Assessment of Fractional Flow Reserve in Patients With Recent Non-ST-Segment-Elevation Myocardial Infarction: Comparative Study With 3-T Stress Perfusion Cardiac Magnetic Resonance Imaging.

BACKGROUND

The use of fractional flow reserve (FFR) in acute coronary syndromes is controversial. The British Heart Foundation Fractional Flow Reserve Versus Angiography in Guiding Management to Optimize Outcomes in Non-ST-Elevation Myocardial Infarction (FAMOUS-NSTEMI) study (NCT01764334) has recently demonstrated the safety and feasibility of FFR measurement in patients with non-ST-segment-elevation myocardial infarction. We report the findings of the cardiac magnetic resonance (CMR) substudy to assess the diagnostic accuracy of FFR compared with 3.0-T stress CMR perfusion.

METHODS AND

RESULTS

One hundred six patients with non-ST-segment-elevation myocardial infarction who had been referred for early invasive management were included from 2 centers. FFR was measured in all major patent epicardial coronary arteries with a visual stenosis estimated at ≥30%, and if percutaneous coronary intervention was performed, an FFR assessment was repeated. Myocardial perfusion was assessed with stress perfusion CMR at 3 T. The mean age was 56.7±9.8 years; 82.6% were men. Mean time from FFR evaluation to CMR was 6.1±3.1 days. The mean±SD left ventricular ejection fraction was 58.2±9.1%. Mean infarct size was 5.4±7.1%, and mean troponin concentration was 5.2±9.2 μg/L. There were 34 fixed and 160 inducible perfusion defects. There was a negative correlation between the number of segments with a perfusion abnormality and FFR (r=-0.77; P<0.0001). The overall sensitivity, specificity, positive predictive value, and negative predictive value for an FFR of ≤0.8 were 91.4%, 92.2%, 76%, and 97%, respectively. Diagnostic accuracy was 92%. The positive and negative predictive values of FFR for flow-limiting coronary artery disease (FFR≤0.8) in patients with non-ST-segment-elevation myocardial infarction (n=21) who underwent perfusion CMR before invasive angiography were 92% and 93%, respectively. Receiver operating characteristic analysis indicated that the optimal cutoff value of FFR for demonstrating reversible ischemia on CMR was ≤0.805 (area under the receiver operating characteristic curve, 0.94 [0.9-0.99]; P<0.0001).

CONCLUSIONS

FFR in patients with recent non-ST-segment-elevation myocardial infarction showed high concordance with myocardial perfusion in matched territories as revealed by 3.0-T stress perfusion CMR.

CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02073422.