Multimodality Cardiovascular Imaging of Patients with Hypertrophic Cardiomyopathy
Cardiac Amyloidosis versus HCM
- Echocardiography is the initial imaging modality for evaluation of the presence, magnitude, and pattern of LV hypertrophy and UEA should be used whenever needed.
- CMR is indicated in patients with suboptimal echocardiographic images, and patients with borderline LV hypertrophy.
- If CMR is contraindicated or could not be performed, cardiac CT is considered next.
- Irrespective of which imaging modality is used, the report should comment on the pattern and extent of LV hypertrophy including maximum wall thickness.
Assessment of Left Ventricular Systolic Function
- Assessment of LVEF should be performed in all HCM patients using echocardiography, with or without UEA, at the time of diagnosis and when there is a significant change in clinical condition. There should be a low threshold for using imaging modalities such as CMR or CT for LV systolic function assessment when echocardiographic images are suboptimal.
- Assessment of global longitudinal strain adds important prognostic data and may be performed in centers with experience and expertise with using strain echocardiography.
Assessment of Left Ventricular Diastolic Function
- A comprehensive approach is recommended for the evaluation of diastolic function in HCM.
- Diastolic function assessment includes mitral inflow velocities recorded at annulus and leaflet tip levels, early diastolic velocity by tissue Doppler measured at septal and lateral sides of the mitral annulus, peak TR velocity obtained by CW Doppler from multiple windows, biplane LA maximum volume index, and pulmonary vein velocities.
- A restrictive LV filling pattern and increased E/e’ ratio in HCM patients is associated with heart failure hospitalizations, reduced exercise tolerance in children and adults, and SCD.
Pitfalls and Challenges in the Evaluation of Left Ventricular Outflow Tract Obstruction
- LVOT obstruction occurs in 70-75% of patients, where there is either a resting or provoked LVOT gradient. A systematic approach using provocative maneuvers can differentiate non-obstructive from obstructive phenotype.
- Most patients with HCM and LVOTO have abnormalities of the mitral valvular and subvalvular apparatus. SAM is a result of drag forces on elongated mitral valve leaflets.
- SAM/LVOTO is not specific for HCM and can occur in other conditions provoked by reduced afterload, reduced preload, and increased LV contractility.
- CW Doppler shows a mid-to-late-systolic peaking, dagger-shaped spectral pattern characteristic of dynamic LVOTO. The LVOT gradient can be determined using the modified Bernoulli equation: LVOT gradient = 4 X (LVOT velocity)2
- Dynamic LVOTO obstruction should be differentiated from fixed subvalvular, valvular, or supravalvular stenosis. The CW Doppler envelope in these latter conditions is usually early peaking.
- The echocardiographic report, in addition to blood pressure, quantification of LVOT gradient, and mitral valve regurgitation severity, should contain a clear statement about the anatomy of the mitral valve, the presence of SAM, the effect of provocative maneuvers on LVOT gradient, and papillary muscle abnormalities if present.
- In symptomatic patients, if a peak instantaneous gradient ≥50 mm Hg is not obtained, then provocative maneuvers should be pursued.
Mitral regurgitation in HCM
- In most patients with obstructive HCM, mitral regurgitation is related to dynamic obstruction with a posteriorly and laterally directed eccentric jet.
- In some patients, mitral valve prolapse or flail is the etiology of mitral regurgitation.
- In some patients, TEE or CMR is needed for better evaluation of the mechanism of MR
Midventricular Obstruction and Apical Aneurysm
- MVO is diagnosed with mid-cavitary obliteration and a systolic gradient ≥30 mm Hg at rest.
- Echo with ultrasound enhancing agents or CMR can identify the presence of small apical aneurysms and apical clots. CTA can be used if needed.
- MVO is associated with higher risk of ventricular arrhythmias and mortality
- LGE by CMR identifies areas of replacement fibrosis.
- T1 mapping can be used to determine extracellular volume fraction in HCM patients.
- LGE patterns and T1 mapping are of value in evaluation of patients with increased LV wall thickness.
Multimodality Imaging for risk stratification and prognostication
- Imaging provides key data needed for risk stratification for SCD.
