Cardiomyopathy

Cardiomyopathy refers to diseases of the heart muscle. In this group of conditions, the heart muscles are intrinsically abnormal. Cardiomyopathy patients eventually develop symptoms of heart failure or heart rhythm disturbances, due to their underlying heart muscle disease. These conditions are often genetic and inheritable.

The various types of cardiomyopathies include:

Hypertrophic cardiomyopathy

• This results from a genetic defect, causing heart muscle walls to be abnormally thick. Due to excessive heart muscle thickness, the heart is stiff and unable to relax normally.
• Patients are prone to developing symptoms of shortness of breath and chest pain.
• Patients can also develop abnormal heart rhythms/ unexplained fainting from electrical disturbances of the abnormally thick heart.

Dilated cardiomyopathy

• This is a condition where the heart muscles stretch (dilates) and become abnormally thin, resulting in a big heart with poor pumping function.
• A mutated TTN (Titin) gene is commonly implicated in this condition.
• Patient can develop symptoms of congestive heart failure and experience reduced lifespan.

Infiltrative cardiomyopathy

• This cardiomyopathy is characterised by the deposition of abnormal substances within the heart muscle, resulting in the disruption of the normal functioning of the heart.

A typical infiltrative cardiomyopathy is amyloid cardiomyopathy, where abnormal amyloid proteins deposit in the heart, amongst many other organs.

Inflammatory cardiomyopathy

• This refers to a group of conditions, where there is unexplained inflammation of the heart muscle. The inflammation is often a result of autoimmunity (immune system attacking own tissue), or in response to an external trigger.
• Some common inflammatory cardiomyopathies include cardiac sarcoidosis, eosinophilic myocarditis, and giant cell myocarditis.

Treatment for these conditions often involve immune suppression drugs, to halt the inflammatory process.

Restrictive cardiomyopathy

• This is a rare condition, where the heart muscles become stiff and fibrosis, affecting its ability to relax normally.

Patients will develop high pressures within the heart chambers and congestion.

Arrhythmogenic cardiomyopathy

• This condition results from replacement of the normal heart muscles with abnormal fibrous and fat material, likely secondary to a genetic abnormality.
• As a result, the heart chambers affected become enlarged and dysfunctional, with concurrent disruption of the electrical conduction system.
• Patients often develop significant heart rhythm disturbances, on top of severe heart failure.

• Shortness of breath (on exertion or during rest)
• Chest pain
• Difficulty in breathing when lying flat
• Waking up breathless at night
• Swelling of ankles/ legs/ abdomen
• Palpitations
• Unexplained fainting spells
• Sudden cardiac death

Cardiomyopathies are diagnosed by integrating patient's signs and symptoms, with various diagnostic modalities.

• Patient symptoms
  • Typical symptoms of shortness of breath on exertion, inability to sleep lying flat, worsening fatigue etc
• Clinical examination
  • Signs of fluid retention (leg swelling, abdominal swelling, fluid sound in lungs)
  • Signs of heart rhythm abnormalities (irregular pulse)
• Blood tests
  • Red blood cell counts, kidney/ liver function, thyroid hormone level
  • NT-proBNP: hormone produced by the heart, which is markedly elevated in most cardiomyopathies
• Electrocardiogram ('ECG')
  • Electrical tracing of the heart, looking for heart rhythm abnormalities, as well as signs of underlying structural heart abnormalities
• Chest radiograph
  • X-ray examination, looking for abnormal heart enlargement/ abnormal fluid collection in the lungs
• Specialised cardiac imaging
  • Echocardiogram: Ultrasound examination which allows doctors to evaluate important morphological features of the heart (shape/ size), as well as heart pumping function ('ejection fraction')
  • Cardiovascular magnetic resonance imaging ('Cardiac MRI'): Specialised scan looking specifically at the heart muscles, to characterise the underlying cardiomyopathy
• Invasive investigations
  • Right heart study: assess pressures in the heart chambers, as well as the blood delivery effectiveness of the heart
  • Endomyocardial biopsy: invasive procedure to sample the heart tissue for microscopic examination and evaluation
• Genetic testing
  • Blood-based DNA testing, to look for the underlying gene defect which can cause the specific cardiomyopathy

Cardiomyopathies are chronic conditions that requires long term treatment and follow up. The Cardiomyopathy Clinic at NUHCS provides a comprehensive programme, to help patients manage their cardiomyopathy.

Lifestyle modifications

• Smoking/ alcohol cessation
• Fluid and salt restriction
• Regular monitoring of body weight/ blood pressure
• Exercise as recommended by the heart failure team
• Cardiac rehabilitation programme enrollment

Genetic counseling/ testing

• As many cardiomyopathies are genetic inherited, family screening/ counseling is especially important for early detection and treatment.
• Genetic counseling is also of paramount importance for patients planning for families of their own.

Medical therapy

• Medications are the first-line therapy options for most forms of cardiomyopathies. They include cardiomyopathy-specific therapies, as well as drugs to manage patient's congestion (diuretics).

Procedures

• Implantable electronic devices (defibrillators/ pacemakers) in patients who suffer from conduction system diseases/ abnormal heart rhythms due to their underlying cardiomyopathy.

Advanced heart failure management

• Evaluation for patients with persistent symptoms for consideration of mechanical circulatory support ('mechanical heart pumps') or heart transplantation

Suitable patients will be followed up in the Cardiomyopathy Clinic, a specialised clinic aimed at providing holistic management of various cardiomyopathies, to improve the long-term outcome for our patients.

• Amyloid cardiomyopathy
• Arrhythmia
• Cardiac amyloidosis
• Cardiac sarcoidosis
• Chronic heart failure
• Congestive heart failure
• Dilated cardiomyopathy
• Hypertrophic cardiomyopathy
• Sudden cardiac death
• Ventricular tachycardia