As David Newman will tell you, the additive prognostic and predictive value for stress tests is fairly weak. CT coronary angiograms are still a test looking for the correct population. Conventional coronary angiography is expensive, invasive, and clearly not appropriate for the massive population of low risk patients we evaluate.
So, how about a non-invasive test that combines three-dimensional anatomic coronary reconstruction with predictive flow dynamics to identify lesions resulting in ischemia? This test is CT coronary angiography combined with computed fractional flow reserve. And, it would be a beautiful thing if it were ready for primetime – but it’s not.
I’ve reviewed a previous trial of FFR(CT). This is a larger study, published in JAMA, of 285 patients with suspected CAD who underwent CCTA with FFR(CT), followed by conventional coronary angiography with invasive FFR measurement. Figure 1 summarizes the results relatively succinctly – but essentially, 56 of the 172 FFR(CT) patients with lesions calculated as ischemic were false positives. On the flip side, 67 of the 80 FFR(CT) patients with lesions calculated as non-ischemic were false negatives. The per-vessel performance of FFR(CT) basically added no additional diagnostic AUC to CT alone.
The study is sponsed by HeartFlow, and authored by several physicians disclosing conflicts of interest with diagnostic imaging manufacturers. Unsurprisingly, the authors try to spin the positive out of it in their conclusions and abstract.
“Diagnostic Accuracy of Fractional Flow Reserve From Anatomic CT Angiography“
http://jama.jamanetwork.com/article.aspx?articleid=1352969