Investigations

• Resting ECG, (Electrocardiogram heart tracing) usually normal between attacks, but may show changes (i.e. previous myocardial infarct [heart attack])
• Exercise ECG – should comply with a recognised protocol (i.e. Bruce Protocol) A strongly positive test within 6 minutes of starting the Bruce Protocol helps to indicate those people who require further investigation such as by coronary angiography due to their being at higher risk of myocardial infarction or sudden death). Exercise ECG changes occur in about 75% of people with severe coronary artery disease (CAD), but a normal test does not exclude the diagnosis. There can be false-negative and false positive tests – particularly in women.
• Radioisotope studies – in which ischaemic areas show as “cold spots” on a gamma camera during exercise.
• Coronary arteriography – demonstrates coronary artery anatomy (usually before coronary artery surgery or angioplasty is considered)
• Diagnostic coronary angiography is performed in order to demonstrate the exact anatomy of the coronary arteries, usually with a view to progression to PTCA (percutaneous transluminal coronary angioplasty) with or without stents, or CABG (coronary artery bypass graft). There is a small risk of mortality in the procedure (less than 1 in 1000). It is always done before surgery.
• Indications for angiography are –
  • Where the diagnosis is not clear
  • Angina not responding to medical therapy
  • Strongly positive exercise test according to the Bruce Protocol
  • Moderate or severe angina
  • Unstable angina (very severe angina)
  • After an infarct (M.I), if well enough

• Chest x-rays – heart size may indicate the heart is not pumping properly, (i.e. the heart is enlarged in heart failure and the lungs may show evidence of congestion)
• Echocardiogram - shows the heart by ultra sound, especially movements of the heart valves, thickness of heart muscle and how well the muscle pumps.