testing based on the Lake Louise Criteria for myocarditis. 1, 2

Initial Evaluation

• Laboratory studies:

  • Cardiac biomarkers: Troponin and creatine kinase to assess myocardial damage
  • BNP/NT-proBNP: To evaluate heart failure severity
  • Inflammatory markers: ESR, CRP to assess inflammatory activity
  • Consider viral serology if viral myocarditis is suspected

• ECG and monitoring:

  • 12-lead ECG to assess for arrhythmias or conduction abnormalities
  • 24-hour Holter monitoring (>100 ventricular ectopic beats in 24 hours suggests inflammatory myocardial disease) 2

Advanced Cardiac Imaging

• Complete cardiac MRI assessment using Lake Louise Criteria:

  • T2-weighted imaging to assess for myocardial edema
  • T1 mapping to evaluate for diffuse fibrosis
  • T2 mapping for quantitative assessment of edema
  • Extracellular volume (ECV) calculation if available 1

• Consider PET imaging:

  • FDG-PET can identify active inflammation, particularly helpful in diagnosing cardiac sarcoidosis 2
  • Combined PET-MRI may provide complementary information on both inflammation and fibrosis

Specific Disease Evaluation

For suspected myocarditis:

• Viral PCR from blood samples
• Consider endomyocardial biopsy in selected cases with persistent symptoms, heart failure, or arrhythmias despite medical therapy 1

For suspected cardiac sarcoidosis:

• High-resolution chest CT to assess for pulmonary involvement
• Evaluation for extracardiac sarcoidosis (lymph nodes, skin, eyes)
• Consider FDG-PET to identify active inflammation 2

Risk Stratification

• Arrhythmia risk assessment:

  • Electrophysiological study should be considered for risk stratification 2
  • Consider ICD implantation for primary prevention in patients with LGE and reduced ejection fraction (<35%) 2

• Functional assessment:

  • Evaluate for wall motion abnormalities and ventricular function
  • Assess for valvular abnormalities or other structural heart disease

Treatment Planning and Monitoring

• Initial management:

  • Rest and limitation of physical activity for 3-6 months
  • Standard heart failure therapy if ventricular dysfunction is present
  • Antiarrhythmic therapy if significant arrhythmias are present 2

• Disease-specific therapy:

  • For cardiac sarcoidosis: Consider corticosteroids (prednisone 40-60 mg daily) with slow taper over months
  • Consider steroid-sparing agents (methotrexate, azathioprine, mycophenolate) for maintenance therapy 2

• Follow-up imaging:

  • Repeat cardiac MRI to assess treatment response and 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

Important Considerations

• The pattern of LGE (subepicardial vs. subendocardial) helps differentiate between ischemic and non-ischemic etiologies 1
• Subepicardial LGE is characteristic of non-ischemic causes like myocarditis or cardiac sarcoidosis 2
• The extent of LGE predicts risk of malignant arrhythmia and heart failure, with persistent LGE after acute phase indicating increased risk of adverse outcomes 2

By following this systematic approach to evaluating subepicardial LGE on cardiac MRI, clinicians can effectively diagnose the underlying cause and implement appropriate management strategies to improve patient outcomes.