From the Guidelines
Diagnosing hypertrophic obstructive cardiomyopathy (HOCM) requires a comprehensive approach combining clinical evaluation, imaging, and sometimes genetic testing, with echocardiography as the cornerstone of diagnosis, revealing asymmetric septal hypertrophy, systolic anterior motion of the mitral valve, and left ventricular outflow tract obstruction, as recommended by the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline 1.
Diagnostic Approach
The diagnosis typically begins with a thorough medical history and physical examination, looking for symptoms like shortness of breath, chest pain, palpitations, or fainting, especially during physical exertion. A heart murmur that intensifies with certain maneuvers may be detected during examination.
- Electrocardiogram (ECG) is usually the first test, which may show left ventricular hypertrophy, abnormal Q waves, or ST-T wave changes.
- Echocardiography is the primary imaging modality, revealing asymmetric septal hypertrophy (typically ≥15mm), systolic anterior motion of the mitral valve, and left ventricular outflow tract obstruction with a gradient often exceeding 30 mmHg at rest or with provocation.
- Cardiac MRI provides additional structural details and can detect myocardial fibrosis, particularly useful when echocardiography is nondiagnostic or inconclusive, as stated in the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline 1.
Imaging and Genetic Testing
- Exercise stress testing may unmask symptoms and dynamic obstruction.
- In some cases, cardiac catheterization helps measure pressure gradients directly.
- Genetic testing can identify causative mutations in sarcomere protein genes, which is particularly useful for family screening, as the condition has an autosomal dominant inheritance pattern with variable expressivity.
Family Screening
Family screening is recommended for first-degree relatives of patients with HOCM, considering the disease's genetic nature and the importance of early detection and management, as emphasized in the 2020 AHA/ACC guideline 1 and the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline 1.
From the Research
Diagnostic Evaluation of HOCM
The diagnostic evaluation of Hypertrophic Obstructive Cardiomyopathy (HOCM) involves several steps, including:
- History-taking and physical examination 2
- Genetic studies 2
- Transthoracic echocardiography (TTE) 2, 3
- Cardiac MRI 2, 3, 4
- Electrocardiogram (ECG) 3, 5
Imaging Techniques
Imaging techniques play a crucial role in the diagnosis of HOCM.
- TTE is considered the gold standard of imaging, but it may not always detect HOCM, especially in adult-onset cases 3
- Cardiac MRI can provide more detailed information about cardiac morphology and function, and can be used to assess the extent of myocardial necrosis and conduction system abnormalities 4
- ECG can be used to identify specific electrical anomalies that may differentiate HOCM from other conditions, and can be used to monitor patients with HOCM 5
Diagnostic Challenges
Diagnosing HOCM can be challenging, especially in adult-onset cases.
- HOCM may not be detected by TTE, and further imaging techniques such as cardiac MRI may be necessary 3
- The disease may present with non-specific symptoms such as dyspnea, chest pain, and palpitations, making diagnosis more difficult 6
- A comprehensive diagnostic evaluation, including history-taking, physical examination, genetic studies, and imaging techniques, is necessary to confirm the diagnosis of HOCM 2