Non-invasive combo outperforms CT angiography alone in heart diagnosis

CT angiography combined with a computational method to determine blood flow was more effective than CT angiography alone for the diagnosis of ischemia, or inadequate blood supply, in a study of patients with obstructive coronary artery disease (CAD).

The study, published online by JAMA, finds that this non-invasive procedure can "impart considerable discriminatory power" in determining which patients should undergo the invasive procedure.

"For patients considered for invasive therapy, this type of test could help exclude those who don't need to be stented. The excitement about this CT approach is that it moves things closer to being able to assess physiology and anatomy in a single non-invasive test," Spencer King III, M.D., of St. Joseph's Hospital in Atlanta told MedPage Today. King was not involved in the research.

The study included 252 patients with suspected or known CAD from 17 medical facilities in five countries. All underwent CT; invasive coronary angiography (ICA); fractional flow reserve, the invasive method to determine blood flow (FFR); and FFRCT, the noninvasive FFR computed from CT.

The researchers reported diagnostic accuracy for FFRCT plus CT was 73 percent for detecting coronary lesions with stenosis of 50 percent or greater, while that of CT alone was 64 percent. However the FFRCT plus CT failed to reach the lower limit of a calculated 95 percent confidence interval, reports News Medical.

Referring to a low rate of false-positives in the study, however, the authors wrote that clinicians may be confident in not proceeding to invasive angiography in patients with stenoses on CT when FFRCT results are normal.

In an accompanying editorial, Manesh Patel, M.D., of Duke University writes that while FFRCT appears to outperform other noninvasive tests, more research is needed, including data on resources required and clinical outcomes.

He said future research on FFRCT should involve patients of varying pretest risks to provide information on the incremental benefit from the test. He also urges that the results be analyzed at local sites, rather than in the core laboratories used in this test. Here's a bit of trivia: It took those core labs about six hours to produce each of the FFRCT results, which could pose a barrier to this method.

A study in the New England Journal of Medicine earlier this year found that conducting heart CT scans in the emergency department actually can save hospitals billions of dollars. It linked CT angiography with a higher likelihood of being discharged and shorter stays overall.

A second study touted the benefits of combining PET and CT scans to more accurately predict risk of a heart attack. It found the key was differentiating between older, calcified plaque in the arteries and newer plaque in the process of calcifying. CT alone can't tell the difference, it said.

Meanwhile, in a third study, a clinical decision-support tool based on American College of Cardiology criteria has been shown to increase the number of appropriate cardiac imaging exams and decrease in appropriate ones.

To learn more:
- read the study
- here's the editorial
- here's the MedPage Today article
- check out the News Medical piece

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