Hypertrophic Cardiomyopathy

objectives

• The classic presentation of hypertrophic cardiomyopathy
• Stress testing in hypertrophic cardiomyopathy
• MPI findings of hypertrophic cardiomyopathy

Title Text

Stress testing: exercise

• Abnormal ECGs are common
• Abnormal ECG changes to exercise are common
• ECG changes in HCM are not helpful in determining underlying CAD
• Purpose:
  • Functional capacity
  • Provocation of LV outflow tract (LVOT) obstruction
  • Prognostic implications

LV hypertrophy - with strain

LV hypertrophy - without strain

Apical HCM

ECG changes with stress - normal MPI

CPET 

• ECG changes of limited use
• The benefit is measurement of anaerobic threshold, expiratory ventilation, carbon dioxide output, ratio of ventilation to carbon dioxide production

Stress echo

• Limitations:
  • at rest regions of hypertrophy have abnormal wall motion. Nearly 75% of patients with HCM can develop LVOT obstruction during exercise
  • use of dobutamine as stress agent is not recommended because it can lead to significant LVOT gradient (in even normal individuals)
    • Leads to new wall motion abnormalities that do not correspond to coraronary artery disease

MPI

• Nuclear scintigraphic MPI: relies on differential between rest and stress, SPECT hypoperfusion during stress, PET: absolute hypoperfusion
• Measurement of absolute myocardial perfusion allows calculation of coronary flow reserve
• High false positive on single-photon emission CT MPI
  • rest-stress related perfusion mismatch is due to microvascular ischemia
• Areas of hypertrophy = hyperintense, lead other areas to appear hypoperfused

MPI

• Septal stress perfusion defects resolve on repeat imaging post septal myomectomy: due to reduction in microvascular ischemia
• MPI is best used as a negative predictor of epicardial CAD

uptake increase with hcm

Tower-Rader, A.,et al. Journal of the American Society of Echocardiography, 30(9), pp.829-844.

uptake increase with hcm

Tower-Rader, A.,et al. Journal of the American Society of Echocardiography, 30(9), pp.829-844.