Diagnosis: A new diagnostic test will help identify more people with coronary artery disease and save others from having to undergo an invasive procedure, a heart specialist has said.
Dr Ross Murphy, who has just returned from the Cleveland Clinic in the US to take up a post as consultant cardiologist at St James's Hospital and the Blackrock Clinic in Dublin, said a series of recent technological advances meant that cardiac computed tomography (cardiac CT) had been "suddenly propelled into clinical practice".
The latest generation CT scanners combine 64 different "slices" of the heart before reassembling the pictures into an image that reveals fat-filled plaques lodged in the coronary arteries.
"New computer algorithms and the ingenious trick of only 'looking' at the heart for a brief moment of every heart beat means that technology is establishing a real role in ruling out disease," Dr Murphy said.
Some 20 per cent of all deaths in the Republic are due to coronary heart disease with about 25,000 people discharged from hospital each year following treatment for the condition.
An invasive procedure, the cardiac angiogram, remains the gold standard for assessing coronary heart disease. Doctors insert a tube through an artery in the leg and thread it into the heart. By injecting dye through the tube, the coronary arteries can be seen on a TV screen, with any narrowing and blockages clearly highlighted. However, there is a 1 per cent risk of complications during the procedure, including heart attack and death.
The test involves lying on a couch while a CT scanner moves over the body. Contrast dye is injected into the patient to show the coronary arteries. However, cardiac CT involves double the radiation exposure of a coronary angiogram.
Pointing out that the cardiac CT will be useful in those patients with an equivocal exercise electrocardiogram (ECG) Dr Murphy said a number of studies presented at the American College of Cardiology meeting in Atlanta last week emphasised the role of the new test in identifying people who really need the invasive catheter test.
"Its best use appears to be in assessing patients as either having no coronary disease or having blockages of less than or greater than 50 per cent of a coronary artery, rather than trying to outperform the invasive angiogram in giving exact percentage blockages.
"In a study from Israel presented at the meeting, cardiac CT diagnosed obstructive coronary disease in a quarter of patients with a negative stress [ exercise] test and excluded coronary disease in over half the patients with equivocal stress tests," Dr Murphy said.