A Validation Study of Nitroglycerin Induced Acute Drop of Pd/Pa (NTG-Pd/Pa) in Clinical Practice

Fractional flow reserve (FFR) is defined as the ratio of mean distal pressure (distal to the target lesion, Pd）to mean proximal pressure (aortic pressure, Pa) in the coronary artery(Pd/Pa) while the maximal hyperemic flow is achieved. Nowadays, FFR-guided PCI is highly recommended for the assessment of physiologic ischemia in intermediate coronary lesions. However, hyperemia with adenosine was an elemental process in FFR examination. Adenosine injection will induce some discomfort, and increase cost expenditure. Based on the clinical and physiologic outcome study, a lot of non-hyperemic indexes had been proposed, and adenosine injection could be waived. Whereas, these novel physiologic indexes are limited to the proprietary software of each vendor, curtailing clinical application. Intracoronary nitroglycerin injection was needed before each FFR assessment. Nitroglycerine will induce an acute drop of Pd/Pa, and this lowest Pd/Pa was determined as NTG-Pd/Pa. NTG-Pd/Pa has a linear relationship with FFR value and has a good diagnostic accuracy to predict FFR≤0.80 in our recent study. There is only one prospective study report on the relationship between NTG-Pd/Pa and FFR. In this study, we aim to evaluate the safety of NTG-Pd/Pa, the repeatability and dose-response of this novel index. Furthermore, we will investigate the diagnostic accuracy of NTG-Pd/Pa, with FFR≤0.8 and Resting full-cycle ratio≤0.89 as ischemic threshold respectively.