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.
Keywords: acute coronary syndrome; fractional flow reserve, myocardial; magnetic resonance imaging; myocardial infarction; percutaneous coronary intervention.
© 2015 American Heart Association, Inc.