What is the role of echocardiography in diagnosing and managing myocarditis?

Role of Echocardiography in Diagnosing and Managing Myocarditis

Echocardiography serves as a valuable first-line imaging tool in suspected myocarditis, providing assessment of cardiac function and ruling out other causes of heart failure, though it has limitations in directly visualizing myocardial inflammation compared to cardiac MRI.

Diagnostic Value in Myocarditis

• Echocardiography is recommended for evaluation of chest pain in patients with suspected myocarditis, pericarditis, or pulmonary embolism 1

• Findings in acute myocarditis are non-specific and may include:

  • Left ventricular systolic and diastolic dysfunction 1
  • Regional wall motion abnormalities (at rest or exercise-induced) 1
  • Unspecific changes in image texture 1
  • Intracardiac thrombi 1
  • Secondary mitral and/or tricuspid regurgitation 1
  • Co-existent pericardial involvement 1
  • Ventricular wall thickening due to interstitial edema (especially in fulminant forms) 1, 2

• Patients with fulminant myocarditis typically show near-normal LV dimensions but increased septal thickness, while those with acute myocarditis demonstrate increased LV dimensions with normal septal thickness 2

Advanced Echocardiographic Techniques

• Speckle tracking imaging is a promising method for detecting myocardial inflammation:

  • Reduction in global systolic longitudinal strain (LV-GLS) and strain rate correlates with intramyocardial inflammation in endomyocardial biopsies 1
  • LV-GLS demonstrates the highest overall effect size in differentiating myocarditis from healthy controls compared to other echocardiographic parameters 3
  • Impairment in LV-GLS is associated with adverse cardiovascular outcomes regardless of LVEF 3

• Real-time myocardial contrast echocardiography can detect perfusion defects:

  • Areas of necrosis and inflammation result in myocardial perfusion defects 1
  • Perfusion defects that don't match known coronary distribution territories should raise suspicion of myocarditis 1, 4

Limitations of Echocardiography in Myocarditis

• Cannot accurately differentiate myocardial edema from wall hypertrophy 1
• Speckle tracking cannot differentiate inflammation-induced strain reduction from other causes (ischemia, infiltrative disease, toxin-related damage) 1
• May appear normal in less severe forms of myocarditis 1
• Limited role in direct visualization of inflammation compared to cardiac MRI 1, 5

Role in Management and Monitoring

• Useful for monitoring significant changes in wall motion during the course of disease 1
• Helps detect complications such as intracardiac thrombi and pericardial effusion 1
• Valuable for longitudinal assessment of ventricular function recovery 2
• Can predict outcomes: patients with fulminant myocarditis show substantial improvement in ventricular function at six months compared to those with acute myocarditis 2

Integration with Other Diagnostic Methods

• Echocardiography should be used as part of a comprehensive diagnostic approach:

  • Helps rule out other causes of heart failure (valvular disease, congenital heart disease, other cardiomyopathies) 1
  • Complements cardiac MRI, which remains superior for direct visualization of inflammation 5, 6
  • Should be considered alongside clinical presentation, biomarkers, and ECG findings 7

• When TTE studies are non-diagnostic, transesophageal echocardiography (TOE) may be indicated 1

Clinical Pitfalls to Avoid

• Don't rely solely on echocardiography for definitive diagnosis of myocarditis; cardiac MRI or endomyocardial biopsy are required for confirmation 7
• Recognize that normal echocardiographic findings don't exclude myocarditis, especially in less severe forms 1
• Avoid delaying appropriate management while waiting for advanced imaging if clinical suspicion is high 8