|Heart image courtesy of Toshiba|
The results the cardiovascular CT imaging community has been waiting for two years are in: Sixty-four-slice CT meets cardiac catheterization in the primary diagnosis of cardiovascular disease and disorders in all populations, according to results of the CorE 64 study announced Monday by Julie Miller, MD, lead investigator of the study and assistant professor of medicine at Johns Hopkins Hospital, Johns Hopkins University in Baltimore, Md. The study also showed that early detection with 64-slice is a good predictor of who will need angioplasty or coronary bypass surgery.
The coronary artery evaluation using 64-row multidetector CT angiography (CorE 64) trial findings were presented at the American Heart Association’s Scientific Sessions in Orlando, Fla. The study marks the first time an imaging study was presented on AHA’s late-breaking clinical trials agenda. Toshiba and Bracco sponsored the nine-center, seven-country multi-center study.
“In patients with suspected coronary artery disease and calcium scores less than 600, 64-row MDCTA can assess the presence of significant coronary artery disease (CAD) and the likelihood physicians will refer for coronary revascularization,” Miller told the AHA audience of several hundred. “This study is the first step to realizing the full potential of CT imaging in predicting coronary artery disease, and these scans complement the arsenal of diagnostic tests available to physicians to prevent heart attacks.”
“Hopefully, we can avoid catheterization methods with patients with normal coronary arteries,” Miller told a press conference.
According to the study, as many as 25 percent of the 1.3 million cardiac catheterizations performed each year in the United States may not be necessary. The latest estimates from the AHA show that one in five deaths in the United States each year is due to coronary heart disease (653,000 deaths in 2004), including 157,000 who die from heart attack. More than a quarter million Americans undergo coronary bypass surgery each year, according to Johns Hopkins.
The CorE 64 study showed that, on average, 91 percent of patients with blockages were detected by 64-slice CT and that the scans were able to diagnose 83 percent of patients without blockages. More than 98 percent of the coronary arteries as small as 1.5mm in diameter could be seen using 64-slice CT. Results showed that the test had good diagnostic ability for detecting blockages >50 percent occlusive (sensitivity 0.85 and specificity 0.90, AUC 0.93). Also, CT showed a similar diagnostic ability to cardiac cath in its ability to identify patients who were felt to have severe enough disease to be referred for angioplasty or bypass surgery, though it was less able to determine which specific vessel of the heart was blocked, compared with cardiac cath.
In the study that began in September 2005 and ended in January 2007, investigators selected 291 men and women over the age of 40 (median age: 59; 74 percent male; median BMI: 27; prevalence of disease: 56 percent) with suspected CAD who were already scheduled to have cardiac catheterization to check for blocked arteries. In all, 868 vessels were analyzed. Each patient underwent a 64-slice CT scan prior to catheterization. Participants were then monitored through regular check-ups to identify who developed or did not develop CAD and who required subsequent bypass surgery or did not need surgery.
After the first year of monitoring, to continue annually until 2009, researchers found that results from CT matched up 90 percent of the time with results from invasive catheterization in detecting patients with blockages. In other measures, researchers found that CT scans were 83 percent to 90 percent accurate, while tests using older, 16-slice CT scans were in some instances only 20 percent to 30 percent as precise.
The study also suggests that the new scanners, which are four times quicker than the more widely used 16-CT, may be a good alternative to cardiac stress testing, which evaluates heart function by measuring the effects of hard exercising. Exercise stress testing generally cannot safely be performed on the weak and elderly.
"Use of 64-slice CT scans will dramatically improve our ability to detect and treat people with suspected coronary disease and chest pain much earlier in their disease," said João Lima, MD, senior investigator of the CorE 64 team. “Cardiac catheterization is