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Using CFR enhanced diagnostic accuracy to detect CAD, helped predict risk by age
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Adding coronary flow reserve measurements to molecular imaging of coronary arteries provided a substantial added value in diagnosing CAD, according to research presented at the Society of Nuclear Medicine’s 59th Annual Meeting. In a separate presentation at the meeting, researchers found the addition of quantitative coronary flow reserve helped identify low-risk cohorts among patients aged 75 years or older.
To evaluate the value of the addition of CFR to molecular imaging, 73 patients underwent 1-day adenosine-stress/rest 13N-ammonia PET/CT myocardial perfusion imaging (PET/CT MPI). Global coronary flow reserve (CFR) was then calculated. Invasive coronary angiography was used as a standard of reference to determine the value of adding CFR as an adjunct to MPI for predicting CAD.
Results showed that the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of MPI for detecting significant CAD were 79%, 80%, 91%, 59% and 79%, respectively. These values improved to 96%, 80%, 93%, 89% and 92%, respectively, when the cut-off for global CFR <2 was added to MPI findings (P<.005).
“The quantification of CFR with molecular imaging provides a substantial advantage for unmasking CAD, even in patients who would otherwise be considered healthy with normal MPI,” Michael Fiechter, MD, of the department of radiology, University Hospital Zurich, Zurich, Switzerland, and lead investigator, said in a press release.
According to Philipp Kaufmann, MD, of the department of radiology and cardiac imaging at University Hospital Zurich, “Although different studies revealed a prognostic value of CFR, this study is the first that systematically assessed the diagnostic value of CFR against invasive coronary angiography as a standard of reference for detection of CAD.”
In the second study, researchers examined 704 participants undergoing PET stress tests and measured CFR. Participants were aged 75 years old or older and were followed for a median of 1.2 years. Researchers determined that age is not necessarily a risk factor for developing CAD.
“This is the first large study of the effects of aging on coronary vascular function in patients,” Venkatesh Murthy, MD, PhD, cardiovascular medicine and imaging fellow at Brigham and Women’s Hospital and Harvard Medical School in Boston, Mass, stated in the press release.
“Aging has been previously shown in small studies to affect vascular performance, but these have generally used less accurate methodologies. We demonstrate that many older adults have preserved coronary vascular function and that this group has an extremely favorable prognosis. They are much less likely to die from cardiac causes compared to those with abnormal coronary vascular function,” Murthy said. “This work suggests that loss of vascular function may not be an inevitable consequence of aging.”
For more information:
Fiechter M. Scientific paper #86.
Murthy V. Scientific paper #22. Both presented at: the Society of Nuclear Medicine’s 59th Annual Meeting; June 9-13, 2012; Miami Beach, Fla.
Disclosure: The study presented in scientific paper #86 was supported by grants from the Swiss National Science Foundation to Drs. Fiechter and Kaufmann.