What studies are warranted in a teenager with newly diagnosed concentric Left Ventricular (LV) hypertrophy consistent with Hypertrophic Cardiomyopathy (HCM)?

Diagnostic Evaluation for Teenagers with Newly Diagnosed Hypertrophic Cardiomyopathy

A comprehensive diagnostic workup including echocardiography, cardiac MRI, ambulatory ECG monitoring, exercise testing, and genetic testing is essential for proper evaluation and risk stratification in teenagers with newly diagnosed concentric LV hypertrophy consistent with HCM.

Initial Imaging Studies

• Transthoracic Echocardiography (TTE): Comprehensive 2D echocardiography is the cornerstone of initial evaluation to establish diagnosis, pattern of hypertrophy, and presence of obstruction 1, 2

  • Measurement of maximum diastolic wall thickness in all LV segments from base to apex 2
  • Assessment of LV systolic and diastolic function 1
  • Evaluation of mitral valve function and presence/severity of LVOT obstruction 2
  • Assessment of left atrial size and volume 2

• Cardiac Magnetic Resonance (CMR): Essential complementary imaging modality that provides superior assessment of HCM phenotype 1

  • Indicated when echocardiography is inconclusive or when additional information may impact management 1
  • Superior for detecting apical hypertrophy and areas of hypertrophy not readily visualized by echocardiography 3
  • Assessment of late gadolinium enhancement (LGE) for myocardial fibrosis evaluation, which has prognostic implications 1
  • T1 mapping to assess diffuse fibrosis, which may predict non-sustained ventricular tachycardia and SCD risk 1

Functional Assessment and Risk Stratification

• Exercise Testing:

  • Treadmill exercise testing with ECG and blood pressure monitoring for SCD risk stratification 1
  • Exercise echocardiography to detect and quantify exercise-induced dynamic LVOT obstruction if resting gradient is <50 mm Hg 1
  • Assessment of functional capacity and response to therapy 1

• Ambulatory ECG Monitoring:

  • 24-48 hour Holter monitoring to detect nonsustained ventricular tachycardia (NSVT), which is an important risk factor for SCD 1
  • Extended monitoring may be warranted in patients with symptoms 1
  • Serial ambulatory monitoring every 1-2 years is reasonable in patients without ICDs 1

• Genetic Testing:

  • Comprehensive genetic testing for HCM-associated mutations 1
  • Particularly important for family screening and risk stratification 1
  • The presence of high-risk mutations may influence management decisions 1

Additional Studies to Consider

• Coronary Angiography (CT or invasive):

  • Indicated in patients with symptoms or evidence of myocardial ischemia 1
  • Consider in teenagers with chest pain or abnormal stress test results 1

• Invasive Hemodynamic Assessment:

  • Recommended when there is uncertainty regarding the presence or severity of LVOTO on noninvasive imaging studies 1
  • Useful in selected patients with persistent symptoms despite optimal medical therapy 1

• Screening of Family Members:

  • First-degree relatives should undergo echocardiographic screening 1
  • For children and adolescents, screening every 12-18 months is recommended 1
  • Yield of echocardiographic screening in first-degree relatives is 10-15% throughout childhood and adolescence 1

Follow-up Recommendations

• Serial TTE studies every 1-2 years to assess changes in LV hypertrophy, dynamic obstruction, and myocardial function 1, 2
• More frequent monitoring may be warranted in patients with high-risk features 1
• Follow-up CMR may be considered to monitor progression of fibrosis 1

Important Considerations and Pitfalls

• Concentric LV hypertrophy may progress to systolic dysfunction in approximately 13% of patients over 3 years, necessitating careful monitoring of ventricular function 4
• LV strain analysis should be considered as reduced strain has been associated with adverse events in pediatric HCM 5
• Mechanical dyssynchrony and diastolic dysfunction are common in LVH and should be carefully assessed 6
• Avoid underestimating the extent of hypertrophy, particularly in the anterolateral free wall, which may be missed by echocardiography alone 3
• CMR may identify regions of LV hypertrophy not readily recognized by echocardiography and may be solely responsible for diagnosis in some patients 3