Diagnosis and Evaluation of Hypertrophic Cardiomyopathy

Authors:
Maron BJ, Desai MY, Nishimura RA, et al.
Citation:
Diagnosis and Evaluation of Hypertrophic Cardiomyopathy: JACC State-of-the-Art Review. J Am Coll Cardiol 2022;79:372-389.

The following are key points to remember from this state-of-the-art review on the diagnosis and evaluation of hypertrophic cardiomyopathy (HCM):

  1. HCM has a prevalence of 1:200–1:500. However, only a minority are clinically diagnosed. It is a treatable disease that can be associated with normal longevity.
  2. Initial assessment of a patient with HCM should include asking about symptoms of syncope, heart failure, chest pain, palpitations, and family history of HCM and sudden cardiac death (SCD). Initial evaluation should also ideally include an electrocardiogram (ECG), echocardiogram, ambulatory ECG monitoring, cardiac magnetic resonance imaging (MRI), and genetic testing. It may also include exercise echocardiography especially if symptoms are mild or absent to provoke an outflow gradient.
  3. Routine clinical evaluation is recommended annually and should usually include an ECG, echocardiogram, and ambulatory ECG monitor. Follow-up may be more frequent in the pediatric population.
  4. Diagnosis of HCM relies on echocardiogram and cardiac MRI showing hypertrophied left ventricle (LV) without dilatation in the absence of other metabolic or systemic disease causing hypertrophy such as hypertension or valvular disease. In adults, diagnosis of HCM is based on a maximum LV thickness of ≥15 mm at any site. In young children, HCM diagnosis relies on LV thickness of ≥13 mm.
  5. LV outflow tract (LVOT) obstruction gradients over 30 mm Hg are associated with increased risk for progression to symptomatic heart failure and can also identify patients who may be candidates for invasive relief of gradient. Exercise echocardiograms are key in identifying LVOT gradients, and when patients cannot exercise, Valsalva maneuver can be a surrogate.
  6. Cardiac MRI provides complementary information with an echocardiogram but can be of advantage when echocardiographic pictures are suboptimal. In addition, it provides more precise estimates of LV thickness, assessment of LV segments that may not be ideally visible on an echo such as apex, and identifies scar burden helping with risk stratification for SCD. The expert panel strongly recommends cardiac MRI with contrast as a component of HCM evaluation.
  7. HCM can be differentiated from hypertrophy related to hypertension by: a) presence of systolic anterior motion of the mitral valve, b) maximal septal thickness of ≥18 mm, c) hypertrophy involving the apex or anterolateral free wall or posterior septum, and d) prominent late gadolinium enhancement on MRI.
  8. HCM can be differentiated from athlete’s heart by: a) presence of cardiac symptoms, b) LV thickness >15 mm, c) normal or small LV cavity dimension, d) diastolic dysfunction, e) systolic anterior motion of mitral valve, and f) dynamic LVOT obstruction with rest or exercise.
  9. Genetic testing for HCM is helpful for screening of family members and in identifying HCM phenocopies (Fabry’s, amyloidosis, or Danon), but is not a prognostic tool. Approximately 30% of patients with HCM have evidence of a genetic etiology with a pathogenic disease-causing mutation. All HCM patients should have genetic counseling relevant to the disease, but genetic testing should not be performed in families unless a pathogenic mutation has been identified. The 2009 Genetic Information Act prohibits discrimination in employment and health insurance based on genotype.
  10. For clinical screening of first-degree family members of patients with HCM, diagnostic imaging usually begins at 12 years of age continuing annually until age 18-21 years. Screening can be extended to every 5 years in adulthood. Imaging should be obtained if the ECG is abnormal.
  11. This panel supports HCM as a disqualifying condition from most sanctioned high school and intercollegiate sports due to its association with SCD. HCM patients are discouraged from sports involving sprinting or isometric weight training. Moderate noncompetitive aerobic exercise programs are acceptable.
  12. Primary prevention ICD is not recommended for at-risk HCM patients as a strategy to allow for participation in competitive sports.

Keywords: Athletes, Cardiomyopathy, Hypertrophic, Chest Pain, Death, Sudden, Cardiac, Dilatation, Diagnostic Imaging, Echocardiography, Electrocardiography, Exercise, Gadolinium, Genetic Testing, Genotype, Heart Failure, Hypertension, Hypertrophy, Magnetic Resonance Imaging, Primary Prevention, Risk Assessment, Syncope, Valsalva Maneuver


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