Comparison of Diagnostic Values of Instantaneous Wave-Free R atio and Fractional Flow R eserve With Noninvasive Methods for Evaluating Myocardial Ischemia in Assessment of the Functional Significance of Intermediate Coronary Stenoses in Patients With Chronic Ischemic Heart Disease

To compare the diagnostic accuracy of instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) with noninvasive methods in assessment of the functional significance of moderate coronary stenoses in patients with chronic ischemic heart disease (IHD). We included in this study 50 patients with chronic or suspected IHD and moderate coronary stenoses (50-70%; 74 stenoses). Values of iFR and FFR were determined within 10 days after noninvasive stress tests (combination of stress-echo and SPECT). The values of iFR and FFR were compared with the results of noninvasive methods by ROC-analysis. Coronary artery stenosis was considered functionally important if at least one of noninvasive tests (stress-echo or SPECT) demonstrated positive result. The results of noninvasive stress-tests were positive in 14 patients (28%). ROC area under the curve (AUC) for iFR - 0.961±0.019 (95%CI 0.888-0.992). The best cut-off point for iFR is 0.92 (sensitivity 100, specificity 84%). ROC AUC for FFR - 0.893±0.041 (95%CI 0.79-0.96). The best cut-off point for FFR is 0.81 (sensitivity 100% and specificity 69%). There was no significant difference between iFR and FFR ROC-curves (р=0.0845). The values of iFR and FFR have equivalent agreement with the results of noninvasive tests commonly used to detect myocardial ischemia in patients with moderate coronary stenoses.