Diagnostic performance of angiography-derived fractional flow reserve in patients with NSTEMI

Noninvasive methods of estimating invasively measured fractional flow reserve (FFR_invasive) are actively being explored, aiming to avoid the use of an invasive pressure wire and the administration of hyperemia-inducing drugs. Coronary angiography-derived FFR (FFR_angio) has already demonstrated its diagnostic performance in the context of stable coronary artery disease. However, its applicability in the context of non-ST-segment elevation myocardial infarction (NSTEMI) has yet to be established. We sought to determine the diagnostic performance of FFR_angio exclusively in patients presenting with NSTEMI. We performed a prospective, single-center, single-arm, double-blinded study comparing FFR calculated by FFR_angio to FFR_invasive in NSTEMI patients. FFR_invasive was measured in all angiographically intermediate lesions (30%-70% stenosis) and was then compared to FFR_angio which was calculated at the same position, by a blinded operator. The primary endpoints were the sensitivity and specificity of FFR_angio for predicting FFR_invasive using a cut-off value of ≤0.80. Among 100 NSTEMI patients who were screened, 46 patients with 60 vessels in total underwent FFR_invasive and were included in the study. The mean value of FFR_invasive was 0.83 ± 0.3 with 22 (36%) being ≤0.80 while the mean FFR_angio was 0.82 ± 0.1 with 22 (36%) being ≤0.80. FFR_angio exhibited a sensitivity of 95.5%, a specificity of 97.4%, and a diagnostic accuracy of 96.7%. FFR_angio can precisely and noninvasively estimate FFR_invasive in acute coronary syndromes and may have a role in guiding treatment decisions related to angiographically intermediate coronary lesions in this context.

FFR_angio has demonstrated its diagnostic performance in validation studies, as a noninvasive and cost-effective method in the context of stable coronary artery disease but its performance has never been exclusively evaluated in NSTEMI patients.

The present prospective single-center study demonstrates the excellent diagnostic performance of FFR_angio in detecting functionally significant coronary artery stenosis in the setting of NSTEMI, providing more confidence in utilizing FFR_angio in this population, avoiding the risk of an invasive pressure wire and the administration of hyperemia-inducing drugs.

Future randomized trials evaluating FFR_angio-guided treatment of coronary artery disease (stable or ACS) are now needed to definitively establish the role of FFR_angio in the physiological assessment of coronary lesions.