CT scan effective at finding heart blockages
November 05, 2007
CTV.ca News Staff : When cardiologists need to know whether a patient has a blockage in their heart vessels, they’ve traditionally performed surgery called coronary angiography. Now, a new study says there may be a less riskier and less invasive method.
A study by an international team of cardiac imaging specialists finds that the latest CT (computed tomography) scan technology is almost as reliable and accurate as surgery at finding blockages in coronary arteries.
Studies suggest that as many as 25 per cent of the thousands of cardiac angiographies or catheterizations performed each year may be unnecessary. These new scans should help cardiologists quickly rule out those patients who can skip the invasive procedure.
In cardiac catheterization, a thin tube is threaded into a blood vessel in the groin area, all the way up to the heart’s arteries. There, a dye is released to produce a clear X-ray image of the beating heart and its arteries. If the dye fails to pass easily through the heart, doctors know there’s a blockage that needs to be removed.
In CT imaging, X-rays are passed through the body, producing digitized signals, or “slices,” that are reconstructed for a precise picture of the heart. The sophisticated scans, called 64-slice CT scans, are very new and were first introduced in the United States in 2005.
In this latest study, researchers selected 291 men and women over the age of 40 who were scheduled to have cardiac catheterization to check for blocked arteries. Each underwent a 64-CT scan prior to having the catheterization done.
Participants were then monitored through regular check-ups to identify who developed or did not develop coronary artery disease and who required subsequent bypass surgery or did not need surgery.
After the first year of monitoring — which will continue annually until 2009 — researchers found that results from 64-CT scans matched up 91 per cent of the time with results from catheterization in detecting patients with blockages.
As well, the scans were also able to rule out those 83 per cent of patients without blockages who wouldn’t need surgery.
The findings were presented at the American Heart Association’s annual Scientific Sessions in Orlando, Fla.
Cardiologist Dr. Joao Lima, the senior investigator of the team, says the results were encouraging.
“Cardiac catheterization is still the gold standard for evaluating clogged arteries, but our results show that this test could easily be the best backup or alternative,” he said.
“Use of 64-CT scans will dramatically improve our ability to detect and treat people with suspected coronary disease and chest pain much earlier in their disease.”
Cardiologist Dr. Julie Miller, who led the study at Johns Hopkins in Baltimore, says this study is the first step to realizing the full potential of CT imaging in predicting coronary artery disease.
Miller says the advanced 64-CT scanners are so good that physicians can measure blockages in blood vessels as small as 1.5 millimetres in diameter. They can also pick up as much as 98 per cent of the heart’s arterial network.