Agreement of the Resting Distal to Aortic Coronary Pressure With the Instantaneous Wave-Free Ratio. Journal of the American College of Cardiology Kobayashi, Y., Johnson, N. P., Zimmermann, F. M., Witt, N., Berry, C., Jeremias, A., Koo, B. K., Esposito, G., Rioufol, G., Park, S. J., Nishi, T., Choi, D. H., Oldroyd, K. G., Barbato, E., Pijls, N. H., De Bruyne, B., Fearon, W. F. 2017; 70 (17): 2105–13


Recently, 2 randomized controlled trials showed that the instantaneous wave-free ratio (iFR), a resting coronary physiological index, is noninferior to fractional flow reserve for guiding revascularization. The resting distal to aortic coronary pressure (Pd/Pa) measured at rest is another adenosine-free index widely available in the cardiac catheterization laboratory; however, little is known about the agreement of Pd/Pa using iFR as a reference standard.The goal of this study was to investigate the agreement of Pd/Pa with iFR.A total of 763 patients were prospectively enrolled from 12 institutions. iFR and Pd/Pa were measured under resting conditions. Using iFR =0.89 as a reference standard, the agreement of Pd/Pa and its best cutoff value were assessed.According to the independent core laboratory analysis, iFR and Pd/Pa were analyzable in 627 and 733 patients (82.2% vs. 96.1%; p < 0.001), respectively. The median iFR and Pd/Pa were 0.90 (interquartile range: 0.85 to 0.94) and 0.92 (interquartile range: 0.88 to 0.95), and the 2 indices were highly correlated (R(2) = 0.93; p < 0.001; iFR = 1.31 * Pd/Pa -0.31). According to the receiver-operating characteristic curve analysis, Pd/Pa showed excellent agreement (area under the curve: 0.98; 95% confidence interval: 0.97 to 0.99; p < 0.001) with a best cutoff value of Pd/Pa =0.91. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 93.0%, 91.4%, 94.4%, 93.3%, and 92.7%, respectively. These results were similar in patients with acute coronary syndrome and stable angina.Pd/Pa was analyzable in a significantly higher number of patients than iFR. Pd/Pa showed excellent agreement with iFR, suggesting that it could be applied clinically in a similar fashion. (Can Contrast Injection Better Approximate FFR Compared to Pure Resting Physiology? [CONTRAST]; NCT02184117).

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