Latest scan can tell need for bypass
Washington: An ultra-fast, 320-detector computed tomography (CT) scanner can tell which people with chest pain need or do not need cardiac angioplasty or bypass surgery to restore blood flow to the heart.
"The CORE 320 study is the first prospective, multi-centre study to examine the diagnostic accuracy of CT for assessing blockages in blood vessels and determining which of those them may be preventing the heart from getting adequate blood flow," says Joao A.C. Lima, senior study author and professor of medicine and radiology at Johns Hopkins University School of Medicine.
"We found an excellent correlation in results when we compared the 320-detector CT testing with the traditional means of assessment using a stress test with imaging and cardiac catheterisation," says Lima, according to a Johns Hopkins study.
The findings, says Lima, will apply to people who have chest pain but are not having a heart attack.
Many people in that situation are sent to a cardiac catheterisation lab for further evaluation with angiography, an invasive test to look for blockages in the coronary arteries using dye and special X-rays.
About 30 percent of people who have such catheterisation are found to have minimal disease or no blockage requiring an intervention to open or bypass the vessel.
Lima says a nuclear medicine stress test with imaging, known as SPECT, shows reduced blood flow to the heart without indicating the number or specific location of blockages.
The 381 patients who completed the study had traditional SPECT tests and invasive angiography.
They also had two types of tests with a non-invasive 320-detector CT scanner.
In the first CT test, the scanner was used to see the anatomy of vessels to assess whether and where there were blockages.
That test is known as CTA, in which the `A` stands for angiography.
Then, in a second CT test with the same machine, patients were given a vasodilator, a medicine that dilates blood vessels and increases blood flow to the heart in ways similar to what happens during a stress test.
The second test is called CTP, with the `P` standing for perfusion.
Carlos E. Rochitte, cardiologist at the Instituto do Coracao in Sao Paulo, Brazil, who led the study, said: "We found that the 320-detector CT scanner allowed us to see the anatomy of the blockages as well as determine whether the blockages were causing a lack of perfusion to the heart."
The 320-detector CT provides a complete picture of the heart by making just one revolution around the body.
The researchers say the two tests combined - CTA and CTP - still produce less radiation than a scan with the 64-detector in widespread use today.
Results of the study were presented at the European Society of Cardiology Congress in Munich in Germany.