WSJ reports expensive high-tech heart scans failed in some cases to detect blockages, or incorrectly identified blockages where none existed, in a new study that concludes the technology isn't ready to replace the more invasive standard procedure. The researchers, publishing in this week's New England Journal of Medicine, did find the computer tomography, or CT, scans were beneficial in identifying patients who need treatment, such as open heart surgery. The study is already provoking debate among cardiologists. Some see the scans as improving patient care while others attack them as a potentially unnecessary technology driving up health-care costs. The industry-funded study, led by doctors at Johns Hopkins University School of Medicine, examined 291 men and women, all over age 40 and suspected of having heart disease. A total of 56% had heart disease. Looking at data from nine medical centers, researchers found that, of those patients with a significantly clogged artery, the scan failed to detect blockages 15% of the time. Of those who didn't have a blockage, the device incorrectly said the patient did have one in 10% of cases. The study compared the CT technology with the current standard, coronary angioplasty, in which a catheter is inserted into an artery and into the vessels of the heart. While more intrusive, the procedure is considered highly accurate.