Case 2.2 – Cardiomyopathy (Dilated) [SDL]

Acute onset of breathlessness may be:

• Cardiovascular
• Respiratory
• Metabolic

A detailed history of the onset of the problem is imperative. Given this man's history, consideration and exclusion of another myocardial infarction with acute heart failure is imperative. The other priorities to exclude as soon as possible include acute pulmonary oedema and pulmonary embolus.

Features that must be sought on history include:

• Pain or discomfort: Type of pain, location, radiation, previous experience with this pain?
• Cough: Productive, non-productive, or blood-stained
• Sweating
• Light-headedness
• Fevers
• Nausea and vomiting
• Lower limb oedema
• Calf discomfort
• Recent travel
• Recent change in medications

Physical examination:

Must start with general inspection of the patient and a rapid assessment of the degree of distress they are experiencing.

• Degree of agitation
• Breathlessness including orthopnoea
• Pallor (peripheral/central cyanosis)
• Prostration
• Pulse and blood pressure
• JVP
• Heart sounds
• Auscultation of the chest
• Examination of lower limb or sacral oedema

The initial investigations include:

• Blood tests: FBC, EUC, TFT, cardiac enzymes
• Chest x-ray
• ECG

Main causes of dilated cardiomyopathy:

• Inherited: Single gene mutations
• Alcohol
• Inherited muscular dystrophies
• Autoimmune to viral myocarditis

Important note: Ischaemic cardiomyopathy must be excluded before dilated cardiomyopathy can be diagnosed.

Echocardiography:

Two-dimensional echocardiography allows a non-invasive, well-tolerated method of examining both the structure and function of the heart.

Advantages over plain imaging:

• Plain imaging (chest x-ray) only shows structure
• Echocardiography shows both structure and function
• Can assess:
  • Ventricular function and ejection fraction
  • Wall motion abnormalities
  • Valve function
  • Chamber sizes
  • Pericardial effusions

Echocardiography is the gold standard for assessing cardiac structure and function in suspected cardiomyopathy.

Two strategies are suggested to prevent heart disease in healthy, but at-risk populations:

Strategy 1: Population approach

• Risk factors of the whole population may be considered through public health messages on diet, smoking and exercise

Strategy 2: High-risk approach

• Target populations are identified and high-risk individuals are targeted for treatment strategies

The National Heart Foundation and the Cardiac Society of Australia and New Zealand have identified these high-risk groups as people with:

• Pre-existing vascular disease
• Diabetes
• Renal disease
• Aboriginal and Torres Strait Islanders
• Familial hypercholesterolaemia
• A positive family history of heart disease
• Metabolic disorder with central adiposity

In this second group, correction of risk factors is considered paramount in order to prevent vascular events.

• Past history or current history of smoking
• Knowledge of a family history
• Hypercholesterolaemia or hyperlipidaemia
• Hypertension
• Diabetes (type 1 or type 2)
• Physical inactivity
• Obesity
• Other dietary factors including a diet that is low in fresh fruit, vegetables and polyunsaturated fatty acids
• Alcohol intake
• Past history of clotting disturbances

Coronary stenting:

Coronary stents allow complete dilation of the artery and reduce the risk in the short term and longer term for re-occlusion of the artery which may occur if an angioplasty alone is performed. This is especially effective when stenting is combined with long-term use of aspirin and/or other platelet receptor inhibitors.

Coronary artery bypass grafting (CABG) should be considered when there is disease:

• Of the left main artery
• More than three-vessel coronary artery disease involving left anterior descending artery, circumflex, right coronary artery
• More than two-vessel disease involving the proximal left anterior descending artery