- Maximum wall thickness ≥30 mm, apical aneurysm, LVEF ≤50%, LGE ≥15%, LVOT obstruction, and enlarged LA are imaging findings associated with higher risk of SCD.
- An UEA is recommended for patients with MVO or apical HCM to evaluate for apical aneurysms.
Multimodality Imaging in Common Clinical Scenarios
- CCTA can be used to noninvasively evaluate the coronary arteries in HCM patients.
- PET and CMR are the preferred techniques for stress perfusion imaging.
- Epicardial CAD in HCM patients is associated with worse outcomes.
- Echocardiography is the initial imaging modality for HCM screening.
- Periodic screening is recommended at intervals that depend on age, presence of a known pathogenic variant, and whether disease is early onset.
- CMR should be considered in patients with technically challenging echocardiograms, and in patients in whom abnormal electrocardiographic findings are present despite an apparently normal echocardiogram.
- For patients on oral allosteric modulators of cardiac β-myosin, monitoring of LVEF is essential to avoid the development of heart failure due to reduced EF.
- Intraoperative TEE plays a critical role in guiding the management of HCM patients undergoing surgical myectomy.
- Myocardial contrast echocardiography plays a critical role in intraprocedural guidance of alcohol septal ablation.
- TEE is critical for intraprocedural guidance of TEER to treat obstructive HCM patients who are not candidates for septal reduction therapy.
Table 1. Typical Features and Findings in Phenocopies of HCM
|Most Common Phenocopies||Clinical Features||Typical ECG Findings||Typical Echo Findings||Typical CMR Findings||Genetics and Additional Features|
Table 2. Differential Diagnosis of SAM and LVOTO
- Elderly with hypertension, sigmoid septum and hyperdynamic LV function
- Compensatory basal septal hypercontractility following acute myocardial infarction with apical dysfunction
- Takotsubo cardiomyopathy with hyperdynamic basal LV function
- Massive posterior mitral annulus calcification
- After surgical and percutaneous mitral valve repair
- After aortic valve replacement in patients with LVH and hyperdynamic LV
- Elderly patients in ICU with anemia, volume depletion, tachyarrhythmias, sepsis
- Medications eg: inotropes, vasodilators and sympathomimetics
- Right ventricular pressure overload like acute COPD exacerbation and/or ARDS
- Phenocopies of HCM such as cardiac amyloidosis or Anderson-Fabry disease
Table 3. Summary of Key Imaging Markers and Approach in SCD Risk Stratification
|Imaging Parameter||SCD risk threshold||Imaging Approach||Practical Points and/or Caveats|
∗∗ In HCM patients without major risk factors for SCD and uncertain on whether to implant ICD, decision on ICD implantation may be reached based on late gadolinium enhancement findings.
Multimodality Cardiovascular Imaging of Patients with Hypertrophic Cardiomyopathy
June 1, 2022
Country of Publication
Hypertrophic cardiomyopathy (HCM) is defined by the presence of left ventricular hypertrophy in the absence of other potentially causative cardiac, systemic, syndromic, or metabolic diseases. Symptoms can be related to a range of pathophysiologic mechanisms including left ventricular outflow tract obstruction with or without significant mitral regurgitation, diastolic dysfunction with heart failure with preserved and heart failure with reduced ejection fraction, autonomic dysfunction, ischemia, and arrhythmias. Appropriate understanding and utilization of multimodality imaging is fundamental to accurate diagnosis as well as longitudinal care of patients with HCM. Resting and stress imaging provide comprehensive and complementary information to help clarify mechanism(s) responsible for symptoms such that appropriate and timely treatment strategies may be implemented. Advanced imaging is relied upon to guide certain treatment options including septal reduction therapy and mitral valve repair. Using both clinical and imaging parameters, enhanced algorithms for sudden cardiac death risk stratification facilitate selection of HCM patients most likely to benefit from implantable cardioverter-defibrillators.
Male, Female, Adolescent, Adult, Child, Infant, Older adult
Health Care Settings
Hospital, Outpatient, Radiology services
Nurse, nurse practitioner, physician, physician assistant
Diagnosis, Assessment and screening
D002312 - Cardiomyopathy, Hypertrophic, D057791 - Cardiac Imaging Techniques
hypertrophic cardiomyopathy, cardiovascular imaging