Application and Performance of CT-Fractional Flow Reserve in Non-ST-Segment Elevation Myocardial Infarction

Abstract

Only half of patients with non-ST-segment elevation myocardial infarction (NSTEMI) have obstructive coronary artery disease (CAD) on invasive coronary angiography (ICA). A non-invasive test that can safely rule out obstructive CAD therefore warrants investigation. Computed tomography fractional flow reserve (CT-FFR) enables hemodynamic interrogation of lesions identified on coronary computed tomography angiography (CCTA) but it has not been evaluated in NSTEMI. Inpatients with NSTEMI were recruited to undergo CCTA with CT-FFR prior to ICA. Blinded CT-FFR was performed using Siemens Frontiers cFFR, version 1.4. Invasive FFR was performed on all intermediate lesions with stenoses measuring >30% to <90%. The performance of CT-FFR and CTCA was compared to the gold-standard of ICA plus FFR. Forty patients (131 vessels) were included. The mean age was 61 ± 11 years and 75% were male. CT-FFR showed good correlation with invasive FFR (r = 0.78) and exhibited excellent diagnostic accuracy for obstructive CAD (defined as FFR<0.80 or angiographic stenosis >90%) on a per-vessel analysis, with a sensitivity of 87%, specificity 99%, positive predictive value (PPV) 97%, negative predictive value (NPV) 95% and area under the receiver operating curve (AUC) 0.93, which was superior to CCTA alone (sensitivity 82%, specificity 92%, PPV 82%, NPV 92%, AUC 0.87, p-value for AUC comparison = 0.04). On a per-patient analysis, CT-FFR had a diagnostic accuracy of 100%. In conclusion, CT-FFR provides additive diagnostic accuracy to CCTA in evaluating patients with NSTEMI and exhibits good correlation with invasive FFR.