Background: Recently, a non-invasive method using computational fluid dynamics to calculate vessel-specific fractional flow reserve (FFRCT) from routinely acquired coronary computed tomography angiography (CTA) was described. The Analysis of Coronary Blood Flow Using CT Angiography: Next Steps (NXT) trial, which was a prospective, multicenter trial including 254 patients with suspected coronary artery disease, noted high diagnostic performance of FFRCT compared with invasive FFR. The aim of this post-hoc analysis was to assess the diagnostic performance of non-invasive FFRCT vs. standard stenosis quantification on coronary CTA in the Japanese subset of the NXT trial.
Methods and results: A total of 57 Japanese participants were included from Okayama University (n=36), Kyoto University (n=17), and Keio University (n=4) Hospitals. Per-patient diagnostic accuracy of FFRCT(74%; 95% confidence interval [CI]: 60-85%) was higher than for coronary CTA (47%; 95% CI: 34-61%, P<0.001) arising from improved specificity (63% vs. 27%, P<0.001). FFRCT correctly reclassified 53% of patients and 63% of vessels with coronary CTA false positives as true negatives. When patients with Agatston score >1,000 were excluded, per-patient accuracy of FFRCT was 83% with a high specificity of 76%, similar to the overall NXT trial findings.
Conclusions: FFRCT has high diagnostic performance compared with invasive FFR in the Japanese subset of patients in the NXT trial.