July 3, 2007 -- Since the advent of multidetector (or multislice) CT angiography over the past few years, one of the big questions has been whether or not this non-invasive imaging technology might ulitmately replace the standard invasive coronary angiogram for the detection of obstructive coronary artery disease. CT angiography is faster, less expensive and safer than a cardiac catheterization.

The question, however, is whether or not a CT angiogram (CTA) is as accurate as the "gold standard" of invasive cardiac catheterization. The CATSCAN study, published last year, showed that CTA had a very high negative predictive value of 99%. In other words, if the CT scan showed no disease, you could trust it. This is a critically important finding, because 30% of standard invasive cardiac catheterizations show "no significant coronary artery disease", yet the invasive cath is almost 10 times as expensive as a CT scan, requires much more time, prep and involves a team of technicians and nurses, in addition to the cardiologist. There is also a 1 in 1,000 risk of death and a risk of complications (vascular or other) of 2 or 3 out of a 100 for cardiac catheterization.

The problem, shown by the CATSCAN study, was that CT performed less well than expected, because there was a high number (29%) of "nonevalueable" segments -- parts of the coronary artery that could not be judged as positive (diseased) or negative using the CT scan. However, the CATSCAN study was done with 16-slice CT scanners -- first generation tools that have since been overshadowed by much more accurate 64-slice units.

Enter the CorE 64 (Coronary Evaluation on 64) study, which is an international multi-center comparison of 400 patients. The CorE 64 study is funded by Toshiba Medical Systems with noted imaging expert Dr. Joao A.C. Lima and Julie M. Miller of Johns Hopkins as principal investigators/coordinators.

The last patient for CorE 64 was enrolled just two months ago, but in March 2007, Dr. Julie M. Miller of Johns Hopkins presented the preliminary data for CorE 64 at a special symposium held during the American College of Cardiology. A video of her presentation can be viewed here. The final results of the CorE 64 study will be presented later this year at the American Heart Association meeting.

The usefulness of CT angiography vs. cardiac catheterization was summed up by Dr. Miller in her presentation

"By the year 2010, the estimated number of cardiac catheterizations could approach 3 million in the U.S. alone, and our estimated normal or insignificant disease rate is approximately 30%. So, although our complication rate is relatively low at 1-2%, if in the U.S. alone we could avoid normal cases, that means 900,000 normal cases, we could avoid 9,000-18,000 potential complications a year and up to 900 deaths per year."

As for complications from cardiac catheterizations, 1-2% is the figure often quoted for major complications from invasive angiography, but many cardiologists feel that 3-6% or higher is a more accurate number -- as evidenced by the number of "minor" complications patients suffer (see Angioplasty.Org's Forum Topic on "Complications from Angiograms").

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