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May 25, 2005

Image-Makers
Does MultiSlice Computed Tomography, or MSCT, have the potential to change how patients get selected for interventional treatment of coronary artery disease? You bet (and several companies are). A study in today's JAMA reports that 84% of the patients studied who did not have significant disease could have been screened out using MSCT instead of the more invasive coronary angiography (commonly known as a "cath") -- a very common procedure (over two million done in the U.S. annually) which, while safe and relatively low-risk, still involves threading a catheter into the heart from an incision in the thigh or wrist, and has a complication rate of 1.8%.

The current standard pathway to the cath lab starts with EKGs and/or an ultrasound stress test, then possibly a thallium stress test (with radiation tracking) and finally a cardiac catheterization, currently the "gold standard" of diagnosis for coronary narrowing. The cardiologist can see clearly where and how significant the narrowing is, and will often treat the blockage on-the-spot by sliding in a balloon and stent through the catheter already in place, adding only 15-20 minutes to the diagnostic procedure and, voila! Artery opened.

But what about the patients who get to the cath lab and find there is no blockage (in this study, they constituted 44% of the sample)? They've undergone a somewhat uncomfortable and expensive procedure and have subjected themselves to the possibility of a 1.8% chance of complications (arrhythmia, stroke, coronary artery dissection, access site bleeding, trauma to the femoral artery and nerves). Not a lot, but it is if you're the patient who experiences one....

Additionally MSCT is rapidly increasing in quality. The JAMA study was done with a Brilliance 16 unit from Philips Medical Systems. But Philips, as well as GE Healthcare, Siemens and Toshiba have already developed 40 and 64 slice units that surpass the one used in the study, and the authors concluded that "With rapidly improving technology, MSCT may well evolve from a useful complement to invasive angiography to a clinically viable alternative" -- MSCT may actually rival catheterization in diagnostic accuracy (in fact, the MSCT scans actually reveal information about the calcification of the plaque that is not seen under fluoroscopic angiography).

This means less invasive diagnosis for patients, lower healthcare costs for hospitals. The new units cost between $1-2 million, but scans are about $700 -- a catheterization costs 5-10 times that. Two millions caths a year in the U.S. Do the math.

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