Agreement of Fractional Flow Reserve Estimated by Computed Tomography With Invasively Measured Fractional Flow Reserve: A Systematic Review and Meta‐Analysis

Background Fractional flow reserve (FFR) is the ratio of blood pressure measured distal to a stenosis and pressure proximal to a stenosis. FFR can be estimated noninvasively using computed tomography (CT) although the usefulness of this technique remains controversial. This meta‐analysis evaluated the agreement of FFR estimated by CT (FFR‐CT) with invasively measured FFR. The study also evaluated the diagnostic accuracy of FFR‐CT, defined as the ability of FFR‐CT to classify lesions as hemodynamically significant (invasive FFR ≤0.8) or insignificant (invasive FFR >0.8). Methods and Results Forty‐three studies reporting on 7291 blood vessels from 5236 patients were included. A moderate positive linear relationship between FFR‐CT and invasively measured FFR was observed (Spearman correlation coefficient: 0.67). Agreement between the 2 measures increased as invasively measured FFR values approached 1. The overall diagnostic accuracy, sensitivity and specificity of FFR‐CT were 82.2%, 80.9%, and 83.1%, respectively. Diagnostic accuracy of 90% could be demonstrated for FFR‐CT values >0.90 and <0.49. The diagnostic accuracy of off‐site tools was 79.4% and the diagnostic accuracy of on‐site tools was 84.1%. Conclusions The agreement between FFR‐CT and invasive FFR is moderate although agreement is highest in vessels with FFR‐CT >0.9. Diagnostic accuracy varies widely with FFR‐CT value but is above 90% for FFR‐CT values >0.90 and <0.49. Furthermore, on‐site and off‐site tools have similar performance. Ultimately, FFR‐CT may be a useful adjunct to CT coronary angiography as a gatekeeper for invasive coronary angiogram.